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Registered User
Join Date: Dec 2009
Posts: 210
Renn Shift problems

Picked up our 914-6 GT Replica today after an engine rebuild ,canít get the car into 1st or reverse with out crunching ,the rest of the gears are really really stif to get into the remaining gears,I bought the linkage set up that was recommended for the car at the same time ,does anyone else have a renn shifter on there 6 cylinder and does it run smooth or do you have problems ,please tell me thereís an easy fix,itís so frustrating
Thanks Brian
Old 02-24-2018, 10:00 AM
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John Rogers's Avatar
Join Date: Dec 1969
Location: chula vista ca usa
Posts: 5,160
Back when I was racing my 914-6 I had one of the first RennShift units and in talking with the maker of them I learned some things, not in any particular order. Make sure the trans mission is in great condition for the bearings and synchros. Make sure the firewall bushing is new or like new and I finally bought one of Jim Patrick's replacement bearings. Make sure the coupler flex joint is like new and I bought a sealed aircraft type used on many race cars from a guy in Maryland, sure was expensive like $150 or so. Make sure the bushing in the transmission shift console has little to no slop in it as the same with cup bushing. Since the shift rod wears from an oil and dirt mixture even a new bushing may not help. There are replacement bronze bushings but I went with a new neoprene one and looped several small nylon wire ties through the hole and around the console to tighten things up a bit, cheaper too.

When I installed the new shifter I had the rear of the car jacked up and moved the trans mission into 1st gear. I had written the shift pattern on the trans case as it is NOT the same directions as the shifter. I had both front and rear rods in place, inserted the shifter and got the pinch coupler in place without moving the rods. I had my daughter (who is a PCA Parade autocross champion) underneath the rear holding the vise grips I had clamped on the rear rod to keep things from moving. I tightened the pinch bolt and adjusted the shifter throw as per James' instructions. I forgot to tell her to let go and take off the vise grips and I could not initially move the shifter and it scared the hell out of me! Once we did that and set the adjustable stops the trans shifted great. I drove around some to get used to things as the feeling of the shifts is definitely different than stock. I found that in the street circuit races I did in Mexico I could actually shift into 1st at 30 MPH which helped on a course that had slow, tight 180 degree turns!

Hope all of this helps and the biggest thing is to make sure the trans is in 1st to get the shifter in correctly. Good luck. Here is the coupler I mentioned.
Old 02-27-2018, 04:53 PM
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Dave at Pelican Parts's Avatar
Join Date: Dec 1969
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"First and reverse crunching" is the classic sign of a clutch that is out of adjustment. It isn't disengaging properly so everything is still spinning when you try to put it into gears.

Tighten up the adjustment on your clutch cable and see if that helps. If it does and then things get worse again, you either don't have a jam-nut on the clutch adjustment, or the clutch tube inside the center tunnel has broken loose.

Pelican Parts 914 Tech Support

A few pics of my car:
Old 02-28-2018, 06:07 AM
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John Rogers's Avatar
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Location: chula vista ca usa
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The way I read the original post was he put the RennShift in but maybe not? Anyways if it was already in there then the clutch could be the issue and it is worth a look. I always set my clutch up to release/engage with 50% pedal travel. Many racers like more many like less and it depends on the way the parts are installed. As Dave noted the adjustment might be off due to just a single ny-lock nut instead of TWO. The tube can come loose at the firewall as he noted and several others: the cable reversing wheel on the trans might be failing if there is one, the cable can be stretching and even the clutch pedal bushing can have failed. I used a custom clutch disc and pressure plate made locally in San Diego so it was very light on pedal feel but was "instant" engagement, like in the 200 MPH 914 that ran at Bonneville with the nitrous Chevy Big Block in it and only 2 gears.
Anyways look closely at the other places I mentioned and if they are suspect then replacement would help.
Old 02-28-2018, 05:54 PM
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Finally got it dialed in on the 6th attempt. See World, What did you do to your car today, thread. But it was completely trial and error, with a bit of luck. The most important thing I failed to do with the previous attempts was making sure after locating 2nd and tightening the bolt down, that when the shifter was in neutral, the shift lever was perpendicular to the shift housing. But as for the secret sauce, it’s time and patience while paying close attention to the JWest instructions.
Rick S, '71 914 3.0, '82 911SC EFI, R Gruppe #309
Old 02-28-2018, 09:02 PM
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