Steve Cattaneo

Adjusting the modulator does not change the shift points on a A28 transmission, this is my final answer.

There are ways of changing the shift points.

1. adjusting the full throttle control pressure valve.

2. changing the springs in the shift command valve. (shift kit)

All of these modifications involve valve body adjustments. Another modification is a first gear start conversion kit. Also, a valve body modification, a lot more complicated.

The vacuum modulator cap number 9264 is part of the vacuum system. If its missing or cracked (it likes to crack) you will have hard shifts or erratic shifts. MB part #1262770081.

If anybody is interested in these modifications, e-mail me and I will post them with pictures.

Steve C.

Ed Ruiz

I was able to change the shift points on my 86.5 AT by simply taking out slack in the transmission linkage. The more slack I removed, it would take a bit more RPM to shift into a higher gear. Also, instead of starting in 2nd, it would always start in 1st. YMMV.

Steve Cattaneo

ED THANKS FOR THE INFO.THE PREVIOUS TWO POST
BELOW (CHANGING SHIFT POINTS) RAISED THE FOLLOWING QUESTIONS , WOUID AJUSTING THE MODULATOR RAISE SHIFT POINTS, HOW TO RAISE FULL THROTTLE SHIFT POINTS
JUST BELOW REDLINE(6000RPM) THE ADJUSTMENT OF THE TV CABLE WAS ALSO DISCUSSED IN DETAIL

STEVE C

Steve Cattaneo

ED THANKS FOR THE INFO. THE PREVIOUS TWO POST BELOW (CHANGING SHIFT POINTS) RAISED THE FOLLOWING QUESTIONS , WOULD ADJUSTING THE MODULATOR RAISE SHIFT POINTS, HOW TO RAISE FULL THROTTLE SHIFT POINTS JUST BELOW REDLINE(6000RPM). THE ADJUSTMENT OF THE TV CABLE WAS ALSO DISCUSSED IN DETAIL.

STEVE C

Randy V

Thanks for the clarification Steverino - my comments were directed at the A21 and A22 type trans found on earlier model years.

Perhaps you would like to let folks know what model years have the A28 transmission?

2V4V

Randy,

The A22.01 - A22.04 were the 3 speed autos. A28.01 - A28.18 were the 4 speed autos.

HTH,

Greg