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Username Post: More 700R4 issues        (Topic#358541)
MikeB 
Ultra Senior Member
Posts: 10066
MikeB
Loc: Plano, TX
Reg: 08-28-03
10-22-19 07:56 AM - Post#2778510    

My buddy has a 37 Chev with 700R4 that shifts out of first gear very quickly under light/moderate acceleration. However, I know the TV cable is adjusted properly because I did it with the pan off and used a geometry corrector bracket on the Edelbrock carb.

When the throttle is closed (and choke open) the lever is just starting to push on the valve -- around .005" pre-load. And the valve is fully bottomed at WOT.

It also doesn't shift into 4th until 50-60 mph, and then it downshifts back into 3rd when even lightly depressing the throttle MPH. Lock-up is not in the equation when this happens, because we control it with a dash switch. (Switch closed + pressure at 4th gear pressure port.) Axle ratio is 3.36 and tires are 27" tall.

Sure would be nice if the trans worked more like a TH350 with a 4th gear. Those transmissions are very easy to set up with little or no mystery involved. Adjustable modulator, some governor mods, and a TransGo 350-1 valve body kit and you're good to go with predictable and consistent shifts.


1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.


 


IgnitionMan 
Valued Contributor
Posts: 3680

Reg: 04-15-05
10-22-19 08:12 AM - Post#2778511    
    In response to MikeB

Remember that the cable for the 700TH doesn't just set shift points, it also sets, and changes the line pressures the trans operates with. If the cable is correct, but the shift points, or other tans operating issues aren't, it may well be something else in the trans other than the cable adjustment.



 
gchemist 
Senior Chevytalk Moderator
Posts: 24963
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
10-22-19 09:33 AM - Post#2778515    
    In response to IgnitionMan

Is it a stock rebuild? Added preload won't hurt it. I'm no expert though. I had to modify my throttle floor plate to get WOT.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles


 
MikeB 
Ultra Senior Member
Posts: 10066
MikeB
Loc: Plano, TX
Reg: 08-28-03
10-29-19 04:52 PM - Post#2779094    
    In response to gchemist

It's a stock rebuild. I might trying increasing pre-load a little to see if that helps, even if it prevents WOT. At least it will tell us something.


1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.


 
paulo57509 
Senior Member
Posts: 398

Loc: Tracy, CA
Reg: 07-18-00
11-01-19 11:02 PM - Post#2779343    
    In response to MikeB

FWIW, it's more common practice to use a governor re-calibration kit to change shift points and not use the TV cable to do this.

1987 IROC-Z 5.0L
1992 Lumina Euro 3.1L
2003 GMC Safari


 
Rick_L 
Honored Member
Posts: 27658
Rick_L
Loc: Katy, Tx, USA
Reg: 07-06-00
11-03-19 11:31 AM - Post#2779455    
    In response to paulo57509

Not just more common, it's also the right way.



 


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