Wheel Bearing Fit Tolerances

[Baz]

We have a set of taylor race 64mm od wheel bearings (FAG brand) and will be running a live spindle setup. So I am interested in what bearing tolerances I should be setting for my aluminum 6061 upright-do other teams have a bogey that they use for the Taylor bearings? I have looked all over the interwebs for the FAG bearing tolerances and have found nothing... and I am not sure how bearing tolerances differ among bearing styles/types, but I'm sure it is important enough that I need a specific tolerance for this wheel bearing. Anyone have any suggestions for where to look for this information?

Thanks!

[Baz]

We have a set of taylor race 64mm od wheel bearings (FAG brand) and will be running a live spindle setup. So I am interested in what bearing tolerances I should be setting for my aluminum 6061 upright-do other teams have a bogey that they use for the Taylor bearings? I have looked all over the interwebs for the FAG bearing tolerances and have found nothing... and I am not sure how bearing tolerances differ among bearing styles/types, but I'm sure it is important enough that I need a specific tolerance for this wheel bearing. Anyone have any suggestions for where to look for this information?

Thanks!

[Richard Pare]

Rather than just giving you the answer, try looking in the Engineering sections of both the FAG catalogue, as well as the SKF. It's there, at least in my older catalogues.

[Baz]

Thanks Richard, I wasnt aware that the FAG catalog might be on their website... looking for it in the media section right now!

[fixitmattman]

Damn near every bearing manufacturer worth buying from will provide in their product literature (99/100 available on the website) recommended tolerancing for various fits of their product. This should without a doubt be your first stop.

Coincidentally these are usually based around the standard limits and fits systems found in any worthy engineering textbook.

[Baz]

Thanks guys.. I was able to find out the needed info... Its funny how you search for hours with no answer, and then you post on here and a few minutes later you realize youre and idiot and then you're headed in the right direction!

Thanks again!

We have a set of taylor race 64mm od wheel bearings (FAG brand) and will be running a live spindle setup. So I am interested in what bearing tolerances I should be setting for my aluminum 6061 upright-do other teams have a bogey that they use for NY Escort (http://www.asianescortsny.com) the Taylor bearings? I have looked all over the interwebs for NY Escorts (http://www.asianescortsny.com) the FAG bearing tolerances and have found nothing... and I am NY Asian Escorts (http://www.asianescortsny.com) not sure how bearing NY Asian Escort (http://www.asianescortsny.com) tolerances differ among bearing styles/types, but I'm sure it is important enough that I need a specific tolerance for this wheel bearing. Anyone have any suggestions for where to look for this information?

[exFSAE]

Out of curiosity, what is the recommendation you found?

From experience I'll say you don't need hardly any interference fit.

Maybe 0.0005 - 0.0010 interference in an aluminum upright, and 0.0000 - 0.0005 interference on a steel hub going into the thing. Basically 1 thou or less in both. All you're doing is locating the pieces.

[Ian_N]

Check out pages 165 onward of the latest SKF catalogue, it'll give you all the information you need.

With regards to an aluminium housing, you'd need a good interference fit though to account for heat expansion from the brakes.

[Richard Pare]

If you are using the "cartridge" bearings - ie - a sealed automobile unit that has 2 angular contact ball arrangements - they generally require slightly more crush than the regular angular contact bearings because of the thin outer race. If I remember correctly, it is about .001" per inch of diameter.

Also, be aware that the FAG automotive replacement units are generally .002" bigger than nominal - ie - a 64mm OD will actually be 64mm+.002". This is because they expect that the automotive strut that it will go into has most likely been stretched with use over the years. SKF automotive replacement bearings are all right on size.

Beware of SKF units made in Brazil - our experience in FF and FC, etc., is that they will last about 1 hour before loosening up.

[exFSAE]

0.001 per inch of diameter is a good rule of thumb for a medium press.. but IMO that's kind of a lot for this application.

Having used a couple different bearing arrangements (including cartridge bearings) on FSAE cars, the medium to heavy press would make the bearing noticeably less free.

As far as I know you only need the interference to accurately locate the thing and keep it from getting tweaked in there. Don't need to transfer any torque, don't need to capture the thing axially (hard stops like c-clips or retaining features are better suited!).

I always had the most success and easiest time with a light press (0.0005" / inch of diameter.. roughly).

Also, keep in mind, many bearing manufacturers make the same item. At times I had trouble sourcing FAG & INA bearings, particularly the nice compact lightweight duty ones well-suited for FSAE. If you go through a place like Applied Industrial and tell them the bearing # (e.g. 3207-2RS) and they can give you a variety of manufacturers.

[Richard Pare]

Maybe. Mabe not. It depends on the temperature that the uprights will get to during the competition.

Naturally, if your uprights don't see much heat because of the low loads and short runs you make, then the lighter fit will suffice.

[kapps]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exFSAE:
Out of curiosity, what is the recommendation you found?

From experience I'll say you don't need hardly any interference fit.

Maybe 0.0005 - 0.0010 interference in an aluminum upright, and 0.0000 - 0.0005 interference on a steel hub going into the thing. Basically 1 thou or less in both. All you're doing is locating the pieces. </div></BLOCKQUOTE>

We've done a little more than that. The .001 per inch is probably a good rule for the commonly used sizes on these cars. We run a thou or two undersize, pop the upright in the oven at 350, let it bake for 20 minutes, then take it out and put the bearing right in.

[Richard Pare]

One other thing to remember - the bearing gets some of it's clearance rating ( its lack of slop) from the press fit, so if you make it too loose, the bearing will be sloppier that it should be. Whether or not that's a bad thing depends on the duty use and other requirements.

[Yellow Ranger]

Exactly Richard.

Also, can you control your tolereances well enough for this to be realistic or are you going to have to whip out the green locktite?

[exFSAE]

Cutting the metal within a few tenths is surprisingly not that bad.

I dunno. Just my preference, but I liked to lean closer to a light press than heavy. I also don't like heating the uprights up if you don't need to. There's definitely a strength versus temperature curve.. all of this stems out of my first year on FSAE where between a heavy press and heat, we failed an upright when pressing the hub in.

But that's a long story...

[Richard Pare]

Heating uprights, regardless of the material, is standard practice, and is actually recommended by the bearing manufacturers.

The idea is to expand the hole just enough for the bearing to almost fall in. Doing this eliminates the usual problem of getting the bearing slightly cockeyed and scraping out some of the wall material.

Alu alloys can easily withstand 250F, and steels 350 or more, without losing their temper and strength.

If heating an alu upright to 200 degrees F makes it too weak to withstand the pressfit, then just imagine how close you are to the edge in your design when it hits 175 out on the track, and adding in all the cornering loads on top of the pressfit stresses.

[exFSAE]

I never said it was a good design http://fsae.com/groupee_common/emoticons/icon_smile.gif