Chevy Nova Forum banner

1 - 12 of 12 Posts

·
Premium Member
Joined
·
3,882 Posts
Discussion Starter #1
okay, so I am starting to scratch my head on this one.
ive got 8.5 10 bolt that my friend set up for me-
new bearings, gears, seals, etc.
works great with no howling or grinding.
but if the car has ANY slight bit of turn at slow speeds (<5mph) i really
notice this "bump bump bump bump bump" (please excuse my crappy reproduction.

it sounds like something is almost binding...
or is this just the clutches slipping as it turns?

thoughts appreciated.

steve
 

·
Premium Member
Joined
·
13,309 Posts
most likely... add a 4 oz bottle of friction modifier to the posi... available at most any good auto parts...
 

·
Registered
Joined
·
2,638 Posts
get a spool. they make weirder noises. well, the tires anyway, not the spool.
 

·
Registered
Joined
·
3,895 Posts
I have a stock GM posi & it does the same thing. By tight do you mean the posi has tight springs?
Yup. Higher amounts of pre-load on the posi's clutch packs.:yes:

If you are still using c-clips, you could be hearing the axles "clunking" against the cross-shaft. :yes:
 

·
Moderator
Joined
·
4,534 Posts
you need a bottle of GM additive 4oz. and the noise will be more present once the diff warms up. Also synthetic fluids tend to chatter more than conventional oil.

Miles
 

·
Premium Member
Joined
·
3,882 Posts
Discussion Starter #8
Yup. Higher amounts of pre-load on the posi's clutch packs.:yes:

If you are still using c-clips, you could be hearing the axles "clunking" against the cross-shaft. :yes:
you need a bottle of GM additive 4oz. and the noise will be more present once the diff warms up. Also synthetic fluids tend to chatter more than conventional oil.

Miles
Thanks to all who replied.
So do you guys think its too tight?
i forget the clearance: shimmed to 6-7 thousands maybe...
oh, im guessing. but it was set up right per the instructions.

any consequences to the way it is- such as increased wear?

thanks again to all.

steve
 

·
Premium Member
Joined
·
15,966 Posts
The clutch snap!
Posi bump!

What ever you want to call it is in the posi unit itself.
It has nothing to do with the ring gear setup or spacing.

There are 2 sets of springs available,

75 lbs springs (found to be yellow or green) X4 = 300lbs pressure.

50lbs Springs Black X 4 + 200lbs pressure Std springs mostly found in the posi units.

If you did not put the friction additive you will get the "BUMP" mostly when unit is hot.

The additive in most cases will work.
GM Limited-Slip "Posi" Additive
Item#: 1052358 (around the 8.00 price range)




I have found a full quart of Lucas gear oil additive works great. And has the additive in it.
Do not over fill, drain the oil. Add the Lucas and fill to full mark with std gear oil
IMO!!


Al
 

·
Premium Member
Joined
·
13,309 Posts
most likely... add a 4 oz bottle of friction modifier to the posi... available at most any good auto parts...
you need a bottle of GM additive 4oz. and the noise will be more present once the diff warms up. Also synthetic fluids tend to chatter more than conventional oil.

Miles
4oz of GM limited slip additive and you will be all set. Its as simple as that.
The clutch snap!
Posi bump!

What ever you want to call it is in the posi unit itself.
It has nothing to do with the ring gear setup or spacing.

There are 2 sets of springs available,

75 lbs springs (found to be yellow or green) X4 = 300lbs pressure.

50lbs Springs Black X 4 + 200lbs pressure Std springs mostly found in the posi units.

If you did not put the friction additive you will get the "BUMP" mostly when unit is hot.

The additive in most cases will work.
GM Limited-Slip "Posi" Additive
Item#: 1052358 (around the 8.00 price range)




I have found a full quart of Lucas gear oil additive works great. And has the additive in it.
Do not over fill, drain the oil. Add the Lucas and fill to full mark with std gear oil
IMO!!


Al
see anything in common here?:D
 

·
Premium Member
Joined
·
3,882 Posts
Discussion Starter #12
The clutch snap!
Posi bump!

What ever you want to call it is in the posi unit itself.
It has nothing to do with the ring gear setup or spacing.

There are 2 sets of springs available,

75 lbs springs (found to be yellow or green) X4 = 300lbs pressure.

50lbs Springs Black X 4 + 200lbs pressure Std springs mostly found in the posi units.

If you did not put the friction additive you will get the "BUMP" mostly when unit is hot.

The additive in most cases will work.
GM Limited-Slip "Posi" Additive
Item#: 1052358 (around the 8.00 price range)




I have found a full quart of Lucas gear oil additive works great. And has the additive in it.
Do not over fill, drain the oil. Add the Lucas and fill to full mark with std gear oil
IMO!!


Al
well that makes sense- i assumed it was in the clutches.
i understand that this is different from the rear end set up now.
i guess i will go get some of this gm stuff.

thanks for the info- very helpful.

steve
 
1 - 12 of 12 Posts
Top