Full manual auto trans question.... C4

elgecko · #1 (**permalink**) 12-20-2006, 06:39 AM

I will be using a full manual valve body in my C4 automatic. Is a kickdown linkage cable from carb still necessary??? How about vacuum connection from intake manifold.
Sorry, I'm kindof a transmission dunce

Dave

cobrashoch · #2 (**permalink**) 12-21-2006, 06:03 PM

Depends on how it's built. Generally no to the kickdown rod, it's only there for a passing gear or kickdowns, but you might still need vacume to the vacume kickdown valve, it depends. A true full manual body bypasses all that stuff however. My question is why? All fully auto transmissions can be made to shift so hard they will knock your teeth out, and can be made to shift up or down on demand too. Yes a full manual is a little tighter on high rev. shifts, but that little bit you gain on a full manual (reverse pattern) shift is very minor considering you are giving up auto shifting and a lot of streetability. Your call,,,,,,,,,,,, but you need to talk to the folks or guy that built the darn thing either way. I'm of the opinon that if it's got a trans brake you need a full manual body transmission.
If you don't have a trans brake you need to let it shift on it's own.

trularin · #3 (**permalink**) 12-21-2006, 06:23 PM

Had one of those in my 73 Mach 1. It was necessary because you did not want to shift into a lower gear and have the trans pull you down. It would tear up the trans and you would be building a new one in 10k miles or less.

SO, the unit I had needed something like 2/3 throttle to allow a down shift.

BTW, I had to install this after I blowup the first unit as I down shifted with 430 HP and used the trans to pulled down the car ( down shifting in a street race ) Blew the clutches and I coasted to the curb. Dang that was a long time ago, 1976 or 77.

Hope this helps.

elgecko · #4 (**permalink**) 12-21-2006, 06:39 PM

I just thought a little driver "interaction" would help me forget about a 4speed and my big feet........ besides, these cars will kill you if you allow the Cobra to think too much on it's own.

I can see where ya coming from Ron. Just would have to remember to downshift when at a street light, I guess.
I talked to the folks at PA transmissions and a manual body is available without a transbrake. What that means Im not sure.
Trularin.....1976...It was me and my MG going after my first wife. Ahhh memories. STOP STOP
Dave

cobrashoch · #5 (**permalink**) 12-21-2006, 08:58 PM

Yes, I understand the valvebody thing and trans brake difference, but I think you are missing the point I am trying to make here. We are not talking about 3600lbs cars here. A mildly built C-4 in a COBRA would be much more complient, safer, and much more fun to drive even with a monster big block. When you do the other stuff you gain a little but you give up a lot in the name of racing. I would much rather see you spend the money on stronger components and a good converter for a lightweight Cobra. Contrary to popular belief, there is a huge difference in converters you know. I've recomended C-4's to Cobra guys down through the years, but there is a definate right way to go about doing it too. I'm not making this stuff up either, I fought the war. To go into futher detail I would have to know more about your car though, and what you want to do with it.
cobrashock

cobrajeff · #6 (**permalink**) 12-22-2006, 06:39 AM

I had a "full-manual" Reverse-Pattern C4 built specifically for my Cobra. This unit was a "lightweight" model, and fully "rollerized". It did not have a trans-brake. I went this way for several reasons;, one, I wanted the lighter weight (cut about 3o-40 lbs. out of a C4) for autocrossing; two, it did not need vacuum (I knew I was going to run Webers and a vacuum source would be a problem); and three, the tranny guy said this was the only way to get "hardest shifting" C4 he could make.

I HATED that tranny. I have been driving Mustangs for forty years, and have become quite comfortable with the standard 3-2-1 shift pattern. I could not get used to shifting it backwards. Another issue was that, among the parts removed to make it "lightweight", were some of the components that provided engine-braking on downshifts. With this tranny, pulling it back to first when you downshifted offered no tranny braking at all - it just "free-wheeled" - it was like you put it into neutral. On top of all that, I blew this C4 up every thousand miles (THREE years in a ROW!).

I had another C4 built with a TransGo valve-body kit (just like I used to in the 70's) and have had very good luck with it. It doesn't shift quite as hard (but it doesn't self-destruct, either) as the full-manual, but, the shift pattern is standard, and you have full manual control of it - if you shift it into "1" at 60 mph, it goes directly to "First". I had to drill my Weber intake and hide a vacuum cannister under the car, but, it has all worked out very well. No more tranny failures in the last seven years.

regards,

Jeff

Toby · #7 (**permalink**) 12-22-2006, 07:55 AM

Hey Dave,
I have a c-4 set up that was in my cobra for sale if your looking. It is not a manual valve body, but has a shift kit and 2400 stall converter, flexplate and even a lokar shifter. This set up was an excellent performer with about 400 flywheel HP. Just in case your looking.

Toby

elgecko · #8 (**permalink**) 12-22-2006, 01:57 PM

The C4 I'm looking for will be mated to a 390Fe with a PA SFI bellhousing adapter. I was hoping to eliminate the kickdown and vacuum connections like CobraJeff said but..........don't think it's worth it.
I have a mock up C4 390 engine combo in my gallery images.

cobrajeff · #9 (**permalink**) 12-23-2006, 08:21 AM

Dave -

The TransGo kits will allow you to eliminate the kick-down linkage (in fact, they recommend it if you plan to rev over 6200rpm). I have always used thr TransGo 47-2 "Competition" kit in my C4's. The tranny will shift automatically, or, you can drive it like a full manual (as I usually do).

I see they now have a 47-3 "Stick-Shift" version - I haven't tried one of those. The TransGo kits are available through Summit Racing.

Jeff

elgecko · #10 (**permalink**) 12-23-2006, 11:00 AM

Thanks Jeff. Sounds like things are being narrowed down for me.
I'll get my trusty Summit catalog out.
Toby, I may be interested in a spare C4 to mess with....I'll PM you.
Dave

cobrashoch · #11 (**permalink**) 12-25-2006, 08:48 PM

Now your talking!
Jeff, sounds like you fought the some of the battles I fought. I'm happy w/my a Coan glide now, but it is high dollar.
cobrashock