When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So lately I'm hearing rear diff chatter from my '72 Supreme. It only seems to happen after driving for an extended period of time (like maybe for an hour or more), so I'm guessing it's only when it's reached a certain temperature. I've checked the fluid level and it's good, and it's not getting excessively hot (about 130 deg). I've put 20K on it since I bought it 7 years ago, and I'm not sure when the fluid was last changed, so I'm thinking that would be a good start.
Yep, We always had to switch out oil about 3 years with the Bigger 31 -33 inch tall tires in the 1/2 trucks. It is a steel clutch thing usually... you might have to shuffle the clutches too that helps. They get glazed and ride on the same clutch and make a nice mirror finish with the other clutch and then go window PAIN of you... So think about that too.
Yep, We always had to switch out oil about 3 years with the Bigger 31 -33 inch tall tires in the 1/2 trucks. It is a steel clutch thing usually... you might have to shuffle the clutches too that helps. They get glazed and ride on the same clutch and make a nice mirror finish with the other clutch and then go window PAIN of you... So think about that too.
You are probably hearing the limited slip clutches chatter. This was a common complaint when I worked at the Buick/Cadillac dealership. People didn’t like the pop/chatter in their big Roadmaters/Fleetwoods!!
Before doing anything, find a big empty parking lot and make about 10 figure 8 maneuvers.
If that doesn’t help, change the fluid. Clean out as much of the old crap as possible, inspect for excessive debris. Refill with the proper fluid(make sure it’s compatible with limited slip) and take it for a test drive with the figure 8s again. Hopefully that solves the issue. If not, add a bottle of limited slip additive.
Hi Dave - Hand tighten all bolts first so they are all snug into the receiving thread holes. Tightening a rear differential cover should be performed in a crisscross/diagonal pattern, IOW begin with one bolt then proceed to the next bolt directly across from that bolt on the opposite side of the differential cover.
Yes. Add a very minimal amount of gasket sealer to surround the entire differential ensuring you encircle each bolt hole. Don't go gorilla nuts on the amount of sealer. I think the torque value for the bolts is 30 ft-lb but look in the CSM.
You've put on 20K miles since taking ownership, your car was at one time a race car, you haven't changed the oil & if you have no receipts validating the last time differential fluid was changed, please change your fluid at your earliest convenience. Your rear end will thank you.
You need to clean both surfaces - cover & differential - be careful - no gouges. Stuff some t-shirts or similar inside the differential in case you have old gasket material flying everywhere while scraping off old gasket. T-shirts are nice because they don't shed lent material & they soak up the old cruddy oil nicely. Once you get to about the final stage of cleaning the mating surfaces, you can use some brake cleaner to wash them. I have bags of steel wool. I use steel wool embedded w/ some brake cleaner to give the mating surfaces a final cleaning rub-down. Clean the bolts well w/ a wire brush. Here's something else I do which is overkill most likely. I put the bolts I removed back into the same holes I removed them from.
Image of the front differential on my F250 4x4 to give you an idea of amount of gasket sealer. Something to note regarding gasket sealer(s). I never tighten bolts to torque value right away. I put on sealer, let sealer set thirty minutes, install cover w/ gasket, hand tighten all bolts, torque to 1/2 torque value, let valve cover set at 1/2 torque values for one to two hours, then apply the final torque. You get a better seal when the gasket sealer has a little bit of time to cure before final torque. Easy peasy. I'm getting ready to change my transfer case fluid in a week or so. This was the 4th time I changed front differential fluid (image). Truck has 200K miles.
You've put on 20K miles since taking ownership, your car was at one time a race car, you haven't changed the oil & if you have no receipts validating the last time differential fluid was changed, please change your fluid at your earliest convenience. Your rear end will thank you.
You've put on 20K miles since taking ownership, your car was at one time a race car, you haven't changed the oil & if you have no receipts validating the last time differential fluid was changed, please change your fluid at your earliest convenience. Your rear end will thank you.
Say what? Didn't you state you haven't changed the diff fluid since you've owned it? Huh?
So lately I'm hearing rear diff chatter from my '72 Supreme. It only seems to happen after driving for an extended period of time (like maybe for an hour or more), so I'm guessing it's only when it's reached a certain temperature. I've checked the fluid level and it's good, and it's not getting excessively hot (about 130 deg). I've put 20K on it since I bought it 7 years ago, and I'm not sure when the fluid was last changed, so I'm thinking that would be a good start.
I have only seen diff chatter once. It was new in the late 90's Ford 3/4 ton we did a synthetic gear oil change at the Ford dealership I was apprenticing at. At the time $22 per quart for Ford synthetic 75W90, ah stealerships. Turns out Ford didn't spec it with posi additive, crazy for that price. It was ugly enough paying $25 a quart, needed two for glorified trans hydraulic fluid, could tell by the clear colour and smell for my Challenger's transfer case two years ago. We added the additive tube and no more chatter in that Ford. We just did a 3.08 posi in my 70 Cutlass S Type O 12 bolt with the brand new $$$ Yukon posi and used 3.08 gears. Boy it sure does grip, squirrely flooring it around corners and no wheel spin. I used 85W140 conventional, supposedly has the additive. Synthetic isn't suggested with most posi but I do run synthetic 75W140 in my Dakota's 8.25" 3.91 posi, sees -40 temps. I stil added a tube of CRC posi additive in the Olds, completely quiet. I like to RTV a gasket to the cover, W27 in this case. Then if it needs pulled, no scraping and redoing. I did have to retighen it after the initial drive and has been good since. I found a surprising amount of metal in the 2.78 open I replaced and I had just done the gear oil a couple of years earlier. Good luck.
You are probably hearing the limited slip clutches chatter. This was a common complaint when I worked at the Buick/Cadillac dealership. People didn’t like the pop/chatter in their big Roadmaters/Fleetwoods!!
Before doing anything, find a big empty parking lot and make about 10 figure 8 maneuvers.
If that doesn’t help, change the fluid. Clean out as much of the old crap as possible, inspect for excessive debris. Refill with the proper fluid(make sure it’s compatible with limited slip) and take it for a test drive with the figure 8s again. Hopefully that solves the issue. If not, add a bottle of limited slip additive.
The figure 8 removes the glazing of the clutch plates, and works oil into the friction I vaguely remember a service bulletin suggesting the figure 8 as the first step.
The figure 8 removes the glazing of the clutch plates, and works oil into the friction I vaguely remember a service bulletin suggesting the figure 8 as the first step.
This should be done at normal parking lot speed, correct?
