mmather1

Hey everyone I just finished rebuilding an 86 700r4 for my car, and installed it... After setting my cable at wot TV full pull, I notice that I cant even get to 3000RPM before my 1-2 shift occurs, I thought this might be tv adjustment, so i pull my cable to full pull and clamped a set of visegrips on it. and went for a drive, All my shifts where very harsh and the 2-3 and 3-4 occured late as expected.... but the 1-2 shift was still early, harsh but early... It has a brand new corvette govornor, and a transgo SK 700 valve body kit installed... Anyhelp would be apreciated Thanks in advanced
Mike

transtalker

if your trans is shifting 1 to 2 at about the same time every time i would say that your 1,2 shift valve is stuck in your valve body i have had some bad experiences with the transgo 700 kits i can provide you with a 700r4 valve body and plate with a hybrid shift kit done to it i take the best i have found of everything and put it together so far it has worked great

godreject

iTrader: (1)

bump having same issues as OP my 1-2 shift is very firm(expected) but way early 2500-3000rpm this is after rebuild makes me wanna go back to the shop and have them check it

scottycamaroz28

I'm having the same similar problem with my 91 z28 with l98. My tranny is new and shift great at WOT but at really low rpms at partial throttle it shifts really low and I barely notice the 1-2 shift. Also it won't even break loose on the 1-2 at WOT and my old 84 TA with l69 and all stock would almost get away from you on the 1-2 shift. Any of you guys have a suggestion ?

Pro Built Automatics

I have not had problems with the TransGo Shift kits, in general, and I have installed hundreds of them. The problem might be as suggested the 1-2 shift valve, and/or the spring is not the right one. Did the valve body that is being used here have any shifting problems before? The TransGo Shift kit you installed? Is it the "full shift" kit? or the Junior? What governor did you have before? And with the Corvette governor, did you install any governor springs?

Pro Built Automatics

I have not had problems with the TransGo Shift kits, in general, and I have installed hundreds of them. The problem might be as suggested the 1-2 shift valve, and/or the spring is not the right one. Did the valve body that is being used here have any shifting problems before? The TransGo Shift kit you installed? Is it the "full shift" kit? or the Junior? What governor did you have before? And with the Corvette governor, did you install any governor springs? A mismatch can sometimes create problems. Ths kit could possibly be the problem, as they have been known to make mistakes.

mmather1

Not sure if the valve body had any shifting problems before, it was just a core that i rebuilt, the shift kit was the SK 700 not the JR , it was the Syskokal or whatever its called.... I had the original governor in it, and it did the same thing, I installed the corvette one in it and there was no real change, IT was the corvette one from SONNAX and it has the springs that came with it installed... is there pressures i can take that might help diagnos this, i have a pressure gauge... Thanks

ed o

Did you check to see if the throttle valve during the overhaul was free internally. I don't mean the plunger but the valve that can't be seen. If you didn't it might be the culprit. There is a little spring that can be installed at the tip of the cable to make the cable pull more at light or no throttle and colapses during wide open. This spring might help. The band applies into second and if you didn't check during overhaul the early 86 drum makes the band fit loose requiring the longest servo pin so that it applies the band fast. The early band drums are smaller around than the newer drums. Hope that gives you some ideas.

ed o

scotty, the jet servo will firm up second and third nicely. It is super easy to install and doesn't require checking for band adjustment, so it can be installed with the trans in the vehicle without worry. I've installed many of these in replacement of a corvette servo to bring real performance to second and third. Second will have more apply area of the piston than a corvette servo, and third will have no cushion spring for third accumulation all by changing the servo.

ed o

godreject you say in your profile you're running a th350 not a 700r4. you should check your vacuum to the modulator. if it's good, adjust your vacuum modulator by removing the rubber hose and using a pocket screwdriver.

ed o

the pressure port for second gear is on the passenger side, it's a pipe plug, and is the one at the furthest to the rear. pressure should be approx. 88-117psi at minimum t.v., and 88-117psi at full t.v...... I would be very careful because if a gauge were to rupture or burn on the exhaust atf is extremely flammable and will burn your car to the ground....
These readings are taken with the brakes applied sitting still and at approx 1000rpm. Pull the shifter down into manual second. you'll need a helper-don't run him/her over to pull the t.v. cable because max t.v. is to be achieved without moving the gas pedal. MAKE SENSE? Don't do this test longer than 2 minutes or poof.

mmather1

Im a Bit confused, if i had the smaller diameter drum, and the shorter band, how would this affect the one to shift, if im thinking right it would cause sliping in 2nd gear, or it would take longer to engage to 2nd, it wouldnt causean early 1-2 shift? am i right?

Pro Built Automatics

Message below.

Pro Built Automatics

Do the pressure test as suggested. There are little if any differences in diameter of the reverse/input drums. Almost all 700R4's had the 3 ring apply pin, which is what I use in most cases. The early drums used a steel apply piston which is heavier, and on a quick 1-2 WOT shift, the piston wants to keep spinning in the drum, which causes problems. The later drums used the aluminum piston (1987 and up units), which solved this, and are the ones to use. The pistons are not interchangeable due to outer diameter differences. See what the presuers are in 1-2-3-4 positions at 1,000 rpm without pulling on the TV cable and repeat the test with the TV cable pulles all of the way out. Bring the numbers here, and maybe between all of us, this might get solved.

mmather1

Ok, I put the pressure Gauge in the mainline port above the shifter.... With the Tv cable unhooked, i got around 78psi in park, 170 or so in reverse, OD(78) D(78) 2(160) 1(78) Im assuming that 2 should be the same as all the others except reverse, what could be causing this?

mmather1

Ok i took a break and went back out to double check the pressures again, and with the cable off it is at like 110 psi in all gears that is was 78 before , reverse and 2nd are still higher? could some of my valve be sticky, I rebuild this trans before winter, and it sat in my garage all winter, im wondering if it was damp could the valves to rust in there and stick? i think i might pull the valve body off and check

mmather1

Ok I removed the Valve body, took it all apart and cleaned it again, When installing everything back into it i noticed 2 things, The valve closest to the roll pin on the TV limit valvetrain was stuck in a bit, not resting on the pin like it should be, and in the 1-2 shift valve train, the valve deepest in the bore is sticking, i am moving it back in forth with a magnet and the odd time it will get stuck and i have to wiggle it to get it moving again, Would this cause the symptoms i am having???? also Is there any way to free up sticky valves?????? Thanks