C6 tranny problem
Thread Starter
|
New User
Joined: Jan 2003
Posts: 7
Likes: 0
C6 tranny problem
'78 f100, 351W, C6 tranny. The shift from 1st to 2nd is hard. Shifts thru the rest of the gears very smooth. It gets worse when acceleration is increased. Need to ease into 2nd gear to avoid it. Fluid levels are fine, vacuum line is fine, just raplaced the fluid/filter, u-joints look good, tightened a loose motor mount. Any ideas? 
Thanks for any help,
Matty
Thanks for any help,
Matty
Posting Guru
Joined: Aug 2002
Posts: 1,214
Likes: 2
From: Minneapolis, MN
C6 tranny problem
Matty,
My guess would be that someone along the line has put a shift kit in it. A firm shift is desirable because then there is less time for first gear to disengage and second gear to engage, meaning less overlap and slippage when both gears are engaged. More overlap gives smoother shifts at the cost of increased clutch wear. However, a shift that is too harsh is harder on the rest of the drivetrain, u-joints etc. Some people go overboard when installing a shift kit, thinking that if a little firmer is good then really hard shifts must be better. I've got the tranny in my Mustang set up that way and it's a blast to drive, gets a little squirrely on the 1-2 shift but oh so fun!
You could try adjusting the vacuum modulator to change the shift points by removing the vacuum hose on the modulator to use a small flat screwdriver that will fit inside the nipple. Screw the adjustment counter-clockwise to lower the shift point. Try a full turn to a turn and a half to start with. This might smooth it out enough for you. If not, you'll have to go deeper into the tranny and un-do what the shift kit did.
Just my $.02
Greg
'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
HONK if you love peace and quiet!
My guess would be that someone along the line has put a shift kit in it. A firm shift is desirable because then there is less time for first gear to disengage and second gear to engage, meaning less overlap and slippage when both gears are engaged. More overlap gives smoother shifts at the cost of increased clutch wear. However, a shift that is too harsh is harder on the rest of the drivetrain, u-joints etc. Some people go overboard when installing a shift kit, thinking that if a little firmer is good then really hard shifts must be better. I've got the tranny in my Mustang set up that way and it's a blast to drive, gets a little squirrely on the 1-2 shift but oh so fun!
You could try adjusting the vacuum modulator to change the shift points by removing the vacuum hose on the modulator to use a small flat screwdriver that will fit inside the nipple. Screw the adjustment counter-clockwise to lower the shift point. Try a full turn to a turn and a half to start with. This might smooth it out enough for you. If not, you'll have to go deeper into the tranny and un-do what the shift kit did.Just my $.02
Greg
'77 F-250 Camper Special 400ci driver
'76 F-250 Supercab 360ci current project
'71 Mach I 429CJ in storage
'79 F-150 for parts
HONK if you love peace and quiet!
Thread Starter
|
New User
Joined: Jan 2003
Posts: 7
Likes: 0
C6 tranny problem
I have a shift kit in my(dare I say) '71 chevelle and it definatley doesn't feel like that. It is a pretty hard shift from 1st to 2nd. I will try to adjust the shift point and see what that does. Could it be a bad modulator? What is the purpose of the modulator? Thanks for the tip.
Matty
Matty
