Rear Track Brace and Toe Link Failure [split from WCLM thread]

3007 Views 16 Replies 11 Participants Last post by Jack, May 20, 2006

marcw

Discussion Starter · May 19, 2006 (Edited by Moderator)

TimMullen said:
Okay, what's the story about the fork lift?

Broken rear toe link! Happened during the first track sesion! :wallbang: Made for a dramatic spin coming out of the Bus Stop section of the track, but luckily no real damage to speak of. Forklifted to Sevens Only (careful on lift points) to avoid possible CV joint damage rolling or driving car.

Stay tuned for a new, re-engineered sub $1,000 fix for this problem.

edit by Randy - This thread was split off from what was News from WCLM created by this image below

<img src="http://www.elisetalk.com/forums/attachment.php?attachmentid=28444&stc=1&d=1147980845">

1 - 17 of 17 Posts

charliex

· #2 · May 19, 2006

we saw the guy with the BRG exige and broken AC after a spin off at the wclm trackday, at the dealership today, another reason not to have it!

Stan

· #3 · May 19, 2006

marcw said:
Broken rear toe link! Happened during the first track sesion! :wallbang: Made for a dramatic spin coming out of the Bus Stop section of the track, but luckily no real damage to speak of. Forklifted to Sevens Only (careful on lift points) to avoid possible CV joint damage rolling or driving car. Stay tuned for a new, re-engineered sub $1,000 fix for this problem.

Pics of the toe link failure, please....or post elsewhere? Thanks. Many seem to be driver's side, inner.

marcw

Discussion Starter · #4 · May 19, 2006 (Edited)

Here is the WCLM trackday failure. It was the passenger's side inner. Sheared right off at the base. Track configuration was CCW.

FWIW, the inner link is attached with a 10mm diameter thread, and the outer with a 12mm thread, so the inboard side is definately the weakest part of the system.

See less See more

Stan

· #5 · May 19, 2006

marcw said:
Here is the WCLM trackday failure. It was the passenger's side inner. Sheared right off at the base. Track configuration was CCW. FWIW, the inner link is attached with a 10mm diameter thread, and the outer with a 12mm thread, so the inboard side is definately the weakest part of the system.

Well most US tracks tend to be CW, hence the higher loads on the driver's side in those instances. For CCW, the loads would tend to be greater on the passenger side. Some estimate that around 1/3 of the steady state cornering loads pass through the toe link.

Looking at the break, there are aspects of fatigue failure apparent. Some joints break on the other threaded element, where it enters the threaded tube. How much track time is on the car, tires used, offs, etc? Whatever you do, replace the other inner joint, and inspect the outers.

lights111

· #6 · May 19, 2006

oh man... sorry to hear/see Marc.

Could you clarify that this happened with the Lotus suspension brace in place? Or are you saying that you're working on one yourself because of this incident?

marcw

Discussion Starter · #7 · May 19, 2006

Hansen: Yeah...this was a bummer! Double bummer because it happened in the first morning run session!!! The rear of the car totally came around on me quite violenly exiting a corner! Youch!

I have heard stories of guys smacking the wall when this toe link breaks at speed. Luckily, no other cars or immovable objects were around at the time.

We tried to get a solution figured out trackside at the shop, but did not have the right combo of metric ball joints / bolts / rods to whip something up.

At the risk of moving this thread further OT, This toe link issue is a real problem as proven today. As I PM'ed to Stan a little while ago, this car has only 2 track days with zero offs, zero acidents, and nothing unusual in its history other than just full-bore track driving. It did not have the brace when this happened. The brace simply provides a second "shear point" meaning essentially that the inboard mounting bolt is secured not only in the front where it attaches to the chassis, but also in the rear, where it attaches to the brace. Going to a double-shear design is nice, but I feel the real issue is the size (and possibly grade) of the inboard mounting bolt itself.

What's happening is that all of this tremendous cornering load is being concentrated on a very small 10mm bolt. The metal fatigue is simply too much and the little guy just snaps without warning, and the results can be catastrophic. I think this is a potentially very dangerous situation that needs to be addressed by anyone who seriosuly tracks their Elise at speed. Im only running DOT tires and im not out there banging into the FIA curbing and it happened to me, so this is a very real issue that potentially affects a wide swath of our club membership.

I think if you track your Elise and this has not happened to you yet, either you aren't going fast enough, or your time has not yet come! -poke-

See less See more

Stan

· #8 · May 19, 2006

marcw said:
Hansen: Yeah...this was a bummer! Double bummer because it happened in the first morning run session!!! The rear of the car totally came around on me quite violenly exiting a corner! Youch!
I have heard stories of guys smacking the wall when this toe link breaks at speed. Luckily, no other cars or immovable objects were around at the time.
We tried to get a solution figured out trackside at the shop, but did not have the right combo of metric ball joints / bolts / rods to whip something up.
At the risk of moving this thread further OT, This toe link issue is a real problem as proven today. As I PM'ed to Stan a little while ago, this car has only 2 track days with zero offs, zero acidents, and nothing unusual in its history other than just full-bore track driving. It did not have the brace when this happened. The brace simply provides a second "shear point" meaning essentially that the inboard mounting bolt is secured not only in the front where it attaches to the chassis, but also in the rear, where it attaches to the brace. Going to a double-shear design is nice, but I feel the real issue is the size (and possibly grade) of the inboard mounting bolt itself.
What's happening is that all of this tremendous cornering load is being concentrated on a very small 10mm bolt. The metal fatigue is simply too much and the little guy just snaps without warning, and the results can be catastrophic. I think this is a potentially very dangerous situation that needs to be addressed by anyone who seriosuly tracks their Elise at speed. Im only running DOT tires and im not out there banging into the FIA curbing and it happened to me, so this is a very real issue that potentially affects a wide swath of our club membership. I think if you track your Elise and this has not happened to you yet, either you aren't going fast enough, or your time has not yet come! -poke-

The early failure could also have been related to too low of a tightening torque at that bolt at the a-arm end. That's not a face burr is it on the flange, need closer up pictures?

The cross section of the brace does not show one massive overload failure. It shows progressive metal going from one side to the other. This gradually leaves less and less actual cross section of metal doing all the work. At some point the thing will snap at some low cross section as shown here.

mlk_f1

· #9 · May 19, 2006

Wow, you are very lucky Marc. :crazyeyes I wouldn't dare think what would happen if it happened to me. Pretty scary stuff. I will now make this fix my priority before my next track day. I guess I just have to buy the expensive Lotus bar for the time being since there is no other solutions out there yet.

mlk_f1

· #10 · May 19, 2006

Any know if this kit below can be a solution?

http://www.eliseparts.com/shop/index.php?main_page=product_info&cPath=164&products_id=307

Stormy320

· #11 · May 19, 2006

Wow - glad your O.K. and your car is O.K.

Hmm - is there any preventative fix for this?

charliex

· #12 · May 19, 2006 (Edited)

Hmm - is there any preventative fix for this?

rear chassis brace,

ronin says 'i told you so'

continued over here
http://www.elisetalk.com/forums/showthread.php?t=23291

khamai

· #13 · May 19, 2006

Can we get back on topic?

I'd be more than happy to separate the rear suspension discussion into it's own thread or Marc can start one in that appropriate section.

Thanks,
Kiyoshi

codymac

· #14 · May 19, 2006

khamai said:
Can we get back on topic?

Seems pretty on topic to me considering the first post shows a photo of the car being forklifted. You can't come by, drop a bomb like that, and not expect people to ask about it.

eliseowner2b

· #15 · May 19, 2006 (Edited)

I sat in that Recaro seat when Hyper-Sport had it out to install the roll cage. It was perfect if not a little snug which I prefer since i need to lose 10lbs. Hyper-Sport is checkig into the seat availability. I measured it and I think it will fit with the stock Elise passenger seat. I picked it up and it seemed lighter than stock too.

On subject...How can I inspect my inner link to see if fatigue is occuring? I've done about 8 track days, 5 auto-x's, and 30 dragon tails. I just put my car on the trailer for a track day at Road Atl tomorrow and read this thread for the first time! (Bad timing!)

Since this happened to a relatively new car could it have been defective from the start? Sure, the parts are the same but the piece could have been weak or installed improperly from the beginning?

What was the date of this track event?

spider

· #16 · May 19, 2006

eliseowner2b said:
Since this happened to a relatively new car could it have been defective from the start? Sure, the parts are the same but the piece could have been weak or installed improperly from the beginning?

What was the date of this track event?

That's what I think, too; otherwise, we should have seen more failures already. Then again, it's better be safe than sorry.

The track day was yesterday (Thursday).

And someone should import those rims and the SC kit.

Jack

· #17 · May 20, 2006

marcw said:
I think if you track your Elise and this has not happened to you yet, either you aren't going fast enough, or your time has not yet come! -poke-

Marc,

As Stan intimated, how many times had you checked and tightened those toe link bolts prior to this unfortunate failure? If they had not been checked at least once after each of your two track days and at least after every 2k street miles, then therein lies the cause of your failure. In fact, my brand new Lotus got delivered with toe links which were not "torque'd" to spec. Everyone needs to check this item whether they track or not.

I do recommend the chassis brace for peace of mind and my Exige has it. But, my Elise saw over 25 track days before the brace was installed (and it was driven fast enough

) and showed no toe link issues. However, the toe links were checked on a regular basis and the bolts "torque'd" to spec quite often.

1 - 17 of 17 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.