Transmissions and DrivetrainNeed help with your trans? Problems with your axle?
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Which direction does the flow go through the TH700 TCC solenoid when unlocked: Against the return spring, or with it?
I get uncommanded lockup in 2nd gear (I know it's not an electrical issue - removed power from the circuit completely, still does this). Doesn't do it all the time, but is particularly bad when I have the shifter in 2nd. Also seems worse when the tranny is cold. Didn't start to do it until I did the shift kit, so I'm thinking higher pressure/flow causes this. It works just fine in 3rd & OD (never locks when it shouldn't, always locks when it should, always unlocks when it should in those 2 gears).
Since unlocked allows flow through the solenoid, reduced flow or inadequate flow would cause lockup (one tranny guy suggested it might be plugged - I don't think so). If the spring is weak, this would lead to my problem, right?
Also, any difference between 3rd gen and Vette solenoids? Vette has larger flow area, perhaps? If I go buy a new one, I'd like to get one that is more likely to stop this problem.
Hmmm... Let me quote this out of the Hydra-Matic Tech Guide:
Quote:
Converter Clutch Apply Valve (227):
Directs converter feed fluid for apply and release of the torque converter clutch (TCC). The covnerter clutch apply valve is held in the released position by spring force until converter singal fluid is directed to the valve (in second, third, and fourth gears). Converter signal fluid exhausts at the solenoid until the electronic control module (ECM) energizes the solenoid. The solenoid is energized by the ECM when conditions are appropriate to apply the TCC.
The TCC solenoid is an electronically controlled exhaust valve. When energized (provided a ground) by the ECM or the temp switch, the TCC solenoid stops converter signal fluid from exhausting. The closing of the solenoid valve causes converter signal fluid pressure to increase and shift the converter clutch apply valve into the apply position.
From that, fluid goes down through the nose of it and against the return spring (the diagrams in the guide also suggests this - to me anyways ).
But it would seem to me that the spring force of the solenoid would not change from gear to gear and if second gear is the only problem it wouldn't be the spring being too weak...... But then again it makes sense as there is nothing else that could allow the CC to apply than the solenoid.... Except maybe the return spring on the apply valve......
__________________ 1987 GTA / Miniram'd 383/ TH700R4 3000RPM stall / 9" w/4.33s : Far from stock, far from done.... Link to the GTA
1999 Trans Am / LS1 / T56 : Patriot Heads and Cam, the usual bolt ons... Link to the Trans Am
Weak apply valve spring - that makes some sense. Of course, I have no clue where the apply valve is. Any diagrams?
Still curious that this didn't start until the shift kit install. Then, it was immediately apparent (thought I had completely screwed up my transmission). It got better over time, but did it bad on me again this morning - in 2nd gear.
The apply valve is accessible from the pan. I don't see how it could go bad from a shift kit install. What shift kit did you install and what all did it involve?
__________________ 1991 Trans Am WS6 Convertible,
1987 Trans Am GTA hardtop
1987 Trans Am CC1, LS1/T56 AFR 205 heads, Comp Cams, LS6 intake
2005 Honda CBR 600RR
2007 Yukon XL Denali
2007 Saab 9-3SS
Transgo. Basically followed the recommendations of Dana at Pro Built. Servo, relief valve, accumulator, etc.
I'm not thinking it went bad from the kit install. Rather, that the kit install changed the pressure/flow that the apply valve sees.
It is also possible I did something when I did the kit (pulled the wrong valve out of the pump, for instance, and had a bear of a time getting it back in). The apply valve is above the solenoid, right? I think I got it back in correctly, but perhaps that is the problem.
Yes, its the valve above the solenoid. I don't see the TransGo changing the amount of fluid going to the valve, I have installed tons of TransGo kits and have never experienced early TCC apply.
I never tried to put the valve in backwards so I don't know if its even possible.
Bringing this back from the dead to provide an answer - finally.
I put a rebuilt '83 TH700 in the Camaro, and the switches & solenoid were different (4 switches & one-wire solenoid in the '83, vs. 2 switches and 2-wire solenoid in the '86 - the engine controls are '86 version), so I put the '86 parts in the '83 transmission. While the solenoid was out, I looked it over carefully and discovered a cube-shaped piece of plastic sitting in the "throat" of the solenoid, slightly larger than the exhaust port in the solenoid. My theory is it was partially blocking the port, and not always blocking it, leading to the sometimes uncommanded lock-up and sometimes normal operation.
Cleaned the piece out, put the solenoid & switches in, works great. Better than the '86 ever was.
(Side note: The input of the '83 was converted over to 30 spline so I could re-use my existing torque converter.)
).
