C6 will not shift into third gear.

[bambinoelchicano]

Hi all I have a 1970 f100 with an auto c6 and about two weeks ago I changed all the seals and the servo gasket and orings but now it doesn't shift into third, it shifts great from 1st to 2nd but when it goes to shift into third it just stays stuck and won't fully shift. I also changed the modulator thinking it would help but no luck. I read on one of the threads about adjusting the band and I tried that also but it didn't help. Someone told me that third and reverse are the same and the truckshifts fine into reverse. Just trying to get her running good, any tips or input are greatly appreciated.

[Donnie]

Why did you change the servo gasket? Was 3rd OK before? Yes? 3rd & rev share the same clutches, so if you have a fast reverse, that means that the clutches in the 3 / R drum are ok. If you had a good 3rd before working on it , I would go back into the servo area,,,check your O Rings for tight fit & your gasket..........The same oel that applys the 3rd clutches also releases the 2nd gear band..Does the band release? if it does your truck will coast, like neutral... If the compression holds it back, the band is not releasing...report back...Donnie

[bambinoelchicano]

Thanks Donnie for the advice, went in there took the servo out and put it in checking that it was able to move in and out with no problem, after all that I drained and refilled the pan with some tranny fluid and some Lucas tranny fix and now it's shifting very nice. Thanks again

[Donnie]

Bambino, all of us on here appreciate it when our advise helps someone and we get a thank you...Your follow up is appreciated..
I do this because the transmission industry has been good to me, I am retired now & want to share with others, because whatever I take with me when I leave this earth...........that knowledge will be of no use to ANYONE.............Donnie

..........................................PASS IT ON