Front Hub Bearings, Again!

[loustaller]

I trial fit the front hubs today and found they were both quite tight but I was able to get them in place with a few taps of a rubber mallet. Once I tighten the spindle nut the hubs do not spin freely but I was able to turn them by hand with minimal effort. The bearings are new and are dry without grease and are the old school ball bearings. Is this OK? Will they spin or turn more easily when packed with grease. Help, I’m having a senior moment!

[Steve Simmons]

It sounds like the spacer between the bearings is off. Measure the length of the spacer and then measure the raised area inside the hub between the two bearings. The measurements should be the same. If not and the spacer is too short, you can use shims to get things lined up.

If the spacer is too long then it needs to be shortened. This should be done as precisely as possible, preferably on a lathe or mill. If it's just a matter of a thousandth of an inch or two, you might be able to get away with sanding it carefully on a very flat surface.

With dry bearings, the bare hub should spin quite easily. Once packed with grease, it will not spin freely unless you have a wheel on it to add momentum.

[loustaller]

Looks like I’m all screwed up! I’ll check the spacer as you recommend and as written up in past posts and see what I come up with. Thanks.

[Duncan M]

How many miles on your hubs? Are they old? The hubs are a high wear item if not adjusted correctly. No way to fix them once worn. The hubs wear where the bearings fit into the hub.

[loustaller]

I’m thinking the hubs are as old as the car. We checked them and they are ok. The car is a low mileage original car that I bought in pieces. As I previously mentioned, I had to persuade the new bearings/hub onto the spindles with a few hard taps of a rubber mallet. I did dress the bearings surfaces of the hub with some crocus cloth prior to putting the hub on. As Steve recommended I’ll check the spacer tomorrow to see if it’s to short causing the bearings to be to tight. We’ll see...

[JohnW]

Just a thought, have you got the correct washer under the hub nut and is it the right way round?

[Duncan M]

With the old hubs off the car, press in the bearings. Once pressed in check them for any movement at all between the outer race and the hub. The way they (hubs) wear out, often they will seem to press in with a normal amount of force, but once in the hub it becomes apparent that they are actually not a tight fit when in place in the hub, and they are flopping around ever so slightly. Also, if the bearings do not require pressing in, and they can be put in by hand, the hub is also worn out.
Either condition could cause a difficult fit when installing the assembly onto the stub axle, because one or both of the bearings is askew. New front hubs run from about $150 - $200 each. AS currently has them cheaper than Moss.

[loustaller]

Out of frustration I disassembled the o/s hub including removing the bearings. I now have all the pieces out on the work bench where I can measure what I have and what I'll need. But before I reassemble the hubs I think I'll bite the bullet and order the roller bearing set FTFU offers.
After reading what I found on line and all the valuable input from you guys I summarized in my small little pea brain the use of the spacer is of upmost importance and it must have the proper clearance between the 2 bearings which is achieved with the use of available shims. It's that simple. (I think!) All the rest is common to most other car applications. Thanks for all the input and suggestions. What a great group of guys to have available!

[Steve Simmons]

Be careful, once you install the tapered bearings, sometimes they go on so tight that you can't take them off again without damage. If they don't go on by hand then it's best to set them up on a dummy spindle, and then pack the bearings and transfer everything to the car.

[loustaller]

Steve, are you saying there’s a possibility of whenever I pull the hub I might destroy the tapered bearings? Is the OD a bit too large which causes the possible damage when removing them? Sounds strange but believable.

[Steve Simmons]

The hub will come off without damaging the bearings. The small outer bearing comes off with the hub and the large inner bearing stays on the spindle. But if you need to remove the rear bearing, and it's tight, then the bearing will likely not survive. The difference is that the outer bearing will be pushed off by its race, whereas the rear bearing can only be grabbed by the bearing cage, which isn't strong enough to handle to pressure. The original ball bearings didn't have this issue because they are one piece unlike the 2-piece tapered bearings. The ball bearings both come off with the hub, and even if the inner bearing stays on the spindle, you can still get it off safely.

But again, damaging the inner tapered bearing during removal is only an issue if they go on tight. In my experience the difference between a loose bearing and a tight one is only about 0.001" between spindle OD and bearing ID.

This is what the rear bearing will look like if it goes on tight and needs to come off again. A puller can then grab the remaining bearing race and pull it off. I don't know a better way to remove it.

[loustaller]

Got it! But I do have a simple question if I may. I've read that the bearings should kind of slip into the hub and also over the spindle. When I first installed the ball bearings into the hub they were very tight and when putting the hub into the spindle I had to encourage it with a rubber mallet then tightening the hub nut pushing the hub to seat. I'm now thinking that's way to tight. If so would it be OK to run some crocus cloth over the spindle to clean it up and remove a bit of material so that the hub/bearing fits with less force?

[Steve Simmons]

The bearings should be tight in the hub, requiring tools to press in place. You really don't want them moving around as you drive, or they will continue to get looser until the hub is ruined, just as Duncan already described above. They should also be tight on the spindle but I feel they don't need to be as tight as they are in the hub since the inner races are clamped tightly by the nut. I've seen bearings that slip on and off the spindle with finger pressure, and those that require tools to install and remove. A bit of grease on the spindle helps. I suppose you could lightly smooth them but I'd be really careful to not make them loose. This probably isn't a recommended practice but with some common sense I think it would be ok. Better yet would perhaps be to measure with a micrometer and see what the spindle actually measures, then compare that with what it should be. The tapered bearings used in the TC front hubs are 20mm and 25mm.

[loustaller]

Steve, thanks for your clear and precise information. You're invaluable input and efforts to maintain this forum shouldn't go without a heart filled thank you! So, THANK YOU very much!

[loustaller]

The stub axle on my TC measures approximately 1.084 OD and the inner bearing ID measures approximately 1.079. I gingerly attempted to slide the new tapered roller bearing onto the axle (spindle) but it won't go on. Should I be able to push it on with the .005 difference?

[Steve Simmons]

Could you have been off by a 10th? A used original stub axle I just measured is 0.984". A brand new stub axle from Bob G measures 0.985". The bearings are 25mm which translates to 0.9842" although I measure closer to 0.9835" on the tapers I have sitting here and I think this is right because it won't go onto either spindle by hand.

What bearing are you using? Assuming you were off by a 10th of your vernier, that would make it 0.979". That seems way too small to me. 30205 or equivalent is the correct bearing.

[Duncan M]

30205 inner and 30304 outer for tapered bearings.

[loustaller]

I bought the bearings from FTFU. They are correct being 30205 and 30304. The inner bearing axle surface measures 0.984 as does the axle Steve has. Should the bearing 'slip' on without use of tools? I'm reluctant to try it causing the bearing to get partially stuck on the axle.

[Steve Simmons]

I have no explanation for why they measure so small. What brand are the bearings? I have some vintage Timken here as well as a new set of API and they both measure the same. I use a small piece of pipe, (de-burred inside) to tap them on. Once they are on, you may not get them off in one piece as pictured above, so make sure you have the shim stack set up before installing. I guess I would try installing them and see what happens but that size difference still bothers me, assuming the measurement is correct.

I've done countless MGB bearings and they go on and off by hand. But not the TC ones for whatever reason.

[loustaller]

Sorry for what might be some confusion. When I mentioned the inner bearing axle surface I was referring to the area of the stub axle where the inner bearing rides, which is 0.984 which is the same size as the one you measured earlier. So I'm thinking the axle is within spec. The bearings are Timken and were purchased from FTFU. I'm going to step back from this for a while because I'm now thinking going to tapered roller bearings might be what I'm looking for. We'll see.