clunk in rear end

[dcmaynard]

I have a 97 and when I push on the gas pedal at low speeds it has a clunk noise. I am thinking that its a U-joint type of thing but I am not sure. Does anyone know where this might be coming from?

[abaird]

Take the drive shaft out and see if the ujoints are in good shape to rule those out. Otherwards, put vehicle in nuetral and grab the driveshaft at the companion flange and try to rotate it. If it moves half an inch I might worry. Some play is normal. Also, it isn't unusual for a rear wheel drive vehicle to have a slight clunk in that situation. My 97 silverado with 140k did it and so does my 03 with 40k.

[dcmaynard]

ok well I am not sure what the flange is but I grabed the shaft right in the middle and it will rotate about 1/2 inch but it has a clunk in it just like what I was hearing. is this good or bad?

[wrparks]

Half inch sounds like a bit much to me. I think mine may turn 1/16 to 1/4, but def not half. If it was me, I'd keep an eye on it for a while and just wait, but it may strand you if you do that.

[silverado122775]

that tells me you need new u-joints

[dcmaynard]

so that is what is wrong with it? when you can turn the Drive shaft that much it means that the u-joints are bad?

[silverado122775]

yep. The u-joints are worn down and Need to replace them.

[dcmaynard]

Well I am no Machanic by any means, So I thought that my Drive shaft needed to be replaced. so U-joints are only about $125 to get fixed.

[silverado122775]

Originally Posted by dcmaynard

Well I am no Machanic by any means, So I thought that my Drive shaft needed to be replaced. so U-joints are only about $125 to get fixed.

The only time you would need to replace your DS is if it was bent, or is the adjuster is shot. otherwise, it would be the u-joints that connects to the DS.

[dcmaynard]

how hard would it be to fix them myself? I was told that you just have to remove the 4 nuts on each and they just drop right out. is that true?

[dcmaynard]

here is another thought. Could it be the gears in the rear end? Just a though.

[abaird]

Four bolts hold the drive shaft in but I doubt they have that much play in them even if they are bad. Usually when a U-joint is bad they cause a vibration or a noise. If they were bad enough to cause excessive play then you could look at the U-joint while you move the drive shaft and you would be able to see the play in the joint itself. If the driveshaft moves but the companion flange or slip yoke doesn't, then they are definitely bad. The clunk is probably in the rear end because of too much backlash caused by worn out gears.
It goes transfer case...slip yoke...u-joint...driveshaft...u-joint...companion flange...rear end
If that helps with terminology.

[dcmaynard]

ok so I think that it is the pinion and ring. but would the spiders be bad as well.

[abaird]

Well, they may not be bad. I said worn out gears in my previous post but I meant just worn gears. When rear ends are set up they are set with some backlash, or play in the ring and pinion gears to allow for heat expansion and lubrication....If you know a lot about rear ends you could tear into it and roll a tooth pattern and measure backlash to see what needs to be done but that takes some special tools and can be a pain when dealing with shims.

As long as you only have some play by rotating the driveshaft and don't have any side to side or up and down movement of the companion flange I might not worry too much about it. Every GM 10 bolt I've ever had has clunked.

[dcmaynard]

Well I have only had the truck for 4 days now and It didnt clunk for the day and a half that I test drove it. So I called the Chevy dealership where I got it from and they are going to look at it for me for free and tell me what is going on. All I know is that this has got me Stressed out when you pay 10K for a truck and it might be junk.