Collective wisdom required on identifying gearbox problem

[Gertvr]

I am new to this forum and and just recently acquired my first project Porsche ('75 911S) to restore and upgrade with my 2 sons. I am not new to cars and have restored several British sports cars and want to start teaching my kids.

With that out of the way here is my problem:

1st project was install a rennshift and new link coupler. Installation was completed and while performing the adjustment of the linkage I requested that my son turn the ignition on to verify that the reverse light is working.

He took it too far and cranked the engine. The car jumped but didn't start.

On the test drive all gears selected fine but.. when moving from 2nd - 3rd there is a grinding noise from the GB, same when moving from 4th - 3rd and 2nd - 1st. The grinding noise correlates to the speed the car is traveling. This is not just happening on selecting the gear but also when disengaging the gear moving the shifter forward.

It didn't do this prior to the upgrade. I subsequently put the old linkage and shifter back and the same thing.

Is this just an adjustment problem or has something gone out of alignment in the GB due to the cranking of the engine while in gear, if so any ideas on how to remedy this?

Any help is greatly appreciated

My apologies for the long post

Gert

[Jim Sims]

"He took it too far and cranked the engine. The car jumped but didn't start."

Set the parking brake next time; but I doubt the "lurching" is the cause of the issue.

"On the test drive all gears selected fine but.. when moving from 2nd - 3rd there is a grinding noise from the GB, same when moving from 4th - 3rd and 2nd - 1st. The grinding noise correlates to the speed the car is traveling. This is not just happening on selecting the gear but also when disengaging the gear moving the shifter forward."

Check the clutch adjustment; it may not be fully releasing.
Remember when shifting a 915 to pause momentarily between gears.

My son and I restored a '73T together (very good investment of time and money) and I have a '76S.
Good luck and have fun.

Cheers, Jim

[Gertvr]

Thanks for the input Jim,

I did the clutch adjustments as described in the 101 Projects but it didn't change anything even taking the adjustment to the extreme with no play in the clutch, still the same symptoms. Selecting 2nd and 4th is smooth without any issues

Is there a knowledgeable person in the North Atlanta area that can help me diagnose the problem before i start tearing the GB apart?

I will do a search on common things to replace on the GB if i have it out of the car. It has about 140K miles on it if it came with the car. I would appreciate any suggestions on what to look for and replace or direction to threads that already discuss this.

Gert