4 Mechanics Have Given Up, Please Read and Help if You Can

[New2DSM2]

Hi guys,

As my name suggests I am relatively new to DSM ownership but not at all new to cars or car maintenence.

Here is the problem I am having I hope you can help me with:

I bought a 1990 Talon TSi AWD 5 speed from a guy for $700. I know what you're thinking (crap) but it wasn't, he was the original owner with the original sticker and he is just an older guy who is out of touch with what the car was really worth. It had 56,000 miles when I bought it (64,000 now). The problem I am going to describe has been there since day 1 owning the car. There is a fairly aggressive 'grinding sound' coming from the right rear wheel area of the car. We have hooked up chassis ears to it, and had thought, determined it is somewhere in the suspension (crossmember, control arms, etc.). The sound is ONLY there when you decelerate in gear (any gear), but it is intermittent, sometimes it is gone entirely, sometimes extremely loud. The sound is best described as 'gear whine' or 'rotational' of some sort. This being the case, we started replacing things (and haven't stopped). So far we have replaced all universal joints, the rear differential, both rear axles, all four rear wheel bearings, all crossmember/carrier support bushings (except the ones in the crossmember itself, because you can't without buying a whole new one). We have taken the driveshaft out altogether (drove and accelerated very very slowly before you start twitching) to see if we could localize the sound and we noticed it was perfectly quiet, no noise whatsoever, which led us back to the rear of the car. Having replaced anything that has gears, universals joints or splines, we don't think it is drivetrain related. Basically, the only things left in the car that haven't been replaced are the control arms bushings, ebrake items and the crossmember (dealer FIRMLY believes this is the problem and wants $1000+ to change a new one into it because of labor @ 10.4 hours). All four of our mechanics feel it is NOT the crossmemeber, but we are at a loss, the noise has lessened a tad but won't go away, and we really don't believe it's the tranny because the noise went away when we drove it with only the front wheel drive, but again I am a newbie so tell me if we are wrong. Any help you guys can lend us would be most appreciated. Also, just want to add I don't really care what it costs (obviously) I just want it fixed so I can drive this peach without grating my teeth when I downshift and decel.

Only mods on the car are a SPEC Stage 3 lightweight clutch and Flywheel, Buschur turbo back, OZ Super Leggeras (brand new) and a Supra SMIC. By the way, the noise was there before the clutch install. (see, I did search first).

Please help, I can't be the only guy in the world of DSMs to run into this problem.

Thanks in advance and sorry this is long but you guys said you needed info for diagnosis

Let me know if you need any other information.

 

[Morphius]

Could be one of the two gear clusters/shaft in the trans. Decel causes a reversal of thrust loads in the trans. Thus, loading the bearings differently.

 

[Dream On]

Yeah if you're in Ohio, try Buschur or Shep. Shep would be the guy to go to if you think its transmission/t-case/rear end related. Super nice guy and he could definately find your problem if its in that area. I mean, he does have the fastest AWD DSM in the world...

 

[Morphius]

I know of 5 guys that have an aluminum flywheel and they have the worst noise, myself included. It's only on decelleration and only when it's in gear.

The lighter mass of the flywheel can change the harmonics of the drivetrain. There is less mass there to dampen out 'noises'.

 

[brisvr4]

I'm not too sure if your gearbox's are the same as our VR4 boxes over here but a lot of us are having the same problem.

A couple of guys have traced what seems to be the cause of the grinding on decel to a worn centre diff.
Apparently the pins wear out and bang around ( sorry if I don't know the correct terminology)

I would imagine that when you took the driveshaft off you greatly decreased the pressure on the centre diff thus stopping the noise for a little bit until you refitted the shaft?

So what do I get if I have it right?

 

[JOEY A]

We have the same trannys as GVR4s the only diff is the GVR4 has a Longer 1st gear, most people will switch out to your 1st gear for the better gearing...

1Gs 1st gear is around 35mph and a galant is somthing like 45mph

 

[kraka]

DAMMNIT!

My car is doing the same thing except only when I accelerate; it's in the same area tho...

BTW: I also run the full 3" Buschur exhaust