1968 Tranny shifting issues

[HappyHour]

Hey CS family...

My CS has been garaged in SF and last weekend after getting tranny fluid replaced (not flushed) and exhaust was looking to drive it back to LA taking 2 days along the coast. Wrong.

My friend who usually excersizes it mentioned second gear was little sticky before it would "thunk" into 2nd gear. Didnt think much of it as just got maintenance done.

Unfortunately after pulling it out out of storage it wouldnt shift out of 1st. The only way I could get it into 2nd was shifting down into 2nd from D then shifting back into D. Problem is can get it to shift into 3rd...just running up RPMs no shifting.

Was wondering if I need to check anything before having expert look into. The fluid was replaced but except for a healthy drip levels looked fine.

Any help to diagnose the issue is appreciated....need to get that Pony back to SoCal.

RobKat

 

[Ruppstang]

Check the modulator valve. One that the vac line is on. Two check if there is any trany fluid in the line, if there is the valve has failed. Also check the fluid level in the transmission. I am no expert but have had a couple of experances with C4s. Marty

 

[HappyHour]

Thanks Marty...actually when I had it in the shop before they mentioned the modulator valve was leaking internally. Didnt seem to effect shifting at the time but looks like Ill have to source the part and replace.

Great to have the CS family on standby!

 

[rvrtrash]

I would also ask the shop that changed the fluid what kind they put in it. If it just started after the fluid change, maybe they put in the wrong type. There's a reason there are different ones.

Steve

 

[HappyHour]

Checking with the shop on the fluid..they are pretty knowledgable with older cars and had long conversation with the owner before taking the CS there (versus Jiffy tranny lube type place).

From a separate Ford thread I was reading about the pricing on the part. They range $10-35 and if easy enough will swap at friends garage. Can anyone confirm the part#?

http://www.summitracing.com/parts/ATP-FX102/

Improve slow, sloppy shifts with the addition of ATP automatic transmission modulator valves. Their valves will keep your transmission shifting on cue, according to load. These ATP adjustable replacements allow you to optimize shift points to meet vacuum load and improve gas mileage and performance. A bad modulator valve can be bad news for your transmission. Get control of your transmission for proper shifting of increased or decreased engine vacuum loads. Replace improper working valves with ATP automatic transmission modulator valves.

 

[franklinair]

I went thru the Summit thread you have listed: 302, 1968= 135-FX102.
Is that what you came up with?
EZ to change, IIRC, it just screws in.

Neil

 

[HappyHour]

That is the part. Ordered it and see if that resolves issue. Stay "tuned" LOL!

 

[robert campbell]

Check the modulator valve. One that the vac line is on. Two check if there is any trany fluid in the line, if there is the valve has failed. Also check the fluid level in the transmission. I am no expert but have had a couple of experances with C4s. Marty

Dito on the fluid in the line. Did you notice any smoke from the exhaust? Usually a bad modulator leaking into the vacuum line creates a large smoke screen! Keep us posted. The adjustment of the kick down cable is also a part of the shift point. If that cable was somehow knocked off, or kinked, or?? during the fluid change if can effect the shifting. It, in fact, controls the shifting more than the vacuum modulator.

Rob