There is a strange growling noise that increases in volume with road speed on my '85 GSL. It's hard to tell where it is coming from, possibly from the rear of the car. There is no noise at when the car is at a stop. By 30 mph it is quite noticeable.

The following repairs were made to try to fix this noise. The rear wheel bearings were replaced. The rear end was rebuilt (not exactly sure what this means, but the invoice indicates the rear end bearings were replaced) and the limited slip differential was replaced with a used unit. These repairs didn't seem to make a difference, the noise is still there.

I would appreciate any ideas...thanks!

 

Probably rear axle shaft bearings..

 

Damn man,sounds like you spent some $$$$ trying to fix this. Is it a whinning that gets higher in pitch with road speed? The only constant that increases with road speed is driveshaft speed and ring/pinion speed. SO Id say either u-joint or ring pinion gears.

 

u-joints in your driveshaft.

 

Possibly, but usually they increase in volume in a turn when the bad bearing gets a side load. And they usually are noticeable at low speeds.

 

I agree. Usually ring/pinions make a high pitched whine that sounds like a jet engine, and increases with road speed.

 

My old -se did this, thought all SA/FB's did that? Just your basic rear end noise. Wait, come to think of it my GS didn't make the noise. Maybe the noise is only heard on LSD models??

 

The noise is low-pitched. The best description of the noise I can think of is a "growl". Not a high pitched whine.

I'm not sure if the noise changes during turns - I'll check this out tomorrow.

I have had the car about 6 years and have not heard the noise before.

 

hmm... mine was more high pitched, like gear whine not grinding/growling.

 

I have one that sounds like a gear whine also that my car has done since day 1. 83 GSL with LSD. Im gonna just try some synthetic oil and see if that helps. I know it needs to be changed anyway .

~T.J.

 

You didn't leave your mother in law's dog tied to the rear bumper, did you? Did you just recently get a hearing aid?


Seriously, have you tried things to see if it changes the growl? Like applying the brakes while applying throttle, or the parking brake? Could it be the 85 Mazda RX7 driveshaft with unservicable u-joints? They can't be lubed, so they must go bad eventually. Maybe rotate the tires?

 

add LIMITED SLIP ADDITIVE... its your 3rd member... trust me.... Replace the 3rd member... change the gear oil and add the ADDITIVE... try MOPAR POSI ADDITIVE or the AUTOZONE stuff will do... It shut mine up...

 

HAS to be your u-joint ... had the same problem, and for an 84-85 , you have to get it welded in .. costs ~65 $ canadian if you bring ur driveshaft in ...

 

Is your car lowered? When I dropped mine it changed the pinion angel and put to much pressure on the pinion bearing which scored it now it growls more with speed. Any other ideas?

 

What is the 3rd member?

 

where the RING and PINION and the LIMITED SLIP DIFFERENTIAL is housed in.... just add the additive... 1" or 2 of dropping your car shouldn't be a problem, because the driveshaft is flexible at the end...(the U joints)... it should cater to your lower height... it could might be your U-JOINTS...

 

R u talking about the "Pumkin"? where the axels go to in the center pod. I did not know thats the 3rd mem. It has to be replaced? The whole thing?
YIKES $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

 

3rd member= Diff= pumpkin= center chunk.

 

I'll check with the mechanic who rebuilt the differential on Monday to see if he added the additive.

The car has not been lowered. As far I as know it is completely stock except for non-functional fog lights.

I was told to test the U-joints by accelerating down hill, then let off the gas. There is a click when I do this, maybe this indicates bad u-joints?