speedbird1229

Hi,

I just had the diff rebuilt with all new parts except ring and pinion. These were in good condition so we thought why not leave them as they are. I don't know if this was the best decision. I test drove the car yesterday and didn't use too much power since I know I have to break in the new configuration and carbon LSD clutches. After having driven about 40-50 miles I began noticing some smooth and low pitch howling from the rear end when slowing down at around 20 mph at idle. I can't understand if some noise comes also when I slightly accelerate since the engine is very noisy and my transmission has some whines in it also.

I will do some more testing tomorrow but how does it look like at this point? I know that old ring and pinion can't work together as well as they did before and some people say they've had their rear ends howling for years with no issues. However, I had a somewhat different noise on a friend's brand new diff from the very beginning and these ring and pinions failed us in just 300 miles.

I've had cars with diff issues before and I must say this howling is not like the bad ones but more like a smooth howl from the gears in tranny...

Is it possible it works itself in and goes away...? Should I drive very smoothly for some hundred miles?

Frank_Nesta

Did you use the GM additive? This has to be added if you are using regular rear end oil. Also to work the additive into the clutch plates you should do some (10) tight figure eights in each direction. But, not sure if this will fix a howling noise?

gkull

Was your R&P removed and the lash reset? I had Richmond 4.11 R&P installed years ago and in the off gas slow down they made a slight howl for years. If the lash is right it is not a big deal.

As to failing in 300 miles it could not have been set right.

doorgunner

Park the car on a level concrete floor.

Block the front wheels so the car cannot roll forward or backward.

Place the car on jackstands high enough that you can get under it.

Put the shifter in neutral.

Check the oil level in the differential.


Rotate the driveshaft slowly to the left until you feel it stop because the slack is now out of the internal gears.

Then rotate the driveshaft to the right until you feel it stop.
Do this method several times.

What to look for:

If you grab the driveshaft with both hands, can you move it forward and backwards (toward the differential and toward the transmission)?

If so, how much will it move?

None?

1/64"?

1/32"?

1/16" or more?

How much do you have to rotate the driveshaft from left to right /right to left......before the internal gears caused it to stop turning in either direction?

None?

Very little?

1/8 turn?

1/4 turn?

1/2 turn?

More than 1/2 turn?

Provide the above information when you have time to do the tests.

Expert members can use this information to determine the amount of slack between the two pinion gears..........and the amount of backlash between the ring gear and pinion gear.

tak82

I have the exact problem in my 82. Replaced bearings and seals and kept original R&P now a have a noise on deacceleration and a slight whine cruising. Been 3 yrs and thousands of miles for me and ok. Was told it's cause the original mesh pattern was changed. As long as the pattern is set up good for backlash on old gears you should be ok. Is this correct rear end experts ?

diehrd

I like doorgunners post ..

speedbird1229

The ring and pinion were removed and put back, these are the original R and P from factory I believe. The lash should be right but who knows, right?

I didn't use GM additive but I used LUBEGARD or something like that. It should be at least as good...

Frank_Nesta

not.

harris1507

Check these treads out.

http://forums.corvetteforum.com/c3-t...ar-set-up.html

http://forums.corvetteforum.com/c3-t...posi-lube.html


And Most of all read this paper on set-up.

http://forums.corvetteforum.com/c3-t...ild-paper.html

I hope this helps!

Frank_Nesta

Great collection of threads and great research.

speedbird1229

OK guys, thanks for all the help. Just an update of the present situation - the noise seems to be gone at this point and drove quite a lot yesterday with no noise being heard. I don't know if maybe the gears were working in when they noise appeared. I will keep my attention on the diff so if anything appears I will have it fixed.

The sad thing is that I assembled the whole thing for two evenings with a couple of friends and I also installed the Dragvette 6-link etc. Now it still needs to be taken apart because somehow the diff rebuilder messed up the diff's front yoke seal and this cannot be changed on the vehicle. At least they will do it this time although I want to be there to see if they put the 6-link back together properly. It's not leaking too bad but oil is slowly dripping from the bottom of the yoke and this is real bad for sure.

I just don't get it how he could have messed up that seal... Maybe it was faulty from factory but I doubt it. I have changed the seal on my Suburban all by myself and it still holds nicely.

speedbird1229

Here's a picture of the freshly built rear-end by the way... That needs to be taken all apart again