Any Early Mustang C-4 Transmission Experts Out There?

[crdnblu]

OK, here goes........My friend has a 66 Mustang Fastback w/ the "dual -shift" C-4 auto trans. (green-dot/white-dot on the floor-plate selector.  The engine is a 289 w/ rebuilt Holley 1850, w/ #2 power-valve, 1/2" phenolic spacer, on an Edelbrock Performer intake, w/ tubular headers.  Also, an unknown origin HOT CAM which only pulls 7-8 INCHES of vacuum @ idle @ aprox. 900 steady RPM in gear.  Mallory Unilite distributor @ 16-18 degrees BTDC initial advance.  
There are NO vacuum leaks!  (tested w/ both a vacuum pump on the trans modulator, as well as spraying carb cleaner into all possible vacuum leak areas; throttle-shafts, etc.)  
 
To the best of our knowledge, the trans is stock w/ a stock, original stall-speed torque converter, so you can imagine the problems this causes.  New ADJUSTABLE trans modulator, @ 2-turns counter-clockwise.  New shifter bushings, new neutral safety switch, ALL lined up to Ford manual specs.    
 
BIGGEST PROBLEM:  Transmission has very good reverse, but won't initially engage ANY forward gears, unless you repeatedly rev the engine, then FINALLY ALL the forward gears work, until you stop the car, turning off the engine, then the problem REPEATS the next time the car is started.  The difficulty in diagnosing the problem for a fix, is that it CURES itself with the above gyrations.    
 
OUR SUSPICIONS:  
1.- One or more STICKING throttle body valves.  
2.- Bands need to be adjusted.  
3.-OR.......the transmission needs a rebuild or replacement (worst-case)  
 
HELP!  Any & all suggestions will be GREATLY appreciated.  
Thanks.......

[Crosley.In.AZ]

 
OUR SUSPICIONS:  
1.- One or more STICKING throttle body valves.  
2.- Bands need to be adjusted.  
3.-OR.......the transmission needs a rebuild or replacement (worst-case)  
 
HELP!  Any & all suggestions will be GREATLY appreciated.  
Thanks.......

you do not post age or history of the trans ,so I suspect you do not know

your suspicions:

number 1 =  nope

number 2 = nope

number 3 =  yep

Sticky valves will not cause no forward.  oil is directed to the forward    clutch via the  manual  valve that is moved with the shifter

Bands have nothing to do with forward clutch pack , as it sounds like the FWD clutch  is not holding. Very common for the inner O-ring on the forward clutch to get very hard and will not seal.    ALSO it may be worn sealing rings or drum where the rings seal  or both

If you shift from reverse ( works) then to forward gear and get nothing....  since reverse works , this tells me there is enough pressure to operate the  trans... so there is a large pressure  leak in the forward clutch

[crdnblu]

Crosley.......Thanks for your rapid reply.  The trans appears to be original to the '66, so the rebuild need certainly makes sense.  In your opinion, what would cause/allow the trans to operate in forward gears after revving the engine numerous times, & not continue to coast along?  Wouldn't a large pressure leak in the forward clutch cause the problem to exist at all times, w/ no recovery?    
Please excuse my ignorance, here......
Thanks......

[Crosley.In.AZ]

Crosley.......Thanks for your rapid reply.  The trans appears to be original to the '66, so the rebuild need certainly makes sense.  In your opinion, what would cause/allow the trans to operate in forward gears after revving the engine numerous times, & not continue to coast along?  Wouldn't a large pressure leak in the forward clutch cause the problem to exist at all times, w/ no recovery?    
Please excuse my ignorance, here......
Thanks......

Hard inner O-ring on forward drum will wear a spot on the piston (aluminum) ... the rev of engine may be forcing the piston up enough to area where the oil would seal off the leak.

Outer seal is square cut..same deal on leakage.  

I am surprised reverse works too.  Direct clutch pack has same problems with age -heat


band adjustments is for low-reverse band  and  2nd gear band.


Reverse band only works in reverse and manual low gear on shifter.  If forward clutch pack  does not hold the car will not move forward.

Make sure some one does proper rebuild on the valve body...  check balls in these old units usually wear down from 1/4 inch to about 1/8 inch diameter.

 

[ACEMAN419]

back in that day fords used ford fluid  because ford uses very tight clearances in the clutch packs  so very little wear causes big shift and slippage problems ,maybe  time to dug into her. the first one i did ,i did like s 350 turbo and i had it out 5 times installed a shift kit and never fixed it so i called my mentor  he explained the tight clearances and that ford  steels came in different thicknesses to make the packs tight as possible so i hope this helps

[crdnblu]

Thanks folks, for all your input.  I've passed it on to my friend; he has decisions to make.  One thing's for sure; when the trans comes out, a higher stall speed converter will be in the works!
He's looking @ the TCI "Saturday Night Special" converter w/ just an added 400-500 RPM stall, as this is a street driven car.

[ACEMAN419]

around here Coan convertor and  trans parts have a great reputation , most the drag racer i know use there stuff if that helps.