I've got a '86 NA base RX7. When I'm going down the freeway and not on the gas and/or decelerating a little, I have a not to loud howling noise coming from the rear end. It doesn't seem to do it when the car is cold, but only after driving it for a while. It doesn't to it when accelerating. It doesnt seem to get any louder, its just one tone.

 

Are your ports working? I had a howl and it went away when I got my ports working again.

 

Thanks, but When I got the car the ports were not working. it was the first thing i checked/repaired on the car. They work fine and its only while I'm coasting/driving down the freeway does it howl.(at way below 3800rpm(when the ports open)

 

I used to have a howl of sorts from my back end that changed slighly with the car speed. It went away after I put in Redline differential fluid.

 

I have a howl from the rearend as well. It gets louder that faster you go but stays that one tone at different volume. I have been told wheel bearings need some TLC. Could be that.

 

I'm using Redline oil in the trans and rear end. I will check the wheel bearings though.

 

Wheel bearings. Get them replaced before they totally fail (causing the wheel to seize up).

 

im having a smiliar problem on my '89 NA, its a real loud howling/whining noise upon decelerating or coasting, in any gear or in neutral. i'll check my wheel bearings tommorow but if its not that what else do i look for?

 

It's a toss-up:

Could be wheel/ hub bearings.... Replace assemblies (repacking may not work if the container ring is mangled);

Or it could be your rear-end.... Drain diff (loosen top bolt, remove bottom one) and then fill will 90W gear-oil, or, like 'WDWFlash' said' use Redline, or some other high-grade industrio-lube.

 

I would suspect wheel bearings first (mainly because they are easier/cheaper).

My only thoughts about the rear end would be that since you only hear the noise under decel or no load, that perhaps the trailing sides of the teeth on the ring, pinion, or both is worn badly (or somehow pinion pre-load or ring gear backlash was knocked out).

 

howl ....sounds more like bearings.
I have a whine, that I KNOW is the rear end... time to find a competent gear shop...

 

Third member type rear ends aren't usually too difficult to work on. But gear jobs always tend to be dreadful no matter what.

Are there companies that even make gear sets for these cars? Or when the rear end fails does that usually mean you're out looking for a new rear end?

 

update: my wheel bearings turned out fine, then i checked the rear diff and it barely had any fluid in it! so i filled it up with that royal purple stuff 75w90 and it reduced the noise by half. it isnt completley gone, so i think my rear diff is deffinatley fucked?

 

It's certainly possible.
Does your car have aftermarket bushings in the diff mounting ears?
They tend to transmit vibration/noise to the floorpan...it's more a drone than a howl though.

 

Front pinion bearing in the differential. It's where the drive shaft connects.

 

clokker, everything looks completely stock down there.

pvillknight7, i just looked on mazdatrix and they sell for 60 bucks each and is stated that 2 are required, yikes! am i better off finding another rear diff from a member on here for cheap?


i dont even know what gear ratio i have as i just recently bought this car, its a 89 NA and has a sunroof, rear spoiler, also has a switch for fog lights, its got vert wheels on so i dont even know what trim level i have.


but thanks for the help guys!

 

I think you can verify if the noise is from the differential by shaking the driveshaft. There should not be any play in the front of the diff. Check out the FSM or Haynes.

 

so just today i drove a real short trip to the gas station and back and half way back i kinda had the same problem as far as abnormal noise from rear upon deceleration in any gear and in neutral...except my noise isnt a whining or a growling...its like a ...well it depends on the speed but its very loud and sounds like a violent clanking....
thought it could be driveshafts, or diff, but...two questions; an old timer buddy o mine who really know datsuns said that he knows for sure that its the throwout bearing and clutch plate...
well im not so sure...
also just changed rear pads...not sure if this has anything to do with it...walked along side the car as girlfriend was driving very slowly so i could see and listen from different standpoint... well first of all the irratic attempt of her slow driving made it kinda difficult but, from the out side it sounded like somthin was 'flicking' the dust cover of the rear brake disc...
gona check the diff fluid level 2morro but i just did that when i baught it not long ago...unless somthin is really wrong with it. hmm...
bearings need changed soon i know....
any ideas? maybe the sound im hearing is quite different then what this thread is about...idk

 

just checked it, driveshaft deffinatley has some play and the gear oil i just put in is leaking from the front of the diff, this diff is deffinatley done, FML!


WTB: s5 n/a ('89) rear diff, i have no idea what gear ratio it is but im guessing 4.30?

 

4.10

 

thanks!

 

It's NOT the wheel bearings. If it was the wheel bearings it would be all the time, not just on decel or cruise. It is without a doubt the backlash in the rear end

Backlash.

Been there, done that, not worth it. Just spend the $55

It's howling becuase it's worn. Replacing it with the same weight oil isn't going to help much unless the oil is LOW, in which case it's probably close to trashed, or the oil is spent. Try some 85w140, that might help.

Really? That's your logic? My car won't start. I bet it's out of gas>

Well, you've redeemed yourself somewhat.

No.... if you're lucky everything was worn.... smoothly... if that makes sense. If there's no step wear on the ring, it could be possible to tighten it back up, start with the 75w90 and see what happens, if it's still there you could bump it to 85w140 and see if it's all gone. I wouldn't toss the rear end just yet. It's always worth trying to fix before throwing something out. This coming from the guy who went through 3 gear sets and 2 rear ends this year.

Yes, yes there should be some play from the time you start to rotate the driveshaft till the moment that the wheels start to move. It just shouldn't be that much. I suspect he'll be able to put the parking brake on, trans in neutral and get an 1/8th of a turn out of the driveshaft.

Yup. Although I'm not convinced that he'll need a totally new/used rear end. It would be wise to try to get the backlash re-set. Probably be cheaper than buying/shipping a new rear end. Takes about a 1/2 hr and any shop that tries to set it up and can't, shouldn't charge him. So, pull the diff (going to have to anyway to swap it if this one is indeed fucked) and take it to someone that knows what they're doing. If it is infact trashed, half the jobs already done.

My cars out of gas, better start looking for a new one......

 

I should have been more specific. I wasnt asking the OP to check for rotational movement of the driveshaft. I meant he should shake the driveshaft up and down relative to the bottom of the car to the roof and feel for movement.

Titanium- you bored?

 

Looking for mount wear? Pinion bearing wear? u-joint wear?

I'm never bored, why?

 

When the bearing in the front of the differential goes bad it allows the mounting flange with the four holes for the driveshaft to move.