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Discussion Starter · #1 ·
This is further to an earlier problem that I had posted on this forum: C4 goes into drive but no shift!! TransGo assembly pic??
Took the car in for exhaust today. First of all it 'jumps' when put into gear, drive or reverse. After backing out of the driveway and shifting from reverse to drive, upon touching the gas there appears to me a momentary 'slip' and then thump it engages and goes. Shifts firm from 1-2 and from 2-3. Problem: Having driven the car for roughly 25 miles I slowed down for an off ramp, felt it downshift and pulled onto the street. Pulled okay in 1st then when it shifted to 2nd it was like someone threw out an anchor or put the e brake on about 4 notches. Felt like it was held back. Pulled it down into low and it went down okay and then picked up speed and shifted manually into 2nd...same thing. Struggled and I didn't want to try it into drive. Pulled into the muffler shop. Spend 5 hours there. Leaving the tranny shifted fine..firm. I left it in a friends shop pending a wheel alignment in the am.
Any ideas. Initially when I had this problem I removed the valve body and cleaned all spool valves etc and polished them. Fluid was replaced then again. Tranny is fresh and has a Transgo stage 2 shift kit and Sonnax billet C servo. It did this before the servo was put in. I rebuilt this trans as I've done several C4's before and a few C6's. I'm at a loss!!! Any ideas??
Thanks...............John
 

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I think most of these inconsistant/intermittent problems seemed to be caused by either VB or governer issues. You have cleaned it out before....did you burn up some clutches? That residue seems to travel everywhere and does take ALOT of time to clean out throughly.
 

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Discussion Starter · #3 ·
Hello cmf60......yes, i did remove the valve body prior to this when I had similar problems. At that time I did find that there was a green varnish like coating forming on the valve body as well as on the spool valves etc and the primary throttle valve. I had rebuilt this trans about 4 years or so ago and put it to one side while I restored the body on the mustang. In hindsight the tranny/motor should have been last. I checked the fluid this afternoon and it is bright pink with no burnt smell whatsoever. So I think it's safe to assume that the clutches are okay. I guess I'll have to pull the valve body again and go through it. A mechanic teacher friend of mine suggested that some C4's had a problem with the torquing of the valve body. He suggested torquine it to the transmission first and then torque the bolts holding the two sections of the valve body together. Your thoughts?
I wonder what gregaust has to say about this?? I'm thinking about putting a filter on the return line at the very least.
 

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In my limited experience, I have had no issues with the torqueing of the VB.....just don't over-do it (torque wise).
That varnish sounds suspect though amd may be causing some valve sticking in there.
 

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I think it is VB related. It is hard to see once VB is out since it is intermittent. On the torque side main thing is not to overtighten.I've never had issues with C4 but did with a C6 that was taking a bit of power and was twisting the case .What you can do is slip the side covers off the VB be disassembling it and check for even the slightest bind of the shift valves. But based on the issues to date i think i would try another VB.
Seems though since it binds from low to 2nd it's like the band isn't releasing. Is the spring in the rear servo ok? Adjustment is correct?
What is 2nd like normally,i assume ok..
I dont think the governor will cause what is happening. Only other thing is a crossleak when VB gets warm.
If all else fails i guess you could try a gasket each side of the sep plate .reason i suggest this is the manual VB i have used here lately have the gasket on the top side of sep plate so might help in this case...
 

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Discussion Starter · #6 ·
Hello Gregaust. I left the city today with the stang with a fresh wheel alignment. I had left it in there since yesterday when the tranny acted up. Car shifted nice and crisp most of the way [email protected] miles. At one point having slowed down to turn onto another road the car downshifted into 2nd fine but when it went into third it felt that the emergency brake had just ratched on 4 notches. Felt like the car was being held back. I pulled it into manual 2nd, it picked up speed and then I manually put it in drive and all was fine until I reached town. Stopped at a stopsign, tranny downshifted fine. Started out in drive, shifted to 2nd fine and upon going into 3rd same thing happened..like it was labouring under load. Pulled it manually into 2nd....fine...accelerated and then bumped it into Drive...all's fine. Initially my problem with this fresh rebuild was that I got the same symptoms when shifting by itself into 2nd?? Now it's third. I've checked band adjustment at least 1/2 dozen times ..it's right on as per specs. I'm thinking about putting a filter on the return line as I did have that problem initially with the front pump bushing popping out due to a mis aligned and welded torque convertor pump snout. There were very tiny brass pieces in the pan and the screen caught most of it. I'm thinking that maybe some of this is still in suspension in the oil. Along with the filter I'm planning on dropping the valve body again and going through the process again of cleaning and polishing the valves etc. IF I had to exchange the valve body , what do you recommend as far as an aftermarket one??? thanks for all the help............John
 

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Discussion Starter · #7 ·
I forgot to add Gregaust..that I do not have a kickdown rod connected. I usually leave them off for seating in the rings as I would rather not have it downshift but rather keep it under a steady load while accelerating. Also I think it has to be modified somewhat as my car was a 2V car and now it's a 4V holley. I don't think that has any bearing on it, agreed?? thanks.......John
 

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The kickdown rod wont cause these issues.
Now the particles in the oil MAYBE.Unless you did a full strip they would still be there.The factory screen is a bit too coarse to catch a lot.An inline filter would definitely help.
The only thing i can think of is if the shift valves are sticking and not moving full travel MIGHT cause 2 gears at once if they move enough to apply the gear but not enough to exhaust the oil from the previous gear.
I'm not even sure that can happen ,just looking for a reason.

Just to clarify,these probs happen either manually shifting or left in drive to shift automatically??

At this stage i would check the VB since the prob is intermittent.Slip the side covers off first and check shift valves for any tightness.Maybe even sit it in the sun to warm up for a while.I know that one is a long shot.
As for another VB even just a stock one cleaned up will do for now to see if the problem changes.
 

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Also,try STUART ANDERSON on the trans forum.He is in Canada i believe and he is very good . He might post on here occasionally too..Worth a try.
 

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Hello one and all.

I would be suspecting either the valve body or governor.

Or both.
The valve body and governor should be flat sanded.
Upper and lower.

A good grade of gasket bewteen the separator plate and don't overtighten the bolts.
If the transmission had been removed for repairs the cooler and lines must be cleaned.
The cooler hides all sort of junk.
 
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