C4 conversion, Linkage ??

[351m]

So, the AOD is cooked in my '90 vic, I have a C4 with shift kit installed ready to go in the car. My problem is, what did you guys use for the Linkage on the trans to hook up the shift cable? Pics would be awesome! I won't bother with the kickdown as I can pull it into second manually easily enough.

I believe I have the small bell C4 and flex plate if that helps.(I will check once the AOD is out of the car)

[gadget73]

Don't know if anyone has done a C4 in a 90+ car with the cable linkage. Older cars had shift rods, and usually the fix is to find 1979 C4 linkages.

[351m]

Hmm, I might have linkage on the TC out at my buddy's. Problem there is the steering. The '80 Grenada the trans came out of had the cable as well but the moron cut it.

I might just have to pull it apart again and swap the mustang C4 linkage into it so i can use the floor shifter.

[351m]

Got it in and figured out. It all seems to work EXCEPT 3rd gear. I have seen this one other time, I had a '79 F-150 with a 302/C6 that had no kickdown, same thing, it wouldn't shift into 3rd. Will I actually need it or am I looking at pulling this car apart again?

[1987cp]

By Third gear not working, do you mean that it's not upshifting to Third at light throttle at higher road speeds? The vacuum modulator helps govern upshift points at part-throttle, and the stock governor will probably force it to upshift at 4000rpm or so at WOT. The kickdown rod is awfully nice to have, but it shouldn't affect anything except when you want to force a downshift with the gas pedal.

What's the background of this particular transmission? By "small bellhousing", do you mean that this is an early case-fill C4 using a 157 tooth flexplate?

[351m]

Update. I was wrong on the bellhousing, it was a big bell, it is working fine, the modulator wasn't getting a vacum signal. I had it tied into the Map line with a T fitting so I dunno what was up with that. Its hooked to the line from the air pump and all is well now.

This trans was behind a 250 I6 in an '80 Grenada, 85,000km on it, all proven with service docs. If the engine wasn't such a low hp pile of crap I would put it in the car too. I still need to throw the H servo in it in place of the A but at least its in and working.

The B&M stage 2 shift kit is decent as well, the shifts seem pretty consistant and firm.

[351m]

Another one bites the dust. Third worked for about 20 miles. Now it jumps about 500 rpm between 2nd and 3rd then slams in. Reverse is shuddering and slipping when I touch the go pedal as well. Out of 3 C4s I have, I picked the shit one.

[1987cp]

Eek, that's a pain if it really is broken. At least it's not that much hassle to swap it out.

[351m]

Well, it woudn't be but because of my little screw up with the saw at work in June I can do some but not all of the swap myself.

I'm gonna try adjusting the bands first, if that works, I will leave it be for now.

[mercman1951]

I know tis is an old thread, but outside of R&R'ing the trans, what parts did you use to install the C-4? Did you have to modify the driveshaft at all or move the crossmember? I assume you swapped to the C-4 flexplate too...?

[DuceAnAHalf]

I know tis is an old thread, but outside of R&R'ing the trans, what parts did you use to install the C-4? Did you have to modify the driveshaft at all or move the crossmember? I assume you swapped to the C-4 flexplate too...?

all you have to do on a 79-90 is move the tranny crossmember to the second set of holes on the frame. the '91s dont have these holes though. the driveshaft is the same. Find a big bell so you can reuse your flexplate, with a small bell you need a new flexplate.

as for the linkage, i used a B&M pro-stick on a full manual C4 so no vacuum lines or kickdown on mine.

[351m]

What Duce said.

Sorry I haven't been online much. I used parts from the AOD's cable and parts of the mount from the Grenada the trans came from, the pointer is only good for a general idea of the gear you are in because the C4's shift arm was a different length.

As for the second holes, my 90 didn't have them, I just made a plate to go between the crossmember and the rubber mount.

Driveshaft was direct fit, I don't have a kickdown, its not needed as long as you don't get stupid with downshifting youself(Don't use second gear after say 55mph, this is only going by where all of mine stop kicking down at.). The Vac line is hooked up to a manifold source as well.

A bit of an update on this swap... I picked the bad trans out of my bunch, the 2/3 shift has a slight flare, and because I no longer had 4th gear, I found out just how bad the engine really was.

[inlinet18]

I'm kinda in the same boat, little different. I have a 79 that I'm looking to swap an efi from an 87 vic. I plan to keep the c4 since my aod is toast. So my understanding is that the kickdown is no major concern? That was my only concern. Just wondering tho. do they make a kickdown that will work with my efi?

[inlinet18]

by the way, hows the 4x4 vic goin? I always wanted to see that!!!!!

[1987cp]

wondering tho. do they make a kickdown that will work with my efi?

Not going to find anything factory ....

You'll definitely want a functional kickdown if you plan on keeping your C4 full-automatic. Vacuum modulator controls part-throttle shifts, kickdown rod is what forces instant automatic downshifts when you need them.

On one hand, it'll probably be relatively easy to make or modify a regular kickdown rod to work with your SEFI setup .... it just has to shove backwards the right amount at the right time .... even running a stock-replacement C4 in my '79, I ended up making a little extension for the kickdown rod so it could be adjusted to actually engage when I wanted it to. I just used some metal with a couple of holes drilled in it and attached it to the end of the rod with a nut and bolt, but a nicer solution would be some sort of slidey-slot arrangement to allow a large range of adjustment as well as positioning flexibility.

You might also check out Lokar offerings, as I seem to recall they offer cable-style kickdowns specifically designed for things other than TV-controlled tranmissions like AODs and 700R4s.