Technical c4 trani question

im building an sdra drag car, it has a 239 flat head and a c4 auto. the trani is new i had it built for a mustang. it has less than 800 miles on it. it has flare up between 2nd and third, am i correct that the intermediate band is to tight? i cant get a torque wrench in there to adjust it to 10lbs, any ideas would be great!

 

Possibly the band is too tight and not releasing fast enough, but I would think that a solid clunk is more apt than a flareup. If you don't have a lot of room for a ft.lb. torque wrench then use an inch.lb torque wrench set at 120 in.lbs. Vacuum modulator misadjusted would cause a sloppy shift too.

 

I think your band is too loose . If you can not get a torque wrench into position . Tighten it until it bottoms lightly and back off 90* try this . I have never used a torque wrens to adjust these bands . But I’m not doing it correctly

 

thank you all!

 

A loose band could create a flare. I'd try the band adjustment first. Like someone else said tighten it until the adjuster bottoms and just a bit more snug to replicate 10 ft-lb. The real adjustment is how much you back it off. The specs I find are 1 1/2 to 1 3/4 turns back off. The suggested 90 degrees leaves the band pretty tight.

With that said, a 2-3 flare suggests a high/reverse clutch slipping. May be caused by a clutch problem, too much end play in the trans, or low line pressure. At high vacuum you should have somewhere between 55 - 65 psi. With no vacuum it should bump to 140 - 150 psi. That is in any forward range, neutral or park. In reverse it should be over 200 psi. Low pressure in reverse, and a 2-3 flare, points to a leak in the high/reverse clutch.

 

The band is 2nd gear, the direct clutch is 3rd. The front band adjustment is 1.5 turns. If it still has a 2/3 flare then it is probably the direct clutch. You could also try modulator adjustment.

 

2-3 flair is most commonly caused by one or more; loose intermediate band, excessive direct clutch clearance, low line pressure, sticky valve body.
The transmission is using fluid volume to release the band and apply the clutch at the same time so if either action is using too much fluid there is a delay in completion.
Which band servo are you using? R has the smallest release piston, but is a rather rare high performance piece (aftermarket repro available). H is the next smallest, and more common.

 

I’ll take 2 R pistons and springs . They have been tough to locate for me .

 

hey all! thanks for the advice! got a 1/4 in in lbs torque wrench, ran it up to 120, backed off 1 and 3/4 turns. cured the problem

 

it was the front band way out of adjustment. got a small in lb wrench in there. thank you all