Everything's OK then NO More Shift

**SBClose** · 10-30-2009, 09:14 AM

Hey All,
I have a early 70's C4 in my '65 Fairlane that was rebuilt by a reputable trans shop with a B&M shift kit about 8,000 miles ago. I've since moved and the shop is 4 hours away so they're not available for consult on this.

The trans was working FINE! Never a slip or flare, nice firm shifts, no trouble, no sweat. THEN- After driving about 15 miles yesterday I parked it for a couple hours and then fired her up again. NO SHIFT. In drive will hold 1st forever- moving the lever to 2 will take in into 2nd- moving the lever back to D will drop it back to 1st. Reverse is fine. Fluid is clean and at proper level.

My guess is that the governor is hung up but I wanted some advice before I got into trouble. The car is parked and will stay that way until I have your input- I really don't want to screw it up.

Thanks for your help,
S

**PaulS1950** · 10-30-2009, 10:38 AM

It could be the governor, or it might be problems in the valve body. The governor can be removed with the transmission in the car by removing the drive line, tail housing and then removing the governor. If you jack only the back of the car to get at it you will lose less ATF. Something caused the governor problem - either debris in the passages or pressures from the valve body. This is a common complaint with the B&M kit - I recommend the TransGo reprogramming kit 40-2 for the 70's C4 - there are few complaints with it.

**Stuarta** · 10-30-2009, 02:55 PM

Do you have good vacuum at the modulator?

**SBClose** · 10-31-2009, 08:45 AM

Quote:

Originally Posted by Stuarta

Do you have good vacuum at the modulator?

Thanks for the input guys, I should have time to swing under there today and poke around though I don't think I'll have enough loose schedule to actually tear things apart. First priority will be checking the lines to the modulator.

Pardon my ignorance in re transmission function but if the modulator were compromised, wouldn't it still shift into third when I moved the lever back to D as a result of fluid pressure alone? It was running at about 3,000 RPM in 2nd when I pulled back into D and it just went back to 1st. (Which made for some very interesting heart rhythms on my part)

thanks again

**MasterAnubis** · 10-31-2009, 09:23 AM

I sounds like vacuum to me too. C4s don't shift without vacuum, at all. The modulator helps determines when to shift. Apparently there are different fix modulators and adjustable ones.

I wanted to refference this thread:
http://www.fordmuscle.com/forums/c4-...-question.html
about the modulator.

If its a $10-$15 part it'll be worth a shot.

.

**SBClose** · 10-31-2009, 10:07 AM

FOUND IT!

An uncharacteristic backfire the other day (weather was cool and the manual choke had been in and out probably causing a pooling of fuel) must have blown the vacuum line off the modulator as the shifting issue started immediately after aforementioned backfire. If all fixes could be this easy!

Thanks for the input as always. This forum site rocks! and keeps me out of a lot of trouble...

S

**71hotrodpinto** · 10-31-2009, 11:24 AM

Quote:

Originally Posted by SBClose

FOUND IT!

An uncharacteristic backfire the other day (weather was cool and the manual choke had been in and out probably causing a pooling of fuel) must have blown the vacuum line off the modulator as the shifting issue started immediately after aforementioned backfire. If all fixes could be this easy!

Thanks for the input as always. This forum site rocks! and keeps me out of a lot of trouble...

S

YEP!
happend to me MORE than once.
If you want to keep your sanity then you might want to check the hose that slipped off. You may need a new one. I tried regular vacumm line and it wouldnt bend without kinking. California mustangs (for example has a formed 90deg bend specificaly for this ap. I think it was about 5 bucks. Worked like a charm for me.
Or you could try and tune out the " uncharachteristic once in a while" backfire"
Just a thought!
GL

**Stuarta** · 10-31-2009, 11:41 AM

Good.
At times it is the simple things that haunt you.

**SBClose** · 11-02-2009, 06:32 AM

Thanks again to all. HotRodPinto, the angle for the hose where it comes out of the modulator is a real pain and my trans mount makes it nearly impossible to get to. I dug through some of my junk drawers and found a 90 like the one you described before I read your post. Fortunately a friend who is a surgical nurse gave me a surgical clamp that is about 12" long. Every toolbox should have at least one!

As for the errant backfire... gotta keep a careful eye on those float levels on a Holley- especially when the weather changes!

Rock On,
S

**gregaust** · 11-03-2009, 03:36 AM

Quote:

Originally Posted by SBClose

Thanks again to all. HotRodPinto, the angle for the hose where it comes out of the modulator is a real pain and my trans mount makes it nearly impossible to get to.

I'm able to purchase the new genuine rubber elbows here through my trans parts guy, should be available over there too.