Print Page - TH-350 Won't Downshift - Kickdown Cable Adjustment Help?

TAC Tech => Mechanical => Topic started by: TonysTA on October 10, 2021, 04:05:46 PM

Title: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: TonysTA on October 10, 2021, 04:05:46 PM: Hi,

78 TA, 403 olds with aluminum intake manifold. I have a 80555C Holley carb. I never had the kick down cable working and could use some help adjusting. As best I can tell, it looks correct but it won't downshift from 3rd gear into 2nd if I pin the gas at 30-40 MPH. There is little to no slack in the cable, could this be an issue with the TH-350 and not the cable? Pics below.

https://1drv.ms/u/s!ArwKVRvkdHS6g6wq0g_6O6pqh9Nvqw?e=jZYYaG (https://1drv.ms/u/s!ArwKVRvkdHS6g6wq0g_6O6pqh9Nvqw?e=jZYYaG)

Thanks,

Tony
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: Wallington on October 10, 2021, 06:12:04 PM: Unlock your kickdown cable tab, pull the throttle fully open all the way, relock kickdown tab.

Being a Holley, I couldn't tell you if the the mount is in the correct location and I think they also have adjustment screws for kickdown tabs/stops. But you have to start with the general setup before you can tweak it.
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: firebirdparts on October 11, 2021, 02:59:09 AM: I agree on the adjustment. I think it's unlikely to be a transmission problem. One problem you can run into is that the cable is unhooked on the transmission end.
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: tajoe on October 11, 2021, 06:07:53 AM: Quote from: Wallington on October 10, 2021, 06:12:04 PM
Unlock your kickdown cable tab, pull the throttle fully open all the way, relock kickdown tab.

Being a Holley, I couldn't tell you if the the mount is in the correct location and I think they also have adjustment screws for kickdown tabs/stops. But you have to start with the general setup before you can tweak it.
Good advice. By your photos, it appears there isn't much slack in the cable, and might be trying to pull the kick-down too early? Not sure how that would affect normal shifting.
You mention the kickdown not working @ 35-40 MPH. Does it ever kick down? At any other speed? And we're assuming the tranny works normally, under all other conditions.
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: TonysTA on October 11, 2021, 05:53:59 PM: Hi,

I will try the test suggested, maybe it's pulling too early because there is no slack. Yes, it shifts on the way up just fine, its when I intentionally pin the throttle expecting it to go from 3rd down to 2nd is when I am met with disappointment.

Thanks for the tips, will circle back with results once I get a chance to test, probably this Saturday.

-Tony
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: Wallington on October 11, 2021, 06:12:58 PM: It's an easy test. You could even add a spot of white paint, tape if it doesn't foul, measure...current setting in case you need to go back or compare. Sounds like even the existing kickdown may not be at the correct setting, disguised by simply booting the pedal!
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: TonysTA on October 14, 2021, 06:12:38 PM: QQ on the test - assuming I should be in 3rd gear going maybe 30 MPH and then punch it?
Title: Re: TH-350 Won't Downshift - Kickdown Cable Adjustment Help?
Post by: firebirdparts on October 23, 2021, 01:47:50 PM: that's probably fine, but 50 would be better. At some speed it would kick down from 3rd based on vacuum alone, and 30 is a little too close for comfort for me. If you want to be 100% sure, of course, you could unhook it and then convince yourself it's different with it hooked up.