Taylor Race tripod failure

[The AFX Master]

I'm in charge of the drivetrain of our 08' car.. But 07 is still running around for driver training and reliability testing.

Since our car's first run, a total of four tripods from Taylor Race Engineering (yes.. 200$+ of sweat and pain) failed in the same car position, and the same conditions, exactly, the inboard tripod on the right side (the largest of the two shafts)
The failure is the same always, the retaining clip that retains the tripod bearing simply "blew up" and all the needles fly around under the grease boot, so the tripod gets almost destroyed.

Our inboard tripod housings are custom made, but the rare thing is that ALWAYS is the same tripod location that catch the failure. Although we're planning to buy a set of tulip stub axles from Taylor next years, we need to solve the damn thing in order to continue our scheduled runouts with the car.

We're mantaining the max angles below 13 degree so vibrations or a wrong tulip stub lenght would be the cause of the failures. Is there another reason?, Or another team had this problem before?

Thanks in advance

[Nick H]

We had a similar problem, and found the problem to be that the 3 bores in the tripod housing that the tripod bearings ride in were too tight around the bearing.

[The AFX Master]

we're running almost 0.5 mm of free play at the tripods relative to the stub axle.. but i'm wondering if more free play would create some surface fatigue due to shock loads on the drivetrain

[Travis Garrison]

.010" on the diameter should be enough clearance for the taylor tripods...are you positive you actually have that throughout the bore? Breaking the retaining clip would seam to indicate a tight spot in the bore.

[The AFX Master]

Although is difficult to measure, i'm near sure that the tolerance is in the same range across the bore because it was made with an end mill and then with a reamer at specified tolerance. The main thing that i think would be problematic is the distance that exists between the corners on the open part of the bore circle, that distance is roughly equal to the minimum diameter at the tripod bearing

[Pete Marsh]

Hi AFX from Somewherebourg?

We have had this problem for some time. The joints them selves changed a little bit some time ago and we had failures in places that worked fine before.
The problem is caused by the retaining ring touching the housing as the joint moves in its clearence.
Increasing the ID of the housing would fix it but we are already maxed out within the wheel bearings we use.
Reducing the driveshaft angle to less than 6 or 7 deg will also fix it.
You can grind down the standard needle retainer or make your own that is lower profile and this will fix it.

If you manage to find a supplier for the old ones let us know as I liked it better when you could just grease them up and put them in and forget about them.

Pete.

[Ppada]

well this is really interesting...
Can you please upload some photos of the broken ones?

[drivetrainUW-Platt]

Are you guys allowing the proper amount of plunge/pull in your driveshaft lengths? An incorrect amount will either smash the axles into the bottoms of the tripods or pull them too far out and wear them quickly.

[The AFX Master]

Totally, In full bump/droop travel i have near 3mm of plunge travel, we cut the filler rod in order to get an extra 2mm in case of a Murphy episode. Some guy of Taylor Race pulled the axles at the competition to feel if the preload was ok, and it was, at least for him.

I'll publish some photos tomorrow when i'll go to the shop. and btw, today was a pilot test endurance day... so another blown 50$ thingie would be on the car right now.

I was wondering if an ordinary external retaining clip would have success on get rid of the failure...

[Scotty]

That person at Taylor Race would be me...Scotty.
If 4 tri-pods have failed the exact same way in the exact same location four different times,I would would have to say it is a tri-pod housing issue and not the joint.
I see this a couple times a year. If you could, Please e-mail me some pictures of the housing.And some drawing too if you have them.

scotty@taylor-race.com

[Patrick]

From my past experiences with these tripods, and after speaking with several other teams regarding very similar failures, it seems that the TRE tripods are very sensitive to the stiffness of the tripod housing. Deflections in the area of housing that captures the roller exposes the roller to the centripetal forces associated with the rotating drivetrain. The miniature (and in my opinion poorly designed) retaining ring gets pushed off, and needles begin to play a game called "lets grenade the tripod housing."

-Patrick DeGrosse Jr.
RPI Alum
NASA - Jet Propulsion Laboratory

[Scotty]

If there are issues with our tri-pod joints I would really like to see pictures of the broken joint as well drawings of the housings to see if we can figure out what the issues are.
I have asked for these on this forum, and in a e-mail as well.

Scotty

[duckei]

Ahhh yes. Nicely put Pat. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Patrick]

Scotty if you recall last year RPI was in contact with you quite frequently regarding our tripod failures. We all (TRE, RPI, Bob Woods) eventually concluded from the pictures and remnants of the housing that housing stiffness was to blame. I just wish the tripods were less sensitive to this issue. (at Michigan another top placing upstate New York school told me that Ford Fiestas use bulletproof tripods? I haven't verified that...)

-Patrick DeGrosse Jr.
RPI Alum
NASA - Jet Propulsion Laboratory

[Scotty]

Point taken Patrick.
And we did work togather to resolve your housing dilemma.
And if I recall once your housing issue was resolved you had no more tri-pod joint issues, and went on to finish all the events at East comp.

The tripod joint you might be thinking of is a 22 spline joint that we supply to some of our Ralt RT40/41 Formula Atlantic customers.
It is the next size up from are small ones with a roller O.D of 29.95mm

[Patrick]

Yea I guess you could say we resolved it... we put a mildly sketchy interference fitting 7075 ring around the housing (think.. girdle) since we were unable to remake new housings. This year we (well.. they... damn graduating sucks) will be lowering the roof of the housing per your recommendations and increasing the wall thickness slightly. Only time will tell if these changes make our drivetrain fully bulletproof.

-Patrick DeGrosse Jr.
RPI Alum
NASA - Jet Propulsion Laboratory

[Scotty]

Please keep me posted on what you guys are doing Patrick.

No such thing as bulletproof......Throw in a safety factor..Call it Bullet Resistant..
Many years in racing have tought me this..