C-4 shift linkage

65fastbackresto

Active Member
Apr 13, 2007
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Picked up my new tranny last night, and the shift linkage is pointed down on it. I still have the old tranny and its pointed up on it. I hear you have to drop the valve body to turn it back over, is this neccesary and is it hard to do?

Also the hole is plugged for the vacuum line on the new tranny, maybe there is another port I haven`t found yet....
 
You will have to remove the valvebody to change the arm. Keep the outer and inner shafts from each trans together, not assembled, but if you try the outer from one with the inner from the other it might not work. Some shift shafts are longer than the others and need a matching kick down lever.
Changing it out is no big deal. You should use an inch pound torque wrench to re-install the valve body. I have done it countless time w/o a torque wrench but it can cause problems if it is too tight or too loose. Too tight can strip the threads or warp the body or so I am told. Too loose can allow fluid to leak and cause it to shift odd.
Is the new transmission a manual valve body? Manual valve bobodies do not use a modulator and a lot of people just plug the hole.
 
No I cant

The place it plugs into looks like maybe it had a bolt in it and broke off maybe, like 1/16th of an inch of "nub" is sticking out of the hole. I`m gonna go get some pics of the old one and new and put them up here in a few minutes.

Ya know, on closer inspection this appears to be some sort of blow off line, does the vacuum line go the the modulator valve.....I bet some of yall are laughing right now.
 
It looks like you have a later model C4 in the second picture. You need to make sure you get the right converter. the 70 and up c4 uses a larger input shaft, so you may need a different one. 70 and up c4 also uses a push in modulator instead of a screw in. What #'s are on each transmission. The number I need are like c7ae-xxxx or d4ae-xxxx. The newer c4's also moved the vent to the top of the tailhousing. That may be what you are looking at. The vaccum line does go to the modulator. Don't worry, we all learned somewhere.
 
Looks like you have done this before

D4-ZP-7A040-AAO. Your right the blowoff thing is on top of the tailshaft. Is this what I`ve heard called a C-5 before? It came with a torq convertor, but I`ve got to get a stall convertor anyway cause of big cam.
 
Engine builded told me

a 2500 rpm stall convertor, said it wouldn`t idle or be very streetable without the stall. Its my guess that the way the larger cams lope and have a rough idle that they prob wont idle good under a load at low rpm`s without a higher stall rating on the convertor, but again, thats a guess.
 
Your new transmission is a column shift C-4. Your old one is a floor shifter model. If you want, I can make you an adapter that will work with your old linkage, I did this on the C-4 I have in my 77 Comet. Worked like a charm. Otherwise you'll need to do what brianj5600 said and swap the linkage arms , you cannot reverse them.
 
D4-ZP-7A040-AAO. Your right the blowoff thing is on top of the tailshaft. Is this what I`ve heard called a C-5 before? It came with a torq convertor, but I`ve got to get a stall convertor anyway cause of big cam.

C5 is a C4 with a lock up converter. They all have part # that start with E2xx. Your is a C4 with a push in mod and a 26 spline input shaft.
Looser converters are needed for big cams for 2 reasons. First, at idle a stock TC is trying to move the car making idle in gear iffy. A looser TC has less drag allowing motors with low vacuum idle in gear easier. Second, it lets the TC slip enough to get the motor close to peak torque. Too tight of a TC kills off line power since the motor struggles, has low torque numbers, until the revs are high enough for the motor to make power.
Since you have the correct shift arm, I'd use it. It is not hard to swap, and it will look factory.
 
Here are a few pics that show the dropping of the valve body and pretty clearly the inside of the tranny where you need to do your linkage mod:

http://www.geocities.com/dennis_2685/frtpump.html

Sample pic:

tranny9.jpg


The linkage is at the top, LH center. You can see most of the big nut above.
 
I neen giving this some thought

I think I`m gonna take it to a tranny shop, cause I want a shift kit in it anyway and I`m afraid I`ll goof something up.

Thanks for the offer Danny, but with the disc brake kit and the suspension parts I got now, I got enough parts to keep me busy for a month before I need the tranny. And thanks everyone else for the advice too.

And thanks for the pic, the linkage part looks pretty easy actually.
 
Looser converters are needed for big cams for 2 reasons. First, at idle a stock TC is trying to move the car making idle in gear iffy. A looser TC has less drag allowing motors with low vacuum idle in gear easier. Second, it lets the TC slip enough to get the motor close to peak torque. Too tight of a TC kills off line power since the motor struggles, has low torque numbers, until the revs are high enough for the motor to make power.

Sorry to Hi-Jack - I have an AOD with a stock convertor with a rather large cam and notice that when I'm stopped, the car really wants to start moving. I guess this is the reason. I also notice that when i'm coming to a stop, the car wants to continue moving making it difficult to stop the last 10 MPH. Is this the reason as well?
 
Geostang

you described the reasons EXACTLY why you need a stall convertor. I`m geussing it either dies completely sometimes or acts like its going to when your stopping and starting too right?

From what I hear if your into burning rubber, you can floor it and its liking dumping the clutch on a manual tranny too.....I personally dont see the bad side of that....
 
you described the reasons EXACTLY why you need a stall convertor. I`m geussing it either dies completely sometimes or acts like its going to when your stopping and starting too right?

From what I hear if your into burning rubber, you can floor it and its liking dumping the clutch on a manual tranny too.....I personally dont see the bad side of that....

No, it idles ok. It does want to die when cold but it's in park still at that point.

I guess maybe this is the reason I can't really spin the wheels with 4:11's without power braking. :shrug: :bang:
 
One more thing on the shift linkage. The inner shaft, kick down, in the picture above looks like a pre 70 trans. The early kickdown needs to be trimmed to work in a 70 and up transmission. They are the same except the early is a little longer with a 90* bend at the end. Put them together and mark the early one and trim it. Make sure the inner shift arm and kick down engages in the valve body before tightening up the valve body.

D.Hearne, all C5's start with E2. They came in case or pan fills. The bellhousings are deeper to make room for the thicker lockup TC. I have heard of some that do not have lockup TC that use E2 cases, but that would be a C4. The only thing that makes a C5 is the VB, input shaft, lock TC and bell housing. E2 cases have better oiling, but everthing interchanges with a C4.

Geo, does your car idle high in neutral and drop a lot when put in gear? A looser TC helps that. Does it feel slow for the first 50-100 feet and then come to life. A looser TC helps that too.