Helping a friend with a no 3rd gear problem. 302/C4

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Helping a friend with a no 3rd gear problem. 302/C4

May 05, 2013, 06:03:55 PM

Looking for suggestions on a friends car. It is a 75 Mustang II with a heads and cam 302 and a C4. The car was running fine but he had to be away from it for a few years, now it wont shift into 3rd gear. I had him put a vacuum gauge on it and it was only pulling 13-14 in hg. He called his dad who said it used to pull 18 in hg.

I'm not all that familiar with the C4. Is that enough vacuum for the vacuum modulator to shift into all gears? The transmission was inspected by the shop that built it and they say it's fine.

I couldn't find an obvious vacuum leak but I assume there is one due to the drastic drop in vacuum.

Any input? Thanks!

Helping a friend with a no 3rd gear problem. 302/C4

Reply #1 – May 05, 2013, 07:18:29 PM

Is the kick down rod moving free not binding or hanging up? And if you suspect to low of vaccum pull the line and put a new one on. Also the vac servo might have a pinhole and not pulling back as far as it should? Just some thoughts to roll over in your head

Helping a friend with a no 3rd gear problem. 302/C4

Reply #2 – May 05, 2013, 07:54:26 PM

We did replace the vacuum line to the modulator but didn't see a change. I looked for the kickdown cable but the only thing I saw on the carb was the throttle cable. Does it possibly connect further down the throttle cable closer to the tranny? Thanks for the suggestions! He is a noob and his dad built the car for him so I am trying to help him get it on the road.

Btw, the cam is a comp cam CL31-246-3

Helping a friend with a no 3rd gear problem. 302/C4

Reply #3 – May 05, 2013, 08:28:04 PM

No cam with a noticeable idle is likely to idle 18" of vac, anyway without any vacuum(remember at WOT there is no vac) and enough RPM it still should shift, my guess it has a issue in the valve body...

Helping a friend with a no 3rd gear problem. 302/C4

Reply #4 – May 05, 2013, 10:11:58 PM

Thanks for the suggestions, I'll pass them along to him. You guys rule!

Helping a friend with a no 3rd gear problem. 302/C4

Reply #5 – May 05, 2013, 10:29:00 PM

I guess I also should have mentioned that the car does shift out of 2nd gear, but seems to just go into neutral. Giving it a moderate amount of gas does make it downshift into 2nd. Again, thanks. My knowledge of transmissions is somewhat limited.

Helping a friend with a no 3rd gear problem. 302/C4

Reply #6 – May 06, 2013, 09:39:13 AM

Might be due for a vb, but the older cars had an actual rod for a kickdown. Goes from the carb down to the tranny if it sticks or is bent wrong it'll cause the tranny to hold gears not downshift and be stubborn. Kind of like the tv cable for the aod but the c4 luckily isn't as fragile about it. They're held on with nylon pushlock grommets and they deteriorate over time and wear and will pop off at random. Most likely at the transmission

Hope it helps him out

Helping a friend with a no 3rd gear problem. 302/C4

Reply #7 – May 06, 2013, 09:45:59 AM

It should go to the little arm under the throttle cable attachment, correct? I did check and there is nothing there. I read that some older Mustangs use a rod that connects down by the gas pedal but have not gotten under the car to confirm.

Helping a friend with a no 3rd gear problem. 302/C4

Reply #8 – May 06, 2013, 02:52:04 PM

A missing kickdown rod/cable isn't the problem, I ran one disconnected for three or four years, only issue was no WOT forced downshifts...

Apparently the direct clutch isn't applying, probably a stuck valve in the valve body...

Helping a friend with a no 3rd gear problem. 302/C4

Reply #9 – May 06, 2013, 03:17:06 PM

He just took it to a transmission shop and they are saying the tranny needs a rebuild even though the shop that built it is saying it's fine. At least it's in more capable hands than mine now, lol.

Thanks again for the suggestions guys.

Helping a friend with a no 3rd gear problem. 302/C4

Reply #10 – May 07, 2013, 05:10:45 PM

the TV rod bushing that went out on me a few years back caused me to not be able to shift out of 1st.
the rod follows the throttle plate movement by way of the gas pedal cable.

any type of plastic slip on shim will due fine as a replacement, the snap in ones are still available.

im kinda with tom on this one though.