Diff Carrier Bearings

[PedalOnTheRight]

In the past, our diff carriers (the part that houses the bearings and supports the differential) have been made from 7075 and quite wide (laterally) in order to incorporate surfaces for the bearing race to resist lateral loading.

I've seen a bunch of designs with very thin (ie <0.75in or so) and am wondering what bearings are being used in these thin carriers.

Here's an example of "thin" carriers.

http://dot.etec.wwu.edu/fsae/HostedPics/2007_FSAE_West/...y/pages/IMG_1498.htm (http://dot.etec.wwu.edu/fsae/HostedPics/2007_FSAE_West/Wednesday/pages/IMG_1498.htm)

[PedalOnTheRight]

In the past, our diff carriers (the part that houses the bearings and supports the differential) have been made from 7075 and quite wide (laterally) in order to incorporate surfaces for the bearing race to resist lateral loading.

I've seen a bunch of designs with very thin (ie &lt;0.75in or so) and am wondering what bearings are being used in these thin carriers.

Here's an example of "thin" carriers.

http://dot.etec.wwu.edu/fsae/HostedPics/2007_FSAE_West/...y/pages/IMG_1498.htm (http://dot.etec.wwu.edu/fsae/HostedPics/2007_FSAE_West/Wednesday/pages/IMG_1498.htm)

[The AFX Master]

We ran 5mm 6061T6 plates this year, on the limit of being thinner.. But be careful with adding enough lateral stability to the plate because due to the low moment of inertia it'll fail due to buckling.

You can do steel or aluminum bearing carriers and press-fit them on the plates

[rjwoods77]

be sure to read the recent post about TRE tripod failures. Be sure not to comprimise the stiffness of your assembly or problems may result.

[PedalOnTheRight]

Thanks for the responses, but I'm wondering about the actual bearings used in 5mm type carriers. What type of bearings are utilized along with their manufacturers? How much lateral support do they typically need? Etc.

[Chris Allbee]

Go online and look up the Timken bearing catalog. The 9100K and 9300K series have a wide range of bearing sizes and load capacities that could be acceptable for that application.

[Conor]

We borrowed a diff out of an ATV and ended up machining the 29mm bearing surface down to 28mm. Then we picked the slimmest SEALED 28mm ID bearing we could find...

[PedalOnTheRight]

Timkin has some great stuff, thanks for the link.

Anyone else that can help?

[Scotty]

Rob,

What does a tri-pod issue have to do with a diff bearing....

Our diff bearings are .706 wide.With an I.D of 2.57 and an OD of 3.93.
They are currantly run on 900 pound cars with 180+ HP at 170MPH.
Generating 1600 + pounds of down force and pulling 3g corners.
With our 02002011 small tri-pod....

I,m not understanding your post here Rob.

[rjwoods77]

I wasnt banging on your stuff Scotty. I just told the kid there was a post talking about diff carrier stiffness and a possible problems that may arise from it that may affect other things in the driveline. The only reason for someone busting your stuff is from misuse or underengineering as we both know that you sell the same stuff in bigger more pwerful cars. Sorry if it came across to you or anyone that you stuff has problems. I was just telling him to get all the information about what is back there and not just focus on how light he can make diff carriers.

[PedalOnTheRight]

Great Rob...

Anyone have relevant information?

[rjwoods77]

Pedal,

No need for the sarcasm. The same guy(afx) that told you his minimum plate thickness,assuming you might use that as a lower end benchmark, is the same guy that is bringing up questions about bust TRE joints about 3 days ago that attributed the problems to diff carrier stiffness. If you take the time to calulate the loads induced from the chain and the torsion of the half shafts, along with any other forces that might be going on(this is the real question to ask, that I dont know because I never dealt with a diff, that really needed to be asked) you will quickly find out what kind of bearing you need. Asking what size bearing to use is equivalent to someone asking what size rod ends to use on a pullrod. Run a couple numbers and find out. Dont take this as me getting smart with you because the whole car I designed/worked on was educated/experience guess instead of a engineered solution.

[scotty young Taylor Race]

Sorry Rob....been one of them days dude.
I did not mean for my post to be offensive.
And thanks for the support Rob....

where is my freakin Tee-Shirt Rob.

Scotty
Taylor Race Engineering

[rjwoods77]

Scotty,

Dont worry brother. I got a good feel of what kind of person you are from our talks on the phone and hanging out in Detroit. I am working on those brakes I was telling you about. Might make SEMA/PRI next year. Next paycheck i'll get the shirts going.

[Foote]

I'll second Chris' suggestion above. Check out the Timken catalog.
I don't remember the model numbers that we used, but they were timken single row tapered roller bearing. We had one big one and one small one - I think the larger one had a 1.75" id (which was too small) and was about 5/8" thick.
I think the carriers were .75" thick
Here's a pic:
http://dot.etec.wwu.edu/fsae/HostedPics/2006_FSAE_West/...1/pages/DSC01564.htm (http://dot.etec.wwu.edu/fsae/HostedPics/2006_FSAE_West/Wednesday_v1/pages/DSC01564.htm)

[Conor]

How much axial loading do the bearings in the carrier actually see? If you have plunging CVs, I would think that whatever movement or load applied axially to the axles would be accomodated for by these type of CVs. Maybe I was wrong in my assumptions... it wouldn't be the first time. We ran single row, non tapered or angular contact bearings in the last vehicle and didn't have a problem.

[The AFX Master]

@ Rob Woods

Remember me to buy a wholesale of your T-Shirts

First, don be narrow minded. The fact that we have a tripod problem doesnt mean directly that you can blame it on a differential carrier or any part because you want. Be an engineer and think a bit without being offensive. sometimes, failure comes from the most shiny and less suspected part.
My point there is that you can do a equally stiffer part from a 5mm plate and a 3/8" one if you put the constraints and do the math where is needed. You can suggest "Do it stiff enough", but you can't say "Don do it with x or y material", because YOU DO NOT know the material/availability/budget of a team. and afaik, 6061T6/7075T6 aren't a walmart hot sale.
I can remember you also that i'm not from the US

do you know how is it constrained?, no, you don't.
do you know displacements/stress and such, no, you also don't.
So i f you don't know the boundary, and the load configuration of the system you can't judge it at least honestly.


@ Scotty

I'm doing some important things apart FSAE since 10 days ago. I'll send you all the stuff related to the tripod failure across the next week. Our last run with the car was possitive, the tripod was intact. Sorry for the long wait

[The AFX Master]

EDIT
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> The same guy(afx) that told you his minimum plate thickness,assuming you might use that as a lower end benchmark, is the same guy that is bringing up questions about bust TRE joints about 3 days ago that attributed the problems to diff carrier stiffness. </div></BLOCKQUOTE>

BTW Rob, You can quote where i said that i did blame the tripod failure on a non stiff carrier?.
In the topic, the common issue was "tripod housing (tulip stub) stiffness"

Dude.. when you'll low your ego down?, isn't it a forum to HELP/Get HELP from/to others??

[rjwoods77]

To think this all started with a comment about taking a look at another post to have more information to battle with. Yeah i got the stiffness thing wrong. Oops. The stiffness of the diff assembly is very important none the same. Our old formula car had problems with this. You sure got sore when I wasnt alluding to anything bad about you. Fuck people need to get some thicker skin.

[PedalOnTheRight]

I appreciate the help that most of you have given especially regarding various bearing types. It's obvious that we all have different ideas about what a "diff carrier" should be (some of our teams integrate them into the rear boxes, others are essentially "floating"). I mainly wanted some kind of idea as to what thicknesses teams were using for diff carriers and some options for bearing types. Any more info on those topics would be helpful.

I'm not talking about being a good engineer and analyzing all the ins and outs, I'll do that on my own time. Just want to get some concepts banging around in my head first.

[Kurt Bilinski]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Conor:
How much axial loading do the bearings in the carrier actually see? If you have plunging CVs, I would think that whatever movement or load applied axially to the axles would be accomodated for by these type of CVs. </div></BLOCKQUOTE>

I agree with this. Assuming you're using IRS, and half-shafts with plunging CVs, it "seems" like the lateral load would be extremely small. Am I missing something?