A1 Racing Arms Catastrophic Failure - BeWare

[LordDigital]

Like most of you guys I wanted to have my rear end fully build.

Further I wanted to install the best off the shelf components available for tha MA70 chassie. Unfortunately there really is not much choice besides the A1 Racing Arms.

Here is a picture of my rear end when I purchased the 6 "Racing" Arms from A1 in 2007 and installed them in 2008. The list of the Arms installed was as follows:

- the A1 "Traction Rod" (A1 part number DGT010) - same as StrutRod in the TSRM
- the A1 "Toe Control Rod" (A1 part number DGT011) - same as "No1 Lower Suspension Arm" in the TSRM
-and finally based on the 2 above ,the A1 "Camber Rod" (A1 part number DGT018) - same as "No2 Lower Suspension Arm" in the TSRM

(TSRM Reference here)


Since I use my supra for competition and track days ,at the beggining of 2009 I performed annual inspection of the arms after the first year of use and discovered the following:

1.discovered that 2 of the uninstalls (hem joint) have developed excessive play and replaced it with A1 replacements.
2.Both of the "No1 Lower Suspension Arm" were making clunking noises at the base ,no play - just used my grease gun on them true the Zekrs and that solved the noise.

I did do a mid year reGrase on the No1 arms last year (2009) in the middle of the season due to the annoying clinking noise again.

At the end of the year I've again discovered some play in the No.2 Arm uniball (hem joint). It is yet to be determined whether or not it is in acceptable range.

The worst part of the A1 racing story came a few weeks ago ,when I was moving the car to my shop. I was going over insignificant bump on a straight line of road at a cold winter day when the A1 Racing replacment for the "No1 Lower Suspension Arm" just SNAPED !

As you migh imagine it took some significant car control skill to react properly and get the car under control ,after 5+ years and participating in numerous AutoX-ing and Time Atack events I consider my car control skills to be above average and some people that took a ride in the supra tend to think that they are pretty damn good (you be the judge video here ). My point is that for a lot of drivers ,that kind of failure would've resulted in an accident ,I was just lucky.


Here is a picture of the failed arm:

More Higher resolution images are availible here


Now my suggestion ,if you are planing on purchasing the A1 "Toe Control Rod" aka "No1 Lower Suspension Arm" ,do not do it.

1.The arms are Mono Adjustable ,unless you have an access to a DSP400 (Like me) you would more than likely never benefit from their advisability because it requires removing the arm from the hub

2.The arms are Steel ,not lighter than stock

0.Well ... if my pictures are clear enough ,many more of them do exist in college books for Material Science ... this is more than likley a classic failure due to the thermal stress of the metal from the poorly made weld (input needed) with a combo of material fatigue...


Last but not least - If you've already installed a pair of these ARMS ,take them off NOW before it is too late...

 

[supraguru05]

I am surprised this is the arm that failed, although after looking at the weld quality it really is no surprise. A certain vendor on this board now makes replacement arms i recommend his.

 

[supra90turbo]

Wow, that's terrible. I have the A1's but never installed them. I wonder what the return policy is after 4 years of non-use

That really sucks...

 

[hvyman]

wow. that sucks.

i think its time for these.
http://www.supramania.com/forums/sh...oduct-available.-Adjustable-rear-control-arms.

 

[92nsx]

Wow those welds on that arm look like SHIT!

Should have went with suprasport's stainless steel arms Yes there heavy, but Jack guarantees you will never brake them as long as your car is under 1,000 HP & there installed properly (shims & bushings, ect). Plus if they would brake he said he will replace them free of charge!

 

[Asterix]

What I see is the tube at the end of the arm that goes between the ears on the car was done wrong. It's the same issue that the Unobtanium nylon bushings caused. It's clear in IMG_2485.jpg.

Because the tube on the end of the link fits perfectly between the ears, there's no room for the arm to rotate except around the axis defined by the bolt through the ears. We all (should) know that this arm doesn't do that. After flexing for a while, the steel gave way where the bending force was largest.

The tube between the ears should have been shorter by at least 1/2" so something squishy, like polyurethane, could go in there and allow the arm to swing about the arc as defined by the 3 lower links.

Asterix

 

[Supraholics]

Sorry to hear that. Get Wes' arms. He's a vendor here. Beechperformance.com. They are much stronger than anything availble right now.

 

[SupraJDS]

Thats why I didn't use mine.. they are crap

 

[Poodles]

Wow those welds on that arm look like SHIT!

Should have went with suprasport's stainless steel arms Yes there heavy, but Jack guarantees you will never brake them as long as your car is under 1,000 HP & there installed properly (shims & bushings, ect). Plus if they would brake he said he will replace them free of charge!

Too bad that's the wrong arm...

 

[IJ.]

What I see is the tube at the end of the arm that goes between the ears on the car was done wrong. It's the same issue that the Unobtanium nylon bushings caused. It's clear in IMG_2485.jpg.

Because the tube on the end of the link fits perfectly between the ears, there's no room for the arm to rotate except around the axis defined by the bolt through the ears. We all (should) know that this arm doesn't do that. After flexing for a while, the steel gave way where the bending force was largest.

The tube between the ears should have been shorter by at least 1/2" so something squishy, like polyurethane, could go in there and allow the arm to swing about the arc as defined by the 3 lower links.

Asterix

Got it in one, there needs to be some rotational compliance as the arms do rotate in travel (this is why there's a spherical bearing in one of the upright pickup points and not a plain bush like the others)

 

[LordDigital]

I am surprised this is the arm that failed, although after looking at the weld quality it really is no surprise. A certain vendor on this board now makes replacement arms i recommend his.

Guru,

"Wes' " arms looks like a great alternative at a great price ,however I have one MAJOR concern with his use of uniballs at the subFrame end.

In my opinion the original Lotus design of the rear suspension was done so that the No.1 arm aka "Toe Control Rod" dynamically induces Toe in/out at various suspension loads. If a uniball (or heim joint) is utilized at the subFrame joint the arms would no longer do that. Unless my presumption for the induced Toe is incorrect ,based on my motorsports experience in chassis setups this would more than likely be a bad thing for AutoX/Track.

---------- Post added at 09:25 PM ---------- Previous post was at 09:19 PM ----------

What I see is the tube at the end of the arm that goes between the ears on the car was done wrong. It's the same issue that the Unobtanium nylon bushings caused. It's clear in IMG_2485.jpg.

Because the tube on the end of the link fits perfectly between the ears, there's no room for the arm to rotate except around the axis defined by the bolt through the ears. We all (should) know that this arm doesn't do that. After flexing for a while, the steel gave way where the bending force was largest.

The tube between the ears should have been shorter by at least 1/2" so something squishy, like polyurethane, could go in there and allow the arm to swing about the arc as defined by the 3 lower links.

Asterix

Asterix,

I believe that you have a valid point here ,I would inspect for marks on the subFrame after I remove the arm but on the pictures it looks like that there was no way for the arm to move on the horizontal plane since the rear part of the arm was almost in direct interference with the subFrame ear. Unfortunately after junking 3 MK3’s I do not have a single OEM toe arm to see if the OEM design had conic-section ends ,if it did we pretty much would know why the A1 arm snapped…

 

[Poodles]

Without a way to rotate a bit (the heim joints give that) you get the failure you had happen. I still wouldn't run heim joints on a street car which is why wes is looking into poly ends.

 

[LordDigital]

Without a way to rotate a bit (the heim joints give that) you get the failure you had happen. I still wouldn't run heim joints on a street car which is why wes is looking into poly ends.

I know that it is all relevant ... but I did over 10k miles in the last 2 years with the A1 arms and Nylon Rear Sub bushings + Tein RA with EDC and some other extras - and the road noise and ride is were not harsh at all.

The main reason is that you get 1 heim out of 3 bushings ,the other 2 are the Hub Side bushing and the subframe bushings...

 

[upgradedsupra]

I run the A1 toe arms and have not had issues. I've been running these since '06 and the driving includes drag racing and I did the streets of willow on the big course too. I probably have over 15,000 miles on them. Maybe yours were made on Monday?

Duane

 

[supraguru05]

Guru,

"Wes' " arms looks like a great alternative at a great price ,however I have one MAJOR concern with his use of uniballs at the subFrame end.

In my opinion the original Lotus design of the rear suspension was done so that the No.1 arm aka "Toe Control Rod" dynamically induces Toe in/out at various suspension loads. If a uniball (or heim joint) is utilized at the subFrame joint the arms would no longer do that. Unless my presumption for the induced Toe is incorrect ,based on my motorsports experience in chassis setups this would more than likely be a bad thing for AutoX/Track.

---------- Post added at 09:25 PM ---------- Previous post was at 09:19 PM ----------

In race cars I would rather have zero things changing especially toe. Not to mention your toe settings should be drastically different road racing to autocross. I don't like the use of rod ends either on his arms, hence why I am on stock arms, but unless you want to go back to stock arms his are the best option right now.

 

[Asterix]

In race cars I would rather have zero things changing especially toe.

The reason the 5-link rear suspension we have works so well is that it keeps the toe under control as the wheel moves around. There's a good reason why arms No.1 and No.2 have ball joints at the spindle. It's part of the system. And, why does the upper arm connect to the spindle with a ball joint? The suspension was designed to have compliance in the bushings for a cushy ride, yet keep the toe under control especially under acceleration and braking when the wheel moves forward and back. Toyota chose different compliances for the different arms to get the whole thing to work well.

I'm with LordDigital - I personally wouldn't ever put rigid joints, like spherical bearings, on these lower arms. It would probably defeat the way the system works and maybe even cause problems like we see here. Rigid bearings on the upper arm is fine. I think there needs to be some compliance where the lower arms connect, except at those two places Toyota put rigid bearings. I could be wrong, since I've never tried it.

My '88 has had polyu bushings in the rear now for 15 years and 100,000 miles without any issues except sounding like a squeaky old mattress when it's warm. However, this recent breakage has me slightly worried, so I climbed under to inspect the arms carefully, and they look just fine. It's never been on a track, but I certainly don't baby it in the roads which aren't exactly smooth. IIRC, I used 85A for the polyu, but it may have been 80A. The arms are stock. (I used 75D for the upper arms, which is quite hard.)

Asterix

 

[LordDigital]

In race cars I would rather have zero things changing especially toe. Not to mention your toe settings should be drastically different road racing to autocross. I don't like the use of rod ends either on his arms, hence why I am on stock arms, but unless you want to go back to stock arms his are the best option right now.

I agree with you that in general on a Race car you set aggressive STATIC Toe-In (for High speed Tracks) or Toe-Out (for Low Speed Tracks such as AutoX).

Most of my Track settings were in the range of -1.5 degree and lower ,which could mean one thing only for a Road car - excessive tire wear. IMO the Road car has its suspension with almost 0 toe and induces Toe In at braking to achieve the rear end stability. Now the BIG question here is how much toe in would be required to have a decent stability on MA70 chassis ... and it is terrible unfortunate that we do not know the answer to this ,the DTM and Group A experience is long lost ,and I frankly don't know anyone that used this chassis for any serious racing in the last 10+years. I'll be very interested to see any pictures of the rear suspension implementation on a Group A or DTM cars ,in the mean time I guess it really is mostly you and me working ot ReInventing the wheel via trial and error...

---------- Post added at 01:45 AM ---------- Previous post was at 01:38 AM ----------

Sorry for the NOOB question but if I have an aftermarket toe control arm with heim joints on both ends then this issue would not be applicable?

Also, I purchased a pair of A1 "strut" rods, are these goig to be succeptible to similar issues?

You might have some other issues with the Heim Joints on the Toe Control but they should not result in failures like the one that I’ve described in this thread

Te rest of the A1 arms (as I mentioned here) are completely different design which combined with the geometry of the suspension makes their use pretty safe.

 

[wesbeech]

Well i will say i just drove my car today for the first time with the heim joints and i dont think they are to noisy you do get some road noise but it is not bad.

 

[LordDigital]

Just to let you guys know -I contacted A1 and informed them about the failure as I mentioned here ,they demanded me to ship them the broken arm together with the original invoice ... an invoice that I do not have and a shipping charge that I don't feel responsible for at all not to mention the fact that they did not offer me a replacement (not that I need it).

After the fact that they only found time to send me ONE single email in 7 days I decided that I will send both arms together with a OEM one to a LAB at my expense and have them investigate the failure ,I don't know how long would this take because I don't even have an OEM arm right now but I'm hoping that I will be able to get at least one out of the TKO Supra which I will be dismantling next week...

 

[Cz.]

They demanded you ship them the broken arm on your dime? Pretty shitty CS as far as I'm concerned. Glad I never got around to buying any of the their parts.
Bumping for any update from them about this.