Transmission Backlash

[Rusty]

Been finding that there's a few more clunks whirrs and bangs on the old girl than there once was (not helped by the carpet still not being back in the car ) so thought I'd have a look on a ramp and see how much play there was in things what spin! While no individual component has an amount of movement that would concern me, the cumulative backlash from the rear wheels to the gearbox is noticeable... I guess I'm in no way on my own here and the only way to sort it is new CVs on all joints and a diff rebuild...

[andy10v]

Been finding that there's a few more clunks whirrs and bangs on the old girl than there once was (not helped by the carpet still not being back in the car ) so thought I'd have a look on a ramp and see how much play there was in things what spin! While no individual component has an amount of movement that would concern me, the cumulative backlash from the rear wheels to the gearbox is noticeable... I guess I'm in no way on my own here and the only way to sort it is new CVs on all joints and a diff rebuild...

Yup, I have replaced, engine mounts, gearbox mounts, diff mounts, 360* snub mount, center prop bearing/mount, tried 3 different diffs and still have lash.

I do wonder about play in the gearbox/center diff internals as well.

[lagz33]

Is lash the kick forward you get after having changed gear and come up on clutch?

[Rusty]

Yeah, it's the transmission slack being taken up in each component to transmit drive to the wheels.

[lagz33]

Oh ive got loads of that
Think its something to do with my rear diff....

[Rusty]

Yes - rear diff mounts x3, centre bearing, prop gearbox mounts x2, engine mounts x2, snub mount, CV joints x10, gearbox, differentials x3 ...

[Lloyd]

I bought a spare rear diff and am currently having it fully rebuilt by JP Race Engineers at Silverstone to fix this lash issue. Will keep you posted.

[Rusty]

Yeah, there's certainly enough in that part alone.

[lagz33]

Theres me thinking it was the sheer oomph of my S2

[Error404]

The majority of this "shunt" is the play in the centre diff - nothing you can do about it unless you want to shell out for a new torsen!
Apparently the 2nd and 3rd gen TORsens don't seem to suffer as much as they have different helix angles on the worm gears, but the torque bias ratio is lower. I'm not sure if they are a straight fit into the CGR / CRB boxes - quite likely I recon.

[Lloyd]

Shunt maybe. I'm hoping to get rid of the wub wub noise at low speed when stopping and turning etc

[re2500]

Im really hoping alot of my shunt gets eliminated when my car is back on the road, ive replaced the following:
All diff mounts
All Gearbox mounts
All Engine mounts
All F+R Subframe mounts
All Wishbone Bushes
Diff and GB fluid.
But im not too hopeful, the diff has a fair bit of backlash. 2 other diffs i have aquired have had the same baclklash, so i dont think there is much i can do about that.
The only thing i havent done is CV's.

Fingers crossed anyway....

[newsh]

Mine has just started clonking again at the back, the joys of the extra 200hp I guess..

[andy10v]

One of the old magazine articles about the s2 complained about the lash/shunt even when new.

[s2driveruk]

mine has a fair bit but having changed everything under the car but to be honest the best cure is not to reallyrush the gearchanges as you would/could in a 2wd car....they S2 box doesnt like being rushed and there is definately less clunk and thunk when slowing them down a tad.