TheExaminer

I just bought a 92 Formula L98, and I know almost nothing about the vehicle history, its a total crap shoot. This morning was the first time I drove it any distance because I just got plates on it. I noticed a low grinding coming from the rear axle at low speed, then when you get to about 40 it turns into a loud whine. As you get closer to 65 its still there but not as bad. It also wasn't as bad on the way home as it was going out, and I figured that might be because it was colder heading out. Its a posi rear end because I jacked it up and turned one rear wheel and both turned the same direction. But my question is, is it the differential whining or the wheel bearings? When I hand turned the wheels, I didn't notice anything too unusual, but Im a novice mechanic and may not be tuned in to it like others are. Im just learning a lot of this stuff, and I figured it might be good to get opinions from guys on here that have more experience
Tomorrow Im going to open up the rear end cover and have a look. I was going to do that anyway because the car has over 150k and it may not have been done. I want to make sure Im not running with no lubricant before I drive it. One of my fears is that its been driven with low gear oil by someone else, and its roached the axle bearings. Any help would be appreciated.....

sofakingdom

iTrader: (1)

Yeah, gotta just pop it open and look...

If it's a 10-bolt, there might actually be 2 noises; a grind at low speeds coming from the axles, and a whine at higher speeds coming most likely from the pinion bearing. No way to be sure without looking; and even then, it can be tough to tell for sure about bearings. Although, if the backlash is greater than .012" or so, odds are, the bearings (either carrier, or pinion, or both) are smoked, otherwise the backlash wouldn't have opened up.

TheExaminer

What is backlash? The amount of free movement between the ring and pinion gears? So what youre saying is, if its more than spec the bearings might be shot. I dont own a dial indicator. May need to get one.

big gear head

Get a hold on the pinion yoke and push, pull and try to move it around. If it moves in any direction other than rotation then you either have bad pinion bearings or a lose pinion nut. This is common.

TheExaminer

Yeah, I'll do that in the morning and post about what I found. Hopefully its only the wheel bearings. If I have to rebuild the rear end, I have a lot of studying to do. Im sure I could install a rebuilt axel assembly, but Ive never tried to actually rebuild one myself. I learned a lot from other poster mentioning backlash, because when I researched what that was I understood what I was dealing with a lot better. Thanks for the tips.

big gear head

The problem with the 7.5 10 bolt is that when a axle bearing goes out it also take the axle out with it. You can't just replace the bearing without replacing the axle too.

TheExaminer

The guy that looked at it today said it sounded like the wheel bearings. You can distinctly hear two different whines-kind of like two singers on two different notes. And theres one from each side. Sounds like stereo air raid sirens. He offered to replace all the seals and bearings on the entire axle for $500, which I thought was reasonable. Probably a good idea to replace them all if you can, and just be done with it. If I tried it myself, Id be $3-400 into it just with the tools and parts Id have to buy, plus Ive never done it before. I'll look into it more next week.

big gear head

Pay attention to what I said about the axle bearings and axles. If he puts new bearings on the old axles and the axles are worn then you wasted your money. If you have bad axle bearings then you MUST replace the axles too. There are special bearings that are made to use with the old axles, but I do NOT recommend using them. They usually cause a lot of trouble and you end up having to do it all over again with the correct bearings and new axles anyway.

TheExaminer

Ok, Ill keep my eye on it. We'll see what he says when I talk to him next week. Worst case I have to buy a couple new axles. Thanks for the info!

JamesC

iTrader: (5)

You might take a look at the Tip/Tricks sticky at the top of the page for info and pics.

JamesC