Transmission will not shift

[taxlex 10]

I bought a 1969 Mustang in pieces. I finally put it together enough to get it started and move. I have not been able to get it to shift out of first gear. I know I have it in drive and not low 1 or 2. I don't know if the downshift lever should be forward or towards the back of the car to get it to shift. I hooked the vacuum line from the modulator to the base of the carburetor. The guy I bought it from claims the transmission worked when he took the car apart (The transmission was not taken apart). Any suggestion would help. Thanks.

[etel64 10]

Hey Jersey taxlex. try correcting the shifter adjustment. play with it while its on stands. last thing you want to do is shift it out of gear and have it roll you over, lol.

In regard to the shifter lever. pushed all the way to the rear of the trans is park. Pushed allt he way forward and it is D1. Loosen the adjusting nut/slide, put trans in park and shifter in park and tighten.

[Boogerschnot 12]

Check the fluid level.. Sometimes they shift funny, or dont shift at all with the wrong fluid level. Also, what type of fluid are you using? Should be type F. Maybe this calls for cleaning out the pan and changing the filter. It wouldnt hurt anything.

[danno 128]

If the tranny was off the car, and it got stood on an end or rolled to one side or the other, there is a chance the fluid got out of place. Some of the valves might not have fluid in them. This is typically not a symptom of low on fluid, when that happens the car will not move at all when you put it in Drive.

 

Is it a standard C4, or is it a C6 or a AOD?

[Mike65 475]

Now that you have the car running pull the vacuum line off the vacuum modulator & see if fluid comes out of the vacuum line, if so the vacuum modulator is bad & will need to be replaced.

[taxlex 10]

I know the shift link is set up correctly.

When it is in park the wheels are locked.

When it is in R it goes backwards.

N no question is neutral.

The next click should be D it goes forward but never shifts.

The next two click works just like D and it never shifts.

There is no oil in the vacuum modulator then I remove the hose.

I added extra oil so it was an inch above the full mark while running but it made no difference.

The down shift lever all the way forward and all the way back makes no difference.

(I used a spring to make sure it really is all the way forward or backwards)

I tried it with vacuum on and vacuum off the vacuum modulator.

The transmission was never stored on end.

I am not sure exactly which transmission I have.

I think it is a C6. I attached some pix that hopefully someone can ID.

Is type F fluid the same as the stuff I bought?

(See attached picture)

It says it is for older fords.

[Brian Conway 264]

Been a while since I've had an automatic but here goes. The C6AR in the photo can be misleading. Should have a metal tag w/ rivet to get the correct ID. The tagprobably starts with a P.

Eleven bolts in the trans fluid pan = it is a C4. Sitting in the car with the shifter handle all the way forward=PARK next is REVERSE and then NEUTRAL. I think you have that so far. All the way toward the seat is First and it does not shift. Next is the GREEN DOT. As I recall does not shift and you can drive around town in this position. Next is DRIVE and is also a driving/freeway gear. This gear will downshift to the GREEN DOT for passing gear. A correct ID Tag will probably help. Ready for some corrections. Brian

[taxlex 10]

I am 100% sure that I am in drive. That is not the problem. It never shifts out of first gear. I think it has something to do with the down shift lever which is next to the gear shift lever. It never shifts when it is all the way forward or toward the rear. There are three vacuum ports on my carburetor. I tried connecting the vacuum modulator to each (See attached photo). The car still will not shift whatever I do. I also do not see any tag on the transmission. I looked all over. Where should it be?

[Boogerschnot 12]

How high have you ran up the RPMs while trying to get it to shift?

[taxlex 10]

I don’t have a tachometer or mufflers and live on a residential street so the best I have been able to do is about 40mph before someone would call the police. I would think it should shift if I kept it at a steady 40mph. My manual says to use Type F fluid but the guy at the auto store said the DEX III/M stuff will work just as good. Could that be my problem?

Edited October 9, 2013 by taxlex

[det0326 179]

I don’t have a tachometer or mufflers and live on a residential street so the best I have been able to do is about 40mph before someone would call the police. I would think it should shift if I kept it at a steady 40mph. My manual says to use Type F fluid but the guy at the auto store said the DEX III/M stuff will work just as good. Could that be my problem?

Are you sure that the vacuum is present at the transmission?

I have known the base plate of the carburetor or intake manifold(which ever it is connected to) to have a carbon like substance that blocks the vacuum. So with the car running at idle pull the hose to the modulator

and see if vacuum is present.

[Boogerschnot 12]

You should be using type F for the trans, and power steering fluid.

[Dave R. 85]

Make sure that the vacuum line is not plugged somewhere. I had a similar problem and it turned out to be a clog in the vacuum line. Dave.

[beecj0 11]

After a rebuild, my c4 had a stuck governor that wouldn't let it shift. Doesn't sound like anyone has had it apart so probably not it. Just thought I'd share.

If you find that the vac line is clear, you should look at the gov or valve body.

[DocWok 30]

First check if you have vacuum down at the modulator valve, the other end of your hose should be connected to any manifold vacuum source.

You then need to test drive it, if you rev it hard whilst you are driving in first gear and it then jumps into second means that your governor is working and that there is a problem with your modulator valve.

[69volunteer 84]

what about the kick down lever. Is that installed? And if it is, is it installed correctly? Just throwing that out there not sure if would impact this situation or not.

 

Sounds like a vac issue to me.

[TimFF 11]

I had a similar ish issue after my car had been trailered 450 miles...

 

Before the trip it shifted really sweetly but the first time I drove it after delivery it was completely different - hung on to first till 25-30mph and refused to hit 3rd until 50. Even when it finally gave in and changed to 3rd the slightest touch of the loud pedal had it in 2nd instantly. All slightly embarrassing in a quiet English suburb.

 

I read a few posts on here which suggested a potential vacuum issue so whipped off the air-cleaner to check - it seemed clear and it's tee'd off the brake booster which I know is OK. So...

 

As mine has a Holley carb rather than Autolite we left the kickdown link loose. I pulled it forwards, zip tied it in place and - one smooth box back! 3rd by the time I'd gone 20 yards.

 

I reckon the (traumatic, wheel bearing failure, recovery truck time) trip down jarred it just enough to keep it permanently in kickdown. The actual movement of the link on mine (390 / C6) is probably no more than 1/2".

 

Maybe...

[rwcstang 201]

not to hack but recently Im having a similar issues with my c4 PA Street Fighter, it doesnt want to shift to 3rd even if i go in all gears, I checked modulator and i have vacuum maybe something is stuck? it was stored over a year but had fluid inside of it I flushed it and added new fluid still didn't resolve issue, I am using Chevron ATF.

 

Im thinking it could it be the kickdown arm though... I dont have a kickdown installed cuz i went with a 351w and original the kickdown arm is to short (Had a 302). any ideas if they sell longer kickdown arms? I have lokars KD cable but i would like to keep it looking original.