jimbr70

My 70 delta 88 is not running so well.... it is staying in first until you really get the speed up then shifts brutally. Same from 2nd to 3rd, but once on freeway it behaves. Sounds like the kickdown switch is ill. Others agree this is the failure mode of that switch?


Any supplier with new kickdown switches? I suspect one can retrofit to one that mounts on the throttle linkages - lots of cars were done that way..


Thoughts? Advice?


Just had tranny serviced and exterior seals all replaced - no leaks!

jimbr70

I've not been to the forum in some time. I had a tough time with CA and NV DMV's and after 4months of 'discussions' and paperwork, the 70 has a title in my name. For a while I thought I'd have to scrap it... them someone in Nevada DMV decided to care and it all worked out. The we had winter. Been going on drives now.. she still has under 50k orig miles but one more outing and it will pass 50k. Only show we'll probably take her to is one that the SF Bay Area club goes to so we can see her siblings . While the car is stunning and original, my show days ended when I sold my '70 vette.


Car is currently ill. Kickdown switch, according to tranny shop, is bad. Looking for replacement source. Not fun around town when any touch of the throttle downshifts.


I did complete the needed suspension work, tires, AC system complete re-do. Very nice. There is some signs of rear wheel issues - either axle seal seeping or brakes - that'll be next.

72455442RA

sounds like the vacuum modulator has vacuum issues

loose rubber hose fit

or

bad modulator

replace the rubber ends on your modulator line ...

or trim 3/8 " off the ends to improve sealing of the hose ...

Scott

Fun71

That's exactly what happens when the vacuum modulator loses its vacuum source.

oldcutlass

I combined your conflicting description thread of your issue with the other thread you started. If its your first post, then yes its the vacuum modulator, the hose feeding it has an issue, or the hose is not connected to manifold vacuum.

If its the second post, it's not that the kickdown switch is bad, its out of adjustment.

jimbr70

Well, thanks! Interesting. I disconnected the kickdown switch, studied how far it travels to make a connection and clearly it is not the issue as slightest gas pedal press downshifts. OK, so vacuum? Found a cracked hose but not convinced it did not crack during the examination. Replaced 3 hoses. Still misbehaves. Put a hand vacuum pump on the line to the modulator - cannot create a vacuum. AH. Either another bad hose down below or bad modulator. Got under and felt the tubing - sure felt like a crack - of course on the back side you can's see from the garage floor. Replaced it. Holds Vacuum. Problem gone!

Fun71

Don't bring your car back to that shop as apparently they don't know very much about transmissions.