The GTM Supercar Build Log

Proper Calibration of the Brandwood Cable-Shift’s Fore/Aft Motion

Since I’ve had the GTM on the road (some 330 miles now) I have had a problem with it randomly popping out of reverse or first gear when starting from a stop, usually only when the box was cold. No grinding, just pops out, as if it wasn’t fully engaged. If I firmly put it back in gear it would then start moving fine. I figured either the cable that controls the fore/aft motion (that allows you to enter the various gears) was not calibrated properly, or my trans was injured.

I contacted Brandwood this week and they promptly replied with instructions as to how you should properly calibrate the cable-shift’s fore/aft range of motion. The directions I received with my cable-shift system were very general and really did not discuss this calibration at all, so I simply ran the cable and connected it and tightened up the jam nuts that hold it on place. With proper instructions in hand I could see that my cable was ‘calibrated’ in such a way that it had plenty of range for 2-4 shifts, but it was about a 1/2″ short of pulling the shift rod out of the transmission all the way on the R-1-3-5 shifts. No wonder I was having problems! With the proper calibration performed, I took the GTM out for a while and had zero issues. Nice!

Here is how to properly calibrate your Brandwood Cable-Shift system for proper fore/aft motion to ensure proper gear engagement:
1. Disconnect the fore/aft cable from the shift rod ‘coupler’ at the ‘ball and socket’
2. Push the transaxle shift rod forward, into the transaxle
3. Pull the shifter handle down, as if you were selecting 2nd or 4th gear.
4. Check that the ‘ball and socket’ connector moves past the shift rod ‘ball stud’
5. Pull the transaxle shift rod out, away from the transmission
6. Push the shifter handle forward, as if you were selecting 1st gear.
7. Check that the ‘ball and socket’ connector  again moves past the ‘ball stud’ on the shift rod. You should see  a slightly greater range of motion from the ”ball and socket’ connector in each direction than the ‘ball stud’ on the shift rod. This ensures that the cable is pushing/pulling the shift rod into/out of the transaxle all the way.
8. If the range of motion is lacking in the ‘1st gear’ direction (ie: when you pull the shift rod out), ‘tighten’ the rearward jam nut . If the motion is lacking when going to grab 2nd or 4th, tighten the ‘forward’ jam nut (the one that is closest to the  motor).
9. Once the range of motion is calibrated properly, put the shift rod in neutral, and the shifter handle in neutral. The ‘ball and socket’ connector should be able to slide over the ‘ball stud’ connector.

Here is a pic of how my calibration ended up looking.

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