C6's, Just How Smooth?......
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From: North of Tulsa, Oklahoma
C6's, Just How Smooth?......
I have a 78 F150 2wd w/ 351m and c6. I never owned a c6 before and wanted to know just how smooth...er not smooth that these transmissions are supposed to shift? When it's shifting, up or down, there is a noticeable 'clunk'. I don't just hear it, I feel it. 
That 'clunk' is not there when I take off from a dead stop, so I would not think that the u-joints are worn. (I'm used to the smooth E4OD transmissions.)
That 'clunk' is not there when I take off from a dead stop, so I would not think that the u-joints are worn. (I'm used to the smooth E4OD transmissions.)
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From: Gainesville, FL
C6's, Just How Smooth?......
CigarXTC
The C-6 is infamous for "Being Clunky". They shift hard, but they don't make noise shifting from gear to gear. Their clutches are made of cast iron, which clunk when shifting. To my understanding, during rebuilds these clutches are replaced with an alternative material which quiets the trans and supposedly is a compromise with respect to trans life. I've heard stories of people putting in shift kits and/or playing with springs and making them "bang" when shifting gears. Usually, a clogged valve body can cause bad shifting but not "banging".
Secondly, improper rear end lash can cause a loud clunk when shifting. Check the rear end.
KingFisher
The C-6 is infamous for "Being Clunky". They shift hard, but they don't make noise shifting from gear to gear. Their clutches are made of cast iron, which clunk when shifting. To my understanding, during rebuilds these clutches are replaced with an alternative material which quiets the trans and supposedly is a compromise with respect to trans life. I've heard stories of people putting in shift kits and/or playing with springs and making them "bang" when shifting gears. Usually, a clogged valve body can cause bad shifting but not "banging".
Secondly, improper rear end lash can cause a loud clunk when shifting. Check the rear end.
KingFisher
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C6's, Just How Smooth?......
interesting....my trans shifts better than any other car or truck i have owned. its quiet and when i towed my brothers chevy to the shop,(no pun intended), i couldnt even feel it shift, just noticed a difference in engine RPM and noise. and this is from the stock C6 that has 90000 miles on it with out ever being out of the truck. maybe i just got lucky, and maybe i just got one that wasnt built on a monday...
77_f250_460
77_f250_460
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From: Texas
C6's, Just How Smooth?......
I just had my C6 rebuilt and a shift kit installed. It shifts quick and firm, but I would not say "Clunky". It feels the way I want it to feel. I really like the way it shifts compared to the E40D in my 1999 f150. That thing takes too long time to shift. My 2 cents, something isn't right. Check Torque Converter bolts and verify that there aren't problems in the rest of the drive-train. If all looks good, the tranny probably needs a rebuild.
Greg
Greg
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C6's, Just How Smooth?......
I agree with prior posts. I've got a recently rebuilt C-6 with a shift improver kit and the thing is silky smooth under normal conditions, but when I rev it up a little, the shifts are very firm yet still smooth.
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From: North of Tulsa, Oklahoma
C6's, Just How Smooth?......
Well, with the way ya'll describe yours, I guess mine will shift smoother after a rebuild. It looks like the original, and has enough gunk crusted on it to appear to never have been removed for service. I guess I'll just live with the not so smooth shifting until it completely gives out on me. Then I'll get it rebuilt. Thanks all.
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From: Gainesville, FL
C6's, Just How Smooth?......
All,
I guess I need to get mine rebuilt to. Now you've got me worried.
KingFisher
I guess I need to get mine rebuilt to. Now you've got me worried.
KingFisher
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From: Iowa
C6's, Just How Smooth?......
I have two C6's. The one in my old '70 is not original(I put it there) and it has a nice firm shift when I'm cruising. However, when I nail the grin pedal, the shifts become very solid and right now, if you know what I mean. Second gear scratches are a common occurance. This tranny acts like it has a shift kit, but I don't know for sure. I got it free.
The C6 in my '78 is pretty lame. Shifts are not as quick, and they're too soft for my liking, especially when towing. This tranny is going to be replaced sooner or later.
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
The C6 in my '78 is pretty lame. Shifts are not as quick, and they're too soft for my liking, especially when towing. This tranny is going to be replaced sooner or later.
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
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From: texarkana, tx
C6's, Just How Smooth?......
Oh gawd, I love my C-6! Remember - the engine and tranny came out of an '86 E350 van....and I plopped it directly into Harrison. Did not change the modulator....just added a deep sump B&M aluminum pan and sooper-dooper B&M cooler. The thing shifts like a dream.....it's so cool.....almost orgasmic...
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank