main wheel bearing retainer ring position

[URracing]

Just a quick question but I'm curious as to see if there anyone has any feedback on this:

We are using aluminum CNC machined uprights where the bearing housing is bored out with a retaining wall on one side of the uright and an inner snap ring groove on the other side. All the snap ring is doing is retaining the bearing from coming out of the upright, simple enough. I'm just curious to see if there is any difference as to whether we should have the snap ring on the inboard side or the outboard side of the upright. The hub centre simply presses into the bearing while a stub axle slides through from the inboard side and secured on the outboard side with a nylock nut. It makes no difference in regards to removing the bearing because the hub would have to be pulled out of the bearing anyway after the stub axle is removed.

Taylor-race generic drawing shows the snap ring being placed on the outboard side of the upright but on ours, we have the snap ring on the inboard side. Does this make a difference?

Thanks IA. Cheers, Brett

[URracing]

Just a quick question but I'm curious as to see if there anyone has any feedback on this:

We are using aluminum CNC machined uprights where the bearing housing is bored out with a retaining wall on one side of the uright and an inner snap ring groove on the other side. All the snap ring is doing is retaining the bearing from coming out of the upright, simple enough. I'm just curious to see if there is any difference as to whether we should have the snap ring on the inboard side or the outboard side of the upright. The hub centre simply presses into the bearing while a stub axle slides through from the inboard side and secured on the outboard side with a nylock nut. It makes no difference in regards to removing the bearing because the hub would have to be pulled out of the bearing anyway after the stub axle is removed.

Taylor-race generic drawing shows the snap ring being placed on the outboard side of the upright but on ours, we have the snap ring on the inboard side. Does this make a difference?

Thanks IA. Cheers, Brett

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by URracing:
Just a quick question but I'm curious as to see if there anyone has any feedback on this:

We are using aluminum CNC machined uprights where the bearing housing is bored out with a retaining wall on one side of the uright and an inner snap ring groove on the other side. All the snap ring is doing is retaining the bearing from coming out of the upright, simple enough. I'm just curious to see if there is any difference as to whether we should have the snap ring on the inboard side or the outboard side of the upright. The hub centre simply presses into the bearing while a stub axle slides through from the inboard side and secured on the outboard side with a nylock nut. It makes no difference in regards to removing the bearing because the hub would have to be pulled out of the bearing anyway after the stub axle is removed.

Taylor-race generic drawing shows the snap ring being placed on the outboard side of the upright but on ours, we have the snap ring on the inboard side. Does this make a difference?

Thanks IA. Cheers, Brett </div></BLOCKQUOTE>

That's exactly how our's is. I really don't think it makes a difference, but for some reason it feels safer to have the retaining wall on the outboard side. Taylor probably just puts the snap ring outboard for easier maintenance.

[Mike Sadie]

it does sound safer having it on the outboard side, because you are less likely to lose a wheel. However, the lateral forces are much higher towards the inboard side, so we feel more comfortable having the lip in. It likely isn't an issue because the press fit most teams use is sufficient to hold the bearing in place.

[exFSAE]

We used a light press fit for our wheel bearings and hubs (steel hubs, aluminum uprights). More of a locating fit than anything. Lateral force may have been enough to move it, not sure.

In any event, lateral force developed loads the inboard side more than the outboard, so logically you'd want to have the snapring on the outboard. Just good practice, no?

[the weldmeister]

what type of wheel bearings are you using?

carrol smith recommends that the bearings be pretensioned against each other with a spacer and a nut - in that case a shoulder and snap ring (circlip) will not do. but i guess if teams who don't pretension their bearings don't have problems, then it's not necessary.

[the weldmeister]

why is it that the inboard side is more loaded than the outboard side?
because of the cornering force from the tyres being pointed inwards?

[Mike Hart]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by the weldmeister:
why is it that the inboard side is more loaded than the outboard side?
because of the cornering force from the tyres being pointed inwards? </div></BLOCKQUOTE>

I personally wouldn't say it's more loaded, but I think what they're trying to say is that when your cornering the outside wheel is going to be trying to push the bearings towards the car. Seeing as I imagine you have some kind of flange or spacer between the two bearings, the outside bearing will be pushing against this whereas the outside one will be pushing against whatever you have to retain the bearing. The inside wheel will of course be loaded less than the outside, so it will be less of an issue. Either way, I personally don't think you really need anything more than a press fit. That's what we do, and haven't had any issues in the 3 years we've been doing it (touch wood!).

[exFSAE]

Initially when no weight has been transferred both tires will react similarly to a steer input, so both the inboard shoulder of the outside wheel, and the outboard shoulder of the inside wheel will be loaded similarly.

Under max load condition though, it'll be steady state corner (assuming youre not hitting a curb...), weight is transfered and outside wheel is really doing all the work.

Weldmeister - that Carroll Smith thing assumes you're using two individual bearings, for example two individual ACBB's. In that case yea you have a spacer in there and preload the bearings.

I never liked doing that. More parts, more expensive. DRACBB's IMO are the way to go. No need for any of that other malarky, and a shoulder + snapring is more than sufficient.

[the weldmeister]

What does everyone else feel about DRACBBs vs. two DGBBs?

With 2 DGBBs, you can have a greater centre-to-centre distance between the bearings, which is better for the strength of the stub axle (though it's not much of an advantage).

What are your experiences with these two kinds of bearings?

[Jon - FBR]

I'm designing some CNC aluminium uprights for our car this year, with the intent of using 2 deep groove ball bearings spaced apart. I understand the idea of preloading taper/AC bearings but does the same idea apply for deep groove?

Also has anyone using aluminium uprights had an issue with the inner bore surface being too soft for the bearing housing? I somehow don't like the idea of press fitting steel bearings into aluminium!

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jon - FBR:
Also has anyone using aluminium uprights had an issue with the inner bore surface being too soft for the bearing housing? I somehow don't like the idea of press fitting steel bearings into aluminium! </div></BLOCKQUOTE>
Put the upright in the oven and the bearings in the freezer?

Regards, Ian

[exFSAE]

Never had a problem with aluminum interior surface being too soft. It will burnish it a little, but the press fit should be light anyway. Shouldn't be shaving material off.

You can do the freezer/oven trick, and some times the bearing just drops right in. If you still have to press it.. be careful with how you have it set up. Alloys like 7075 don't take well to heat and if your setup is silly can snap in half.

Trust me http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Steve O]

Our uprights have a machined in outboard retaining wall and a retaining wall that bolts onto the outside of the inboard side that acts as an inboard retaining wall...We have also realized and been told that this is not necessary but it DOES eliminate the above question from entering our heads completely.

Steve

[S. Race]

If you design the press fit right, the steel bearing into an aluminum housing is just fine.

2 deep-groove ball bearings do give you the advantage of increasing stiffness by adjusting the bearing spacing, but the assembly becomes more complex. You shouldn't need a spacer between two deep groove ball bearings as the inner ring won't separate like a taper roller would. Bearing preload can be applied by whatever holds your hub into the bearings.

Did I hear right earlier that some teams are relying on a press fit to hold cornering loads? I hope not!

[C.Zinke]

I am also in favour with two seperate bearings. The weight of the two bearings in our Setup (picture 1) is just 245gramm. The spacer between the bearings takes a lot of the stress caused by lateral forces (picture 2) so that the spindle can be made with lower wall thickness.

The press fit of the inner bearing should take the lateral load, if the tire is loaded as inner tire. As i am a little afraid of using a press fit only i installed the retaining ring. What is the weight of your bearing solution?

http://img229.imageshack.us/img229/5559/10rj0.th.jpg (http://img229.imageshack.us/my.php?image=10rj0.jpg)

http://img120.imageshack.us/img120/7107/quer3cd1.th.jpg (http://img120.imageshack.us/my.php?image=quer3cd1.jpg)

Regards

Christopher

[LU-Bolton]

I would like to second what C. Zinke has said about the above issues. The main objective when running a setup such as Chris' is that you are drastically increasing the installed stiffness / weight of your wheel assembly. Did you guys really think that the compliance in your wheel assembly is coming from a component like the uprights??? Any physical test on wheel assembly stiffness will show this.

I've run many different setups in my FSAE years, but I really like what the Lions team has come up with. Great job guys! If I had access to the casting operations that you do, I probably would have built uprights similar to yours also. The only reason I was against running this setup was that thin section deep groove bearings are very expensive. On the order of $100+ / piece for a name-brand. You need, 8 per vehicle... plus spares. So that's $1000+ for wheel bearings as opposed to maybe $200 for a set of double row angular contacts.

Moral of the story: Go get a bearing sponsor.

Aaron Cassebeer

[Kirk Feldkamp]

Yikes. Now that's rasing the bar for FSAE! How many cores does that upright take? While it could be only one core, that's still got to be a pretty complex tool to make! Ok, well, 8+ tools (front/rear, left/right, cores & cavities) for the whole car. Good way to learn, but probably not very cost effective. Do you have a casting house sponsor or do you have casting capabilities at your university?

-Kirk

[C.Zinke]

Its not that complex. Of course, normal casting would be far to expensive. We use a rapid prototyping casting process.

The tool is printed. That means that a machine builds up a layer of 0.2mm sand. This are the first 0.2mm for the casting tool. The sand that is used for the casting tool will be glued together. After the first layer has been glued a new layer of 0.2mm sand will be put on top of the old layer. This repeats until the tool is completed. Its very similar to lasersintering, but only with sand and glue. After that the tool is hardened in an oven. Then you can use this tool for one part. The tool will be destroyed after the casting.

So the costs are similar to milling a upright with this geometry. The advantage is that you can design a closed profile that is stiff and light. Furthermore milling would be very complex for us. This is because we use so agressive kinematics in our car. The problem with this part is that we can design for a maximum of 90Mpa stress due to the high load-cycles caused by the ABS-System. So its quite difficult to design the part right.

To stay on-topic: What is the typical weight of one bearing per upright? Of course, i can look at typical bearings, but i first have to calculate one ;o). So anybody like to share?


Regards

Christopher

[Nihal]

The Common VW double row angular contact bearing weighs in at 1lb 2 oz.

[billywight]

Christopher-

You might want to doublecheck the boundary conditions on your hub analysis... Why are the drive pins deforming so much when the main spindle shaft is not? Can you really say your wheel centre is that compliant?