C-4 Transmission Problems

[Smitty]

Okay Ford guys or any Transmission gurus; I have a C-4 behind my SS Mustang and I tried it this weekend for the first time with the SS engine and the car was real sluggish. When I got to the et shack I bumped the car up to 1st gear and tires tried to grab. I bumped it back to high gear I got back to the trailer. After checking fluid I managaed to get it up on trailer and checked my linakge to ensure it was catching on the blanket. I found it was overfilled slightly and had pushed out the vent. After letting the car cool off I backed it off the trailer and proceeded to move the car in first gear, car acted as if something was holding it, I bumped second gear and the wheel wanted to drag again, almost like it was trying to go into reverse.
Does anyone have any clue what might be the problem, this is the first time it has happened. The trans has a reverse manual valve body with brake, I beleive it is a Dynamic. Any tips would be appreciated.

[Bill Harris]

It sounds like the trans brake is being partially applied when it shouldn't be. Most C4's implement a transbrake by applying the forward clutch, direct clutch and reverse band at the same time. Normal first is the forward clutch and maybe the reverse band (if there is engine braking in first), so if it is dragging in first it points to the direct clutch being applied. That would cause it to drag in second too since the direct drum is stopped by the intermediate band in second, and if the direct clutch is trying to apply at the same time, it will lock up the trans (likely one will slip, but it could lock up solid). There would be no problem with third, since the direct clutch is supposed to be applied in third. My guess would be that there is some pressure being sent to the direct clutch all the time.

A couple of things to check:
1. A lot of aftermarket C4 shifter arms are not keyed to the shaft and can slip. Check to make sure that when the shifter is in a particular gear that the transmission manual valve detent is properly aligned for that gear.

2. Has the valve body been out of the trans and apart since it was run the last time? You might have some leakage between passages so that the direct clutch is being applied when it shouldn't be. These things are very susceptable to passage leaks if the valve body bolts are not torqued properly, or if ANY of the bolt holes are stripped.

3. Check the trans-brake solenoid operation and adjustment. It will could allow the direct clutch and/or reverse band to apply at the wrong time if it is out of whack or the valve it is controlling is hung up. Is the trans-brake electrical switch OK?

C-4's are going to puke out of the vent even if the fluid level is OK. You should pull that little vent thingy and tap the hole with a pipe thread (1/4" I think) and put a hose fitting in it. Then run a hose to a puke tank to catch the fluid. Otherwise the bottom of your car is gonna look like the Exxon Valdez paid a visit.

[Chris1529]

I'm with Bill. It sounds like the brake not working properly.

As far as the linkage goes, I like to pull the pan off so I can see the detents as well as feel them.

If it is a racing C-4 from Dynamic, it should already have the vent tapped.

Is this a new transmission or did you run it with another combo? If you have run it before, what else is different? -the bellhousing, converter, spacer plate?.......

[Smitty]

Originally Posted by Bill Harris

It sounds like the trans brake is being partially applied when it shouldn't be. Most C4's implement a transbrake by applying the forward clutch, direct clutch and reverse band at the same time. Normal first is the forward clutch and maybe the reverse band (if there is engine braking in first), so if it is dragging in first it points to the direct clutch being applied. That would cause it to drag in second too since the direct drum is stopped by the intermediate band in second, and if the direct clutch is trying to apply at the same time, it will lock up the trans (likely one will slip, but it could lock up solid). There would be no problem with third, since the direct clutch is supposed to be applied in third. My guess would be that there is some pressure being sent to the direct clutch all the time.

A couple of things to check:
1. A lot of aftermarket C4 shifter arms are not keyed to the shaft and can slip. Check to make sure that when the shifter is in a particular gear that the transmission manual valve detent is properly aligned for that gear.

2. Has the valve body been out of the trans and apart since it was run the last time? You might have some leakage between passages so that the direct clutch is being applied when it shouldn't be. These things are very susceptable to passage leaks if the valve body bolts are not torqued properly, or if ANY of the bolt holes are stripped.

3. Check the trans-brake solenoid operation and adjustment. It will could allow the direct clutch and/or reverse band to apply at the wrong time if it is out of whack or the valve it is controlling is hung up. Is the trans-brake electrical switch OK?

C-4's are going to puke out of the vent even if the fluid level is OK. You should pull that little vent thingy and tap the hole with a pipe thread (1/4" I think) and put a hose fitting in it. Then run a hose to a puke tank to catch the fluid. Otherwise the bottom of your car is gonna look like the Exxon Valdez paid a visit.

Bill,

Thanks for the reply. My car has all of the symptons you described. The only thing I did different was remove the delay box, installed a new transbrake switch (Harrington), and added a trans blanket. I did my burnout as stated and launched the car and everything seemed fine just real sluggish. It sounds like from what you are saying I can disconnect the switch and see if the transmission acts normal. On my transbrake switch I can barely touch it and you here the solenoid click even without fully depressing the switch. I think I will completely remove the switch from the car and try it. Thanks for the tips.

Smitty

[Smitty]

Originally Posted by Chris1529

I'm with Bill. It sounds like the brake not working properly.

As far as the linkage goes, I like to pull the pan off so I can see the detents as well as feel them.

If it is a racing C-4 from Dynamic, it should already have the vent tapped.

Is this a new transmission or did you run it with another combo? If you have run it before, what else is different? -the bellhousing, converter, spacer plate?.......

Chris,

Thanks for your reply as well. The trans is built C-4 from a local guy with dip stick in pan. Trans and covertor have always been paired together, I just put in a new SS 351 Cleveland. 8 inch convertor from TCT flashes too 6300 so I launch at 5600. Only thing I did was add the required saftey stuff for the class, flex plate shield and saftey blanket.

Smitty

[Freddie]

I run a c-4 in my car, I had issues with it being very sluggish in 1st, and not shifting into 2nd right away when I first set it all up. Turned out when I changed to the SFI flexplate, I needed to space the trans to the motor a little more for propper converter clearence. I wiped out the front pump, and trans locked itself in park.

Not sure if this helps any, but this was my only bad experiance with c-4 issues. Once we got this fixed I have over 100 passes on my trans with no issues.

[Smitty]

Originally Posted by Freddie

I run a c-4 in my car, I had issues with it being very sluggish in 1st, and not shifting into 2nd right away when I first set it all up. Turned out when I changed to the SFI flexplate, I needed to space the trans to the motor a little more for propper converter clearence. I wiped out the front pump, and trans locked itself in park.

Not sure if this helps any, but this was my only bad experiance with c-4 issues. Once we got this fixed I have over 100 passes on my trans with no issues.

How can I tell if my clearence is off? I added the TCI SFI plate and Flywheel shield.

[Smitty]

Originally Posted by 1664SSJA

When you install the trans/converter, do you have some back and forth movement of the converter? It can slide back and forth before "pushing" it onto the flexplate and installing your coverter bolts?

If there was any movement it was very little, I don't recall have to move it far to get the bolts into the flywheel; not to the point where it disengaged from the front pump.

[Bill Harris]

You should have at least an 1/8th of an inch of gap between the flexplate and the converter drive lugs when the trans is bolted to the engine. You should be able to spin the converter freely after the trans is bolted to the block but before you install the flywheel/converter bolts.

On the transbrake solenoid issue, just disconnecting the electrical switch might not make any difference. Is the solenoid external, mounting where the original modulator was? If so, you need to make sure that the valve that the solenoid activates is installed properly, not backwards, and moves freely. Is there supposed to be a spring on that valve? Is it there and installed correctly? Is the solenoid installed to the proper depth?

[Smitty]

Originally Posted by Bill Harris

You should have at least an 1/8th of an inch of gap between the flexplate and the converter drive lugs when the trans is bolted to the engine. You should be able to spin the converter freely after the trans is bolted to the block but before you install the flywheel/converter bolts.

On the transbrake solenoid issue, just disconnecting the electrical switch might not make any difference. Is the solenoid external, mounting where the original modulator was? If so, you need to make sure that the valve that the solenoid activates is installed properly, not backwards, and moves freely. Is there supposed to be a spring on that valve? Is it there and installed correctly? Is the solenoid installed to the proper depth?

I will check the clearance on the convertor and flexplate; the convertor was spinning freely after everything was installed, no dragging. The brake does have an external solenoid however this was never removed and it was all working fine prior to me removing the engine. The original B&M switch was wired through a Dedenbar RTD-6 Delay Box, I have since removed the delay box and ran a wore of the main solenoid for my starter to one side of the switch and the wire from the solenoid on the brake to the opposite side of the new transbrake switch.