drivetrain disaster during testing

[drywater]

guys
if you look at the image you will get a fair idea of what had happened
during the testing of our car prior to the formula student competition at uk this year we encountered this
the driver heard the slipping of the chain ,he stopped and then we saw that inboard boot of the cv joint had tore apart completely.When i opened the cv housing i found that the lock of in one of the bearings of tripod had been broken and the bearing was about the come out..but was still in place.
what my query is why had this happened
was this because of false positioning of the boot on the driveshaft(we had used taylor race cv joints and boots)?
or was it the broken seal on the tripod?
after that night i got the tripod repaired and set the boot at a new position .luckily that problem didnt occur again and we ran successfully at the event

[drywater]

guys
if you look at the image you will get a fair idea of what had happened
during the testing of our car prior to the formula student competition at uk this year we encountered this
the driver heard the slipping of the chain ,he stopped and then we saw that inboard boot of the cv joint had tore apart completely.When i opened the cv housing i found that the lock of in one of the bearings of tripod had been broken and the bearing was about the come out..but was still in place.
what my query is why had this happened
was this because of false positioning of the boot on the driveshaft(we had used taylor race cv joints and boots)?
or was it the broken seal on the tripod?
after that night i got the tripod repaired and set the boot at a new position .luckily that problem didnt occur again and we ran successfully at the event

[FryGuy]

The most likely cause is too high of misalignment in the bearing. The max angle for the Taylor race bearings is 20 degrees (i can't remember if that is total or each way). If you have more than that you will likely overstress the bearing balls and break the clip. I doubt the boot had anything to do with it.

[VFR750R]

Seeing the grease on everything, i concur the boot being ripped did not cause this particular failure.

Street car cv's fail when the grease is washed out after a tear in the boot. You didn't put nearly enough miles or drive in nasty enough conditions (water/salt) to wash out the grease and cause that type of failure.

If your designed halfshafts angles stay at less then 20deg throughout the a-arms motion, also consider deflection of all related parts. Sometimes stack up of tolerances/deflections can be enough to see failures where theory says there is plenty of saftey factor.

[Magnarama]

Hard to tell from that picture but it looks similar to what happened to us last year during testing. When we looked at ours it looked like the most likely failure mode had been that the retainer for the bearings had failed, which then let the roller bearings loose and then everything went up shit creek.

I'm not convinced that it was a misalignment issue either, as we've run that car pretty hard at comp and for driver training and hillclimbs since replacing it with no issues. We recently did a bit of a teardown on the CV's for interest's sake and the tripod housings hadn't shown any extraordinary wear and the bearings all seemed fine.

Would definitely agree that the torn boot shouldn't have been an issue, looks like there's still enough grease in there to prevent failure.

[Brett Neale]

We had a similar failure on one of our TRE tripods last year. They were run at quite an angle, but nowhere near 20deg. We found that the clips on the end that hold the needle rollers in (those pressed sheetmetal things) could be replaced with a properly sized circlip, being sure to keep the needle rollers from coming out when you replace them. We pretty much concluded that this sheetmetal clip failed on ours causing all the needles to fly out and chew everything up...

Of course, this isn't really TRE's fault, as they recommend minimising driveshaft angles to prevent this sort of failure.

EDIT - hehe thanks for that Tommo... you post ninja you...

[drywater]

thanx all of you
i think i can conclude that it was due to high angles of the halfshaft and the depressing condition of the tripod bearing retainer clip.

[Thrainer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Brett Neale:
We had a similar failure on one of our TRE tripods last year. They were run at quite an angle, but nowhere near 20deg. We found that the clips on the end that hold the needle rollers in (those pressed sheetmetal things) could be replaced with a properly sized circlip ... </div></BLOCKQUOTE>

Hi there,
we're having the same issue with the Taylor tripod's needle retainers. Even though we didn't have an incident, each tripod had one retainer that was bent.

That's an interesting solution, using a circlip, but I'm not sure if it's more or less risky.
Do you still have the same angle in the driveshaft? How long have the circlips held up? Did you do any modifications to the circlips?

I keep reading these tripods can handle up to 20?. That simply doesn't seem to be true. I've heard of several teams, including ourselves, that had severe issues at around 10? max.

Regards,
Thomas
AMZ - ETH Zurich

[drywater]

@Thrainer
we had the same angle witht driveshaft ,instead of a circlip i placed a alumunium plate as a retainer .its far better than a stock retainer.
i will post a picture as soon as our car is back to india.

[FryGuy]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Thrainer:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Brett Neale:
We had a similar failure on one of our TRE tripods last year. They were run at quite an angle, but nowhere near 20deg. We found that the clips on the end that hold the needle rollers in (those pressed sheetmetal things) could be replaced with a properly sized circlip ... </div></BLOCKQUOTE>

Hi there,
we're having the same issue with the Taylor tripod's needle retainers. Even though we didn't have an incident, each tripod had one retainer that was bent.

That's an interesting solution, using a circlip, but I'm not sure if it's more or less risky.
Do you still have the same angle in the driveshaft? How long have the circlips held up? Did you do any modifications to the circlips?

I keep reading these tripods can handle up to 20?. That simply doesn't seem to be true. I've heard of several teams, including ourselves, that had severe issues at around 10? max.

Regards,
Thomas
AMZ - ETH Zurich </div></BLOCKQUOTE>

Keep in mind that it is 20 deg. of full misalignment, not just up and down. If your axles are angled forwards or backwards, that adds to your misalignment and needs to be considered. Im not saying that's your problem just that its something that needs to be considered.

Regardless, the tripods are going to work best and most reliably if angles are held to a minimum.