i have a question about my c-4, i just stuck a stock 302 out of a 1979 musting into my mav to satisfy me until the 351w is complete, my problem is that i had a brand new tranny sitting out in the shop for about two years. i just stuck it in with the 302 with a 2000 TCI stall convertor and a B&M shift kit, i Put in the street/strip kit and now i have no forward gears unless i rev the motor to about 4000rpm then it barely creeps forward, i dont know if it is in the clutches or if i screwed up the valve body when i put the kit in. The reverse works great and there is no hesitation or slipping in reverse, the fluid is right where it needs to be, any help would be appreciated, thanks Justin
I was going to ask about the same question. I've got a truck witha C6 and 302 and it would drive alright but now it does exaclty what yours does, and I have no clue.
Usually when a c4 moves backwards, but not forwards, the forward clutch pack is not engaging correctly. This could be caused by worn/damaged friction plates, low pressure (internal leak), and a few other things....but 9 times out of 10 the forward clutches are toast. If you can rev it and it starts to move, that's normally a clue that the friction material is gone and the plates are now all steel....and when you rev the engine to get it to move, the clutches are slipping and eventually get hot and try to lock themselves together. Good news is C4's are really easy to build. Bad news is the tranny's got to come out. Good luck
Put a gauge on the port located on the side of the tranny and see what your main hydralic pressure is doing when you engage gears . A huge drop and no recovery would indicate a seal problem or a leak somewhere . If drops slightly and recovers then the clutches are probably toast . There is a chance that the torque converter is NOT full of oil . I guess you could take off your oil cooler line and try a pressure reading there . It should be around 60 psi . If you have nothing then there is something wrong with the converter/ cooling loop .
C4 This is a common problem with any auto trans that has been sitting for some time. The seals will become brittle and leak. If the clutches were not soaked in trans fluid for at least 30 min before assy, they will sometimes become deteriorated and at first engagement, disengage themselves from the steel and thus, no movement. Everyone is right in there answers, pressure reading will tell the most. Also you can drop the pan and look for signs of clutch material in the filter or pan. Valve body leakage is another nasty culprit in C4's. The convertor spins the front pump and the hydraulic pressure is forced through the valve body passage to the foward clutch pack, it forces a piston foward against the discs to engage the various drums and bands that turn the output shaft in the desired direction. No pressure from leaks or burnt clutch facings and the car will not move etc. Ever use a hydraulic jack that will not go up or leak down etc? Same basic principal. Anyway you look at it, the trans should be removed and checked for all the above symptoms. Good luck as always.
