Lighter, race oriented Suspension Parts, Primarily Uprights

[Scargo]

I have been going through an arduously slow process of searching the internet for alloy uprights to reduce unstrung weight. Though I've found a couple for Subarus, I'm shocked by the prices and wondering if there are other alternatives, like alloy production parts from a 'Vette, BMW, Lotus, etc? Are there other options from other FFR kit lines that have been around longer?
Obviously, an 818R or an S doesn't even begin to need the cast-iron mass or strength of parts designed for withstanding rallying a 3200 pound car; especially in the front.
Where should I be looking? Racecar Engineering mag? Other kits where the suspension is not donor related to cast-iron parts? Perhaps custom, but made in enough volume that parts are affordable?
Surely there's something adaptable for a pure race R version. I apologize if it's right in front of me but I've not kept up with the racing scene for a while. In the past, while at the track, I've pretty well been in a cocoon of cars similar to my STI and not looking at much else.

[Slatt]

Likewise, agreed, +1. Having around 25% of the front mass unsprung creates a desire to upgrade, doesn't it?

I think there are three things we'd like to do: reduce unsprung weight (more important in front), use stronger bearings which don't require pressing in/out, and convert to the 5x114.3 wheel bolt pattern (more important in back).

I assume you found the MSI uprights? LICMotorsports has something, too. It looks like the only real option is to get MSI for the front, along with a defibrillator, and for the back use an STi hub and machine down the upper attachment surface to match the FFR kit piece.

I dunno yet what that STi hub would affect for axle fitment, but it does rule out the FFR Wilwood rear brake options. Can anyone answer whether an STi rear hub is a one-for-one swap in part (after grinding down the strut mounting surface)?

[Scargo]

There's also Roger Clark Motorsports (builders of The Gobstopper).
I'm really trying to look beyond bolt-on solutions. Like, What do Sports Racers use?

[Bill Waters]

Great original question, Scargo. I have the same question, but haven't yet put the effort you (and others) have in finding the lighter spindles.

Because the real factor we need to minimize is the overall effective spindle weight (spindle + disc & hat), I am using the Wilwood hat and disc assembly (13 inch) which should, I hope, lower the overall weight as compared with the stock disc. Not to mention the benefit of the superior braking aspect. I don't know by how much it will reduce the unsprung weight. I will know this first-hand soon, as I'll have them both here and can directly weigh them. Taking the same approach with my V8 Miata resulted in a significant weight improvement.

Just a thought.

Bill

[Scargo]

Thanks, Bill. I have Stoptech's BBK on the STI and know I am saving substantial weight. I saw a nine pound, per wheel, savings just when I went from the stock rotors to two-piece Brakeman rotors! I saw savings in the rear with Gyrodisc two-piece rotors, though I can't recall how much.

[RM1SepEx]

Why don't you consider the FFR hot rod uprights?

[Scargo]

For the 33 configuration, would that part be considered a spindle? It might have possibilities. The more I read about suspension geometry, the more I wonder if (because the geometry of a steered suspension is such a complex design), that finding a reasonable (semi-plug and play), substitute might be very difficult.
I think I will see what FFR engineers have to say. Perhaps a spindle could be easily reworked for an optional 818 part.

[RM1SepEx]

if you want simple install you could make a billet aluminum one to match dimensions, the composite welded steel plate and cast iron current piece may be impossible to recreate. I think that if you really analyze it you may be best served by coming up with a lighter stub axle and lighter brake components and stick with the rest...

After watching the new FFR DVD this morning... the Hot rod one is too different in configuration. I think that the inverted ball joint setup of the Subaru may be hard to replace...

The current aluminum lower, coil over shocks and adjustable uppers are damn light, as is.

[Santiago]

As I see it (for what that's worth), you've got three options if you're really concerned with the basic 818's unsprung weight (esp. up front):
- The Easy Route: 2-pc rotors, lighter calipers (ala Wilwood), and the lightest wheel/tire combo you can find (likely 17" dia. w/ 205 or 215 race rubber)
- The Bucks Route: one of those defibrillator-requiring Subie-motorsports uprights
- The Engineers Route: fabricate your own while figuring out the suspension geometry anew

The trouble with looking to "common" routes taken by sports racers and such is that those uprights are (a) often made for insanely light cars...think "half-an-818" and (b) more importantly made to work with very differently configured upper and lower A-arms. If you used one of those (assuming it was strong enough and fabb'd your own lower arm or made it work with the OEM lower) you're still looking at having to use an adapter similar to the one FFR came up with for the Subaru spindle so that it'll mate with the geometry intended by the upper A-arm. Unless...unless you fabricate a completely new upper A-arm and likely re-mounted it in the frame.

I think this is what RM1SepEx was getting at; this is a very tall order and the reason I call it the engineer's route. You're basically reworking the entire front suspension. Any effort to preserve what FFR did is going to land you in one of the first two options.

Personally, I'm with Slatt; I'd also really like to get the stronger/non-press-in bearings and 5x114.3 bolt pattern. I thought there was a thread somewhere with folks discussing a spline count concern with the axles and STi hubs... Anyone? If FFR doesn't come up with a solution here, I fear custom half-shafts are in my future because I want these two of the three Slatt laid out. [Oh hell sure, not like my budget isn't thoroughly trashed already.]

Best,
-j

[Scargo]

J, thanks for the long dissertation on the subject. It has been part of my thought process, but not well spelled out. From my limited knowledge I know that what we have is a serviceable design and I don't think I want to start remaking the front framework and all the mounting points on the car. As it is, I am willing to mod the mounting points of the lower L arm and do some mods to it, based on it being a 2008+ STI. I would prefer a full swivel joint on the front in addition to replacing the rear joint with a solid spherical one. I might even lighten the arm.

There certainly seems to be custom oval track spindles, but I, or someone, would have to come up with the geometry for it. They look to be a more affordable option than the big bucks, compromised billet aluminum ones available for AWD.
We just don't need the massive housing, bearings and heavy "floating" spindle that we are asked to make do with.
I have sent a message to Jason Lavigne, asking for advice and suggesting a spindle option be offered.
Glyn

[Mechie3]

Hmm...my post didn't make it from my phone. People already touched on MSI. Here is the link to their uprights:

http://www.mooresport.com/indexe.php/products/chassis/impreza-uprights

Note the $5k price! Several reasons for that: It's a large chunk of aluminum, lots of machine time and multiple setups, low volume, those who need this part will pay that price anyways, and the design time.

I could machine one if I had dimensions. Thing is, I've never designed a suspension upright, wouldn't trust myself to get the loading conditions right to design something that wouldn't fail. A wheel coming off at even highway speeds wouldn't be fun. I designed and machined hubs for my F500, but if that fails (hasn't in 2 years...) My butt is only 3" off the ground so there's not much distance to fall, it'll be on a closed course, and I've seen wheels come off F500's in person. The car just rides on the belly pan until it stops. Bigger cars that drop when a wheel comes off tend to do other things.

Here's another cool thread with work done on an older WRX. Stratodasser works for Praga cars. He did't mention that in his thread when I asked if he'd share models. Praga makes some legit ground up race cars.

http://imagizer.imageshack.us/v2/640x480q90/826/avly.jpg

[Scargo]

Craig, Something like these? (http://www.colemanracing.com/Spindle-Assembly-Modular-Wide-5-And-5-x-5--P4710.aspx) I'm working off my Ipad, at a resort. Sorry I didn't imbed pic. Any more frustration with the limitations/shortcomings of the IPad and it would become a projectile!
I know people who could design it and do reverse engineering if necessary, but I'd probably be paying for it and I have no interest in making/selling parts. I am supposed to be retired and "playing".
Upper arm mount points would probably need to be lowered since I see no reason for an extension like is currently added.

[Santiago]

$525 for a pair of spindles...sexy!

Dropping the upper arm mount would be the way to go, especially if you "only" have to drop it - as opposed to draw it inboard of the frame's current tubing, build a standoff to mount it outboard of the frame, or just ditch the supplied A-arm in favor of one that will mount where you want it and still work with the geometry of the lower. Time to call in favors to those designers.

-j

[RM1SepEx]

just modify the bolt on upper joint piece to use the FFR adaptor, make a new bolt on lower to use the Subaru ball joint and stick with the FFR geometry but have a much lighter spindle assy... What bearings brakes etc work with this spindle?

[Scargo]

just modify the bolt on upper joint piece to use the FFR adaptor, make a new bolt on lower to use the Subaru ball joint and stick with the FFR geometry but have a much lighter spindle assy... What bearings brakes etc work with this spindle?
I believe Wilwood, which (I think), opens up possibilities for others. The thing I am concerned about, since it does not pass my seat-of-the-pants engineering, scratch and sniff test, is the moment arm length of the FFR add-on piece. I would like something stronger or shorter. A longer king-pin axis could be better, but I am not sure, given the small triangulation at the top and the length of the FFR add-on piece which might not be stiff enough at extreme racing conditions.
Purely my impressions and the fact that I'm on vacation and drinking scotch!

[RM1SepEx]

Yup, takes a bunch more detailed analysis... but it deserves a look if someone wants to reduce weight.

Minimal marginal returns for the $ and effort tho...

[Santiago]

Minimal marginal returns for the $ and effort tho...

That's my concern, especially when you look at "The Easy Route." You're going to save a bunch of weight there over a host of other set ups, and it's all low-hanging fruit. By the time you've made it to looking at spindles for weight, you should have already shed off a lot more unsprung weight than you're going to get out of spindles.

But if there's motivation and money enough for the task, hell yeah, go for it. I hope it comes out well. These cars are nothing if not opportunities for people to realize their own visions of how to build them.

Best,
-john

[D K]

Quick question:

Aside from running lighter rotors and calipers (which are independent of uprights and hubs) how much weight are you trying to save per corner?

My guess is you can probably save a couple of pounds, not a whole lot more.

Is it worth it when you can get a large portion of the weight savings by doing calipers and rotors?

You could do something like FF2000 A arms and hubs, but then you would need to re-engineer the frame for correct roll center.


Another thing to think is that even though the 818 is much lighter than a WRX, if you plan on running on slicks, you will be generating a considerable amount of force.



Lastly, if someone wants to go through the trouble of designing an upright (cough), I might have the possibility to do some FEA.

[Xusia]

FEA? Free Engineering Analysis??

[Santiago]

DK,

If you have access to running FEA, would you consider doing one on the existing OEM upright - and then a modified OEM upright?

I was looking at some pics of one and thought that an alternative route to go might be lightening the existing one. It has what looks like quite a bit of excessive metal that may be trimmed off (particularly between the brake caliper mounting ears) and other areas that might be relieved of mass (via drilling or routing). I wouldn't be confident of just hacking away at a spindle and then running it with fingers crossed. But if we did some before and after FEA analysis, we might have some promising mods within reach.

Just a thought.

Best,
-j

[RM1SepEx]

FEA? Free Engineering Analysis??

finite element analysis

https://www.solidworks.com/sw/products/simulation/finite-element-analysis.htm

[D K]

DK,

If you have access to running FEA, would you consider doing one on the existing OEM upright - and then a modified OEM upright?

I was looking at some pics of one and thought that an alternative route to go might be lightening the existing one. It has what looks like quite a bit of excessive metal that may be trimmed off (particularly between the brake caliper mounting ears) and other areas that might be relieved of mass (via drilling or routing). I wouldn't be confident of just hacking away at a spindle and then running it with fingers crossed. But if we did some before and after FEA analysis, we might have some promising mods within reach.

Just a thought.

Best,
-j

How much material would you be planning on removing?
100g?
200g?

All that work for such little reward (IMHO of course)...
What would that do to your lap time? 1/1000th? 1/100th? Certainly not 1/10th

There are other areas WAAAAAYYYY easier (and cheaper) to lower lap times.

I do have access to FEA, but it's not a free for all. A very good friend of mine is part of the FSAE program at OSU and they have done pretty well over the years :)

[Mechie3]

Can you ask you friend what sort of free body diagrams they make for the uprights? Ive guessed at some but Since I dont work in an automotive field never had anyone verify them for me. The FSAE forums just makes fun of people that ask. I too have fea software. I can post some of my past projects for my F500.

[Santiago]

DK,

I'm not personally planning on doing anything with the spindles aside from cleaning them. And in my previous post I also said I thought there were easier routes to go to lower unsprung weight - easier than doing anything whatsoever with the uprights.

Bringing up lap times is something of a red-herring. This thread isn't about generic ways to improve performance, much less about ways to significantly improve performance (if it were, do you really think we'd be talking lighter spindles?). Anyone seriously hanging their hopes on significantly lower lap times from a modest reduction in weight probably hasn't been on track before.

Scargo and others were specifically raising the question of what options there were for lighter uprights. Personally I think they're up against a difficult task of either paying out the nose for high-end parts or redesigning the front suspension. Both options are costly enough to make one reconsider, esp. since I don't think anyone here was suggesting that succeeding was going to produce a magic bullet. In that vein one might consider traditional means of addressing weight that cut a middle ground between difficult and giving up on the project. Drilling, cutting off excess, and otherwise whittling down an existing part are staples in the hot-rodding community. These are options to consider.

FEA peaked my interest simply because I wouldn't think twice about hacking away at some non-critical part but I would be very wary of even suggesting someone consider doing it on a suspension part. Realistically, I wouldn't likely do the mod anytime soon even if the analysis was performed - but there are others in this thread who seem to have a deeper interest in addressing the uprights than myself. So that's where the suggestion was coming from.

Best,
-j

[Scargo]

I think Santiago has made a good case for my interest in alternatives for the front suspension.
Might I liken it to having a car that is fast but looks like hell? Something that offends the engineering sensibilities in all of us? It is a little like saying I can use the spindle off my John Deere and my 818 will still go fast.

Let me back up and say that I thought less unstrung weight was a "holy grail" kind of thing in racing design. Am I wrong?
if you reduce unstrung weight then the springs and shocks required are smaller, lighter and cheaper. Rotating mass is sometimes reduced, which is important. Loads and demands on systems go down and responsiveness goes up.
I feel sure there is an inexpensive solution to this that doesn't require reinventing the wheel and using FEA. ;)
Im still waiting to hear from Jason.

[Slatt]

In theory, yes, low unsprung weight IS the holy grail, and many have given up looking for THAT. :p

Another thing to consider is that none of the road test reports we've seen have said anything like "but the front end seems too skittish over bumps". At some point we need to just build it and drive it and then see what the car tells us.

There is the option of using spindles from older and lighter Subarus.

[Xusia]

A couple things to keep in mind:

1. Lowering unsprung weight probably will not have a significant effect on lap times, but it could dramatically improve the suspension, increasing confidence, providing advantages over tracks with rough patches, etc. However, that said...

2. The shocks were valved and sprung for the stock Subaru parts. Changing the weight - higher OR LOWER - could also adversely affect handling. These things all work together and you can't change one without considering the effect on the others.

In the end I personally feel that unless you have an unlimited budget or just really, really want some cool uprights, performance/racing parts money is better spent elsewhere first.

[Slatt]

Item #2 there is absolutely true but rather than being a 'problem' it just emphasizes the reason for our desire to get our options / opportunities sorted out before spending. For example, I don't want to waste $$ on 4-way adjustable dampers if my overall setup is going to end up quite similar to FFR's 'stock' setup. FFR and KONI made a great effort to tune this car and I trust them. Myself, I'm just about done looking into it, I don't like the other options, and will prolly run 'stock'. And just to be clear, I'm not sharpshooting anybody, just trying to add to all the good points made here. :)

[D K]

DK,
Bringing up lap times is something of a red-herring. This thread isn't about generic ways to improve performance, much less about ways to significantly improve performance (if it were, do you really think we'd be talking lighter spindles?). Anyone seriously hanging their hopes on significantly lower lap times from a modest reduction in weight probably hasn't been on track before.
-j

Ok, fair enough - but at the end of the day: what's the point if you are not trying to go faster?
The only quantifiable return on a huge investment like this is lap time - IMHO.

And if you are talking about doing this to a street car/version, then I really wouldn't think that is worthwhile.




Let me back up and say that I thought less unstrung weight was a "holy grail" kind of thing in racing design.

While most of our suspension is 'strung' to some degree, I think you meant 'unsprung'.



if you reduce unstrung weight then the springs and shocks required are smaller, lighter and cheaper.

Rotating mass is sometimes reduced, which is important.

Actually the responsibility of the springs is to carry the 'sprung' weight of the car which doesn't change with a small change in the weight of suspension components.

Rotating mass, which is the MOST IMPORTANT kind of unsprung weight to lose is just that: rotating mass - wheels, tires, brake rotors and hubs.
Since this thread was talking mostly about uprights, this doesn't apply.



A couple things to keep in mind:

1. Lowering unsprung weight probably could dramatically improve the suspension, increasing confidence

Ok. Increasing confidence does what? It makes you faster.


2. The shocks were valved and sprung for the stock Subaru parts. Changing the weight - higher OR LOWER - could also adversely affect handling.

Lowering unsprung weight gives the shock an opportunity to act faster.
In order to take advantage of that, you need a car that is dialed in and a driver that can feel the difference.


In the end I personally feel that unless you have an unlimited budget or just really, really want some cool uprights, performance/racing parts money is better spent elsewhere first.

Aint that the truth!!

In my humble opinion, replacing suspension components with lighter weight parts would only make sense on the R model.
And then, they would only make sense if one was dialing in the last 10th or 2 at a track.
Before ANY of that takes place, the entire suspension would need to be heim jointed. Having rubber bushings in the system while talking about custom, light weight race components seems stupid.
At the moment, FFR specs a stack of washers for the LCA mount - removing a few pounds per corner is not what car needs at the moment.

Also, if someone is trying to lose some weight in the suspension parts, there are a couple of things to consider.
How much are you trying to save? 1kg? 2kg?

Let's say a decent brake kit will save you 3-4kg's. If you really want to go for it, get a proper race, mono bloc brake kit and that would save you 5-6kg. The difference in price for the decent and mono bloc brake kit is probably cheaper than having custom components made....

What I wish FFR did was to give an option of mounting different suspension components.
For instance: they could spec out the frame with 986 or 987 spindles/hubs, etc.. Of course you would have an issue with the bolt pattern but custom hubs are much cheaper than custom uprights.
That way you would get the best of both worlds.

As I said, those are just my opinions.


D

[Santiago]

Believe it or not, looks like a lot of consensus here. I do think there's more to owning a car than a single quantifiable figure (lap times), so I wouldn't use that as the sole metric to evaluate the success of a project. For example, (mostly I agree with DK here) confidence has its real pay-off in a driver who can take the car further to the edge of its performance potential. Check. But it also has an effect on how much you enjoy driving the car, and I think that's an independent variable. Throw me in a car that feels like it's going to kill me while I'm driving it on a ragged edge, then throw me in another more confidence-inspiring yet ultimately slower car, and I'm pretty sure I know which car I'd like to live with and run every-other weekend. I'm not making a living racing here, so there are many other aspects of the car that matter just as much as lower lap times.

Back to the agreements: I can't find much sense in the expense of the project aside from an R car either (even granting my take on that "confidence" factor - it's really only in play on track). I also think that for an R-car there are many other things to set as higher priorities (incl. ditching pliable bushings). If it's not really low-hanging fruit, then there are more important things to get squared away first before sweating/spending on the next round of improvements (aero daddy-O...aero-aero-aero...).

D, I seem to recall recently reading that FFR has plans to accommodate the STi hubs within the next 6-8 months (inline, I believe, with rolling out provisions for the 6-speed tranny). My understanding was that one of the obstacles to using those spindles (apart from some minor change in the mounting-flange width) was a difference in spline count. So I'm guessing that they're now working through different hub requirements. The STi hubs may not be what you would prefer, but they do get us different bolt patterns, bolt-on hubs, and stronger bearings. Not bad.

I suspect FFR's business model of sticking to the single-donor philosophy is the main reason these provisions were not initially offered (and why they don't tend to offer frames with wider flexibility built into them).

Best,
-john

[Xusia]

k. Increasing confidence does what? It makes you faster.

Reduces stress, decreases chance of driver error, enhances enjoyment, etc. Aside from confidence, suspension improvements can also increase comfort. This is NOT to say softer=more comfort. Regardless of the stiffness, a well sorted suspension that reacts correctly to the road surface is more comfortable (at any given stiffness than one at the same stiffness that isn't as well sorted - I hope that sentence made sense).

Overall, I agree with you DK (just not that lap times are the only reason to make improvements - as a general statement). And I agree there is a lot of consensus in this thread. Perhaps we can move on, and back to the discussion of lighter, race-oriented suspension parts - EVEN IF THEY AREN'T PRACTICAL?? :)

[Xusia]

I suspect FFR's business model of sticking to the single-donor philosophy is the main reason these provisions were not initially offered (and why they don't tend to offer frames with wider flexibility built into them).

This kit is barely 6 months old. If you look at kits they have been making for a very long time, there is plenty of flexibility. The 818 will get there, though apparently not as fast as we would all like. <-- I include myself in that group. I was originally going to wait for a coupe with roll up windows, but ultimately decided I just couldn't wait that long. So that will probably be 818S #2. Or I'll retrofit. Point is, we need to be a bit patient and give them some slack. After all, look at the performance of the car they actually delivered for $10k. Astounding!!!

[D K]

I think we are all in general agreement.

Although, a lap time is still what you want. Even if you don't plan on using it.

For instance: a car that can do a 1:19 at Big Willow is a lot more fun to drive at 1:25 or 1:30 than a car that is capable of doing a 1:29 and you are trying to drive it at 1:30....

You can always back off performance for comfort, reliability, fuel economy - whatever. But having a car that is capable of more performance is a benefit.

Having a car with lighter suspension components is a benefit because of increased performance potential, not increased comfort.

However you deal with the extra performance is up to you, but the only real measurement is still a lap time.

D

[D K]

Why doesnt somebody design a cantilever suspension for the front?

If you design it with the same motion ratio, you could even re use.the shock

Just a thought

D

[Canadian818]

Why doesnt somebody design a cantilever suspension for the front?

If you design it with the same motion ratio, you could even re use.the shock

Just a thought

D


Isn't the whole point of cantilever suspensions that you can save weight by running smaller coilovers?

[wleehendrick]

Isn't the whole point of cantilever suspensions that you can save weight by running smaller coilovers?

And on Formulas cars, to get the coilovers out of the airflow for aerodynamics, right?

[D K]

Yes, and save huge unsprung weight

[D K]

Ill take D:

All of the above

[Bob_n_Cincy]

Yes, and save huge unsprung weight
I don't understand why this saves unsprung weight.
The weight of the cantilever arm is heavier the a standard control arm.
Please explain?
Bob

[longislandwrx]

DJM also makes them and they make rears, and much cheaper than the MSI parts, but at these price points I think its crazy to do this on an 818.

Pretty sure these were the uprights used on the RCM car

http://www.djm-motorsport.co.uk/Subaru%20-front-alloy-uprights%20.html

lighter wheels and brakes will save as much weight at a fraction of the cost... if you are looking to spend 100k on a racecar, is the 818 the best starting point?

If you have deep enough pockets, i'd love to see someone use them though, cough Snap-On guys cough.

[Scargo]

I am working on the cantilevered coil overs in my head and on the internet. No kit yet to measure from...
A chunk of weight would be shed with losing the strut mount and FFR extension bracket. Some weight would be gained with linkage, but I believe the bell crank ratio can allow for smaller stroke, lighter coil overs which can be mounted low and horizontal.
Im still hopeful that I can find a reasonably priced, ventilated racing spindle to adapt. I reserve the option of designing and casting some. Who has that RP printer? :p

[Xusia]

I am working on the cantilevered coil overs in my head and on the internet. No kit yet to measure from...
A chunk of weight would be shed with losing the strut mount and FFR extension bracket. Some weight would be gained with linkage, but I believe the bell crank ratio can allow for smaller stroke, lighter coil overs which can be mounted low and horizontal.
Im still hopeful that I can find a reasonably priced, ventilated racing spindle to adapt. I reserve the option of designing and casting some. Who has that RP printer? :p

The strut mount and extension bracket are used to connect the knuckle/hub to the upper control arm - they have nothing to do with the shock. So if you eliminate them, how would you attach the knuckle to the upper control arm?

[D K]

I don't understand why this saves unsprung weight.
The weight of the cantilever arm is heavier the a standard control arm.
Please explain?
Bob

Because you are moving the shock from unsprung mass to sprung mass.
Or, more accurately, a percentage thereof.

D

[Scargo]

The strut mount and extension bracket are used to connect the knuckle/hub to the upper control arm - they have nothing to do with the shock. So if you eliminate them, how would you attach the knuckle to the upper control arm?
As I said, I hope to find a spindle to use where I would only have to lower the upper arm mounting points. If I were to cheap out, I think a stock upright could be modified to accept a ball joint. I had a '64 Chevy Nova SS that had modified spindles for accepting disc brakes. Of course, if I went this route, it would get magnafluxed and stress relieved.

[Scargo]

An RX-8 spindle looks like it might be a candidate for my car's front suspension redesign. I am also looking into blade type anti-sway bars. (http://s1107.photobucket.com/user/SLO_Z28/media/SCCA/139.jpg.html) Another. (http://www.locostusa.com/forums/download/file.php?id=2407)

[RM1SepEx]

You would need to move the rack, the steering arms are waaaay higher, the Subaru units have the steering arm much closer to the lower ball joint. Time to do some bump steer calculations

https://www.google.com/search?q=rx8+front+spindle+photo&tbm=isch&source=iu&imgil=KTAsSpJ1IYu3hM%253A%253Bhttps%253A%252F%252F encrypted-tbn0.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9 GcQCAVjG9pcwxnleAddjxRRhzzM9t8pNSBVXeya6HePPUNxHpT Rwcw%253B640%253B480%253BpN6_jSv6bGRdzM%253Bhttp%2 5253A%25252F%25252Fwww.hollanderparts.com%25252Fus ed-auto-parts%25252F2004%25252Fmazda%25252Frx8%25252Fleft-l-%25252F515~rx8%25252F515-58979l~spindle-knuckle--front%25252F&sa=X&ei=5rrRUtHvPMXNsQS_4YH4Cw&ved=0CDsQ9QEwBQ&biw=1024&bih=461#facrc=_&imgdii=_&imgrc=KTAsSpJ1IYu3hM%253A%3BpN6_jSv6bGRdzM%3Bhttp% 253A%252F%252Fapi.hollandersolutions.com%252FAsset s%252FY%252FWHETSTOMN%252FPart%252F93413%252FImage %252F1%3Bhttp%253A%252F%252Fwww.hollanderparts.com %252Fused-auto-parts%252F2004%252Fmazda%252Frx8%252Fleft-l-%252F515~rx8%252F515-58979l~spindle-knuckle--front%252F%3B640%3B480

[Scargo]

Thanks. I see that. Well, it was my first reasonable looking candidate. Somehow I did not do my search well enough and I never saw that view of the part. Move the steering arm? Anyway I have hope.

[RM1SepEx]

Google makes almost everything easy re basic searches

You may be able to relocate the rack... I don't have the back flexibility to check and you would need some part dimensions to verify.

Nothing is going to just meet all of your req w/o mods... you are looking at redoing the entire front suspension after all!

[Xusia]

Hey Scargo,

This thread has meandered a bit - remind me again, what problem you are trying to solve with the uprights?

[RM1SepEx]

The existing front suspension is a heavy iron and steel kludge because it re-uses the stock FWD components with provisions for axles.

If I was going to go to cantilever/inboard shocks like on the hot rod you can open up the upper ball joint position, it wouldn't have to be so high as is common now.

you are talking a HUGE rework, just take the low hanging fruit, brakes, wheel tires, perhaps hollow aluminum stub axles and work on other "stuff"

BUT everyone evaluates their goals and spends their own time and money... welcome to the world of hand built cars! :-)

[Xusia]

That's the "what," not the "why." I could make the assumption the goal would be something like better handling, but this car already handles so much better, and is able to brake so much deeper, than the vast majority of cars, I find it hard to believe that would be the goal in this case. Also, Scargo hasn't driven one, so he doesn't even yet know if this is an area that needs improvement.

So, since it doesn't make sense to me, I thought I would ask and get the answer straight from the horse's mouth. :)

[RM1SepEx]

Only the builder can answer why... :)

[D Clary]

Every one want to go fast and get lighter. I am interested in anything that can accomplish that safely and within certain budget restraints. That been said I have dealt with cantilever suspension before and it is not lighter. It has less unsprung weight but the trade off for weight and the monkey motion I don't believe is worth it. The uprights are heave and if you could get more purpose ones made that would be attractive.

[DodgyTim]

I understand lighter is better, but given the lap times the factory R is putting out, I'm not convinced the geometry is too bad

If it were me, and I had the time but not the money, I'd

1 Build the standard kit, with other good lightweight components such as alloy LCA's and light wheels, tires etc
2 Drive it and see how it goes
3 If you are unhappy with it, remove each upright assembly (the subaru bit + the FFR mod), make a jig to suit the upright, then custom fabricate a new super lightweight upright to suit the standard geometry

Replacing the upright without modifying everything else (except maybe the shock) would give the most bang for the effort

[Scargo]

I found this thread about various spindles (http://www.locostusa.com/forums/viewtopic.php?t=1292) people were using or considering using for their Locosts. This is a thread from 2007 through last year.
What is stopping me is I don't have a GD front upright/spindle assembly. I need the weight and the geometry before I can start a selection process. Anyone have the weight and can measure the geometry? Look at the linked thread for how they measured theirs.
For instance, a 1999-2005 Pontiac Grand AM has an aluminum upright but it's a McPherson strut design. That might work out quite nicely and require little if any work. It is upgradable to a GM (Corvette, etc.),BBK and is a standard 5 X 114.3 (4.5"), lug pattern.

Yes, there is additional hardware and weight for linked, lever style, inboard shocks and there is work and expense involved. I will certainly get all the "low-hanging fruit" first. The other is the chocolate.
Without rehashing why what I'm proposing is viable and trying to justify it, let me just say that this is a "bucket list" project for me. I'm 67. I don't see myself ever doing a kit race car again. I don't even know if I can drive the thing without looking foolish. I've done OK in my 7:1 p/w STI (and was planning 6.5:1), but I chose to race it just because it was AWD. Now, I'm going back to RWD that will be around 5:1 p/w ratio. I won't know if I still have what it takes till I get it on the track. I'm hoping I'll build something that is unique, competitive and desirable. I don't have unlimited funds for the project but I think that, if I'm careful with my money, I can build almost anything I want. I am still able to do any of the work myself and am really only limited by the lack of a machine shop and a few metal fabbing tools.

PS: I think I misspoke when I used the term "cantilevered". They are certainly levered and linked. I am unsure of the technically correct description.

[metalmaker12]

As far as I can notice at 1/4 tilt 30-40 tighter turns 60-70 straights the car turns in very solid with no roll at slightly lower than required S ride height. I have no front sway bar yet either. It seems to have a very balanced feel and power is everywhere so you have to be careful with the throttle. When the weather breaks I am going take it out to a big open lot and hammer it to shake out the bugs. At this point I see no reason to even think about changing anything. FFR tested this car and it is doing very well with the way it set up. Making it any lighter may also not help, since some weight is good at higher speeds and at some point stability is very important. I am very happy with its power to weight of about 5-6 lbs per hp and see no real need for any more than that. About est 300-315whp, dyno in the next month or so. Keep an eye on my thread. I also only rate power to weight on whp.

Also, what power you running in the Sti, it's about a 3,200-3,300 car so 5 lbs per hp you would need like 650 whp-700 crank

[Bill Waters]

A few of us discussed earlier in this thread that, given that for most of us, anything other than the OEM spindle assembly is going to be impractical or unavailable, that there are a few ways to lighten the entire final assembly and that this may therefore be the best approach for the majority. The Wilwood two-piece rotors & hats and calipers are one thought.

I just received Chassis # 114 on Friday and have almost completed disassembling my 2006 WRX donor, so I haven't been able to finish evaluating all the pieces, but I wonder if we can't also strip a chunk of weight from the front spindle assembly by removing much of the front outer CV housing which serves as the actual spindle unifying the spindle housing, bearing, and rotor. I haven't gotten them apart to weigh them, but it seems to me we could cut a pound or so per wheel here. Does any body know?

Bill

[Mechie3]

I don't know the actual weight, but a lot of us have cut off the CV housing right where the ABS ring mounts.

[longislandwrx]

You can also remove the dust shields, bolts, and mounting tabs which will save some weight.

[Bill Waters]

I wouldn't be surprised if all these measures cut 2-4 lbs. from each wheel. Not bad.

Bill

[Scargo]

...I also only rate power to weight on whp.

Also, what power you running in the Sti, it's about a 3,200-3,300 car so 5 lbs per hp you would need like 650 whp-700 crank

I'm running at 400/400 (http://www.efilogics.com/dyno/index.php?gb=0&hp=1&torque=1&rpm=1&sl=1&sln=1&sat=0&cb=0&dgr=1&smm=0&sg=1&runid1=2382&rgb1=000000255) in the STI. I said I was planning for 6.5:1 in the STI. It's right at 3K lbs. so 3,150 with me in it. My build was going to make 475 easy. That's where I came up with that number.
Now, with the motor destined for the 818 I will dial it back. I am going to run a dry sump. I am planning on running an undermount turbo if it will work. I misspoke when I said 5:1. I meant 5.5:1 if I shoot for the ST1 class with NASA.

[Oppenheimer]

Just like HP is not as important as power/weight ratio, its not unsprung mass, but rather sprung/unsprung weight ratio that is going to have the impact to feel and confidence (we buy and build and track these things for the fun of it, and fun is not soley dependent on lap times).

The 818 greatly reduces the sprung weight, but the unsprung weight stays the same. So the sprung/unsprung ratio suffers compared to donor. So this unsprung lightening effort seems like a worthy cause.

The thought that seems the most intriguing to me is the idea to look at suspension components from other Subies. Maybe older, lighter vehicles that hopefully share the same basic geometry as the intended donors. Seems like we need some Subie experts that can help out here.

[Xusia]

The sprung/unsprung ratio is something I hadn't considered, but since these cars use completely different suspension designs, does it really apply? For all intents and purposes, that's like comparing the sprung/unsprung weight ratios of a Evo and a Boxster. A comparison can be made, but is it of any use?

[Scargo]

RE, Using other Subaru front suspension components:
I have thought along similar lines and don't know the answer. I have been focused on GR bodied STIs and little else. Way back, I kinda wanted an SVX until I read the revues and thought it would end up being a white elephant.
The BRZ is Subaru's first RWD car that I can find. It and the Scion share the same McPherson strut design. Perhaps it might be lighter, but it's still a compromise I'd prefer not to use (of turning a McPherson strut suspension into an unequal arm suspension).

[jimgood]

I don't understand why this saves unsprung weight.
The weight of the cantilever arm is heavier the a standard control arm.
Please explain?
Bob

Cantilever is the term FFR use and they use this design on the '33 Hot Rod. Moves the spring and shock inboard. When they are mounted outboard (most situations), some percentage of their weight is sprung (attached to the frame) and some percentage is unsprung (attached to the lower control arm). So only a percentage of their weight is considered unsprung.

Should be pretty obvious by looking at the pic of the front suspension below.

http://www.factoryfive.com/wp-content/uploads/2011/12/hrrollingchassis-694x413.jpg

[jimgood]

PS: I think I misspoke when I used the term "cantilevered". They are certainly levered and linked. I am unsure of the technically correct description.

Cantilever is the term FFR use and they use this design on the '33 Hot Rod.


I don't understand why this saves unsprung weight.
The weight of the cantilever arm is heavier the a standard control arm.
Please explain?
Bob

Moves the spring and shock inboard. When they are mounted outboard (most situations), some percentage of their weight is sprung (attached to the frame) and some percentage is unsprung (attached to the lower control arm). So only a percentage of their weight is considered unsprung.

Should be pretty obvious by looking at the pic of the front suspension below.

http://www.factoryfive.com/wp-content/uploads/2011/12/hrrollingchassis-694x413.jpg

[Xusia]

Wow. It would be really nice if that front end was an option on the 818.

[Scargo]

26052I'm back at it again. Do aluminum spindles have a place in road racing? I think of how the brake heat might affect them. I know there are some being used out there; usually they are special designs, often large, thin, open castings.
2607026071
For a Subaru:
26072 However, I am trying to get away from a "compromise front suspension", even though these would pair well with the 818 parts.
Just read that the MSI parts do not save weight (http://www.iwsti.com/forums/3022952-post143.html).

With the spindles below there is the issue of the LCA ball joint. Can you adapt a ball joint to the LCA? It would need to flip 180 degrees. Do I scrap the Subaru LCA for something better and change the mounting points? Most of these come with no drop or 1-2" of drop.

For '64-'72 Chevelle, Cutlass, El Camino, GTO. Uses sealed ZR1 Corvette hub assembly. Any brake kits for late model Corvettes will fit. Sturdy aluminum!
26053
Pinto style:
26054These light and strong spindles might be better sized for an 818. I'm guessing BBK's are not a problem.

Some parts I'm considering. Talk amongst yourselves... Talk to me...

[Scargo]

In the same context as above, is using adjustable control arms, top and bottom a good idea? We have the FFR supplied UCA which seems to get clamped (with the three bolts) into a stationary position. I found multiple "adjustable" LCAs for various cars that seem like they might fit the bill except I worry about how rigid and race-proof they might be. Here is an example:
26097
I perceive a lot of moving/movable parts and possible flexibility.

These, for an E30, are what I may try to copy if I fab my own, but with Hyme joints.
26102

BTW, the stock STi LCAs from my '08 STi weigh 7 pounds each, which includes the ball joint. I can't find a way to adapt them to a spindle that accepts the tapered shaft of a ball joint.
Anyone care to comment? Please!

[Santiago]

I have an Agent 47 SLA system on my Mustang that uses lower control arms that look like the first one you posted. There's no slop in them at all, since once mounted the pivot points are stationary. They can be plenty race-proof, but you need to attend to some basics (that should've been done on the A47 kit...grrrr!) or maybe just be aware of a couple of needs this style has.

1. The main arm's bracket takes on the full brunt of braking forces (as transmitted to it via the strut). So the bolt used here should be an AN bolt (shouldered according to proper thickness requirements). DO NOT use a regular threaded bolt, and really no suspension bolt should be fully threaded ever regardless of what grade it is (which has no bearing on the threads' tendency to chew into surrounding steel) - take a look at every OEM bolt in newer cars, they all have the proper shoulder length for their application. The kit I received didn't have the proper bolt, and I didn't know any better back then. Sure enough, the vibrations eventually wallowed out the hole. In the process it weakened the surrounding steel, which led to the bolt doing tiny shifts in its (now) oblong hole. Under heavy braking, that was fun! :mad: So to prevent that, make sure you precisely drill that hold and get an AN bolt that fits w/such small clearance you almost have to tap into position.

2. That same hole/bracket takes a beating with a heavy car like the Mustang. I don't think the 818 is going to be as punishing, so I think the sort of 1/8" thick stock used on the A47 arm would be adequate. If I build my own for the Mustang I'll likely opt for a heavier stock on this particular bracket. The previous set of arms also didn't have wide spacers to spread out the clamping force on it and the hole also puckered a bit as the surrounding steel buckled (another reason to go thicker). I think the idea many builders have in making these arms is to make them as light as absolutely possible, but they end up skirting safety limits in the process.

3. Some of my experience is likely due to shoddy communication between customers and A47, as they repeatedly gave me the wrong torque specs and such. I finally just went ahead and used broader engineering guidelines, switched to AN bolts, broader hardened washers, and gave the bolts more torque to keep movement to a minimum. I haven't had any trouble with the arms since, they articulate phenomenally well, and the range of adjustment they permit for whatever alignment specs you desire is pretty sweet.

Best,
-j

[Scargo]

Thanks, J.
I'm liking these for a BRZ from Racer X Fabrication. $609. Includes ball joints.
26126

[Scargo]

Just look at this cool suspension hardware that's on a Lambo.
26214
More at http://www.edmunds.com/car-reviews/track-tests/2012-lamborghini-aventador-suspension-walkaround.html (http://www.edmunds.com/car-reviews/track-tests/2012-lamborghini-aventador-suspension-walkaround.html)