Rear End Clunk

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scremn

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I have a 1972 Dodge Demon with a 340-4 speed. It has an 8.75 rear
end with a sure grip with 4:56 gears. It is a 489 case. The rear end is
making a clunking noise when I get on the car and when I back off the
car.The u-joints are fine.I can drive the car and under normal driving,
it is fine.When i jump on it,it sounds like the rear universal is going to
come through the floor board or the pinion is slamming forward. The gears
were installed two years ago.I do have a driveshaft loop.It will be coming
out friday.Sure-grip problem or maybe excessive backlash.Sure-grip has
never been rebuilt.The rear end is coming out friday.I pulled the axles.
They are fine.They are Moser axles with green bearings.I value your
input.
 
scremn said:
I have a 1972 Dodge Demon with a 340-4 speed. It has an 8.75 rear
end with a sure grip with 4:56 gears. It is a 489 case. The rear end is
making a clunking noise when I get on the car and when I back off the
car.The u-joints are fine.I can drive the car and under normal driving,
it is fine.When i jump on it,it sounds like the rear universal is going to
come through the floor board or the pinion is slamming forward. The gears
were installed two years ago.I do have a driveshaft loop.It will be coming
out friday.Sure-grip problem or maybe excessive backlash.Sure-grip has
never been rebuilt.The rear end is coming out friday.I pulled the axles.
They are fine.They are Moser axles with green bearings.I value your
input.
Click to expand...

Check that you have enough space between the pinion snubber. Is there a rubber bumper on it?
 
Several things can do it. Excessive backlash. Broken side or spider gears. Driveshaft hitting the loop. Even a problem in the trans. like excessive gear play can clunk. Just have to go down the list and check everything.
 
I have removed the snubber to eliminate that possibility. Drive-shaft
is not hitting the loop. I will let you know what I find when I remove the
pumpkin.That will be done on Friday.I am curious how the transmission
might cause this problem if by chance the rear end might be ok.Thanks
for the info gentlemen.
 
Gosh! I'll keep whatever you find out in mind just in case mine ever starts acting funny. I have a 4-speed,489case also.
 
Mines a 340,4 speed with .489,4.10,s.Last summer mine was clunking at the track,ended up being the rear.Was the cone-type was toast!Just a thought.You have to take your center section out,you,ll know then!Good Luck!
 
I dropped off centersection last week to Babbit Bearing and got a call
today.Spider gears are no good and the cause of the noise.A clutch type
posi is ordered and hopefully will have rear end back by Tuesday.Everything
else looks good.
 
scremn said:
I dropped off centersection last week to Babbit Bearing and got a call
today.Spider gears are no good and the cause of the noise.A clutch type
posi is ordered and hopefully will have rear end back by Tuesday.Everything
else looks good.
Click to expand...

Did it have a clutch type before the rebuild?

The reason I'm asking I had a Auburn cone type that didn't last long at all.... just wondering if you had the cone type that went bad.
 
I'll bet the holes for the cross shafts were hogged out to an oval .
 
The car had a cone type posi.I cannot complain,that is the original posi
in the rear end and I have owned the car since 1974.Got my moneys
worth,that's for sure.
 
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