Rear vibration noise

[jlouns]

I have just bought a 1991 Winnebago Warrior Class A 30 ft.
I have noticed a low pitched noise coming from the rear axle area that I can hear only when traveling at low speeds with no brake or gas applied.
Also can hear a slight groan when going around corners sometimes.
The tires appear to be of different ages, I have not noticed any smells, leaks or abnormal temps coming from the rear end. The u joint was replaced in 98. I have not checked the rear end oil ( never done it before)
and was looking for some help in what to look for, or ask for, before I take it in and get raked over the coals.
thanks

[David Worley]

Well, this is sort of a good news/bad news/no news answer. To make a long story short, I'd get it into a shop for testing.

The reason for that is, suspicious rear-end noises can come from several sources. The good news, I think, is that it doesn't sound typical of a ring and pinion gear problem. A ring/pinion gear problem is typically more noticeable during acceleration/deceleration, and gives a sort of clanging or bucking at steady speeds, depending on how bad it is. Offhand, I would think you have a bearing going bad, but which one? That requires some first-hand investigation. And, a 1998 u-joint is not exactly new, whether it has 100 miles or 100,000 miles on it. For a u-joint, a little regular exercise is a good thing.

Proper lubricant for the differential is pretty critical. Especially if you happen to have a limited slip differential. I can't tell you the number of warranty issues/arguments/tech bulletins that have sprouted because of the disagreements over the correct lube or additive for limited slip differentials. It seems the consumer never wins in those cases.

Tires is a whole 'nuther issue. If you have a seriously mismatched set of tires, you should bite the bullet and get new ones all around. For an rv, it is a given you will need to replace your tires due to age long before you wear out the tread. Five to six years seems to be about average. Yes, tires are a major investment, but the damage done when an overage tire disintegrates at highway speed could pay for several sets of premium tires. And pay attention to tire pressure and loading, too. Can't stress that enough.

It's worth taking the time to shop around for a reliable drive-train specialist in your area. Query some companies with fleets of trucks as to whom they use and how satisfied they are. Ask about warranty on their work, and trust your instincts when you get to the shop. If your gut tells you you're being hustled, you probably are. An honest shop will make certain you fully understand everything, and won't treat you like an idiot. I used to bend a few wrenches for a living, but now I just simply prefer to pay someone else to do the work. So, if I'm treated like a moron, that's a clear sign that I know more than they do, and it's not the first shop I will have walked out of. Last dealer shop I walked out of lost not only the service on my personal truck, but service on my fleet of work trucks, and the sale of a new vehicle for my daughter. Hmmm, pretty costly mistake on the part of one jackass service writer, wasn't it? Don't let yourself be raked over the coals. There are more good shops than bad, but there are enough bad shops that you have to pay attention.

Dave

[mi self]

The first thing is to check the lube in the axle. There should be a plug in the front housing or rear cover. remove it and use a clean piece of tubing, wire or finger and stick down in the hole. Pull it out to see what the level the lube is. If it is just a little below the hole thats ok. if not ask a auto parts man what weight lube to use, and fill it up just to the hole. Just reinstall the plug. The next thing to do is jack up one side (just a little)use 'jack stand' and block the other wheels so it won't roll & fall. Turn the wheel and see if you can hear any noise and where it is comming from. From the wheel= wheel bearimg, Prop shaft= bearing or center bearing. Comming from the center housing 'Well' it all dependes on how bad the noise is. If not to bad (you have to listen for it)you can wait an see if it gets any worse. It could be normal wear. My motor homes had a little noise. Also put on a matching set of tires

[Russ Chastain]

The tires appear to be of different ages...

One thing you want to be certain of is that both tires and wheels are identical in size. I've always been told by folks who should know that different sizes will ruin a differential.

Russ

[Carl]

All good advise. Check it out as soon as you can. It could be anything from a bearing going out, which is my thoughts or a bad ring gear and pinion to a bad "crush bearing" in the youk. If the lube is low or non existant due to a bad seal, the problem will not be fixed by just adding 80/90 weight lube. If it is a U-joint, you should hear a sharp Clicking noise when you put it in gear, either forward or back. Another indication of a bad U-joint is a noticable vibration when you look in the rear view mirror. Inside mirror, not outside, extended mirrors. My bet is you have a wheel bearing ready to go. Carl