Hi all- I have a '70 250ci with (I believe) an 8 inch rear. When I put the car into reverse from park, i hear a realtively loud, metallic 'clunk' from the rear. It doesnt' make the noise at all (or if it does, its usually pretty quiet) when I put it in drive. I've had the u-joints looked at, so they're aren't to blame, and the noise definitely comes from the rear of the car, so I have ruled out the transmission. I don't here any other noises coming from the rear when I'm driving or anything like that....is my rear end just about shot?
I suppose it could be one of the rear end gears, but I think a closer look at the u-joints is in order.
I think you have a definate worn internal part in the rear end. Ruling out the u-joints, I would get under the car and slowly twist the yoke on the chunk, one way and then the other. See if there is excessive movment before the gear teeth engage etc. I have found that in most cases, the pin that goes through the differential gears is worn badly or the holes in the carrier are wallowed out and allowing that clunking sound. Could be numerous other things too. such as worn splines on the axles or gears, broken or worn teeth and or bearings etc. Sometimes you can drive them that way for years and just put up with it, but my advice is to pull that chunk out and check it out or put another one in if it comes with the same gear ratio. If the car has a lot of miles on it, would not hurt to get that old grease changed anyway, can look at it and see if there is any particles or pieces of metal in it. I think Andy Sutt pulled one out of an older pu and found one of the carrier cap bolts was laying in the housing. Let us know what you find out.
Yup, he's correct... I changed the chunk in my 76 F-100 a few weeks ago... It had never been apart since it was assembled in the factory. I was "scooping" the old grease out of the housing and was like "what the heck is that in there" dug out a carrier cap bolt... This rearend should have came apart LONG LONG time ago. As there are only 2 bolts per carrier cap. It had been driving for who knows how long like this, and I'm glad I fixed it before she finally did decide to go. I would agree also that just pulling it apart to make sure things are all within specs is one of the cheapest things you can do. Costs about 10 bucks for a tube of cylicone and 2 quarts of fluid. Sorry for the long post P.S... the rearend still drove and ran fine, and I had NO clue that it was missing that bolt. I just wanted to go to 3.50 gears instead of the 2.75 to wake up that stock 302/C6 combo a tiny bit
