Auto ‘78 KE30 Kick back issue

[nrjones19]

Hello.

 I own a ‘78 KE30 with an automatic transmission (GM trimatic). I want to keep her as original as possible I am not planning on converting her to a manual.
 

Recently I have encountered a intermittent problem with the transmission, usually at higher speeds (90-110km p/h), where I’ll be driving along and everything is fine, no noises or smells, and I’ll adjust my throttle position ever so slightly and the transmission will suddenly kick back into second gear, revving the guts out of the little engine. If I pump the accelerator or put my foot down it will go back into 3rd but as soon as I release the throttle again it will kick back into 2nd again. It might do this a handful of times and then goes back to normal. It doesn’t do this on every drive either, or for example, today I had driven 200kms  without a peep and then suddenly it happened.

Transmission fluid is full, my mechanic checked and tightened vacuum and had a quick look at the kick back switch but said it was set so it didn’t have the option to be adjusted. My mechanic isn’t a transmission specialist so is a bit stumped.

Is my transmission dying? Or could the kick back switch need replacing? Or is it something else? Does anyone have any ideas? 
 

Your help is much appreciated 😊

Cheers,

Naomi

[altezzaclub]

"I’ll adjust my throttle position ever so slightly and the transmission will suddenly kick back into second gear, revving the guts out of the little engine."

I remember this happening before I converted mine to manual.  You could drive along just before the point of it kicking back a gear.

" If I pump the accelerator or put my foot down it will go back into 3rd "   Now that is really weird! Usually I lifted off and it went back up a gear to 3rd, but then I'd lost so much speed I had to carefully to work it back up without it kicking down to 2nd again.  Long slight uphills where I live.

" as soon as I release the throttle again it will kick back into 2nd again." Yes, that is the opposite of what should happen. 

Isn't there a second cable on the throttle that does the kickdown at high throttle openings??  and a vacuum line from the inlet manifold to the box so it can sense inlet vacuum??  Its been so long since I had an auto now.  If you disconnected them, can you drive it on the gearlever??  It should lack the kickdown then and just go up and down the gearbox depending on the rpm.

[nrjones19]

Thanks for your response! I really don’t know enough personally about how auto transmissions work, so every little bit of info and advice is fantastic 😊

[altezzaclub]

Its a Holden trimatic from BorgWarner, so hunt down the Holden forums too.  Its only twice as heavy as a manual box, soaks up about 15bhp and is horrible to drive, so when you convert it you'll be amazed at how much better the car goes!

Try this-

 

http://www.gmh-torana.com.au/forums/topic/25920-trimatic-problems/

[nrjones19]

6 hours ago, altezzaclub said:

Its a Holden trimatic from BorgWarner, so hunt down the Holden forums too.  Its only twice as heavy as a manual box, soaks up about 15bhp and is horrible to drive, so when you convert it you'll be amazed at how much better the car goes!

Try this-

 

http://www.gmh-torana.com.au/forums/topic/25920-trimatic-problems/

Thank you so much for that link! That explains and identifies the problem I’m having exactly.

You are awesome 😎 

[altezzaclub]

Glad to help-  let us know if that fixes it.

The car looks great in the photo, worth looking after!

[nrjones19]

I had the kick back solenoid replaced and a transmission service including some of the linkages tightened, new fluid and filter, and she is running like a dream again!