C4 shifting problem

AJONE · 03-14-2007, 12:37 AM

I have a 1967 C4 sitting in front of a 9'' with 3.50 gears and behind a 350 HP 302 crate motor. I rebuilt the trans 2 years ago with a napa rebuild kit and a Transgo shift kit and stock converter. It would shift firmly and felt nice and tight. over the last few months the trans will occasionally drag out shifts making it feel stock. it also feels like it has the slightest surging somtimes under a good load; i.e. merging on the freeway. Any ideas what the problem/solution is? sticky/plugged valve body? band adjustments? rebuild the whole thing again? I will try to reply in a timely manner to any questions.

Thanks
AJ

goodyear1984 · 03-14-2007, 02:02 AM

hey by draging out do u mean the shift points arent the same? if so mabey check the shift modulator.i think its on the drivers side of the transmission and theres a vaccum line on it..take the vaccum line off and see if theres tranny fluid coming out of it or out of the vaccum line..if there is then get a new one cuz the diafram if broken
good luck

Rev · 03-15-2007, 12:39 PM

Adjust the bands and see if that helps. If that doesn't help, then the clutches are probably going away. My C-4 (with about the same power as yours) would last only a couple of years with regular abuse. The last time, I specifiied high performance bands and clutches for the rebuild, and it has held up better and longer. The high performance bands and clutches did cost about twice as much as regular ones, but anything to keep from having to pull that tranny out and reinstall it in my driveway is worth a lot to me.

Rev

03-14-2007, 12:37 AM	#1
AJONE Registered Member Join Date: Mar 2007 Location: SANTA ROSA Posts: 4	C4 shifting problem I have a 1967 C4 sitting in front of a 9'' with 3.50 gears and behind a 350 HP 302 crate motor. I rebuilt the trans 2 years ago with a napa rebuild kit and a Transgo shift kit and stock converter. It would shift firmly and felt nice and tight. over the last few months the trans will occasionally drag out shifts making it feel stock. it also feels like it has the slightest surging somtimes under a good load; i.e. merging on the freeway. Any ideas what the problem/solution is? sticky/plugged valve body? band adjustments? rebuild the whole thing again? I will try to reply in a timely manner to any questions. Thanks AJ

03-14-2007, 02:02 AM	#2
goodyear1984 Registered Member Join Date: Dec 2006 Location: new york Posts: 482	Re: C4 shifting problem hey by draging out do u mean the shift points arent the same? if so mabey check the shift modulator.i think its on the drivers side of the transmission and theres a vaccum line on it..take the vaccum line off and see if theres tranny fluid coming out of it or out of the vaccum line..if there is then get a new one cuz the diafram if broken good luck __________________ 347 stroker all forged,arp everything,stud mains w/girdle,7qt pan,full roller, custom cam, aluminum heads swirl valves 5 angle valve job.quick fuel 750,areomotive pump,cobras w/nitto drags,and m/t et drags for the track, ford racing 373 gears,centerforce clutch,tko500,underdrive pulleys,bassani x-pipe,flowmasters ^best et so far 11.6 1.61 60ft coming soon 9sec et's 1992 mustang gt 2001 gmc 1500 4x4 78 century boat 92 skidoo

03-15-2007, 12:39 PM	#3
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Re: C4 shifting problem Adjust the bands and see if that helps. If that doesn't help, then the clutches are probably going away. My C-4 (with about the same power as yours) would last only a couple of years with regular abuse. The last time, I specifiied high performance bands and clutches for the rebuild, and it has held up better and longer. The high performance bands and clutches did cost about twice as much as regular ones, but anything to keep from having to pull that tranny out and reinstall it in my driveway is worth a lot to me. 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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