Flathead with c4 trans shifts to quick

[George/Maine]

I have a c4 that shifts to quick from 1 to 2nd and 3rd also.I know of 3 that do the same thing.We think its do to the vacume of the flathead maybe to low.I have a 255 8ba with c4 running gears, to equal 2000 rpms at 55 mph.Any feedback on your setup. Thanks.

[ford1]

where are you taking the vaccum from? carb or manifold?

[jdl]

Is the trans modulator the adjustable type? read the last two questions on this web site...

http://www.tciauto.com/Products/TechInfo/FAQ.asp

Also read the last picture on the modulator on this web page..

http://www.mustangandfords.com/techa...tailshaft.html

[estout81]

Has the "kick down" linkage been hooked up? You can also adjust the gov. for higher shift points.

[bbrocksr]

Low vacumn causes late / hard shifts, high vacumn causes early/soft shifts. To adjust your modulator pull off the vacumn line and turn the screw in about one turn and road test. This should raise your shift points.
Hope this helps, Bill

[George/Maine]

Sponsored Links (Register now to hide all advertisements)

I have a line off the manifold used to be wipers line.I check the vacumn and its 15 lbs ,says thats ok.
I don,t have a kick down.When you are moving and you kick it down it should down shift.Question if its not connected will it shift ok or not.This trans shifted ok when in Granada.another trans does the same and another car same thing.I,ll try to adjust the modulator.

[bbrocksr]

The kickdown/ throttle rod must be connected as shift quality and speed are a result of throttle opening and manifold vacuum.

[Ol' Ron]

The rear gear of 3.o is a good gear to run, I'm using 3.3 from a 51 Merc.

[coilover]

You MUST have the throttle pressure (kick down) rod hooked up or it will quick shift and also be spongy. Try this: the throttle pressure lever is right beside the shift lever on the transmission; take this lever and temporarily tie it where it is rotated in the opposite direction that it is now (it only moves a little bit). It usually feels like it is turning against light spring pressure when in the "kick down" position. Take it for a drive and it will have to get over 30mph or so in first gear before the govenor will force it to shift. If there is not room for the pivot assembly and tubular rod Ford used just get a cable and use it. Since the rod pushes and a cable can't you will need to come in from the rear so the cable can pull on the lever. On my 37 Buick with a Turbo 350 behind it's straight 8 Everything was so tight that I didn't use a kick down cable but used a threaded rod with a clevis and by trial and error got it adjusted to where it shifts out of first around 22mph and from 2nd to 3rd at about 35mph. This is high enough throttle pressure to give a firm shift but of course it doesn't have a "passing gear" but with the torque of the straight 8 I don't need one.

[40 Deluxe]

This should serve as a reminder that when we backyard engineer something (like this C4 swap) we can't just throw out the factory bits and pieces willy-nilly! They're usually there for a reason. Since the trans shifted properly "in the Grananda", first question should be "What's different? What changed during the swap?" Then, "Why isn't there any linkage on that lever on the side of the trans? Was it there before?" We can save ourselves a lot of grief with just a little effort!

[grego31]

What adapter kit did you use?

[George/Maine]

I do have a Locker kit to install but haven had time to put it on.Have to look at 97s and see how to hookup ,trans end pull with new lever.The 350 chevy does,nt need it ,only for passing gear.Both Speedway and Flatomatic do same thing,and with 3 different trans.So I guess I better put it on to shift better.Thanks for help.

[okiedokie]

My C4 acts the same. I have a Lokar cable connected and adjusted to no slack at WOT, vacuum modulator replaced and adjusted several times. It shifts just fine manually. I will soon pull the rear housing and take a look at the govenor.