I think my scoob's always had a bit of drivetrain backlash but recently it's really started bugging me.

So can anyone answer...

1. Is it normal to have a bit of backlash - not HUGE amounts, but, for instance, parked and with the handbrake on stick it in 1st and gently apply a bit on torque though it and the in reverse, let the clutch in again and there's a clunk as the "slack" get taken up.

2. Whats the most likely culprit (box, diffs, UJs etc)

3. For previous vehicle experience, worn engine, gearbox mounts cam play a large part in apparent backlash when on the move, is this the case with the scoob? should I look at replacing any?

dr_jones - 97 JDM WRX STi

mine does this . but it's the handbrake shoes .they're useless. the car rocks backwards when you apply it on a hill too.
might not be that...but where's it coming from?

Steve

Hard to say for certain but I had a look last night and the most likely culprist is the rear diff - theres definately a bit of play there, i can rotate the prop a noticeable amount befor it engages.

Any idea how much is acceptable?

Without removing the diff unit and checking the meshing gap between the teeth, its a bit hard to say exactly what is acceptable, as you also have to take into concideration, there may be play on the driveshaft splines too as they engage onto the diff unit.
but dont get the brake pad movement mixed up, as they do make a loud clunk noise when cjanging direction from forward to reverse [sorry if trying to teach to suck eggs on this bit !].

i would simply say, so long as there is no bearing or whine noise when driven perhaps best to leave well alone as to eradicate all the play in the system is not going to happen, there will always be some "tolerance" in each component within the system.

Cheers,

Pretty sure it's not brakepads, however after further investigation last night I'm now not convinced its actually transmission related at all.

I tried roscking the car back and forth and listening for the cluncks - it only moves about 40 mm forward and back between clunks. I then tried the same on a Mk3 golf and found at leat 60 mm.

Thinking about the problem I have when I'm actually driving, it seems the car is jerky on slight throttle openings and between gear changes (hence me immediately jumping to the drivetrain problem conclusion).

The feeling the car has is very much like what I got when I fitted a VTA dump valve and thus confused the MAF....

Could it be my MAF is on it's way out? I did have some trouble starting it yesterday and have had a few pops from the exhaust recents...

Hi,

An excellent question, and one I was thinking through myself. I wonder if the increase in percieved shunt is not due to wear and tear / increased free play in the diffs and driveshafts as slightly rough running caused by mod, deterioration of ground points as the car ages or something else similar (ref: earthing mod.

I've noticed on my MY98 that tip-over into overrun seems a bit more abrupt than I remember - not sure if this is cause or effect. The car is due a service and I'll get the engine / gearbox / diff mounts checked for wear. I will also perform an earthing improvement mod suggested by Link Electrosystems.. I'll scan a picture and post it if you're interested - should be the same ECU pin-out for your STI IV.

Cheers,

Alex


[Edited by AlexM - 9/5/2003 3:01:52 PM]

Cheers - If you would I'd be very interested to see it.

Hi Dr Jones,

I recently purchased a an STI 2005, Wide Track, DCCD... And on the way back from collecting the car I noticed this Whinning sound (Especially in 6th gear when engine sound/rev is low) that I would describe as Straight Cut gearbox sound. Hope there is nothing bad with it.

But also my car does what you describe in the quote above. With handbrake ON, and gear in, the wheel can rotate qui a lot.. strange. Think it can only be the brake shoe as explained by someone else.

So I wanted to have an update on what happened with yours since that message.

Angus