Ok, How do you really adjust the front wheel bearing? I did the fiero brake store swap on the front end about a year ago. Ever since the swap I noticed a the right front seemed to wobble or pull around 70 mph. I thought I needed new tires, but since they had about 75% thread left I ruled that out. I used the Fiero Service Manual to set the wheel bearings. 12# pounds of torque then back off until the cotter pin lines up. This seemed to leave the wheel to loose which resulted in the wobble. I could wobble the right tire by grabbing it at 12 o'clock and 6 o'clock position. The same motion produced no movement on the left front tire. So when I went to readjust the right front wheel bearing I noticed the nut was not even finger tight. I could grab it with my fingers and move it. I retorqued to 12# and backed off until the cotter pin aligned. I took it for a spin and it was perfect. No wobble at all. Ran up to 100mph smooth. So what is the best way to adjust the wheel bearing?

A lot of it is feel and experience. To start with, a common mistake when repacking or replacing wheel bearings is that you just put them on, adjust them, and drive away.

The first thing you should do is really tighten them down until there is some DEFINITE drag on them and turn them over a few revolutions. This will get the excess grease out of there that can throw off the feel of things when you really do adjust them. After you've really tightened them down, loosen them up a little at a time until you can feel some play in the bearings. Grab the rotor at the top and bottom and try to wiggle it. Can you feel any? No? Then loosen it some more until you can feel some definite play. I don't mean so much that you hear it rattle in the bearings, but you should feel some play when wiggling it.

Now slowly tighten the nut in about 1/4 turn increments. Turn the rotor a revolution or so and check again. Still feel play? Tighten another 1/4 turn or so. Keep doing that until the play is all gone. As you're tightening, wiggling, and rotating, you'll feel things getting more solid as you go. When you have no more play, but feel no tightening drag on the rotor as you turn it, you're there.

Now you have to see if any of the holes line up. If you're lucky, the cotter pin will drop through. If not, you need to make a decision whether to loosen or tighten. If it's just a matter of a tiny fraction of a turn, go that way. If it's a matter of splitting the difference, first try to tighten it to get the hole to line up. When you have the cotter pin in, if you feel some definite mechanical drag on the rotor, you're too tight and you'll have to back it off a notch.

Like I said, it's mostly feel and experience. I can tell you one thing though, there have been more bearings ruined from being too tight than being installed too loose when it gets to the final tightening phase. A set of tapered roller bearings with too much preload that aren't designed for preload won't last very long at all and will loosen themselves from wear, and loosen themselves much looser than where you'd have had them set if you backed it off that 1/6 of a turn.

John Stricker

quote Originally posted by 3800dude: Ok, How do you really adjust the front wheel bearing? I did the fiero brake store swap on the front end about a year ago. Ever since the swap I noticed a the right front seemed to wobble or pull around 70 mph. I thought I needed new tires, but since they had about 75% thread left I ruled that out. I used the Fiero Service Manual to set the wheel bearings. 12# pounds of torque then back off until the cotter pin lines up. This seemed to leave the wheel to loose which resulted in the wobble. I could wobble the right tire by grabbing it at 12 o'clock and 6 o'clock position. The same motion produced no movement on the left front tire. So when I went to readjust the right front wheel bearing I noticed the nut was not even finger tight. I could grab it with my fingers and move it. I retorqued to 12# and backed off until the cotter pin aligned. I took it for a spin and it was perfect. No wobble at all. Ran up to 100mph smooth. So what is the best way to adjust the wheel bearing?

I agree with the bearing answer, Yello eats bearigns every 3 thousand or so miles,, I think this time was the cure, if not I am changing rotors.. just one of those wierd fiero things I guess,...Maintanance

yeah, this is a tough one for me to describe also. Its all by feel. But, I will also add - use the right grease. I had a Volkwagen Rabbit that I went thru alot of wheel bearings. then, on the last set, I had used up all my grease, bought a new tub, and them bearings lasted to the end of the car. dont remember what the wrong grease was, but it was called wheel bearing grease on the tub, but I think it was lithium based - like CV joint grease. anyways, when tightening the wheel nut - I spin the wheel (I do it with wheel on for more leverage) untill theres definite drag. stop tightening, but spin some more, then turn nut back to nearest cotter pin hole.

Pyrthian,yellow86se,jstricker thanks for the info. After my readjust all is well. Thanks

Absolutely do this ONLY with the pads out and calipers off. (actually, the calipers don't matter if the pads are out, just no reason to be on there).

How do you define a little? Well, it's more than none but less than a lot.

Loosen them until you have just a TINY bit of wiggle on them. Spin the rotor. That's a good approximation of what it feels like with "0" preload. Anything you have MORE than that IS preload.

If you want to get scientific about it, loosen them like I said above, take an old belt (the kind you wear, not the alternator kind), wrap it around the hub, hook a fish scale on the end and pull on it. It will read some number of pounds. As you tighten it up, you can keep checking that and when you get a couple of pounds more than 0 preload, stop. Again, this isn't usually necessary, but it is how we set the preload on some industrial transmissions.

Ideally, there would be a sleeve and positive stop on the nut and washer. Tighten it down to the stop, measure your freeplay, then shim it to some spec for preload, usually just a couple of thousandths tight. You COULD figure this out if you wanted if you knew the pitch of the thread I suppose.

WRT the grease, with rare exceptions, any good moly-disulfide grease will work just fine. What are the exceptions? Mostly the operating conditions. If you're packing bearings in a boat trailer, for instance, you want something with a LOT more fiber material in them to hold it in the bearings and a lot more tolerance to water. If you're running a strictly 1/4 mile car, don't pack them at all but put a few ounces of 90wt gear lube in them (DO NOT TRY THIS ON THE STREET!!!)

I personally prefer Massey Ferguson EPMSO2 grease, but that's just me.

Some of the easiest wheel bearings to adjust are on equipment with a grease zerk in the hub and, in fact, I've even drilled some to put one in. Then you can put the bearings in dry, adjust them appropriately, and grease them when you're finished. I wouldn't do that on a Fiero front hub though because it's just not necessary.

John Stricker

quote Originally posted by 3800dude: what do you consider little drag? Can you turn the wheel by hand with no effort or do you need to push or pull with force? Do you do this adjustment without the brake shoes installed? If the brake shoes are installed do you feel more drag? Do you go so tight that the wheel stops moving and then back off?