LSH77VETTE

Hello all,

I have noticed on my 77 that when I am backing and turning in reverse I hear a growling noise. This seems to be getting progressively worse as time goes by. Any ideas what it could be and how to fix?

I don't notice any noise when moving forward or when turning moving forward. Only in reverse.

Please advise. Any help or suggestions would be greatly appreciated.

thanks

MelWff

if you havent changed the fluid in the rear that would be the first and least costly thing to do. Anything else involves removal of the rear for rebuilding. Just a guess, excessive play in the pinion gear.

LSH77VETTE

Thanks for the info. I'll try changing the fluid. I am figuring I would need gear lube and ani slip additive? Can I get those at any auto parts store or would I need to get that from a dealer?

lakerider57

You can get GM additive and oil from most auto parts stores.

lakerider57

On second thought, I now remember getting my GM additive on-line and got gear oil from auto parts store.

LSH77VETTE

I'll probably try to change the fluids this coming weekend. I have not looked at the rear dif yet but I'm assuming there are drain and fill plugs on it like most other vehicles?

resdoggie

Nope. Fill plug only. Cheap oil suction guns are readily available and used also to refill diff.

https://www.harborfreight.com/oil-su...gun-95468.html

LSH77VETTE

I need to buy an oil suction gun in the next day or two, and I am expecting my GM gear lube and slip oil to deliver yet this week as well. I hope to do this oil change no later than this coming weekend. I noticed that the fill plug has a square head on it. Not much room to reach it because it's in a pretty tight and confined space. Doubt I an get a wrench on it. Any tricks on what to use to remove it? Will socket work on the square head plug?

JayRay

Pull of your passenger side tire and you will have direct access to it. I believe you can use a 5/8" 8 pt socket on an extension.

LSH77VETTE

Update. Received my shipment of GM gear lube and GM antislip. I picked up a suction gun at Harbor Freight. Not worth the $12 bucks it cost me because it sucks (and not literally which is the problem). I tried to siphon the oil out as best I could. I may try to pick up another suction gun from the autoparts store such as Advanced Auto, but since the price of the ones they have in stock are pretty much around the same amount, I'm not sure it will be any better that the Harbor Frt one. Anyway, I feel like I have sucked out about as much of the fluid as I can but don't feel as if I pulled out 2 quarts worth. I feel as if there is still allot left in there that I can't get out this way. Anyone else feel the same when changing their dif fluids? Were you able to get 2 new quarts back in there after using the suction method to remove the old?

theandies

Turkey baster with a long bit of hose on it should work. Something not mentioned is have you checked your parking brake setup. It could cause a noise that you are experiencing and only do it in reverse.

LSH77VETTE

Thanks !! I'll give the turkey baster and hose a try. I didn't think about the parking brake possibly being an issue. What could be wrong with the parking brake to cause this issue if in fact that is what it is? What should I look for?

thanks !

LSH77VETTE

On a related note, when I purchased my gear oil and limited slip lubricant, I only purchased one container of limited slip lubricant. I have read where several had to add a second bottle so I called my local Chevy dealer and inquired if they had it in stock. Turns out they do, but the parts guy there tried to tell me that with the synthetic gear lube, the limited slip additive is not needed. I kindly told him that I think I'll still come buy and pick it up anyway as it would not hurt to use it...................not sure this guy knows what he's talking about. I'm definitely going to put in the limited slip additive and the original GM gear lube. Not taking any chances on that. Just wondered if anyone else has ever been told this about the synthetic oil?

JayRay

Some of the synthetics already have the additive in it. I use Royal Purple and it is one that already has the additive.

theandies

Loose or broken shoe springs or misadjustment could cause a groan or ticking noise especially when going backwards. If the shoes are worn they would be 99% worn in the forward direction causing issues only when backing up as in the shoe or shoes getting caught in the drum portion of the caliper making noise.
Just another suggestion.

LSH77VETTE

I'll definitely have to check this out because the noise I hear sounds like the sound I have heard when you barely push the brakes and let your vehicle start moving (with the brakes still grabbing). I hope that is not the issue..........don't really want to have to get into a parking brake job. But if I do, how bad is it to replace the parking brake shoes and get to them?

C6_Racer_X

Manual transmission?

Check the lube in the transmission as well, and change it if it's past time to do that. If you don't know when/if the gear lube in the transmission has been changed, it's way past time.

theandies

It's not a bad job. It's just a normal drum brake setup only smaller. Just check your rotor run-out when you are through. Go with stainless steel replacement parts so they will hold up longer.
I had a groan when backing up after I installed my offset trailing arm assemblies (full assemblies from Van Steel with parking brakes etc) and it turned out I didn't adjust the parking brake cable correctly the first time. Once I got it adjusted the groan went away.

LSH77VETTE

Thanks
I'll definitely check them out. I finished up the differential gear oil change this weekend but have not had a chance to get her out of the garage to see if that solved my noise issue. Hopefully in the next few days I'll have time to take her for a spin. If I still hear the noise, I'll dig into the E brakes and see if that could be the issue. Thanks again for the info.

LSH77VETTE

No, my tranny is an automatic. Thanks for the suggestion though.