C4 Transmission Problems!!! Please Help

toolski378 · 10-26-2006, 07:31 PM

I have a 66 coup and I am having trans problems. It seems to shift fine into the first gear when I step on the gas but it revs really high before dropping into the next gear. If I take my foot off the gas and reapply it sometimes drops into the next gear. The fluid levels are fine.

Phillyfanfrombirth · 10-26-2006, 08:11 PM

A couple ideas...

Vacuum line?
Kickdown linkage?

mustangII460 · 10-26-2006, 08:39 PM

Check your modulator valve at the right/rear corner of the tranny. A vacum line runs to it.

The line could be broke/rotten or the valve could be bad itself. Alot of times fluid will suck up into the the intake from the valve when its bad.

If you take it off, dont lose the little metal rod, inch or so inside when you unbolt it.

The nipple that the vacum hose plugs onto also is a screw. You can turn it 1/4 turn to adjust shift points.

stanger66 · 10-26-2006, 09:27 PM

which direction would you turn it to have longer shift times to act like OD for third gear so when you are on the highway between 60-80mph the engine not racing.

10-26-2006, 07:31 PM	#1
toolski378 Registered Member Join Date: Oct 2006 Posts: 2	C4 Transmission Problems!!! Please Help I have a 66 coup and I am having trans problems. It seems to shift fine into the first gear when I step on the gas but it revs really high before dropping into the next gear. If I take my foot off the gas and reapply it sometimes drops into the next gear. The fluid levels are fine.

10-26-2006, 08:11 PM	#2
Phillyfanfrombirth Registered Member Join Date: Dec 2004 Location: South Central PA Posts: 358	Re: C4 Transmission Problems!!! Please Help A couple ideas... Vacuum line? Kickdown linkage?

10-26-2006, 08:39 PM	#3
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	Re: C4 Transmission Problems!!! Please Help Check your modulator valve at the right/rear corner of the tranny. A vacum line runs to it. The line could be broke/rotten or the valve could be bad itself. Alot of times fluid will suck up into the the intake from the valve when its bad. If you take it off, dont lose the little metal rod, inch or so inside when you unbolt it. The nipple that the vacum hose plugs onto also is a screw. You can turn it 1/4 turn to adjust shift points. __________________ Frank

10-26-2006, 09:27 PM	#4
stanger66 dreaming about mustangs Join Date: Mar 2006 Location: laurel, md Posts: 178	Re: C4 Transmission Problems!!! Please Help which direction would you turn it to have longer shift times to act like OD for third gear so when you are on the highway between 60-80mph the engine not racing. __________________ Ross 06 Saleen S281SC Convertible 6spd 04 Freestar(wife) 66 mustang w/orig. Carroll Shelby racing 7 spoke 14X7's aluminum 02 pontiac sunfire 2.2 ecotec(great gas mileage) still GM junk

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