C-4 ????s

sleeperstang · 03-21-2002, 10:49 AM

I have a 65 stang with C-4 tranny. I'm not sure how c-4s, in stock form, generally perform, but mine shifts from 1st to 2nd gear almost immediately after taking off, and then shifts from 2nd to 3rd gear somewhere around 30-35 mph. To me it seems as though the shift points should come a little later as that would help catch engine at better rpms. Is it common for C-4s to be geared this way? What can I do to change this without any major modifications (in other words, is there some valve or something that can adjust this, might be dumb question, but i gotta ask)? Finally, what modifications are there that can be done (shift kits, gearing, rearend)? I plan on tuning my engine to about 350 hp when completely done, might go little higher, no more than 380 hp completely streetable with low end being my target. Thanks for any help.

Sleeperstang <-----I know, 380 hp might not let it be a sleeper no more

P.S. By the way, my budget could go as high as $350 for any tranny modifications, I do plan on putting a T-5 at a later time.

mean81GT · 03-21-2002, 12:58 PM

well, i had a c-4 built for my car, drove that for a year, and then went to a 5 speed. after launch, when i floored it, it would shift from 1 to 2 somewhere around 20 mph. then it would shift into third at around 65. when i had the tranny built, they beefed it up a little, and threw in a shift kit. the gearing was not touched. either you have a problem, or the tranny has been altered. I don't know this, but maybe ford made a c-4 with different gearing? i don't know if they did or didn't, but mine was different from yours.

thunderbolt · 03-21-2002, 01:02 PM

Don't know about your gearing or shifting points, but the c4 built prior to 1970 was a notoriously weak. If I was going to build a motor, I would have the tranny built to handle it (c4 can be built very tough) and put in the desired shift kit at that point.

89LXFLEA · 03-21-2002, 02:31 PM

TRY AN ADJUSTABLE VACUME MODULATOR
VALVE AROUND $25.00 FROM LOCAL PARTS
STORES MOST AFTERMARKET VALVES ARE
USUALLY ADJUSTABLE.YOU ONLY NEED
A POCKET SCREWDRIVER.I WOULD ALSO
GET A SHIFT KIT INSTALLED. AND THEN
GET A CONVERTER PROB AROUND 2800
RPM FOR ALMOST STOCK.

Ron1 · 03-21-2002, 08:38 PM

One way to control the shift points on a C4 is to install a manual valve body. It will stay in the gear you select until you hit the shifter. Might be something to consider when you do the rebuild. They come in both the normal pattern as well as reverse pattern, where 1st gear is the top position, for 2nd down one and 3rd down one more. It does take a while to use to, but it works great. Ad a shift light and you got it made.

Ron

Rev · 03-21-2002, 08:48 PM

Ron is right as usual, but you do lose any automatic shifting functions with the manual valve body.

Rev

Ron1 · 03-21-2002, 10:16 PM

Now Rev...now I need to fitted for a larger helmet...nice thing about these forums, when you do make a mistake there are others who can correct you when you are wrong, and you learn from it. There is a TON of knowledge here.

Ron

03-21-2002, 10:49 AM	#1
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	C-4 ????s I have a 65 stang with C-4 tranny. I'm not sure how c-4s, in stock form, generally perform, but mine shifts from 1st to 2nd gear almost immediately after taking off, and then shifts from 2nd to 3rd gear somewhere around 30-35 mph. To me it seems as though the shift points should come a little later as that would help catch engine at better rpms. Is it common for C-4s to be geared this way? What can I do to change this without any major modifications (in other words, is there some valve or something that can adjust this, might be dumb question, but i gotta ask)? Finally, what modifications are there that can be done (shift kits, gearing, rearend)? I plan on tuning my engine to about 350 hp when completely done, might go little higher, no more than 380 hp completely streetable with low end being my target. Thanks for any help. Sleeperstang <-----I know, 380 hp might not let it be a sleeper no more P.S. By the way, my budget could go as high as $350 for any tranny modifications, I do plan on putting a T-5 at a later time. __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress

03-21-2002, 12:58 PM	#2
mean81GT Registered Member Join Date: Nov 2001 Location: NY Posts: 299	well, i had a c-4 built for my car, drove that for a year, and then went to a 5 speed. after launch, when i floored it, it would shift from 1 to 2 somewhere around 20 mph. then it would shift into third at around 65. when i had the tranny built, they beefed it up a little, and threw in a shift kit. the gearing was not touched. either you have a problem, or the tranny has been altered. I don't know this, but maybe ford made a c-4 with different gearing? i don't know if they did or didn't, but mine was different from yours. __________________ I'm a glutton for punishment.

03-21-2002, 02:31 PM	#4
89LXFLEA Registered Member Join Date: Nov 2001 Location: KENNER,LA Posts: 200	TRY AN ADJUSTABLE VACUME MODULATOR VALVE AROUND $25.00 FROM LOCAL PARTS STORES MOST AFTERMARKET VALVES ARE USUALLY ADJUSTABLE.YOU ONLY NEED A POCKET SCREWDRIVER.I WOULD ALSO GET A SHIFT KIT INSTALLED. AND THEN GET A CONVERTER PROB AROUND 2800 RPM FOR ALMOST STOCK. __________________ 89LX 302 C4 4:10GEAR X CAM,GT40 IRON HEADS,PERFORMER RPM 650 HOLLEY NO STALL YET, GRIFFEN RADIATOR,MAC EQUAL LENGTH SHORTIES,H-PIPE,PRO DUMPS NOW IT IS A LITTLE FASTER AT 12.94@106.38 RICE HATERS CLUB MEMBER # 47

03-21-2002, 08:48 PM	#6
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Ron is right as usual, but you do lose any automatic shifting functions with the manual valve body. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe

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03-21-2002, 01:02 PM	#3
thunderbolt Registered Member Join Date: Oct 1998 Location: Houston, TX, USA Posts: 380	Don't know about your gearing or shifting points, but the c4 built prior to 1970 was a notoriously weak. If I was going to build a motor, I would have the tranny built to handle it (c4 can be built very tough) and put in the desired shift kit at that point.

03-21-2002, 08:38 PM	#5
Ron1 Registered Member Join Date: Sep 1999 Location: Vancouver, WA USA Posts: 439	One way to control the shift points on a C4 is to install a manual valve body. It will stay in the gear you select until you hit the shifter. Might be something to consider when you do the rebuild. They come in both the normal pattern as well as reverse pattern, where 1st gear is the top position, for 2nd down one and 3rd down one more. It does take a while to use to, but it works great. Ad a shift light and you got it made. Ron

03-21-2002, 10:16 PM	#7
Ron1 Registered Member Join Date: Sep 1999 Location: Vancouver, WA USA Posts: 439	Now Rev...now I need to fitted for a larger helmet...nice thing about these forums, when you do make a mistake there are others who can correct you when you are wrong, and you learn from it. There is a TON of knowledge here. Ron