C-4 WOT UPSHIFT TOO LOW

LXHATCH · 07-26-1999, 08:59 PM

anyone here familiarw/ c-4s?
if so i have some questions regarding wot upshifts, i have a 3500 stall converter,
and 373 gears, the problem is isthat i have modulator adjusted allthe way in and backed out 1 turn so its as highas it getsat wot and i can only get 3500 out of it,
(wot shifts) what im looking for is 5500
rpm wot shifts. what do i need to do in order to raise this,?
is the governor the prob? the trans was originally out of a 308geared car,and im thinking thatthe governor needs recallibrated
to the 373s, any suggestions?
thanks lxhatch

66fastback · 07-27-1999, 03:53 AM

Sorry, I'm no help on this one. The only auto car I had was a long time ago, and the C4 shifted about the same way your describing. Of course it was a stock engine and in my opinion, the cam was falling off above that point anyway, so I didn't really lose anything. If your's will pull to 5500, then I can understand the frustation. Hang in there, someone here will know.

------------------
66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?

red · 07-27-1999, 09:11 AM

I just went through this with my '65, c4 trans, 302 engine combo.

Make sure the kickdown is hooked up.

Switch the vacuum from your carb to the manifold and plug the carb vacuum port, if your EFI then get a vacuum gauge and check to see that your pulling around 15 psi at Idle and pressure goes down when you hit the gas.

Since you have the screw in type modulator, if these don't work you will probably have to drop the valve body and change the springs. Probably best left to the transmission shop since I have never seen spring assortments available. We went through 4 stock valve bodies and two shift kits, all had different springs, before we got a combo that performed as desired. My stall is not that high though (around 2500). If it comes to this let me know and I'll find out which spring to change from my trans guy and see if I missed any steps.

P.S.
If this is a street driven car, you probably should not let the trans shift automatically at that high of an rpm (5500). Manual shifting engages the bands simultaniously and gives a stronger shift (read will not dammage the trans as much).

-JON

[This message has been edited by red (edited 07-27-1999).]

LXHATCH · 07-27-1999, 03:35 PM

the trans when we first put it together,
shifted at 2500 at wot ,and was in third by 200 ft or so, then i took the governor back to the rebuilder, he ground lots of weight off the bigger gov plunger,and just a little off the small plunger..anyhow this brought part throttle to 2000 or so and wot to 3500.
this grinding was done between the lands on the valve, anyhow he said that, the large plunger,is for part throttle, and the small one is for full throttle,
i hate to keep bugging this guy but i think i need more weight off the small plunger,
or a stiffer spring in there.
as far as the bands, not engaging the same when its in drive this thing hits really hard in drive or, manually, except below stall its a little sluggish. normal i think.
i dont have a kick down hooked up yet, how much of a diff will this make?
maybe thats my prob...
also this is an efi 5.0 car 1989
the reason i posted here is cause its an older trans. best mod i've done to car besides the gears.
thanks for all and any
suggestions.
LXHATCH

red · 07-27-1999, 04:45 PM

Hook up the kickdown!

You will have to rig up a linkage from the accelerator to the lever near the neutral safety switch that will push down the lever when you mash the gas to the floor. Go to a car show and look at the different kickdown setups. I don't see how you could easily modify the '65 style kickdown linkage to work on EFI. We have plenty of mustang II guys on this board, post a question and ask how there kickdown's are setup. Maybe they have an accelerator cable instead of a rod as in 1965.

It will delay the shift points by increasing the pressure in the valve body so the 1-2 shift valve and the 2-3 shift valve will open later, in most cases much later. That way you don't have to find stiffer springs. I would guess it will give you >>1000 RPM difference.

Manual shift under wot will extend the life of your transmission, period.

-JON

Mach · 07-27-1999, 10:16 PM

This Mustang II guy has had two automatic cars in his driving life. Both had the kick down disabled.

The 390 because when I wanted to use WOT torque I couldnt choose my gear, in my II because I didn't like unexpected downshifts in a corner.

Ultimatly, I canned the linkage because I'm a controol freak when it comes to machinery.

I was going to make the same suggestion as LXHATCH: remove weight from the govenor. I learnt the govoner is what has the most controol over shift points when I ,, Uh, sort of jammed it with the 390. ( I , Ahem, wonder which thing I did to cause that. ; )

Mark.

07-26-1999, 08:59 PM	#1
LXHATCH Registered Member Join Date: Dec 1998 Location: FLINT/ MICH Posts: 96	C-4 WOT UPSHIFT TOO LOW anyone here familiarw/ c-4s? if so i have some questions regarding wot upshifts, i have a 3500 stall converter, and 373 gears, the problem is isthat i have modulator adjusted allthe way in and backed out 1 turn so its as highas it getsat wot and i can only get 3500 out of it, (wot shifts) what im looking for is 5500 rpm wot shifts. what do i need to do in order to raise this,? is the governor the prob? the trans was originally out of a 308geared car,and im thinking thatthe governor needs recallibrated to the 373s, any suggestions? thanks lxhatch

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07-27-1999, 03:53 AM	#2
66fastback Registered Member Join Date: Mar 1999 Location: Dallas, TX Posts: 208	Sorry, I'm no help on this one. The only auto car I had was a long time ago, and the C4 shifted about the same way your describing. Of course it was a stock engine and in my opinion, the cam was falling off above that point anyway, so I didn't really lose anything. If your's will pull to 5500, then I can understand the frustation. Hang in there, someone here will know. ------------------ 66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?

07-27-1999, 09:11 AM	#3
red Registered Member Join Date: Sep 1998 Location: Millburn, NJ Posts: 310	I just went through this with my '65, c4 trans, 302 engine combo. Make sure the kickdown is hooked up. Switch the vacuum from your carb to the manifold and plug the carb vacuum port, if your EFI then get a vacuum gauge and check to see that your pulling around 15 psi at Idle and pressure goes down when you hit the gas. Since you have the screw in type modulator, if these don't work you will probably have to drop the valve body and change the springs. Probably best left to the transmission shop since I have never seen spring assortments available. We went through 4 stock valve bodies and two shift kits, all had different springs, before we got a combo that performed as desired. My stall is not that high though (around 2500). If it comes to this let me know and I'll find out which spring to change from my trans guy and see if I missed any steps. P.S. If this is a street driven car, you probably should not let the trans shift automatically at that high of an rpm (5500). Manual shifting engages the bands simultaniously and gives a stronger shift (read will not dammage the trans as much). -JON [This message has been edited by red (edited 07-27-1999).]

07-27-1999, 03:35 PM	#4
LXHATCH Registered Member Join Date: Dec 1998 Location: FLINT/ MICH Posts: 96	the trans when we first put it together, shifted at 2500 at wot ,and was in third by 200 ft or so, then i took the governor back to the rebuilder, he ground lots of weight off the bigger gov plunger,and just a little off the small plunger..anyhow this brought part throttle to 2000 or so and wot to 3500. this grinding was done between the lands on the valve, anyhow he said that, the large plunger,is for part throttle, and the small one is for full throttle, i hate to keep bugging this guy but i think i need more weight off the small plunger, or a stiffer spring in there. as far as the bands, not engaging the same when its in drive this thing hits really hard in drive or, manually, except below stall its a little sluggish. normal i think. i dont have a kick down hooked up yet, how much of a diff will this make? maybe thats my prob... also this is an efi 5.0 car 1989 the reason i posted here is cause its an older trans. best mod i've done to car besides the gears. thanks for all and any suggestions. LXHATCH

07-27-1999, 04:45 PM	#5
red Registered Member Join Date: Sep 1998 Location: Millburn, NJ Posts: 310	Hook up the kickdown! You will have to rig up a linkage from the accelerator to the lever near the neutral safety switch that will push down the lever when you mash the gas to the floor. Go to a car show and look at the different kickdown setups. I don't see how you could easily modify the '65 style kickdown linkage to work on EFI. We have plenty of mustang II guys on this board, post a question and ask how there kickdown's are setup. Maybe they have an accelerator cable instead of a rod as in 1965. It will delay the shift points by increasing the pressure in the valve body so the 1-2 shift valve and the 2-3 shift valve will open later, in most cases much later. That way you don't have to find stiffer springs. I would guess it will give you >>1000 RPM difference. Manual shift under wot will extend the life of your transmission, period. -JON

07-27-1999, 10:16 PM	#6
Mach Registered Member Join Date: Jun 1999 Location: North East Ohio Posts: 23	This Mustang II guy has had two automatic cars in his driving life. Both had the kick down disabled. The 390 because when I wanted to use WOT torque I couldnt choose my gear, in my II because I didn't like unexpected downshifts in a corner. Ultimatly, I canned the linkage because I'm a controol freak when it comes to machinery. I was going to make the same suggestion as LXHATCH: remove weight from the govenor. I learnt the govoner is what has the most controol over shift points when I ,, Uh, sort of jammed it with the 390. ( I , Ahem, wonder which thing I did to cause that. ; ) Mark.