Rear area grinding pop noise? What could it be?

[jretrodude]

Driving the GN the other day and I noticed a loud grinding pop like noise coming from the drivers side rear tire area? It only made this noise when I go into reverse and idle backwards? Could it be loose lug nuts or my z rated wide tires in the back rubbing? Only seemed to this once I installed an ATR rear sway bar and boxed upper and lower control arms? I was thinking maybe to much weight in the back end? But only started the other day?? I sure hope my rear end isn't going out? The same noise was on my 88 Monte SS too but nothing was upgraded on that car? Also has new springs and shocks as well.

 

[whitehot1]

My guess would be that the gear oil/positive traction lube has broken down. I would drain out and change the gear oil and add a bottle of positive traction lube as soon as possible and that should stop that noise for you.

 

[earlbrown]

When I installed my ATR bar I used the non locking bolts that came with it. They never would stay tight and were constantly loosening up. There would be plenty of clunks and pops when that happened. The fix was to either reinstall the stock fasteners or get some new grade 8s and aircraft self-locking nuts.

 

[longball]

if it only happens when in reverse - try what whitehot1 recommended - change oil and posi-lube.

 

[Phatman]

Send me my $15 and I'll tell you how to fix it...

 

[jretrodude]

Hi phatman sorry forgot all about that I will paypal you next Friday night, keep in touch with me so I don't forget that. Also can I find the rear end lube oil at advanced or auto zone? Will I have to change out the seal under the cover? Thanks.

 

[jretrodude]

Also what weight and brand? 75w-140 or 80-90? I'm thinking royal purple how many bottles do I need for a complete refill 1 or 2 and what gasket do you recommend the blue fel-pro or a OEM type gasket? Also my mechanic says it may be the u-joint? I've also heard if you have posi traction to get a special oil because of the additives and chemicals needed for the posi? I'm pretty sure I have limited slip but not sure? What is the code for posi or limited on the trunk label? Thanks.

 

[whitehot1]

Here is a link that can help you with the gear oil change and also some other things you might want to think about doing to help maintain your car to keep it running right.

http://www.gnttype.org/maint/basics.html

 

[Chuck Leeper]

G80 is the code.
Very well can be the joint.
2 qts is enough.
The additive is a small bottle.. Just a few ounces.
Felpro gasket is good. I use a thing coating of gasket dressing on both sides.

 

[jretrodude]

Isn't the additive in the royal purple? Also I do have a G80 code so that means I have the posi? Not limited slip

 

[Chuck Leeper]

R

Isn't the additive in the royal purple? Also I do have a G80 code so that means I have the posi? Not limited slip

RP may have the additive... Check the bottle. If it doesn't work, you can always add it later.

G80 = limited slip = "posi".
You will know when you take the cover off.

 

[whitehot1]

As mentioned make sure it's not something mechanical that is causing the noise such as u-joints,loose bolts,etc.

Some of the gear oils have the posi/limited slip additive added into the oils. I used the Lucas gear oil the last time i changed mine and it's supposed to have the additive but i had to add a bottle to stop the noise when turning or backing-up.

Here is a link to autozone for the additive.

http://www.autozone.com/autozone/ac...l-additive/_/N-259n?itemIdentifier=17352_0_0_

 

[jretrodude]

Cool I'll have to check on that. How many bottles of oil and additive do I need 2 of each? And is there only one u joint to change or two? And just to clairify the G80 code does mean I have posi? Thanks.

 

[dwall]

G80 = posi

http://www.gnttype.org/numbers/rpo.html

 

[whitehot1]

Cool I'll have to check on that. How many bottles of oil and additive do I need 2 of each? And is there only one u joint to change or two? And just to clairify the G80 code does mean I have posi? Thanks.

2 quarts of gear oil is needed and 1 bottle/tube of additive if it's needed. There are 2 u-joints and there installed on the driveshaft 1 on each end,if you have never removed/replaced u-joints before it would be best to find someone that has to help you or find a shop to do them for you. And yes the G80 code is for posi/limited slip differential. The parts store will have the rear cover gasket just ask for it at the counter.You may need some sealant for the gasket if you don't have any, permatex no.2 form-a-gasket works good or rtv smear a light coat on each side of the gasket.

 

[jretrodude]

I just changed the oil today on the rear end looks like it was done before? But new lucas 80W 2 bottles and one of the additive trans x. Now my other question is what size are our fuel tanks? I filled up from empty put about 13.5 gallons in and the tank was full but my gas gauge didn't move past 3/4 of a tank of gas? Stayed like that until I got home and now it's between 3/4 and full? Doesn't seem to move and was working fine before? New fuel pump hot wire kit and tank installed about 3 years ago? Any suggestions on what to look for? Thank you Also I've noticed that ever since the fuel tank was put in the gas pump clicks off for some reason? Not sure why it does that when it's not full? And I know it was full also because the fuel was coming back out of the neck?

 

[earlbrown]

I believe it's rated at 17 gallons. The most I ever stuffed in mine was something like 17.8 gallons when I was on fumes.

It's pretty common for them to stall at 3/4 then take an hour to hit full. Sometimes flicking the plastic in front of the gauge will wake it up.


Shutting off the hose is VERY common. Sometimes I have to hold mine just perfect (giggity) and it still cuts off on the slowest click. I can't tell you how many times I've thought about building a better flowing fill neck.

 

[dnoel]

I just changed the oil today on the rear end looks like it was done before? But new lucas 80W 2 bottles and one of the additive trans x. Now my other question is what size are our fuel tanks? I filled up from empty put about 13.5 gallons in and the tank was full but my gas gauge didn't move past 3/4 of a tank of gas? Stayed like that until I got home and now it's between 3/4 and full? Doesn't seem to move and was working fine before? New fuel pump hot wire kit and tank installed about 3 years ago? Any suggestions on what to look for? Thank you Also I've noticed that ever since the fuel tank was put in the gas pump clicks off for some reason? Not sure why it does that when it's not full? And I know it was full also because the fuel was coming back out of the neck?

Is your noise still gone? Just wondering, thanks!


Posted from the TurboBuick.Com mobile app

 

[jretrodude]

I changed the differential oil put in a full bottle of the additive (trans x) and 2 bottles of the lucas 80w as advanced didn't carry the 80 in royal purple. Seems to be ok but I haven't driven it much since changing it out? I may have heard a little grind or pop but not as bad as it was? Also I talked to a local GN owner and he said he experienced the same thing on his and he informed me if the car does not get driven for awhile something with the shoes gets stuck or rusty and said if you do a couple of figure eights in a parking lot it should fix the problem? Then if it sits for a couple of weeks it will do the same thing?

 

[Hatdragracer]

For what it is worth, I had a similar issue where I would hear a very unpleasant growling noise when in reverse. I also changed the rear end fluid and added posi fluid. The noise remained. For the life of me I couldnt figure it out until recently I pulled the engine. Come to find out my GN1 stretch intercooler was tapping the steering box when in reverse. It is worth checking your engine and tranmission mounts if you are still hearing mechanical noise when in reverse.