700r4 locks solid in reverse
Thread Starter
Instructor
Joined: Apr 2010
Posts: 114
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From: MD
700r4 locks solid in reverse
What will cause a fresh rebuild of a 700r4 to apply the forward clutch in reverse? Forward clutch is not engaged in neutral or park (no drag) but car will bind up hydraulically in reverse. It can be overcome with a blip to the throttle. It comes with a loud clunk from the trans and then it's bound up again. When hot, it will back up 6 inches before you can feel the hydraulic circuit lock up. All forward gears worked fine at first including converter lock up. Tv and shifter linkage are correct. After 5
miles of test driving, it started taking off in second. It will shift to first with full throttle or pulling shifter into first.
The builder is blaming me for not flushing. The cooler and radiator were brand new with install. The 3 foot lines weren't flushed. Pan looked like this after 10 miles.
miles of test driving, it started taking off in second. It will shift to first with full throttle or pulling shifter into first.
The builder is blaming me for not flushing. The cooler and radiator were brand new with install. The 3 foot lines weren't flushed. Pan looked like this after 10 miles.
Thread Starter
Instructor
Joined: Apr 2010
Posts: 114
Likes: 0
From: MD
No transbrake on this one. It's just got the basic performance build. Monster shell, drilled vb, bigger boost valves, z pak, pump, shift kit. It just applies the forward clutch when I put it in reverse. Locks up and won't move.
I'm trying to reserve judgement on this until the problem is resolved. I forgot one thing, when the trans came out, it shifted fine and had no metal in it. The New motor going in would've killed the trans so I had it built.
I'm trying to reserve judgement on this until the problem is resolved. I forgot one thing, when the trans came out, it shifted fine and had no metal in it. The New motor going in would've killed the trans so I had it built.
Last edited by MDstar2; Aug 4, 2014 at 06:32 PM.
Advanced
Joined: May 2014
Posts: 56
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From: Lake Forest Park WA
**** "Monster shell, drilled vb, bigger boost valves, z pak, pump, shift kit." ****
The fact that it shifts normally forward, and reverse binds with FWD clutch, almost sounds like you are getting mechanical holding action out of the clutches. Closer study to the actual "feel" when in reverse,
"It comes with a loud clunk from the trans and then it's bound up again. When hot, it will back up 6 inches before you can feel the hydraulic circuit lock up."
If the reverse piston seals or clutches where the culprit I don't think you would be able to move 6 inches when hot, or not have the FWD clutch over power the reverse clutch.
However there is the possibility of shell or a sun gear binding being mistook as opposing gear clutches, but not as suspect AS:
It does sound a little like the builder may have botched the valve body mods.
If this is the case you may not have to remove the trans to fix, try a known good valve body.
The fact that it shifts normally forward, and reverse binds with FWD clutch, almost sounds like you are getting mechanical holding action out of the clutches. Closer study to the actual "feel" when in reverse,
"It comes with a loud clunk from the trans and then it's bound up again. When hot, it will back up 6 inches before you can feel the hydraulic circuit lock up."
If the reverse piston seals or clutches where the culprit I don't think you would be able to move 6 inches when hot, or not have the FWD clutch over power the reverse clutch.
However there is the possibility of shell or a sun gear binding being mistook as opposing gear clutches, but not as suspect AS:
It does sound a little like the builder may have botched the valve body mods.
If this is the case you may not have to remove the trans to fix, try a known good valve body.
Thread Starter
Instructor
Joined: Apr 2010
Posts: 114
Likes: 0
From: MD
It's an 89 car and the original trans from that car. Reverse is solid when applied with the shifter. It clunks when you override what ever it's holding it with heavy throttle and then locks right back up. All forward gears work fine. Locked up right from the first time in reverse. I was told all valves in pump and vb were binding because I didn't flush. All coolers were brand new installs with trans and motor. Brand new converter as well. I'm waiting to see what happens now. Builder has trans and coolers for flushing and rebuild.
Burning Brakes
Joined: Mar 2013
Posts: 1,131
Likes: 5
From: Illinois/Wisconsin Line
When the trans came out it Shifted fine and it had no metal in it Now after a performance build it will not move and Your saying its not the rebuilders fault? Don't get it? What u think u did something wrong by just bolting it back in? You said no metal was in the pan after you took it out so no planetarys were tore up and why would you flush the line of any debris. Their was nothing to flush.
Did u drop the valve body and give it to your rebuilder without one? If not its his problem/fault IMO
Did u drop the valve body and give it to your rebuilder without one? If not its his problem/fault IMO
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Burning Brakes
Joined: Mar 2013
Posts: 1,131
Likes: 5
From: Illinois/Wisconsin Line
Possibly
Aside from rebuilding the valve body, the solenoids should be tested, along with the temperature sensor and pressure sensors. A plain ohmmeter will be sufficient. Your transmission service manual should list the appropriate resistances for the solenoid coils, and normal states of the pressure switches.
The separator plate should also be inspected closely where the check ***** seal. Repeated operation of the checks will cause the ***** to actually pein the openings in the stamped steel plate until the holes are distorted and enlarged. Given enough wear, the ***** can go through the plate and render the check system ineffective. That can completely lock the transmission depending upon which valves are involved. Any wear should be addressed. The plate can either be replaced or repaired. Hard inserts are available to replace the worn areas. Larger check ***** can also be used, but 0.285" is about the safe diameter limit so that the ***** do not interfere with flow in the forward direction.
Aside from rebuilding the valve body, the solenoids should be tested, along with the temperature sensor and pressure sensors. A plain ohmmeter will be sufficient. Your transmission service manual should list the appropriate resistances for the solenoid coils, and normal states of the pressure switches.
The separator plate should also be inspected closely where the check ***** seal. Repeated operation of the checks will cause the ***** to actually pein the openings in the stamped steel plate until the holes are distorted and enlarged. Given enough wear, the ***** can go through the plate and render the check system ineffective. That can completely lock the transmission depending upon which valves are involved. Any wear should be addressed. The plate can either be replaced or repaired. Hard inserts are available to replace the worn areas. Larger check ***** can also be used, but 0.285" is about the safe diameter limit so that the ***** do not interfere with flow in the forward direction.
Melting Slicks
Joined: Feb 2003
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From: Saskatoon Sask.