C-4 ??

[Bad67MF]

I just bought a C-4 used "HP rebuilt" I just put it in and it shifts fine manually but if I let it shift auto. it will shift from 1-3 w/o 2nd sometimes it does shift right but not smooth. I have no background history on the rebuild could this be a full manual or do I have a problem?

 

[Edbert]

If it shift at all without you doing anything it is not a manual only. I don;t know enough to diagnose the skipping of 2nd but if it is a high performance build it will NOT shift smooth. Short and abrupt shift are what you want for short ETs and reduced heat/wear (of the tranny not the tires, LOL).

 

[geostang351]

Sounds like a shift kit is installed. As for the shifting itself, is the vacuum hose hooked up?

 

[The Dan]

I agree with geo, sounds like the vacuum modulator might be an issue. It will defineatly mess with the shifts if not working properly. You could always change it out just to rule it out. They're pretty cheap.

 

[golf4283]

maybe he has a green dot c4 so he has it in the start in 2nd gear and go to third. The C4 tranny's of 65-6 used a c4 that you can either set it in low or set it in drive or you can set it in 2nd gear start to 3rd gear because if slippery weather.

 

[84convertablegt]

yeah, sounds like a green dot issue. make sure when u shift into drive, you go 2 clicks past neutral, not 1. otherwise youll be starting in 2nd gear, and shifting directly to third... and your performance will feel like crap... i was a little confused when i first got my 65, but now i have a late model style streetfighter c4 in there, so i dont have to worry about that. or possibly a vaccum mod. problem, they are cheap and easy to replace. just make sure you get the right one.

 

[Bad67MF]

Sounds like a shift kit is installed. As for the shifting itself, is the vacuum hose hooked up?

Yes it is hooked up, and holds vacume but I guess that doesn't mean it works. I will switch it out anyway I also had my suspicions about that.
I don't think it is a green dot, whatever that is. it is out of a 1978 F100
Also it is in D when it misses 2nd. When I get in the gas a little more than normal from a stop it will go from 1st to 3rd with no 2nd.

 

[The Dan]

If it is from a 1978, then it is not a green dot. If the modulator is not the problem, then you may be in for some difficult trouble shooting. If it is a recent rebuild, then the obvious would be that something didn't get replaced correctly. Good luck with figuring it out, I know how frustating it can be.

 

[ravenblack67]

Readjust your bands.

 

[Bad67MF]

Readjust your bands.

Did that.

 

[ravenblack67]

I dug into the manual last night. You may have a bad low/reverse clutch pack. It could be the clutches or the clutch piston or the clutch drum. The only way to be sure is to pull the pan and conduct air checks.

 

[Bad67MF]

I changed the modulator. While I was under there I re-adjusted the bands-10ft.lbs.ea. backed off the low reverse 3 turns and the intermediate 1 3/4 is this correct for a 1978 C-4? One book I have says ft. lbs and one says in. lbs. Anyway when I went for a test drive it shifted VERY smooth, you almost couldn't tell it switched gears. Then from the next stop and start it went from 1-2 and then almost stoped the car like the brakes were on I then put it in N and back to D and it seemed to shift fine after that except for being super smooth . Any answers??

 

[The Dan]

Not to sound insulting, but is the fluid level correct? For it to "feel like the brakes were applied" sounds like the bands are getting a lot of friction. If it is not the fluid, than I say it has to be the band adjustment. I know the book says 10 ft lbs, but something like band adjustments are ball park figures, you may have to keep tweaking it until it finds its happy place.

 

[Bad67MF]

Not to sound insulting, but is the fluid level correct? For it to "feel like the brakes were applied" sounds like the bands are getting a lot of friction. If it is not the fluid, than I say it has to be the band adjustment. I know the book says 10 ft lbs, but something like band adjustments are ball park figures, you may have to keep tweaking it until it finds its happy place.

The fliud is full, I will play with the bands a little a see what I get Thanks

 

[Bad67MF]

The fliud is full, I will play with the bands a little a see what I get Thanks

Would it be better to run the bands a little looser or tighter??