What shift coupling ?

[majordad]

The shift coupling in my 72s has been there for over ten years and shows signs of wear. I’m wondering which one to replace it with , the standard part or one of the precision items from Rennline etc ? Car is driven for road use only and tours.

[911hillclimber]

Decades ago I replaced my stock slotted hole bushes for some from Automotion.
The new ones had round holes so removed the slack in the fore/aft movement.
They are still in there about 60k miles in.
You will never remove the designed slop in the 915 trans so there will always be some but I think that is a good thing.
Now the car is only road driven it is a delight.
I suggest you replace every bush in the system at the same time, low cost, max effect.

[Ian Comerford]

You have a few options. You could replace your existing bushes with new standard ones, replace them with Superpro ones which are a bit firmer or go for one the more expensive UJ couplings from Stomski or similar. The main issue with these is that they transmit more noise into the cabin which you may not want.

[majordad]

Thanks for the replies. Food for,thought. Noise into cabin is not an issue.

[jwhillracer]

Hi Dave,
Check and if necessary change your engine and gearbox mounts as well, if there’s excessive movement in those it can also spoil the gear change.
Cheers
JW

[gridgway]

From my experience of replacing here, the standard ones are completely fine!

[911hillclimber]

This is all subjective and much like short shifter s etc. I did my conversion of the joint to simple round hole bushes about the time I fitted my 3.2 into the 73T.
I was road/hillclimbing the car then. The drive train would move all over the place, felt like axle tramp in a Morris Minor when dumping the clutch at 4500 rpm etc.

Installed poly bushes in the engine/box mountings and the shift was transformed, no violent shudders etc, really good, and Jonathan is dead right.

Today the car is long retired from hillclimbs, just a nice classic car cruiser and the engine is back to rubber mountings but kept the round hole joint bushes.

The round hole bushes reduce the fore/after clearance considerably but transmit all the engine movements to the lever = harshness.

I don't notice much harshness but i don't thrash the car either.

I've removed all short shift gear levers etc too back to factory and enjoy the car far far more.

I am sure if I hillclimbed the car now it would not be as good as it used to be where speed and accuracy of the shift is critical when chasing 1/10th of a second here and there.
None of that matters on the road in a cruise mode classic car.
Just my experience and opinion, other thoughts equally valid!