Auto Trans Shifting Quickly

[DeLorean937]

So I've been reading day in and day out about our transmission computer and shifting control. I came across an article which says the car will switch gears in the higher RPMs. Is this something that the kickdown cable controls? It takes off in 1st but then switches from 2nd then 3rd very quickly. I have seen where people can rebuild there board using the new capacitors and repairing soldering joints but before I start tearing into it I was hoping to get some input.

[bytes311]

So I've been reading day in and day out about our transmission computer and shifting control. I came across an article which says the car will switch gears in the higher RPMs. Is this something that the kickdown cable controls? It takes off in 1st but then switches from 2nd then 3rd very quickly. I have seen where people can rebuild there board using the new capacitors and repairing soldering joints but before I start tearing into it I was hoping to get some input.

The shifting computer was one of the first things to go in my car which I tried repairing myself with new components but with very little success. Ultimately I ended up sending the unit to DMCH and they replaced the old board with a new, modern board and that fixed my sporadic shifting problems.

I also heard that low AT fluid can cause similar symptoms.

[PJ Grady Inc.]

Low fluid will cause slipping when cold. Very low fluid will causing slipping all the time and the trans will be toast very quickly. This is probably a computer governor problem but it doesn't hurt to check fluid level, line pressure, and detent cable adjustment first as should be done when servicing it anyway. We also carry reconditioned governors FWIW.
Rob

[DeLorean937]

Low fluid will cause slipping when cold. Very low fluid will causing slipping all the time and the trans will be toast very quickly. This is probably a computer governor problem but it doesn't hurt to check fluid level, line pressure, and detent cable adjustment first as should be done when servicing it anyway. We also carry reconditioned governors FWIW.
Rob

Sounds great! Rob, do you sell just the new boards alone so that I could install them? I will check the fluid level again but if remember correctly I changed it not to long ago and filled it to the correct level. As far as checking the line pressure would you be referring to the vacuum line to the front of the transmission? I have a new kickdown cable that I will install this weekend since the old one is cracked and see if I can adjust it to a point of correct shifting.

[PJ Grady Inc.]

Sounds great! Rob, do you sell just the new boards alone so that I could install them? I will check the fluid level again but if remember correctly I changed it not to long ago and filled it to the correct level. As far as checking the line pressure would you be referring to the vacuum line to the front of the transmission? I have a new kickdown cable that I will install this weekend since the old one is cracked and see if I can adjust it to a point of correct shifting.
No we only sell reconditioned CG's. There's too much to go wrong for the average DIY'er.
Rob

[DeLorean937]

No we only sell reconditioned CG's. There's too much to go wrong for the average DIY'er.
Rob

Ok that works. How much do the reconditioned units cost?

[Farrar]

The shift cable may be too loose. (I can't remember the official name for this cable. Sorry.) It's a very fine adjustment -- I think the Workshop Manual says within 3mm -- too loose and your shift points will be in very low RPMs, too tight and your shift points will be in the very high RPMs.

[PJ Grady Inc.]

Ok that works. How much do the reconditioned units cost?
PM sent.

[Ron]

Is this something that the kickdown cable controls?
$.02

No...kickdown is handled by the microswitch mounted with the WOT microswitch. Both are supposed to be activated at full throttle.

The cable is a detent cable, as Rob mentioned. It requires ~0.3 mm clearance at the quadrant, as Farrar mentioned (actually 0.3mm - 0.5 mm, see WS Manual G:05:02 for procedure).
+1 on other tests Rob mentioned before purchasing a GC.
...probably good to replace it if it is original anyway. The trans is not very forgiving at all with a bad GC!

[Farrar]

Thanks to Ron for correcting my lack of decimal point. :)

[Jonathan]

Here are a couple photos showing the far end of that cable underneath. One picture in the idle position and the other with the gas pedal all the way to the floor.

http://dmctalk.org/showthread.php?10336-Assorted-helpful-technical-photos&p=152180&viewfull=1#post152180

[David T]

The cable DOES vary the shift points and the WOT (kick-down) switch forces downshifts depending on the car's speed and the motor's RPM's. The vacuum line varies the line pressure, softening the shifts. When doing service you should start with ALL of the external On-Car checks. Among them should include a visual inspection of the wiring harness to the shift computer to make sure it isn't damaged and is well secured away form the exhaust pipes.