Hardcore Proper Suspension Location Slop Removal

[Blwalker105]

With proper deference to previous unread threads and upon test-fitting of my new 818C's front and rear suspension pieces, it has become painfully obvious to my aviation-oriented brain that the factory-supplied hardware is woefully inadequate. I have much difficulty accepting coarse-threaded, poorly fitting, suspension locating hardware that puts bolt threads in contact with frame location bosses in almost every one of the factory's brackets. Even in street trim, having proper grip-length bolts to extend the shoulder past the brackets should be a no-brainer, but that is not what I am seeing. I know, this is probably too Anal Retentive to register on anyone's joy meter, but that is my 2-cents.

As a newbie to the breed, I will be posting a list of Aircraft Spruce AN hardware that will conform to tougher build standards with position-specific part numbers. It will be a very good happiness-per-$$$ unit cost.

[Hindsight]

Some have created a complete metric fastener list for those who want only metric hardware. It's posted here somewhere but I am not sure if they are the right dimensions to prevent what you are talking about. You might consider McMaster Carr.... might be cheaper than Aircraft Spruce.

[Blwalker105]

Don't think cost is much of an object here. Most of what I've seen can be solved non-metric with minor modifications. Off the top of my head, less than $200 per car would solve a world of slop, including those of us putting our lives on the line tracking these cars.

[Santiago]

Welcome Blwalker!

I don't think you're being anal retentive by insisting on good/solid fastener practice. For some reason enthusiasts in aviation have long since been ahead of their automotive counterparts...as if the danger is not just as great sliding off track as when you're falling out of the sky (note: the early history of automotive racing proves otherwise). I don't get it, but I'm with you 100% - the supplied hardware is good for mock-up purposes at best. Nothing in a suspension link-to-frame mount should be fully threaded or improperly sized.

If you will be tracking your car in earnest, you should know that at least one R-builder (Chad Plavan) has already found his rod-ends were not up to the task. They failed after a few events. EDIT: The rod ends he used were not the ones supplied by FFR (as I originally thought), rather they were from a different supplier. I've run rod ends on my cars before, but unless I've got part numbers and know who manufactured them, I regard them as more "set-up/shake-down" parts.

Best,
-j

[Mulry]

I know, this is probably too Anal Retentive to register on anyone's joy meter, but that is my 2-cents.

Not too A/R at all. Bring it!

[jceckard]

What some call A/R, I call detail-oriented.

[DSR-3]

The very first part that I assembled on the car- Wilwood pedal mount plate, was met with the same disappointment. Luckily I still have a pretty good AN hardware selection and was able to do it how I like. I really had hoped building a production kit that comes with spec. hardware would not be an exercise in re-doing these types of things, as it can get costly in time and money. Having not even looked at other fit's, I guess I'll be prepared...

[longislandwrx]

I look forward to seeing this list.

[RetroRacing]

We have almost every bolt supplied with the kit still, we used all new grade 8 or 10. metric, and changed most of the heim joints.

[PSUalum1986]

I too want to see this list. Anyone who doesn't replace any and all of the offending hardware needs to read Carroll Smith's series of books (Prepare to Win, Tune to Win, Engineer to Win, and Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook). The late Mr. Smith knew and understood enough to help lead Ford to victory at Le Mans.

[Blwalker105]

I should have the results of my suspension update soon. The hardware is coming from CoastFab.com. I went a little over-the-top and ordered flanged, locking nuts and the cost was $255 plus shipping. My rear lateral links came with their own hardware, including nice shouldered bushings so I did not get new hardware for their pivot points. When I see the price breakdown, I will estimate how much more these will cost for those using the factory lateral links.

[Pearldrummer7]

Blwalker- I think that's a good idea for suspension components. I am curious why you'd use AN threads instead of just using finer metric or SAE threads. Any comment about that?

[DanielsDM]

Blwalker- I think that's a good idea for suspension components. I am curious why you'd use AN threads instead of just using finer metric or SAE threads. Any comment about that?

AN Bolts use the same fine thread (UNF) as SAE/Imperial fasteners (10-32, 1/4-28, 5/16-24, 3/8-24, 7/16-20 etc...). Not to be confused with AN Fittings. AN Bolts have about the same strength as grade 8 bolts but are tougher, i.e. they can bend much more without breaking. Also AN bolts are available with more options for shoulder length so you don't have the thread taking the shear load.

[Pearldrummer7]

AN Bolts use the same fine thread (UNF) as SAE/Imperial fasteners (10-32, 1/4-28, 5/16-24, 3/8-24, 7/16-20 etc...). Not to be confused with AN Fittings. AN Bolts have about the same strength as grade 8 bolts but are tougher, i.e. they can bend much more without breaking. Also AN bolts are available with more options for shoulder length so you don't have the thread taking the shear load.

Ah, sorry. I misunderstood the AN part. Not allowing the bolts to rest on the threads is a good idea if you ask me. It concerned me upon installing them...

[Blwalker105]

Ok,
Here's the results of my efforts so far:

The front suspension requires very little modification. Only the bracket
holes for the Front Lower Control Arm pivot point and the Lower Control
Arm pivot point bushing need to be enlarged from 12mm to 1/2". I have
yet to get very far on the rear suspension, so I will list only that
which I have verified, which is the Rear Forward Lower Control Arm pivot
point and the associated bushings in my aftermarket rear arms.

Front Upper Control Arm Mounts AN8-20A 4
Front Top Shock pivot AN8-25A 2
Front Lower Shock pivot AN8-20A 2
Front Lower Control Arm pivot AN8-35A 2
Rear Forward Lower Control Arm pivot AN8-34A 2
Jet Nuts MS21042-8
12 so far

All of these fitments will require numerous washers to allow for the
unthreaded shoulders of the bolts. Washers are relatively cheap, at $12
for 100 standard thickness and 100 thins. Do Not scrimp. Most of my
applications require 1 standard washer under the bolt head and 2
standards under the nut. Be extra careful not to get false torque
readings tightening against the shoulder: if the bolt head spins at the
proper torque reading, YOU NEED TO ADD A WASHER UNDER THE NUT!!

Hopefully, these pics will post:

https://imgur.com/A8P5Lew
https://imgur.com/nWYS0va
https://imgur.com/BHZ0BuV

[Blwalker105]

Here is the price list for the hardware I ordered from CoastFab. Do not make the same mistake I did by ordering these killer-cool, attached-washer KFN-series jet nuts...they cost $7.50 each!! Just get the standard MS21042-8 jet nuts and save yourself $70. https://imgur.com/5DCwoYJ

https://imgur.com/x8vEEqh

The rear suspension is going to be much more problematic than the front, mostly due to the close proximity of the lateral link brackets to each other and to frame pieces. It's going to be very difficult to get either an air drill or 90 degree adapter with a 1/2" bit in between everything. I am rethinking the work/reward ratio back there. Another possibility that I have not investigated is to purchase metric bolts that are indexed by grip length. I have the main Fastenal warehouse right down the street so maybe I'll drop by for a look-see.

All of my aftermarket rear suspension arms, with one exception, have rod-ends with bushings which will need to be shortened to fit in the factory pivot point brackets and re-drilled to 1/2", so it's going to take me a little longer to get things mocked up back there. The exception is the rear of the trailing arm where it mates to the bottom of the spindle. I pressed out the factory rubber bushing assemblies and replaced them with split polyurethane bushings. I had forgotten to order bolts for these areas, but they will be AN8-31A and I will have to drill out the locating holes and the new bushings to 1/2".

[Blwalker105]

If I had to do this over again, I would have used Pegasusautoracing.com. They are one of the few who carry the MS21042-8 jet nuts and their prices are about 15% lower than Coastfab across the board.

[Santiago]

You might also try aircraftspruce.com for good prices and good selection.

[RetroRacing]

We were able to drill out all of the rear suspension for new bolts, but yes, you do need a short bit and an angle drill. We are running the R , so not sure if the S will be the same for you. In hind sight, and for our next R, we will probably just cut the mounts off and put in new ones rather than drill again.

[Blwalker105]

Yes, I am very familiar with Aircraft Spruce after 5 years of building N36LV, but more than once I received bolts that were 1 or 2 AN sizes off and they do not carry the -8 jet nuts. Very few retailers carry these MS21042-8 nuts due to their cost.

[Blwalker105]

Thanks, RetroRacing. For the front transverse link I decided to go with a 12 x 90mm bolt, cut off a little thread length and washer it up a bit. I have found that metric bolts are available only in 10mm increments and the tolerance for thread length is between 30-39mm...not very precise.

The bracket change would be far cheaper and expeditious.

[ssssly]

What did you end up doing for the rear end?

[Blwalker105]

Let me check my notes and get back to you.

[Blwalker105]

Firstly, I purchased aftermarket lower lateral links and lower trailing arms from eBay. For the lateral links, I used the included hardware inboard and the long donor bolt and hardware outboard. For the upper lateral link I used AN8-21 bolts inboard and outboard. For the upper trailing link, I used an AN8-22 at the front and an AN8-21 at the rear. For the lower trailing arm I used an AN8-32 at the front and an AN8-27 at the rear. MS21042-8 nuts were used everywhere.

[Blwalker105]

It wasn't really a big deal to drill out the various brackets for the 1/2" hardware. All my hardware came from Pegasus Racing.

[ssssly]

Thank you much!

[mikeinatlanta]

I love seeing threads with this level of work. Thanks for posting. Most of my fasteners have been converted to aircraft hardware.

[UnhipPopano]

Two questions. First, in looking at the OEM nuts, they identify the use of "Self Locking" and "MS21042-8 nuts" are not self locking. How are you going to prevent the nuts from working loose?

Second, there is a lot of communication where the bolts and the bushings corrode together and fuse unless there is a liberal amount of anti-sizing grease used. This indicates that there is a tight fit between the bolts and the bushings. If you are drilling the bushings out, how do you control the clearances and if the bushings are surface hardened, are you not removing that hardening and should have early failure?

[DanielsDM]

Two questions. First, in looking at the OEM nuts, they identify the use of "Self Locking" and "MS21042-8 nuts" are not self locking. How are you going to prevent the nuts from working loose?

https://www.pegasusautoracing.com/productselection.asp?Product=MS21042

MS21042 (jetnuts) are self locking, deformed thread at the top of the nut. You cannot thread these on by hand. Primarily used high temp areas where nylon locking nuts cannot.