MonteCarloSS.com
MonteCarloSS.com

CELEBRATING 20 YEARS!

Previous Thread
Next Thread
Print Thread
#1068421 - 11/02/20 05:58 AM TH350 Late Shift at WOT  
Joined: Mar 2019
Posts: 46
Supa.Slo.SS Offline
Member
Supa.Slo.SS  Offline
Member

Joined: Mar 2019
Posts: 46
Rancho Cucamonga CA
Hello everyone, so 84 SS all orginal (except 262 cam, eddy intake & TES Headers) with electronic carb, HEI distributor & computer. Was running good until it didn't. Transmission won't shift "correctly" at wide open throttle. Currently, RPMs shoot up to 5000 5500 at WOT before I chicken out and let go of the gas. Here is the rookie mistake I made, I started messing with the kick down cable before realizing a vacuum line had cracked behind the carb. Now, for the life of me I can't re-adjust the cable which leads me to believe something else is wrong, I have read it could be the governor except it shifts into every gear driving it normal or even at half full throttle. I also read the vacuum modulator could be the cause but I disconnected the vacuum hose to it down at the transmission and there was no trans fluid in the line which I also read is a sign of a failed manipulator but again no fluid so I am not sure that's it either. Could it be I just need to keep adjusting the kick down cable tooth by tooth? I did try the typical method of adjusting the cable ie adjusted with full throttle and let the cable pull out as far as it wants but then I get the opposite problem, trans won't down shift instead it will just slowly raise the RPMs at WOT. I did disconnect the cable from the carb and manually pulled it and nothing "feels" wrong good tension and cable springs back. If it matters, before messing with the kick down cable I did remember the adjustment being what looked like all the way in towards the firewall. It might also be worth mentioning when I use full throttle to adjust the cable it pulls it out alot further. Also, when I go WOT and manual shift it into gear there is not no change, ie if i put it the gear at 4200ish RPM it won't shift into gear and the RPMs just keep climbing. Any ideas?

#1068426 - 11/02/20 04:13 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Apr 2011
Posts: 1,259
Hunter79764 Offline
10+ Year
Hunter79764  Offline
10+ Year
Member

Joined: Apr 2011
Posts: 1,259
Grand Prairie, Tx
The way I understand it, the vac modulator takes care of part throttle shifts, the governor controls WOT shifts, and the kickdown controls "kicking down" into passing gear. Someone better versed may be able to comment on relationships between those, possibly the kickdown cable telling it to look tot he governor instead of the modulator. But from my limited knowledge, it sounds like a governor issue. Maybe one of the weights broke, causing it to not engage until an insane RPM or something. I'd try looking there next.


Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1068429 - 11/02/20 05:17 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Jan 2000
Posts: 5,658
mmc427ss Online content
20+ Year
mmc427ss  Online Content
20+ Year
Member

Joined: Jan 2000
Posts: 5,658
Pottstown, Pa

#1068437 - 11/02/20 09:05 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Mar 2019
Posts: 46
Supa.Slo.SS Offline
Member
Supa.Slo.SS  Offline
Member

Joined: Mar 2019
Posts: 46
Rancho Cucamonga CA
Thanks for the info Hunter79764 & mmc427ss.

Based on the reading I think I will start with the governor, although in the Jalopy read his was not shifting at all, mine does which makes me think its not that but it's an easy thing to remove & check before I spend money on something else.

#1069189 - 01/12/21 09:55 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Mar 2019
Posts: 46
Supa.Slo.SS Offline
Member
Supa.Slo.SS  Offline
Member

Joined: Mar 2019
Posts: 46
Rancho Cucamonga CA
Hello everyone, I know its been a while but final got around to working on the trans.

SPOILER ALERT symptoms are still the same.

UPDATE: short & sweet, took out the governor, springs still attached and center "piston" moving freely, ie not stuck. Cleaned it anyway and re-installed it. Second, vacuum modulator was not "leaking" trans oil from the vacuum fitting but went ahead and replaced it anyways with one from Advance Auto.

Still won't shift at WOT unless I left off the gas a bit. I was reading about "recalibrating" the governors but I feel like this is more to "change" the shift points and won't actually fix the underlying issue.

HELP!

#1069190 - 01/12/21 10:57 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Mar 2019
Posts: 46
Supa.Slo.SS Offline
Member
Supa.Slo.SS  Offline
Member

Joined: Mar 2019
Posts: 46
Rancho Cucamonga CA
Food for thought.. maybe its not a transmission problem.

Reading on different GM forms running similar q-jet carb/engines, they are saying fuel starvation or the opposite. WOT not enough fuel causing it to loss power or the opposite too much fuel and it bogs ie losses power which are my symptoms. Still haven't read the fix.

Some say use SeaFoam treatment in the carb to clean up the secondary jets.

My Q-jet is CC & had been sitting since 2006, only sprayed it down with Carb cleaner & re-installed. Ran fine until it didn't.

#1069203 - 01/13/21 09:04 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Apr 2011
Posts: 1,259
Hunter79764 Offline
10+ Year
Hunter79764  Offline
10+ Year
Member

Joined: Apr 2011
Posts: 1,259
Grand Prairie, Tx
I almost never advise against a good seafoam treatment, not sure how it might be causing this problem but it can't hurt and will likely help power, performance, and MPG's as well.

I'd spend some more time looking at the kickdown cable, something tells me that there is a part of the transmission "Logic" that tells the transmission to shift by the vac modulator or the governor by looking at the kickdown position. Mine needs to have the governor adjusted (badly) after my swap many moons ago, when I have the kickdown attached it shifts way too early at WOT but part throttle and cruising works as intended. I sometimes disconnect it in order to let it run higher and manually shift it for drag racing, and I've also adjusted the modulator to shift at the right point for WOT (with kickdown disconnected) which results in way too high of RPM's at part throttle, but shifts right at WOT.
I'm not recommending that you do any of that, I've just spent a lot of effort being lazy on mine, but all of that leads me to think that if your cable is not adjusted properly and/or broken, the governor settings might not be doing anything at all and acting like the gov is broken.

Last suggestion (in order of typing, not importance) would be a fluid/filter change. It's entirely possible a chunk of crud is blocking a passage for WOT shifts and some fresh fluid will dissolve/dislodge the crud and get you back in shape.


Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1069212 - 01/14/21 12:11 AM Re: TH350 Late Shift at WOT [Re: Hunter79764]  
Joined: Mar 2019
Posts: 46
Supa.Slo.SS Offline
Member
Supa.Slo.SS  Offline
Member

Joined: Mar 2019
Posts: 46
Rancho Cucamonga CA
Originally Posted by Hunter79764
I almost never advise against a good seafoam treatment, not sure how it might be causing this problem but it can't hurt and will likely help power, performance, and MPG's as well.

I'd spend some more time looking at the kickdown cable, something tells me that there is a part of the transmission "Logic" that tells the transmission to shift by the vac modulator or the governor by looking at the kickdown position. Mine needs to have the governor adjusted (badly) after my swap many moons ago, when I have the kickdown attached it shifts way too early at WOT but part throttle and cruising works as intended. I sometimes disconnect it in order to let it run higher and manually shift it for drag racing, and I've also adjusted the modulator to shift at the right point for WOT (with kickdown disconnected) which results in way too high of RPM's at part throttle, but shifts right at WOT.
I'm not recommending that you do any of that, I've just spent a lot of effort being lazy on mine, but all of that leads me to think that if your cable is not adjusted properly and/or broken, the governor settings might not be doing anything at all and acting like the gov is broken.

Last suggestion (in order of typing, not importance) would be a fluid/filter change. It's entirely possible a chunk of crud is blocking a passage for WOT shifts and some fresh fluid will dissolve/dislodge the crud and get you back in shape.


Thanks for the response Hunter. I actually tried over several days adjusting the Kickdown cable tooth by tooth but I found that, basically one tooth one way or another would result in either the same symptom or the opposite were it won't respond to WOT and just climb slowly. It's almost like I needed an extra tooth in between these two positions so I basically told myself that wasn't it. I know the cable is at least partially good because when I disconnect it & pulled on it by hand & I can feel the spring tension return.

Fresh oil does not sound like a bad idea either, i'll drain and re-fill as well as a seafoam treatment & report back.

#1069431 - 02/02/21 03:34 AM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Jan 2021
Posts: 3
Youngjojo214 Offline
New Member
Youngjojo214  Offline
New Member

Joined: Jan 2021
Posts: 3
Dallas, tx
I’m having trouble with my trans I bought a 84 mc ss recently and it shifts here and there but the trans slips a lot I think it may be the torque converter I’m not sure but does anyone know any good performance transmission shops in Texas preferably near Dallas

#1069436 - 02/02/21 05:21 PM Re: TH350 Late Shift at WOT [Re: Supa.Slo.SS]  
Joined: Apr 2011
Posts: 1,259
Hunter79764 Offline
10+ Year
Hunter79764  Offline
10+ Year
Member

Joined: Apr 2011
Posts: 1,259
Grand Prairie, Tx
I know a guy down in Ennis, he built 2 4L60's for my DD suburbans. He's a 1 man shop, but has operated for years by word of mouth only and came highly recommended by a friend who owns a heavy equipment business and has used him for the passenger trucks etc.
Danny Christian 972-351-2034


Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway

Random Images
500/thumbs/teaser13.jpg
by JAWSS
500/thumbs/Sea_Pirate_07.jpg
by NYmonteSS
500/thumbs/CAM00264.jpg
by lou84SS
500/thumbs/montefront.jpg
by Mr-SShadow
519/thumbs/DSC00028.JPG
by Ted88SS
Help MonteCarloSS.com


Recent Contributors
kevins88ss
Authorized Vendors
Tell them you saw it
on MonteCarloSS.com!


CustomMonteSSParts.com
Dixie Monte Carlo Depot
GSI Interiors
HRpartsNstuff
Mikes Montes
Savitske Classic & Custom
Powered by UBB.threads™ PHP Forum Software 7.6.0