Dirty rotten stinking piece of C4 garbage!!!!!

[adsm08]

So I am clearly not happy with an automatic transmission, not something new.

I am bringing the 64 Mustang project to the home stretch. I got the engine running a few weeks ago, filled the tranny fluid and started putting the trans through it's paces with the rear on jack stands. It went forward just fine, but wouldn't engage reverse.

I got busy with other stuff, left it sit for a few weeks, came back, threw a pressure gauge on it, put it in R, and had the specified 150-ish PSI on my gauge, cool valve body is working. Look at the rear wheels, and they are spinning backwards. I figure something in the valve body was hung up from sitting dry for a while and sitting in ATF freed it.

This afternoon I finally got the car to the point of moving under it's own power. I put it down, fired it up, and pulled it outside so I could clean up and scrub the floor. Got all that done about 9PM, go hop in, fire it up, the dirty whore won't go into reverse. It felt like it engaged for a second or so, but I had the parking brake set so it didn't go anywhere.

My shift detents are not well defined, in that I can't easily feel them through the shifter, but R should be the easiest to find. I did not throw the pressure gauge back on it tonight since it was dark out, I hadn't eaten in over 12 hours, and I didn't feel too good after pushing the car uphill into the garage. Also my floor was still wet.

Does anyone have any ideas on why I seem to have intermittent reverse?



EDIT: Screw this car. I am going fishing tomorrow.

 

[sheltonfilms]

Does “L” work? If that doesn’t work either it’s part of the low/reverse band mechanism/circuit


Sent from my iPhone using Tapatalk

 

[adsm08]

As far as I know Low is working. I get forward motion in all forward ranges, but the car is not ready to be driven, so I can't say that it is actually in low and not just still in drive.

 

[adsm08]

Ok, so I got back to it for a few minutes tonight.

Wheels off the ground, went into reverse, wheels spun backwards (I think, I realized a few hours later that I was no longer sure which way they went). Line pressure started at 150 PSI, which is the spec, but it wasn't steady, it was bouncy. If allowed to idle with the brakes applied the needle would start to jump violently between 125 and 175. If I tapped the throttle it would settle down for a bit. Releasing the brakes did not change it.

Then I set it down and tried moving. It would go forward, no backward.

Went back out about 5 minutes ago because I realized that I wasn't sure which way the wheels had been going, and while pressures are acting the same, I had no power to the wheels.

 

[sheltonfilms]

Did you have this car previously moving or bought it as is?

Sure it has enough fluid? Let it run for a while, shift through all gears before checking?




Sent from my iPhone using Tapatalk

 

[adsm08]

Did you have this car previously moving or bought it as is?

Sure it has enough fluid? Let it run for a while, shift through all gears before checking?




Sent from my iPhone using Tapatalk

We bought the car in driving condition, but the trans was starting to slip and leaked like a sive, and had unknown miles. I had the trans apart, did a soft rebuild, new clutches, bands, seals, etc.

Fluid level is correct, it has been running, shifting through the ranges long enough that all the fluid passages should be pumped up and purged of air.

The part that is really bugging me is the intermittent engagement, and the inability to move the car's weight in reverse, but no issues going forward.

That plus the fluctuating fluid pressure makes me think the issue may be in the valve body.

I think am going to try readjusting the bands, and if I still have issues then I guess the pan comes down.

 

[sheltonfilms]

Did you replace the reverse servo piston with the rebuild? Seal could be cracked and won’t allow full hydraulic pressure to build so the band doesn’t clamp well. Could also cause the fluctuating pressure readings.

Reverse piston can be pulled out externally on a C4 right (no need to pull trans or pan)?


Sent from my iPhone using Tapatalk

 

[adsm08]

Did you replace the reverse servo piston with the rebuild? Seal could be cracked and won’t allow full hydraulic pressure to build so the band doesn’t clamp well. Could also cause the fluctuating pressure readings.

Reverse piston can be pulled out externally on a C4 right (no need to pull trans or pan)?


Sent from my iPhone using Tapatalk

It's been a little while since I did the trans, we had some issues getting the engine running, but I believe I replaced the servo piston. The trans tunnel is very tight on this car, I think I would probably have to pull the trans to do the servos.

On the bright side, if I pull the engine and trans together it takes half an hour. Maybe 45 min to install.

 

[adsm08]

Ok, so life got in the way, and then I got a few days break, adjusted bands, no good, possibly worse. Pulled the pan and valve body and air tested. High/Reverse clutch is not engaging under air and the circuit leaks badly.

Took another two weeks to scavenge some metal, built a transmission holding fixture that bolts to my engine stand. Got the trans up on it this morning and took the HR clutch out and air tested just the clutch pack. It works fine. It goes "put" when I cover two holes and put air to the 3rd, no hissing.

High/Reverse is the top of the stack, and the rear snout of the pump goes right into the "front" of the clutch drum. So am I looking at bad lip seals along the back of the pump?

 

[kimcrwbr1]

Did you pull the valve body apart and clean all the crap out? Its a pain in the ass but it sounds to me like you have a valve sticking in the body?

 

[adsm08]

Did you pull the valve body apart and clean all the crap out? Its a pain in the ass but it sounds to me like you have a valve sticking in the body?

Valve body is working. I get mostly proper, but somewhat erratic line pressure in reverse. An air test showed a leak in the high/reverse circuit. It looks like it might be between the pump and drum. I found time to do a little tracing this evening and when I put the drum on the pump and put air to that hole on the pump it isn't sealing.

 

[adsm08]

I chased this, I'm pretty sure I have the leaking circuit fixed. New problems.

Now when fully assembled the transmission output is very hard to turn clockwise, and fully locked up going counter clock wise. I tore it all apart (again), couldn't move the output shaft when it was the only thing in the case.

Got it out, put it in and out a few times, and it moves now. Started putting the guts back in, and tested it piece by piece. The output shaft got harder to move with each added component (added weight) but still moved. I got to the high/reverse clutch installed and it was stiff but still moving. I put the pump in, did not torque the pump bolts yet, they are finger tight, trans output shaft is locked up again. It will turn one way, not the other.

What is going on with this thing? I have never seen one do this before.

Tail housing is not installed yet, so I have confirmed it is NOT in park.
Also,

 

[Uncle Gump]

I'm feeling your pain on this one... but it's been way to long for me since I've been in a C4 to be of any help.

It seems strange the it will turn one way and not the other. Kinda rules out the stack just binding up... seems that would lock up both directions.

 

[adsm08]

I'm feeling your pain on this one... but it's been way to long for me since I've been in a C4 to be of any help.

It seems strange the it will turn one way and not the other. Kinda rules out the stack just binding up... seems that would lock up both directions.

Right. The whole thing is spinning right up until I put the pump in.

I tore it down thinking maybe something had gone wrong in the one way clutch, but when it started working I took it all apart, and up until I put it all back together. And the center race of the one-way clutch spins just fine when it is all apart.

If nobody here can point me in the right direction I'm probably gonna haul it off to the trans shop and let this thing be someone else's problem.

 

[bobbywalter]

never noticed this thread. i will have to get to my note book. i have cracked a few cases with horror show results with these. they rock for 2wd drag racing though.


all the thrust goes to the rear...the selective kits and roller kits are worth the effort. maybe your housing is worn ...assuming your reusing the oem cage and thrust? stack up correct? springs right direction?