Aluminum tripod housings - interior hardness

[Jersey Tom]

I'm sure a lot of teams have run Taylor Race drivetrain parts. They're well-designed and work.. but are overbuilt. I've been wanting to take a stab at aluminum tripod housings, with a hard anodize to give the interior a hard case for the tripods to roll around in.

Asked Craig Taylor about it, and his comment was that even with a hard anodize you wind up getting brinelling on the interior. I know teams have done it before. Any takers? Comments on interior wear resistance?

[Jersey Tom]

I'm sure a lot of teams have run Taylor Race drivetrain parts. They're well-designed and work.. but are overbuilt. I've been wanting to take a stab at aluminum tripod housings, with a hard anodize to give the interior a hard case for the tripods to roll around in.

Asked Craig Taylor about it, and his comment was that even with a hard anodize you wind up getting brinelling on the interior. I know teams have done it before. Any takers? Comments on interior wear resistance?

[Erich Ohlde]

7075-T6 ran on our 06. No problems. We ran both comps and several autocrosses on these and have developed no additional slop.

[Marshall Grice]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> 7075-T6 ran on our 06. No problems. We ran both comps and several autocrosses on these and have developed no additional slop.

</div></BLOCKQUOTE>

Same here.

[Jersey Tom]

Interesting! Bare, or hard anodize? Have you taken it apart and taken a look at the insides?

[Erich Ohlde]

Bare, It was apart before and after Cali. No noticeable deformation

[Erich Ohlde]

nope. and that is with pneumatic clutch that doesn't do anything but hard drops.

[Kevin Hayward]

At UWA we ran them bare, hard anodized, and two different designs of steel inserts (maybe a third after I left)

When run without inserts there was noticeable wear after short amounts of testing. It did not seem to get rapidly worse after the first few runs. Hard-anodizing made little to no difference on the amount of wear.

In the end we decided steel inserts were the way to go. With the aluminium the part pretty much became a component that would be replaced semi-regularly within the life of the vehicle. We usually have a vehicle running for 2-3 years of testing depending on how much trouble they produce. With a decent steel insert design they became a check it and leave it part.

For the purposes of a competition a bare aluminium housing will do the job fine and you shouldn't even notice a problem. That's pretty much what we ended up running in our first comp with aluminium housings as our hard-anodized jobs had worn beyond what we deemed acceptable during the testing leading up to the competition.

Cheers,

Kev

[Erich Ohlde]

Did you aluminum housings have much slop in them?

[ACXY]

Hi everyone,

I have been trying hard to do a proper FEA on a steel design but it always fails pathetically at the point where the tripod balls come in contact with the housing. The fact that you guys are running aluminium ones has definitely intrigued me. Can anybody care to elaborate more?

For those schools who have ran the aluminium tripod housing, I suppose it was also integrated with the spindles? What was your minimum side wall thickness?

Many thanks in advance!

Rgds,
Anthony

[Chris Allbee]

Our team tested two different grade aluminums for our tripos housing. 2024 inboard and 7075 outboard. The 2024 showed noticeable wear after as little as 10 hours of testing (checks at 1, 3, 5, and 10 hours testing before comp). The hard anodize would reduce sliding wear, but wouldn't really have any effect on bearing surface deformation so we opted not to go for it. If you are only concerned about running the car for 1-2 years of competition and then come autocrossing then the 7075-T6 or 7055-T6 should do nicely.

ACXY, how are you applying that load in your FEA? FEA is notoriously finicky about needing precise boundary conditions and it is easy for even one over-simplification to skew results tremendously. On another note, our minimum sidewall thickness is somewhere near 5mm, don't have the exact measurement in front of me.

[Kevin Hayward]

Jayhawk,

The housings had minimal slop, until the Aluminium started to deform.

Kev

[Alastair Clarke]

ACXY - I wouldn't use FEA to examine the stresses where the tripod rollers/balls make contact with the housing. It's a simple Hertzian contact problem for which you can make hand calculations to determine subsurface stresses etc. If you wanted to FEA the problem, and get realistic results, you'd need a very fine mesh in the region of contact. FEA of contact problems is full of potential trouble - it will be simpler to use the Hertz equations to calculate stresses in the contact region. If you do go on to get FEA contact stress results, it'll still be a good idea to have the Hertz stress calcs in order to verify your FEA.

Problems like this is one area where I'd put money on FEA NOT giving the right results first time (trust me, contact FEA of Hertzian contact is part of my PhD which is giving me monster headaches at the moment!).

Try Ken Johnstone's book "Contact Mechanics" for the details of how to do the Hertzian contact calcs (or find a tame tribologist if you've got one in your uni).

Best of luck

Alastair

[ACXY]

Chris, I totally agree that the boudary conditions need to be extremely accurate for ideal results. In my worst case scenario, max torque (as expected at 1st gear) is applied at the contact surfaces with the splined end restrained. By the way, was the sidewall thickness higher or lower than 5mm?

Alastair, thanks for the advice. Though I have no idea what Hertzian contact is (Goodness me, do they even teach this in class? lol), I'll definitely go look up Ken Johnstone's book. Hopefully, with the guidance of probably my faculty advisor, I will be able to make sense of it.

To all, pardon my ignorance but, in a differential, e.g. Torsen with a steel side gear (with hardness RC ~30-40), don't you guys have any problems with the aluminium splined end wearing/deforming?

[Erich Ohlde]

we bolt the tripod housing to the steel stubshaft.

[pablo180]

For the teams running aluminum housings...how much do they weigh?

[Chuck Maddocks]

if you are using the maximum torque in first gear for your fea, you will end up overdesigning your components. can you spin the tires in first? the maximum torque should be traction limited

[adrial]

We used 7075 Al tripod housings outboard in '05, they worked well for competition but developed slop as testing progressed over the summer.

For '06 we moved to a steel insert, and we caught shit from the design judges for making the car "too reliable"

As for the hard anodize..I dont think it would be much help as Chris Allbee mentioned.

Yes, you should be designing for breaking the tires loose. But lets not forget about impact...but thats what safety factor is for in the world of unknowns that is FSAE at most schools.

[Jersey Tom]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">For '06 we moved to a steel insert, and we caught shit from the design judges for making the car "too reliable" </div></BLOCKQUOTE>

Man that is some BS. Knocking you for a GOOD design in a damn design judging event. Shoulda smacked the guy.

[clausen]

Hi,

http://www.kandamotorsport.com.au/ have made hundres of hard anodised aluminium tripod outers for formua fords. They're perfectly reliable and last forever.

Regards

[RKemmet]

no need to annodize we have ran 7075 tripod housings for 3 years now we have noticed afte the initial wear from the first hard launch, there is no further wear. We have our housings down to .25lbs, these also can take more loading than the units taylor race sells (according to our FEA). We have a picture somewhere with the evolution of these housings from our designs.

Ryan Kemmet
University of Arizona

[ErickN]

Hello All.

I am the lead machinist on the LTU team this year and I have made 4 aluminum 7075 tripod housings for our car this year. After seeing the posts about possible internal galling and compression failure, I chose to recut the inner tripod bores to allow for a steel liner to be placed in there. I also saw this approach from a company online that sell them this way as well.

I will have an extra one to show anyone interested at comp so stop on by.

I used .035 wall thickness high strength steel so we will see what happens.

I also made the aluminum diff housing, aluminum rear uprights, and many other billet aluminum parts on our CNC mill this year so it has been a long, yet rewarding year thus far.

Good luck to all and I hope to see everyone at comp!!

[Boston]

Anybody willing to give up the dimension for the radius of the TRE tripod balls? Prints show the length from one face to the other, but not the radius.

[RacingManiac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kevin Hayward:
At UWA we ran them bare, hard anodized, and two different designs of steel inserts (maybe a third after I left)

When run without inserts there was noticeable wear after short amounts of testing. It did not seem to get rapidly worse after the first few runs. Hard-anodizing made little to no difference on the amount of wear.

In the end we decided steel inserts were the way to go. With the aluminium the part pretty much became a component that would be replaced semi-regularly within the life of the vehicle. We usually have a vehicle running for 2-3 years of testing depending on how much trouble they produce. With a decent steel insert design they became a check it and leave it part.

For the purposes of a competition a bare aluminium housing will do the job fine and you shouldn't even notice a problem. That's pretty much what we ended up running in our first comp with aluminium housings as our hard-anodized jobs had worn beyond what we deemed acceptable during the testing leading up to the competition.

Cheers,

Kev </div></BLOCKQUOTE>

Love to see pic of the steel insert version, our 2005 car had aluminum hub with tripods and we had to replace them(swap front to rear as they are of the same design) midway through testing season as it has developed noticable slops. We have since went back to the steel hubs and taking reliability over weight penalty. I've been toying around with the idea of a steel insert version but having trouble visualizing how to actually package one...

[Scorpio]

here you go:

http://www.pegasusautoracing.com/group.asp?GroupID=TRIPOD

[kwancho]

Wow, I've never seen those before. Sweet. Same size as the TRE stuff?

[Scotty]

Those are the ones we make for the larger formula cars like Van Diemans and such.

If you are interested in some close up pictures
shoot me an e-mail .scotty@taylor-race.com

They are not the same size as our 86mm housings.
They are 94mm and we make them in 2 differant widths.The 26mm wide is 8.5 onces
And the 40mm wide is 13 onces.

You can do a part number search on our site .

www.taylor-race.com (http://www.taylor-race.com)

under part numbers 02002061 & 0200206 for more info.