scottjkj1
Registered Member
What does the TCC solenoid do in the tranny, does it lock up 2-4 gear? And what does the 4th gear pressure switch do and how does it work in conjunction with the TCC switch.
CK5
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700r4
- Thread starter scottjkj1
- Start date
TCC = Torque Convertor Clutch. All this solenoid does is control the lock-up of the convertor.
scottjkj1
Registered Member
Ok you somewhat answered half the question....
Thunder
3/4 ton status
Yes the 700r4 will lock up in 2 thru 4th gears. The pressure switch(s) is a normally open switch that closes when it sees its set pressure point allowing the TC solenoid to lock up the TC. If there is not enough line pressure in fourth gear to close the switch it wont allow the TC to lock.
scottjkj1
Registered Member
Ok, I have an override switch on my 700r4, when I flip the switch in 2-3 I notice the RPM's dropping, obviously working, But I dont notice a difference in the RPM's when its in 4th, anybody have any idea why this is?
I don't know which year your 700 is, but most of them have two circuits for the lockup. One depends on the manifold vacuum. The other one is direct through the 4th gear pressure switch (and usually another NC switch that opens only during the 4-3 down****). They enter the tranny on two different wires. So your bypass switch is only cutting the first circuit. The idea is that you "always" want lock up in 4th gear, but only want it in 2nd and 3rd under certain load conditions.
The TCC solenoid is a path from the TCC apply piston to the oil pan. When it is not powered, the hydraulic pressure that *would* apply the TCC leaks off. That hydraulic pressure is not always there - there is a valve in the valve body that supplies it based on TV pressure (and governor pressure, I think).
Some setups over the years were simpler than this.
Here's the best diagrams I could find (most are incomplete or simplified setups for aftermarket transmissions):
The TCC solenoid is a path from the TCC apply piston to the oil pan. When it is not powered, the hydraulic pressure that *would* apply the TCC leaks off. That hydraulic pressure is not always there - there is a valve in the valve body that supplies it based on TV pressure (and governor pressure, I think).
Some setups over the years were simpler than this.
Here's the best diagrams I could find (most are incomplete or simplified setups for aftermarket transmissions):
Thunder
3/4 ton status
Maybe you should post up more info on your trans &truck If you need help with the problem.
scottjkj1
Registered Member
Well I installed the B&M lockup controller and I think its worth it. It will now lock up in 3rd at a pre determined speed, I believe I got it set at 40mph. This is nice because Ill keep it in 3rd alot in town and it will lock up. Ive noticed a big difference in the tranny temp now just running around town. One question though, will it cause any problems changing from 3rd to 4th and back while its locked up. It seems fine and it shifts nice.
If it's locked up, it's hard on the converter clutch. It's not intended to bear much load, which is why it was designed to unlock before a shift.
Real light throttle I doubt it will hurt MUCH, but it's supposedly not a good idea. My buddy has quite a few hard hard miles on his Monte SS with a built motor and the TCC solenoid "forced" on with a checkball, so I dunno what the life span is. Guys at the track will tear them up in pretty short order with full throttle shifts, but the ones I was reading about were in the 10's too. Trucks are heavy however, and that counts for a lot.
Real light throttle I doubt it will hurt MUCH, but it's supposedly not a good idea. My buddy has quite a few hard hard miles on his Monte SS with a built motor and the TCC solenoid "forced" on with a checkball, so I dunno what the life span is. Guys at the track will tear them up in pretty short order with full throttle shifts, but the ones I was reading about were in the 10's too. Trucks are heavy however, and that counts for a lot.
