What's the clunking noise??

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737jetdr

737jetdr

FABO Gold Member
FABO Gold Member
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Hey everyone. I put a supposedly rebuilt 489 center section in my 8.75 rear axle a couple of years back. Bought it at an estate sale. Gentleman who owned at had passed away. It has a limited slip but I can't remember if it's clutch or cone type. I get a loud clunking/ popping or ratcheting sound when I turn left from time to time. Doesn't make the noise if I coast through a left turn or if I've got some gas applied. Only seems to do it under part power or if I try to accelerate from a stop when I turn left. No other noises while driving. At first I thought it was because it was new but I've got a couple thousand miles on it now. Is this thing eating itself? Any suggestions? Thanks in advance.
 
did you use an oil with friction modifiers in it or a sure grip additive ?
 
Add another tube of modifier. Find a open parking lot and drive in figure 8's for about 10 laps. See if that fixes it.
 
I don't believe it's a locker. I had one of those in a bronco before. This is way louder than that. Is there a particular brand of modifier that works best?
 
You can get the Mopar on at most dealers, it works the best in my option. Some say the ford on is also good. Dose the axles have the cone bearings? and are the preload set correct. The preload is on the left side.
Good luck.
 
If it is louder than a locker you better pull it out. My locker can be fairly loud been that away since day one 25 years.
 
Green bearings. I will try a bottle of additive. Getting the Motorcraft that Dr. Diff sells. If it doesn't improve I will pull it out. Right now I just try to drive it in a way to keep it from doing it but it's rather annoying. As far as comparing noise lever to a locker, it's been over 20 years since I had mine. I know it could be loud at times too.
 
Not an empty propane tank rolling around in the trunk?
It likely isnt, but i have seen it before.
 
Quick update, I added a bottle of the Motorcraft additive today and drove to work. So far the noise is very minimal compared to before. I haven't had time to do the figure 8s in the parking lot yet. Not sure what is in the little magic bottle that smells like T-Rex puke but it seems to do the trick. Thanks for the help everyone.
 
737jetdr said:
Quick update, I added a bottle of the Motorcraft additive today and drove to work. So far the noise is very minimal compared to before. I haven't had time to do the figure 8s in the parking lot yet. Not sure what is in the little magic bottle that smells like T-Rex puke but it seems to do the trick. Thanks for the help everyone.
Click to expand...
Fish oil. And yes it stinks to high heaven!
 
SGBARRACUDA said:
Fish oil. And yes it stinks to high heaven!
Click to expand...
Sulphur, zddp and some organic oils.
Used to be sperm whale oil. If i recall it was extracted from a gland in the brain of the whale.
Some serious classic car guys will search out old limited slip diffs just to get the old friction modifier.
 
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