please help with hard shifting tranny

[mxmattd]

i bought my mustang a couple years ago looking to drive it on the weekends and fix the minor problems it had. one of these problems is a very hard 3-2 downshift in the c-4 tranny. I was told it was rebuilt about a year or two before i bought it, but the problem seems to be getting worse. sometimes when its very cold, it doesn't want to upshift from second to third, and when it does, it doesn't shift back down when i stop. any ideas what could be causing this? as always i pray for an easy (cheap) fix

 

[rbohm]

i would replace the modulator valve as that is usually the culprit. they are not expensive, probably $15 iirc. get the one with a single nipple. also set the adjustment screw about halfway out as an intial adjustment.

 

[bnickel]

i had a similar problem with mine and it was due to a bad governor, which resulted from the the front pump chewing itself to pieces. the modulator shouldn't have any effect on the downshift as it only controls upshifts.

 

[mxmattd]

bnickel-

what parts had to be replaced in your case? did you have to have the tranny rebuilt?

 

[TOM B]

I just posted this on another Question, before you take anything apart try
some LUCAS trany shift improover, This stuff works, I tryed the rest and found Lucas works as it says. OH yea, Maybe I should say that Im a mechanic now for 30 years.
I think I just gave my age away.

 

[bnickel]

bnickel-

what parts had to be replaced in your case? did you have to have the tranny rebuilt?

in my case the trans did have to be rebuilt because when the pump started to self destruct it sent metal shaving all through the trans which is what made the governor hang up. it had other problems as well but mainly what you describe. it's actually quite amazing that it was still working at all . the pump had literally started to grind itself to bits and there were grooves at least 1/4" deep all over it, it was mess.

 

[D.Hearne]

Last C-4 I had, had the same problems. This was due to it sitting up and the seals drying out inside. It eventually quit pulling altogether. I too would try the Lucas stuff first before a rebuild. Their Transmission treatment saved me a rebuild on an E4OD. But then again the trans fix Lucas stuff frees up sticky parts, I don't recall it doing anything about bad seals. Cost you $10 though to find out. The stuff also worked great on the C-6 in my 68 Merc. Poured one bottle in it, drove around the block 4 times and it shifted almost like new.