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-   -   C-4 shifting troubles (http://www.hotrodders.com/forum/c-4-shifting-troubles-111944.html)

haley72 03-21-2007 08:49 PM

C-4 shifting troubles
 
I own a 72 Comet with a 302 and a C4 tranny. I built a high hp 302 for it. I just last night got the car back from the tech. I had him install a Hurst V_Matic floor shifter. He says the linkage is hooked up right. My issue is that the car will not shift into 3rd gear. It shifts into 2nd easily. When it gets to 3rd however, it acts like its in neutral. I rev on it and nothing happens. Theres nothing behind the throttle. If I let up on it and let the rpm come down, it kinda "clunks" really soft and I can feel the drive train again. I got a electric ignition for it. Its the kind that just drops right into the dist. all you have to do is set the rev limiter. I don't know what that was set at. You think maybe its set too low? I tried everything I could think of. I played around with different vacuum ports for the vacuum modulator, I checked the fluid. I put in a product called Lube Guard, its supposed to loosen up stuck valves and stuff like that. It didn't work either. The car has been sitting for little over a year. I don't know if something isn't hooked up right or what. Any suggestions?

Crosley 03-21-2007 10:10 PM

Quote:

Originally Posted by haley72
I own a 72 Comet with a 302 and a C4 tranny. I built a high hp 302 for it. I just last night got the car back from the tech. I had him install a Hurst V_Matic floor shifter. He says the linkage is hooked up right. My issue is that the car will not shift into 3rd gear. It shifts into 2nd easily. When it gets to 3rd however, it acts like its in neutral. I rev on it and nothing happens. Theres nothing behind the throttle. If I let up on it and let the rpm come down, it kinda "clunks" really soft and I can feel the drive train again. I got a electric ignition for it. Its the kind that just drops right into the dist. all you have to do is set the rev limiter. I don't know what that was set at. You think maybe its set too low? I tried everything I could think of. I played around with different vacuum ports for the vacuum modulator, I checked the fluid. I put in a product called Lube Guard, its supposed to loosen up stuck valves and stuff like that. It didn't work either. The car has been sitting for little over a year. I don't know if something isn't hooked up right or what. Any suggestions?


trans needs full manifold vacuum from the carb.

Does Reverse works correctly? Holds good?

Check the vacuum modulator hose at the modulator. Pull hose off , check for fluid drips from the modulator. Fluid dripping from the mod is bad.


Ignition timing on the engine does not really affect shift timing of the tranny much. Unless the engine is running very poorly

haley72 03-22-2007 08:39 AM

I was thinking the same thing about the mod. If that checks out or if I replace it and it still doesn't shift, I think it could be because I have a pretty tall cam. Maybe it isn't creating vacuum. Do you think that could be?

KULTULZ 03-22-2007 11:46 AM

Did it shift into 3rd before the shifter swap? Usually, when one falls out of range going from 2nd to 3rd, the governor is at fault.

haley72 03-23-2007 08:31 AM

turns ouut it was the vac mod. the vscuum lines were cracked and split. with that replaced, it shifts into 3rd but at 45mph. we are going to adjust the mod and the shifter leankage. that should take care of it.

Sean's 03-23-2007 10:02 AM

C-4 shifting troubles
 
Yeah I was gonna suggest adjusting the Mod << When you Camm you Pull less vaccum at an Idle Generally speaking .
But on the shifter <<< Ive been this route on C-4 and C-6 Tranny's and Hurst shifters .
Trying too remember what it was I did ???????
Well from what I cant barely remember of them it seem's I built a plate for the Linkage .
Beleive it was a slider plate ?
But if you study on the linkage for Ford's that comes with Hurst shifter ?
It Suck's, as best I remember was a 1 size fitt's all .
3 or 4 rods connected together .
But some how I fabricated a plate reduced the amount of part's too 2 Rodd's and a Plate .
Well if I could see it I could remember what it was I did too it . << Worked out lott better than what came with the shifter .
But I simplified the one on my Ford truck . < as in less moving parts , More direct shift , Reduced the slopp considerably in the Linkage ETC .
Ohh well when it lock's up , or doesnt shift intoo gear all the way , or pop's loose ?
Study on it some !
As I remember I fabricated a Plate for my C-6 Tranny that worked super cool !
Or post a Pic of the tangled mess they sell with the shifter as Linkage ? Sean

haley72 03-24-2007 09:28 PM

Im not really in a position to fabricate anything. But that sounds like a good idea. I dont think its the shifter. It was really smoth going into 2nd. No grinding or hanging up. I really think its the mod. I know for a fact the tranny is good, it only has about 10'000 miles on it rebuilt. I just have a big cam now. I wonder if I have enough vacuum to run the heater vent??? I might be back on here the next really cold day asking why my heater isn't working at speed. Thanks for the input :)


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