Double axle failure on the AEM 818R

[SixStar]

Looks like we found another limit. At a local autocross Sunday we had not one but both axles completely fail. Good new is there were a lot of people there to help push.

400wtq through a RA 5MT running a Modena TBD, running 285/30-18 R1S competition tires at 32psi. Car weighs ~2,190 or so with driver, 4k launch. This was the 9th time the car had been launched in it's life, 4th that day. No big event just lurched forward about an inch and stopped.

Just wanted to share. Part of the excitement of building a race car from scratch is finding failure points, upgrade, replace, move forward!

46196

46197

[Hindsight]

Same thing has happened to at least two others here. If I recall correctly, the axle broke at the same place.

I'd call The Driveshaft Shop and get some custom axles made from them. They handle 750WHP.

[SixStar]

Same thing has happened to at least two others here. If I recall correctly, the axle broke at the same place.

I'd call The Driveshaft Shop and get some custom axles made from them. They handle 750WHP.

$500 per side is mighty steep IMO. We're going to go with a local Colorado company that's known for making some very strong bits.

[taco20]

Let us know what your Colorado company comes up with and if you will start selling the fix?

[SixStar]

Let us know what your Colorado company comes up with and if you will start selling the fix?

We've run into some serious issues building the four axles for kit 80 and 85, I'm not sure the labor involved would jive with a reasonable price. Not exaggerating we disassembled over 3 dozen OEM axles to get enough parts to make 4. I know another local builder ran into similar issues with his axles.

If we can find a way to build complete axles good to 500wtq for less than a G I'll pass that information on for sure.

[Mitch Wright]

Check in with Mark Williams Engineering (Colorado Company) They specialize in driveline parts for Drag and road race cars.

[STiPWRD]

We've run into some serious issues building the four axles for kit 80 and 85, I'm not sure the labor involved would jive with a reasonable price. Not exaggerating we disassembled over 3 dozen OEM axles to get enough parts to make 4. I know another local builder ran into similar issues with his axles.

If we can find a way to build complete axles good to 500wtq for less than a G I'll pass that information on for sure.
Could your shop remake the FFR axles out of a stronger material? The subaru CV joints seemed ok, although I can't recall if someone else broke those as well.

[Hindsight]

Not exaggerating we disassembled over 3 dozen OEM axles to get enough parts to make 4.

Why? So far the only other person I'm aware of who had that problem was someone who built with an STI donor. If the front inner and rear outer CVs don't fit on the driveshaft FFR sent you, then you just need to call FFR and they will send you a new one with the correct spline counts. The axles I received in my kit for a 2007 donor worked fine with my 2007 donor CVs. Or am I misunderstanding the reason you went through so many OEM axles?

If someone in Colorado can make 500 WHP capable axles for less than $500 per side, and you aren't going to offer them, I'm sure a number of folks here (myself included) would love to hear who the company is and how much they are asking.

[SixStar]

Why? So far the only other person I'm aware of who had that problem was someone who built with an STI donor. If the front inner and rear outer CVs don't fit on the driveshaft FFR sent you, then you just need to call FFR and they will send you a new one with the correct spline counts. The axles I received in my kit for a 2007 donor worked fine with my 2007 donor CVs. Or am I misunderstanding the reason you went through so many OEM axles?

If someone in Colorado can make 500 WHP capable axles for less than $500 per side, and you aren't going to offer them, I'm sure a number of folks here (myself included) would love to hear who the company is and how much they are asking.

Nothing worked/fit, it took that many to find four inners and 4 outers that did work with the 80237 shafts. I'll be honest I didn't know that they even made a different version. I know we had trouble recently with another pair of axles for a customer that was a very similar situation, nothing seemed to work. I chalked it up to the aftermarket rebuilds he sent us. In the end he went with 100% new DSS axles.

I'll for sure let the community know what we end up doing regardless.

[Sgt.Gator]

Broken axles is a problem in the Legacy Spec B drag race community. In regular Legacy GTs it's the R160 rear diff that gives out before the axles, but the Spc B uses the much stronger R180, so it's the axles that snap. They have developed a custom solution with a vendor because all Legacys use the 5 x 100 hub like a WRX.
The Driveshaft shop has developed a kit for the conversion including new upgraded hubs. However it's $1800.http://www.driveshaftshop.com/import-axles/subaru/2006-2009-legacy-spec-b/subaru-2004-2007-sti-axle-hub-kits-900hp-level-5-axle-hub-kit I'm sure they could develop a kit for the 818.

One other thought though....if you upgrade the axles the next thing to break will be inside the transmission. It's a LOT cheaper to replace axles than the tranny. I'm waiting to see how the Subaru tranny that was designed for handling at most 50% of the total all wheel HP/Torque (front wheel HP/Torque) will fair running 100% in a 818. With street tires it may never be a problem but sticky race tires + upgraded engine power may break both the 5 speed and 6 speed trannys.

[Hindsight]

A few folks have already trashed their 5-speeds (even the later "stronger" versions), so the verdict is already in on that. I think everyone who did trash them was running more than stock torque numbers though. No one has broken a 6-speed, that I have heard, and I doubt anyone will. PPG gears are always an (expensive) option for the 5 speed and I haven't heard of anyone breaking them.

Back to the Driveshaft Shop.... I don't think you'd need the setup with the custom hubs. They charge like $750 for a set of front or rear WRX axles that will take 750hp. I don't think we can use these as-is because of the different inner vs outer CVs we are running and the different shaft length but I'm sure DSS could custom make something that uses the OE hubs to keep the costs down.... I should call and ask. This all assumes that the CVs they would want to use to support ~700hp would work with our hubs.

[AJW Performance]

We've seen this before. Custom is the way to go if the car is going to be launched often.

[Bob_n_Cincy]

A few folks have already trashed their 5-speeds (even the later "stronger" versions), so the verdict is already in on that. I think everyone who did trash them was running more than stock torque numbers though. No one has broken a 6-speed, that I have heard, and I doubt anyone will. PPG gears are always an (expensive) option for the 5 speed and I haven't heard of anyone breaking them.

Back to the Driveshaft Shop.... I don't think you'd need the setup with the custom hubs. They charge like $750 for a set of front or rear WRX axles that will take 750hp. I don't think we can use these as-is because of the different inner vs outer CVs we are running and the different shaft length but I'm sure DSS could custom make something that uses the OE hubs to keep the costs down.... I should call and ask. This all assumes that the CVs they would want to use to support ~700hp would work with our hubs.

I've heard about the 4 or 5 cases of snapped axles. I think I only remember 1 MT5 issue. Were there a lot more?

Our 818 FXT engine with MT5 has been through a couple hundred hard autocross Launches. 10 to 15 feet of dual rubber each time.
Rear tires were Federal 595s 205, Toyo R888s 225 or R888s 255 (current tires).

Our clutch is a KSB04-HD-OFE rated at 350 ft lbs. I feel that by limiting the torque of the clutch you can protect the transmission and axles.

Our clutch (350) times 13.5 give us about 4725 lbs of thrust. Over 2Gs.

That's my plan, it's working so far, I will keep you informed.
Bob

[Hindsight]

AeroSTI just broke his transmission a few days back. FFR broke theirs on one of their early 818s (they did a 6-speed install shortly after). I think Jerome broke his.... not gears but the R&P if memory serves me correctly. Might not have been Jerome but I remember seeing the pic of the mangled ring and pinion and I thought it was Jerome's.

[JeromeS13]

AeroSTI just broke his transmission a few days back. FFR broke theirs on one of their early 818s (they did a 6-speed install shortly after). I think Jerome broke his.... not gears but the R&P if memory serves me correctly. Might not have been Jerome but I remember seeing the pic of the mangled ring and pinion and I thought it was Jerome's.

It was mine, from a 2012 WRX 5MT.

[C.Plavan]

I would rather break axles than a trans. Mine have been holding on fine since December 2015. I do not launch the car at all.

[Hindsight]

I talked with the Drive Shaft Shop.

They will do custom axles with billet CVs and all for $1,000 a pair. That should be for a 750hp rating. Or, they will provide custom strengthened axle shafts for use with your existing CVs (much like FFR supplies, only stronger) for $500 a pair.

[Aero STI]

I talked with the Drive Shaft Shop.

They will do custom axles with billet CVs and all for $1,000 a pair. That should be for a 750hp rating. Or, they will provide custom strengthened axle shafts for use with your existing CVs (much like FFR supplies, only stronger) for $500 a pair.

That's great news and the prices aren't bad. I won't be surprised when my axles let loose after installing the 6 speed.

[Speedy G]

Can we maybe get a group buy going? I'd be interested in the full axles. Sixstar, was there any wheel hop or was it just the dynamic force of the launch that killed them?

Speedy G

[Hindsight]

I could probably setup a group buy if there was enough interest. Probably need to get at least 10 people on it though.

[Mulry]

I'd be interested in a group buy on the $500 set.

[SixStar]

So far we have one quote of $500 just for new axle shafts using factory CVs.

Our transmission is built and I have no worries it can handle the power, especially given that it's only doing half the work. IMO the weak point on any pure race car should be the tires.

[Speedy G]

So we have at least 2 interested in a group buy?

[STiPWRD]

I talked with the Drive Shaft Shop.

They will do custom axles with billet CVs and all for $1,000 a pair. That should be for a 750hp rating. Or, they will provide custom strengthened axle shafts for use with your existing CVs (much like FFR supplies, only stronger) for $500 a pair.

I interpreted this as $500 per pair of axle shafts for any one person, i.e. if we had a group buy, I'd hope the cost would go down. $500 is reasonable but just seeing if we could get a better deal through a group buy.

[Hindsight]

I interpreted this as $500 per pair of axle shafts for any one person, i.e. if we had a group buy, I'd hope the cost would go down. $500 is reasonable but just seeing if we could get a better deal through a group buy.

That is correct. If a couple more people chime in with interest, I'll start a new thread dedicated to the group buy and if it gets to over 10, I'll get updated pricing.

[STiPWRD]

That is correct. If a couple more people chime in with interest, I'll start a new thread dedicated to the group buy and if it gets to over 10, I'll get updated pricing.
I'm interested but was also saving for the new front end so I don't have an urgent need for the axles. Could you ask them what the cost would be if we did find 10 or 15 people? The right deal might be worth it for me.

[Hindsight]

I checked back with them. We could get a group buy discount but it wouldn't be very big. This is because they have an existing dealer network (and all the pricing considerations that go along with that). Maybe ~$50 off the fully assembled axles and ~$25 off the bare axles.

So a group buy probably wouldn't be much of a benefit here. I do think the prices are pretty good for what you are getting.

By the way, I misquoted the HP rating above; It is 500HP, not 750, but that shouldn't be a problem for us.

[metalmaker12]

I broke a cv, so we need stronger axles and cv's guys, driveshaft shop needs to make em for 818.Last time I checked with them 750-1k a set of 600 plus hp axles

[Frank818]

DSS can no problem make a kit for the 818, they are as we speak building mine for my Porsche trans with bored Subaru hubs (and that's more custom than stock 818). They have a limit on the power, as the axles' diameters are small cuz of Subaru's design, but they can build one no problem.

[Aero STI]

750hp was a great figure. I suspect 500 hp axles won't cut it for me.

[Scargo]

This hard launch stuff with huge, sticky tires is crazy. I thought it was well-known that the five-speed Subies couldn't take it. You're using a lot more torque than half of what was used (per wheel) as a stock fendered AWD WRX.
Perhaps not what everyone wants to do, but a lighter touch (until you're rolling) at the beginning of an auto-X run could make the difference. I see people use that approach all the time in various cars.
I've got DSS custom axles made, but they're for a six-speed. The hard lesson may be that the five-speeds are just not suited for racing in our cars, regardless of the light weight. We all love big torque.

[Hindsight]

I'd really like to be able to run a 5 speed, and be able to run the car in HPDE track days as well as drag-race days. HPDE is more fun to me, but it seems all the car shows that include racing are limited to drag-racing only and I want to be able to participate in those. The 818 should be a decent drag racing car anyway, with the light weight and high HP number potential, but as you mentioned, some weak points. I think the 5-speeds will hold up fine to hard drag racing launches if you use PPG gears (which are very expensive) and DSS axles (which don't come cheap either). Six speeds are very sturdy and would be cheaper than a PPG 5-speed setup but personally I feel too many gears and too much shifting for a car as light as the 818 (and with a lot of power). At the end of the day it still comes down to the old saying, "Speed costs money; how fast do you want to go?"

[bbjones121]

750hp was a great figure. I suspect 500 hp axles won't cut it for me.

I bet it would... There is no way you would shock load them with 750 hp. You probably wouldnt exert your max torque until you are already moving. There would be no tires you could fit on the 818 to do a launch and keep traction. Maybe if you glued your tires to the ground first, then tried launching.

[bbjones121]

I am in for stronger driveshafts. Wish FFR would sell them as an option.

[Hindsight]

I bet it would... There is no way you would shock load them with 750 hp. You probably wouldnt exert your max torque until you are already moving. There would be no tires you could fit on the 818 to do a launch and keep traction. Maybe if you glued your tires to the ground first, then tried launching.

That's what I was thinking. Unless you are running wrinkle-wall drag slicks, I'd be surprised if any tires you could fit on the 818 would allow you to put more than 500HP to the pavement.

DSS can probably make some custom axles over the 500hp rating. I didn't ask about that though because I think only one person here is crazy enough to exceed that ;)

[Frank818]

There are limitations on the torque the axles can handle, due to the fact the axles are small in diameter. They are not like VW or Porsche.
I have asked for the maximum torque handling they can build. Once I get my shafts, I'll let you know, but DSS never precisely answered the question as to how much torque they can handle, they always stayed away from the answer. At least for me.

[bbjones121]

There are limitations on the torque the axles can handle, due to the fact the axles are small in diameter. They are not like VW or Porsche.
I have asked for the maximum torque handling they can build. Once I get my shafts, I'll let you know, but DSS never precisely answered the question as to how much torque they can handle, they always stayed away from the answer. At least for me.

I don't blame them. Why accept responsibility for something that depends on so many factors out of their control.

[Bob_n_Cincy]

Some guys might laugh at me for my next statement.

The engine horsepower has very little do with breaking axle shafts.

Let me explain this using my 818.
My engine is max out 210hp and 230 ft-lbs of torque.

Imagine this. Tires strapped down to the trailer very tightly. A super big clutch rated at 2000 ft-lbs. I rev the motor to 6000 rpm in first gear (13.5:1). I pop the clutch, the total torque to the axles would be 27,000 ft-lbs of torque. A bunch of things would break instantly.

Fortunately my clutch is rated at 350 ft-lbs. In the same situation as above, 350 x 13.5 = 4725 ft-lbs total torque to the axles.
If I was running a LSD each axle would have to withstand 4725 ft-lbs.
With my open diff, the torque is equally split between my 2 half shafts. so each half shaft only has to handle 2362 ft/lbs.

Your clutch rating is the biggest player in protecting your transmission and half shafts.

In my opinion, DSS should put a torque rating on their half shafts. With a little math, we could see if they will break.

Bob

[bbjones121]

I think they should test them compared to stock and say they are "x" amount stronger than stock. We know what stock does in real life.

[Mechie3]

They might not put a rating on it simply because shock loads are likely to break them and are in excess of sustained rated engine torque. Joe blow does a clutch dump, breaks an axle and complains because his car dyno'd at 400ft-lb but his 500ft-lb rated axles broke and now he wants his money back.

[305mouse]

Better to break axles than the tranny. It's a pain, but you'll save time and money in the long run.

[Bob_n_Cincy]

By the way, Axles do bend before they break.
46486
If you have any worries, you can put some lines on them so you can eye out for pending failure.
Bob

[Santiago]

I *heart* Bob_n_Cincy.

Great idea! For a heavily tracked R-car this should be standard practice. Is there any rule of thumb for how much they'll twist before giving up or are we just going to have to set baseline data for it?

Best,
-j

[Bob_n_Cincy]

I *heart* Bob_n_Cincy.
Great idea! For a heavily tracked R-car this should be standard practice. Is there any rule of thumb for how much they'll twist before giving up or are we just going to have to set baseline data for it?
Best,
-j

I have no clue, Good question for DSS.
Bob

[bbjones121]

They might not put a rating on it simply because shock loads are likely to break them and are in excess of sustained rated engine torque. Joe blow does a clutch dump, breaks an axle and complains because his car dyno'd at 400ft-lb but his 500ft-lb rated axles broke and now he wants his money back.

Exactly!

[Evan78]

They put HP ratings on many of the products on their site. I'm guessing that what Frank is referring to is a reluctance to give a rating on a custom job. As Bob pointed out, torque seems more relevant than HP.

Frank - are you saying that they wouldn't give you a HP or Torque rating, or did they only avoid answering the torque question?

[Wayne Presley]

Torque is the only relevant factor.

[bbjones121]

Haha. Yes, torque is all that matters. They put horsepower because that is typically what the general public knows. What the general public doesn't know is that hp is derived from torque and rpm. Without a known torque value, you couldn't calculate hp. So to Wayne's point, torque is the only technically meaningful value.

[Evan78]

Even better would be torque at the axle instead of wheels since every car has different gearing.

[DanielsDM]

Even better would be torque at the axle instead of wheels since every car has different gearing.

Yes, "torque at the axle" is what matters. Which is a function of crankshaft torque and gear ratio. The momentary torque the axle sees will by much higher during a hard launch than the calculated value of crank torque times gear ratio. How much higher depends on how much the clutch slips and and how much grip the tires have.

[Frank818]

Frank - are you saying that they wouldn't give you a HP or Torque rating, or did they only avoid answering the torque question?

To me HP means nothing. Because HP is derived from torque, torque is the true measure. I said HP on my post (I think?) cuz many people use that figure (even DSS).
They never gave me a number they would stick hard on. I don't blame them, there must be a good reason. All I know is they (my shafts) will handle over 400wtq, probably 500+, but the way they answered to me meant that even with 400 they could break, they never said "if they break we refund you". They used words like "strong", "not very strong", "stronger", "strongest I got", "a lot stronger", etc... relative words.

Actually I re-read my emails... The guy said "I guess our axles would handle 450hp". Those are the chromoly axles, hardest one they have for the Subaru diameter. That is with the stock Subaru 24 splines, which are the weakest point. I have asked them to bore me the hubs for stronger splines and he said "this would make our axles a lot stronger". But no number... To me it means over 500hp or over 500tq, probably similar.

I will ask them again by saying in writing that even if I have 200wtq and they break, I won't sue them. Maybe they will give me some kind of number. I just want a ballpark, if he says they handle 700+ or not more 400, that's a huge difference, I'm sure they have an idea. They have a lot of customers breaking their Subaru parts (axles, CVs, splines).

[Evan78]

I wouldn't expect any number to be terribly precise. Everyone should be aware that once you take them out of a lab and put them in the field, there are too many variables to trust the number with much certainty. Considering that they have ratings on a lot (or all?) of the axles on their website, they must have some way of establishing a ballpark. I doubt they've faced any lawsuits from someone that broke one of their axles. If that ever happened, you'd probably find a bunch of disclaimers on their site.

[Bob_n_Cincy]

I've heard about the 4 or 5 cases of snapped axles. I think I only remember 1 MT5 issue. Were there a lot more?
Our 818 FXT engine with MT5 has been through a couple hundred hard autocross Launches. 10 to 15 feet of dual rubber each time. Rear tires were Federal 595s 205, Toyo R888s 225 or R888s 255 (current tires).

Our clutch is a KSB04-HD-OFE rated at 350 ft lbs. I feel that by limiting the torque of the clutch you can protect the transmission and axles.

Our clutch (350) times 13.5 give us about 4725 lbs of thrust. Over 2Gs.

That's my plan, it's working so far, I will keep you informed.
Bob

Like I promised 9 days ago. "I will keep you informed"
Michael and I had a great weekend auto crossing. Between us we had 27.001 runs.
Everything was running perfect until our very last run opportunity.
So Michael was on the edge of making a 60 second lap all day. So his launch might have been a little extra.
Here are the results.


https://youtu.be/HS9kN_Pd_78

[Hindsight]

Doh! Another failure.

Talked with DSS again. The custom Axles are good for 3000 foot lbs of torque which is about 450 at the flywheel. As Frank mentioned above, the weak point is the small diameter on the outer end. DSS makes larger diameter Axles that come with custom hubs which will be good for 850 foot pounds of torque at the flywheel. Waiting to hear back from them on cost but I would imagine $1900 for those. Not needed for most of us, but it's an available option.

Pretty sure they rate them at HP because that's what people know and usually torque is within 15% of peak HP so it's close enough.

[Frank818]

$USD1,300.

I know this isn't my thread, but it's about options for broken axles, so I guess it's relevant.

Here's my breakdown:

- DSS bigger/stronger WRX outer CVs: $500 (pair);
- DSS chromoly as-strong-as-possible-for-that-diameter bars: $400 (pair);
- Porsche G50 108mm inners: $200 (pair);
- Broaching Subaru hubs to fit the bigger outers: $200 (pair).

Now I got numbers. They have seen these bars and outers CVs on much heavier cars with 700whp+ and some work no problem, some failed. All parts can fail, there is no weak point a lot weaker than the other parts. Depends of all the variables, driving style, tires, weight, road condition, etc. They think with such light car (950-1000kg) there should be no problem to handle well enough 700+. Weight is helping here.

[Mechie3]

I'd be in for the $500 shaft upgrades.

[bbjones121]

Same here

[Canadian818]

I'd be in for the $500 shaft upgrades.

But when you start breaking CV's or transmissions will you still think it's an upgrade? It seems endless, I'm going to end up 7-8k in drivetrain between ppg gears, limited slip, and upgraded axles/cv's....

[bbjones121]

But when you start breaking CV's or transmissions will you still think it's an upgrade? It seems endless, I'm going to end up 7-8k in drivetrain between ppg gears, limited slip, and upgraded axles/cv's....

Probably don't need ppg. That would save you lots.

[Hindsight]

You know the saying... speeds costs money, how fast do you want to go?

I don't think I've seen anyone break the transmission with a stock engine setup. I think all the failures have been with higher than stock outputs. I THINK the same is true on the axles but am not 100% sure of that.

The bottom line is that there are a lot of weak points in the system when you go much above the stock HP rating. Known weaknesses are:
- Pistons
- Clutch
- Axles
- Transmission
- Intake charge cooling

If you want to keep costs low, just stick with the factory output. If you want to go faster, it's going to cost a lot more. It's not like working on a muscle car or a Toyota that was engineered for nearly double the stock output (though don't get me wrong, I wish it were).

[SixStar]

Another weekend, another failure.

We're looking into it but it would appear to be an alignment issue. I neglected to mention minimum track width when I had the car aligned and my guess is they're binding and snapping off from lack of plunge. The settings are all we have changed since the car was built and there's no reason they should be failing at this rate all of a sudden due to power. Going to have a pair built regardless.

EDIT: Not track width. We're 3/4" over min per side. Also this failure was a shattering of the OEM outer, I predicted this before the car was ordered, that part of the CV was never made to handle a fraction of thee power these cars can make (even stock)

Time to call DSS I suppose.

46585

[Canadian818]

Probably don't need ppg. That would save you lots.

I'll update my build thread soon, I'll need them soon enough. ��

[Hindsight]

I would not trust the 5 speed much over 250whp. Keep in mind that is well over stock HP which is 227 or something, at the crank. 6 speed would hold up to whatever you throw at it. 5 speed would need the PPG gears. Cheaper to go 6 speed but heavier and is a lot of gears for a light car.

[C.Plavan]

Again, Limited, but lots of track time since December of last year (283HP/304TQ) to rear wheels. ~2270 weight with me. No launches, but I abuse the crap out of it otherwise with Hoosiers R7's- with crazy fast laps (for 20 min each session lol). Still on original used transmission (78k miles), and original CV's- No issues. Pick your poison I guess.

[RM1SepEx]

higher than stock HP and TQ and shock loading is def the issue and remember in stock config the power is divided front and back vs just back. I would assume that the outer CVs might be a weak link... what is dist front to back with a stock Subaru?

We see axles, CVs and trans issues at autocross but they always grenade when those cars leap off the line due to such great grip. An 818 will always be limited by tires...

[RetroRacing]

That looks like an issue with the metal, I would magnaflux the next set regardless....in know we will be!

[SixStar]

We have several 5MTs in the 12s with no issue. Fluids and the loose nut behind the wheel go a long long way. Saying that all 5 speeds will grenade at X power is a bit of an overgeneralization. I've broken 5MTs on stock WRXs, I destroyed an RA box with a massive 265wtq, I've destroyed an RS transmission with 105wtq. Previous life and current abuse factor in heavily. In the end they're all just parts and results may (and do) vary.

[Hindsight]

Are the 5MTs in the 12's running front wheel drive only?

[Sgt.Gator]

I would not trust the 5 speed much over 250whp. Keep in mind that is well over stock HP which is 227 or something, at the crank. 6 speed would hold up to whatever you throw at it. 5 speed would need the PPG gears. Cheaper to go 6 speed but heavier and is a lot of gears for a light car.

I disagree. The 5 speed has a reputation for being weak but that is not what I have experienced. And there are differences between the older 5 speeds based on model of car and year. For sure old 2002 WRX 5 speeds are not as strong as newer ones. I think they made the change to thicker/stronger gears in 2008. The 2005 + Legacy trannys are stronger than old WRX trannys. I'll do some research and put together a chart with what years and models have the different gear strengths, I know I've seen it all posted on NASIOC and Legacy GT forums.

Anyway in my case my Legacy GT 5 speed survived 2 seasons of professional endurance racing on the Factory Subaru Road Race Team in the Grand Am Cup, a season of Tarzan Yamada driving it in Time Attack, then a year of my amateur shifting in the ICSCC conference racing. And that's in a 3300 lb race car. It's still fine and I will probably use it in my future 818R. Possibly one of the reasons it lasted is the SRRT installed a tranny cooler and pump after the first test session (I have the log book). I wonder when I read about LGTs breaking 5th gear if that's because they overheat the transmission for long periods (even towing).

I swapped it out for the 6 speed not because of the tranny, but because the R160 diff is very weak. As long as I was changing to the R180 diff I went ahead and did the entire swap. Since 818s don't use the rear diff it's moot here.

[PleiadsMan]

also depending on how heavy your wheels are and how sticky your tires are will make a huge difference. I killed many stock tires at the track just by using softer tries all around.

[Sgt.Gator]

I found the info in a couple of places:

http://www.rallispec.com/gea_syn_rst1140_t.html

http://flatironsrally.typepad.com/faq/2010/05/comparison-of-subaru-gear-sets-wrx-legacy-gt-sti-ra-and-more.html#tp

The short answer is the Legacy 2005+ and the WRX 2008+ have stronger gears in the 5 speed line.

[SixStar]

We run RA gears in the 818R. For best results they should be OEM and NOT micropolished.

[Mechie3]

But when you start breaking CV's or transmissions will you still think it's an upgrade? It seems endless, I'm going to end up 7-8k in drivetrain between ppg gears, limited slip, and upgraded axles/cv's....

I think I'd rather break something that is contained than an axle that can whip around. My donor (my former DD/AX car) already broke one trans. Third gear acceleration (not on a shift) and it popped. I still run a stock clutch to help prevent some shock loading but when I autocrossed I was able to spin all 4 on launch with Rcomps. :D

[Scargo]

We run RA gears in the 818R. For best results they should be OEM and NOT micropolished.
I am curious about your statement. First, I'd never heard of micropolishing till now and secondly, I looked it up and there are varying opinions of its efficacy. What about REM isotropic finishing or, as it is also called, Isotropic Super Finishining (ISF)? Combinations of processes like Microblue (http://www.microblueracing.com/smooth-slippery-racing-solutions.html) and REM?
One person said (http://www.eng-tips.com/) "I've had several friends swear that they have seen ~2% gains on a chassis dyno using this."
What's the problem with doing it?

[nkw8181]

looking at doing the 6 speed swap and while I'm at it upgrading the axles ( I have an 06 wrx as a donor) so I am interested in the axles. what all are they including? would you still need your own outer CV parts?

[SixStar]

Zach (Fate066) is my trans guy and he can elaborate but basically by taking metal off you're increasing lash/slop and therefore failure. I'm sure if they loosen all the wheel bearings they'll see an increase in power too.

[STiPWRD]

looking at doing the 6 speed swap and while I'm at it upgrading the axles ( I have an 06 wrx as a donor) so I am interested in the axles. what all are they including? would you still need your own outer CV parts?
The 6 speed axles are a larger diameter than the 5 speed or FFR axles so they should be much stronger. It sounds like DSS can provide either just the axle shafts or the shafts and CV joint assemblies.

[Scargo]

DSS did my axle assemblies for my six-speed to STi rear hubs. I got their heavy-duty inner CV joints and custom length axles made to couple with the rear STi outer CVJ. $755. I think the axles are 500 HP rated.
From their invoice:
2 - CVJ5114 STI rear outer CV made from 4340 with 32 spline race


2 - Inner CV Inner CV joints for front STi Diff ('05-'07 STi 6-speed)

[Frank818]

DSS can provide anything you need. If you want just the bars without CVs (as FFR), they can do that. If you want CVs with that, yes, if you want broached hubs, yes, upgraded CVs, yes, I bet they can provide a Koenigsegg inner CV (what on earth you got as a tranny?? :)) but they can't go bigger than the biggest diameter possible on the hubs, whichever hubs you may use.

[nkw8181]

Can they put a larger wheel bearing in the wrx hubs if bored out? On a side note just picked up a jdm spec C 6 speed!

[Hindsight]

I'm not positive but since they offer the extra-strong axles with new hubs, I believe the hubs will fit the existing spindles and bearings with no boring required. I'm sure they just machine the inside of the hubs out and then machine new splines so that the inner diameter is larger and the splines count is optimal. That will probably make the hubs a bit thinner but I assume that's not an issue nor where the weakest point is.

[Frank818]

Hindsight nailed it. You cannot put bigger bearings with Subaru hubs, there would be no more metal left. They just bore the inside of the hub and machine new splines.

I should get my axles Tuesday or Wednesday, I'll post pix.

[BrandonDrums]

750hp was a great figure. I suspect 500 hp axles won't cut it for me.

I wonder if it's 500hp per axle or both :p Have them send you a free pair to try out and perhaps you can report back haha.


Hindsight nailed it. You cannot put bigger bearings with Subaru hubs, there would be no more metal left. They just bore the inside of the hub and machine new splines.

I should get my axles Tuesday or Wednesday, I'll post pix.

I wonder if there are any larger subaru spindles that will be comparable in bolt points that could be used. The Tribeca and Baja in particular come to mind. Might be worth a look through www.opposedforces.com to see if they fit the bill.

[onelastproject]

You have to pay to play. Launching with slicks will cause breakage, get better axles then you have tranny issues as you all know. Launch with slicks and understanding what the lack of mechanical sympathy does typically leads to expectations be realigned, expectations is typically the biggest thing that typically needs to change. . There is no cheap solution to 400 HP and slicks as much as people hate to hear that. One can back off a bit or fork out more money of your truly serious. If you are here you go. Good news is they have the for the older lighter 5MT from the WRX as well. Of course then there is case flex issues. You can also look into case braces they have them out of NZ. Been there done that. 11 years ago. Good luck!

http://www.mrtperformance.com.au/performance/transmission/271-mrt-unbreakable-gear-sets

[nkw8181]

Sixstar how did you fit 285's?

[Frank818]

Got my axles and hubs last Tuesday:

4689146892

[nkw8181]

Is it not a male to male axle??

[STiPWRD]

Is it not a male to male axle??
Frank is running the G50 transaxle, not a subaru trans.

[Courtnie Provencher]

Only somebody with a race car could find excitement in parts breaking, I love it! Keep pushing forward! :)

[nkw8181]

Sorry had an aha moment. Is DSS a vendor?

[Frank818]

Don't think DSS is a vendor on this forum but they source the FFR shafts for the 818, as what I've been told.

Yes, I'm running a male to nothing axle, as I don't consider the G50 inner CVs are either males or females. lolll

[bbjones121]

Don't think DSS is a vendor on this forum but they source the FFR shafts for the 818, as what I've been told.

Yes, I'm running a male to nothing axle, as I don't consider the G50 inner CVs are either males or females. lolll

You mean one side is genderqueer

[Evan78]

Looks like it would be called a flanged end to me.

[Frank818]

Yeah genderqueer. :)

It's just a flange that you bolt to the flange on the gearbox. 6 50mm bolts.

[bbjones121]

Sorry, got a little carried away, anyway...

[SixStar]

Sixstar how did you fit 285's?

Nolan,

Sorry for the MASSIVE delay. I've had a lot going on the past 6 months.

I have ARP studs and 17.5mm spacers running 18x10.5 wheels. The tires are 285/30-18s. They do rub slightly on the inside of the aftermarket lateral links but only when pressures are low.

53122

[Scargo]

I have ARP studs and 17.5mm spacers running 18x10.5 wheels. The tires are 285/30-18s. They do rub slightly on the inside of the aftermarket lateral links but only when pressures are low.

53122
What offset? Obviously they are under there... Amazing!
I tried fitting my STi's 285/645 Continental slicks on 18x10.5" (38ET) on mine and just did not see how it was going to work without body mods.

[Kurk818]

That looks insane! Would love some more angles :)

[nkw8181]

Ithe just looks like any larger then my 265's will rub on the body. How do you avoid this?