Increased noise with polyurathane diff bushings
 

I swapped in a rx-7 diff housing on my wifes 97 after being rear-ended. I have noticed that there is a lot more gear whine above 55mph. Is this normal for doing the bushing swap? I am just trying to make sure there is nothing else wrong with the diff or drivetrain. I am fully aware of the fact that the stiffer bushings wil not damp out the vibration and noise that a ssofter rubber bushing would.

I have more whine after putting in the poly bushings too.

same here, it sounds grate.

I also have the ass tingling at 3k rpms with the MMRs.

Was the same on my NA as well.

Good deal! I mean it sucks for my wife but at least I don't have to worry that something is messed up. I will be putting these same bushings on my 91 once I get the torsen swapped in. Luckily my wife mostly drives it around town at less than 55mph where it seems to be quiet. I drive at 60-65 for most of my 35 mile trip to work and it has been driving me crazy for the past few days. Hopefully the 91's exhaust will mask the diff noise.

I noticed a lot of whine when I did the swap too. Mostly from my wife though. "You work on that car too damn much".

Yeah, the car's a little noisier too. Less rubbery though so it's a trade off.

I noticed the whine also... but I have another question I don't think I want the answer to.

After the diff bushings I noticed a bit of what feels like excessive gear lash maybe? If I let off the gas, then get on it there is a bit of a tap noise. Sounds like there is too much space between the gears and when it switches faces it hits with a bit of force. Is this normal or a sign something is effed? I figured maybe it was the lack of dapening in the drivetrain allowing me to hear it.

Here is the catch.. it's a Kazz diff. I had heard they have a lot of lash built into them. I know they make A LOT (and I mean A LOT) of noises already, but this one worries me.

if its not diff noise, then it might be the driveshaft u-joints (it's thats still what they're called). mine wore out and started making a sound like that. later it caused a vibration. bought another and the sound and vibration were gone.

I'm just so fucking deaf from all the gear noise I don't whine anymore...

This. Feels like the car is shaking itself to pieces at a certain rpm on decel.

so its not a good idea to replace the bushings? or is there something that isnt as noisey