Ollyh2015

Hi I have a 99 sti bit of info it's forged running 400hp when I bought it was told it had the blob eye gearbox to find out it's just a standard box same what's on my catalunya version anyway on the way home it started making a grinding noise at low speed, when I let the revs off! If I keep revs on it stops and if I put the clutch in and coast it stops aswell, but if I'm doing say 40/50 or more it doesn't do it at all could anybody shed any light on this as it's my first scooby and don't know much about them tbh thanks in advance for any input very appreciated

buxtonous

iTrader: (1)

are u sure its coming from the rear diff? i suppose u could check the rear diff oil for metallic swarf...?

Ollyh2015

I have no idea at all I'm just presuming it's that

InTurbo

iTrader: (3)

Haven't jacked the car up recently have you??

Only reason I ask is I had a similar thing. One day massive grinding noise every time I let off in gear.

S204Darren

Is it a standard diff?

Ollyh2015

I haven't no why could that cause it though ? The guy I got it from never mentioned it so I just presume it's a standard diff yeah could be wrong

oilman

iTrader: (9)

Might be worth trying a 90LSD oil to see if that stops it, sounds a bit like it's got a LSD and doesn't have a LSD oil in there at the moment. The Fuchs Titan Race Gear 90LS, Castrol Axle Z or Motul 90PA are ideal.

http://www.opieoils.co.uk/c-679-sae-90-gear-oils.aspx

Cheers

Tim

InTurbo

iTrader: (3)

The problem I had sounds very similar to yours.

If I let off in lower gears from 3k I would get this loud grinding noise from the rear of the car.
And if I put clutch in or accelerated it stopped.

Turned out to be a bent out rigger bracket. Worth checking yours to see if it's the problem only takes a few minutes to take it off.

Link below

https://www.scoobynet.com/drivetrain-11/1024747-possible-solution-for-people-suffering-with-diff-whine.html#post11683528

K3ogh_sti

cheers for this Darren im going look into this when im back from Germany, mine does exactly the same, I presume all models have the said bracket?

InTurbo

iTrader: (3)

Yeah they do. If you look under the car you can undo the 3 bolts and remove the plate to see if it bent.

If you keep the car on the ground you can do one side at a time without the need to hold the diff as it's still being supported by the other side.

You can also put the long bolt back in without the plate and do a quick test drive to see if the noise was coming from that side then vice versa.

K3ogh_sti

got any better pictures of where it is on your phone or anything mate? il know where to look straight away then when im back, facebook message me them if its easier bud? I cant quite work out those pictures in the link

InTurbo

iTrader: (3)

Below your rear doors. If the bracket gets bent it touches the diff carrier rather than being isolated by the bush and transmits lots of noise into the cabin.