Does anyone know how to make a C6 shift at around 5500-6000 RPM's at WOT? I'm pretty sure I need to get another governor or modify the one I have. Anyone with experience in this department please help. Of course I can shift it myself, but I don't want to have to do that all the time. I have heard that early CJ tranny's had different weights in the governor which allowed it to wind up more. Anyone know anything about that? Sorry such a long post. Thanks in advance.

 

Sure you can change the shift points. Changing the springs in the governor valve will do it, but you can also try a longer rod behind the modulator valve. Take it out and play with different lengths until you find the happy spot.

 

The modulator only controls partial throttle shifts, right? Where can I get different springs for the governor? Thanks.

 

[font size="1" color="#FF0000"]LAST EDITED ON 07-Mar-01 AT 10:26 PM (EST)[/font][p]Any transmission shop should have the springs. If you change the length of the pin though, you can fool the transmission into shifting at higher RPM's.

 

Have any of you guys actually done this? How much RPM at WOT did you gain? How much do you have to change the length of the pin? Thanks

 

You might be better off just swapping out the valve body for a manual valve body where you can hold in any gear untill YOU decide to shift the trans. Here is why: The govenor is harder to work on in a C-6 than in a Ch***, at least in a Ch*** (Turbo 400)you can take out the govenor and change springs and weights with just removing four bolts and slipping the govenor out. The other factor is the govenor and vacuum modulator kinda work together to determine the shift point and part of that equation is a function of engine load (available engine vacuum)...so you might finally get the right combination to get the truck to shift at 6,000 RPM in first gear, but when you go to second gear the load changes on the engine and your 2-3 gear shift might come out around 5,000 RPM instead of 6,000 RPM. When you go to a full manual valve body, both the govenor and the modulator are eliminated or bypassed so you determine what the shift points will be. You will have to shift all the time, but at least with an automatic and your sitting in traffic, you don't have to hold the clutch in Deen



Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

Do you want the truck to just stay in low gear longer? The governor valve changes gears in relation to driveline RPM. The modulator changes gears in relation to engine RPM. Between the two of them, under normal takeoff you should shift to 2nd at 15 mph and 3rd at 38. By using heavier governor springs, you cause it to shift at higher driveline speeds (also higher engine RPM). By changing the length of the modulator pin, it takes more or less vacuum to move the spool in the valve body depending on whether you shorten or lengthen the pin. Since there is less vacuum at higher RPM (engine), you can aquire higher RPM (engine) with less spool travel , causing the transmission to remain in the lower gears longer. This is a simpler way because you don't have to remove the drive shaft and tail cone and still not know for sure what you'll end up with. Any good transmission shop should be able to get the pins for you. Also if you try using a modulator valve from a smaller engine setup it may get you what you want since the internal spring in the modulator valve is smaller.

 

Thanks for all your posts. I was actually just checking out a diagram of the governor/modulator relationship in an auto mechanics book.
As for the manual valve body, my whole point was to have an automatic tranny. Thanks but no thanks. I don't want to have to shift all the time.

 

Bigsnag, I can understand why you wouldn't want to shift all the time...my main point was to show that if you wanted to have both gear changes occuring at the same RPM (6,000) that it's not going to happen by just playing with the govenor/vacuum modulator. Try calling TCI Automotive (662) 224-8972 and ask for Tech, they should be able to get you really close on the right govenor weights/springs. On my C**** (Turbo 400) I had to totally eliminate a weight on one side and use a slightly lighter weight on the second side, plus turn the modulator in an additional full turn to get the 1-2 shift up to 6,000 RPM. Let us know how it turns out. Good luck, Deen


Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

TCI and B&M couldn't help me at all. If it's not one of their products, then they don't seem to know anything.

 

Try Frank Lupo at Dynamic Converters (877)846-5876 if he doesn't know, I have phone numbers for 8-10 other specialty race transmission shops...keep calling.


Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

Wow! Thanks a ton, Deen. I'll definitely try them.