I've been noticing more slack in my drivetrain lately. More than I had with my 5MT. My question is this: is there a spec for how much the driveshaft can turn before "takeup"? When I'm under the car, I can rotate the driveshaft about 4 or 5 degrees by hand (all wheels on the ground). Also, what is the limiting factor here, the trans or the rear diff?

This annoys me when driving and going from throttle on to throttle off in first or second gear. I'm also concerned this may be a sign of something wearing...

i dont know, it must be normal cause thats how mine was when i was under the car turning it, i was concerned too but just assumed thats how it was supposed to be.

i dont know for sure though, anyone:confused:

Ben

I've got a 6mt with an R160 and haven't noticed it. How much did you torque down the bolts on the center collar (the bendy part in the middle) to the frame? Did you re-use the bolts on the yoke into the rear diff?

I've got a 6mt with an R160 and haven't noticed it. How much did you torque down the bolts on the center collar (the bendy part in the middle) to the frame? Did you re-use the bolts on the yoke into the rear diff?

The centre collar was just "zapped" with my IR impact gun (I know, I know) and I did re-use the bolts into the diff collar. I'm 99% sure this is coming from the ring and pinion backlash in combination with the trans backlash.

Does this mean the 6MT has more backlash than the 5? Since my R160 with the 5MT didn't exhibit this behaviour, that seems to be the 'X' factor.

I can live with the current behavior as long as I can tell myself its normal...

I just went through the service manual again. No spec on rotational slack, just runout. I did find something I hadn't seen before though. The rear shafts are marked left and right. I'll have to check to see if I got mine in right. Wonder what effect that would have?

There are definitely backlash specs in the manual. That's what you are feeling. There is backlash between the axles and the diff and the pinion gear to the ring gear, so it may feel like a lot when it really isn't. My Kaaz rear LSD seems to have a lot of backlash but I've been told it's normal.

The pinion to ring gear backlash is set by the side retainer shims. Who converted your R160 to a 3.9? How was it converted? Was it a legacy turbo diff that you put the LSD from a WRX into? When you put the diff back together you should measure the backlash, runout, and torque it takes to rotate the assembly. Generally you can "feel" when it's within spec pretty easily if you know what a factory built one feels like.

There are definitely backlash specs in the manual. That's what you are feeling. There is backlash between the axles and the diff and the pinion gear to the ring gear, so it may feel like a lot when it really isn't. My Kaaz rear LSD seems to have a lot of backlash but I've been told it's normal.

The pinion to ring gear backlash is set by the side retainer shims. Who converted your R160 to a 3.9? How was it converted? Was it a legacy turbo diff that you put the LSD from a WRX into? When you put the diff back together you should measure the backlash, runout, and torque it takes to rotate the assembly. Generally you can "feel" when it's within spec pretty easily if you know what a factory built one feels like.

You're right, there are backlash specs in the manual for the rear diff. But my question remains, what is the limiting factor, the rear diff, or the trans backlash? I know for sure that I don't have a spec for backlash on the 6MT.

Elsewhere there is a thread about my trials when converting the ring and pinion; short story, the first set was done by a shop but they didn't last 200 ft. The second time, I bought a complete pumpkin with 3.90 and lsd from Lachute which was factory assembled.