C4 - Wont shift into 3rd gear - FIXED = STUCK 2-3 SHIFT VALVE

[kayakersteve]

Any C4 gurus? I tried a quick search, but didn't find any hits. Just recently, my C4 has stopped shifting into 3rd. All other gears work fine, including reverse.

Tranny was rebuilt 25-30 years ago, but has low mileage. Mildly built 302 in front of it. Has shift kit installed when rebuilt last. B&M shifter. Tranny fluid looks and smells fine and is at capacity.

 

[Viperwolf1]

Could be a bad seal on the direct clutch or a problem in the valve body. Now the direct clutch is also used in reverse, but in reverse the oil pressure is boosted so it can make a bad seal seem to work ok.

 

[kayakersteve]

Well, I figured I have gotten a lot of time out of the last rebuild - was hoping for something simple! Any other last ditch (easy to fix) things I should look at???

I have a spare C4 in the barn - maybe I will get it rebuilt and do a swap.

 

[clarkaw1]

Could it be poor vacuum, maybe a crack vac hose the feeds the vacuum thing-a-dohecky on the trans. Maybe enough vac to shift from 1st to 2nd but not enough to go to thrid???

 

[TwoDalesDad]

Dyson...builds a great Vacuum.....My Wife says so.....lol

 

[Action]

Make sure your kick down lever is not stuck.
Jack

 

[Viperwolf1]

Lack of vacuum or stuck kickdown will affect the 1-2 shift as well as the 2-3 shift.

 

[kayakersteve]

Funny thing about the KD lever - I never installed it when I put the tranny in over 25 years ago. I know! Beleive it or not has worked well in spite of that. I will recheck the vacumm line, but looked good at first glance.

 

[Action]

kd lever

I don't run a kick down lever either. But from time to time it will get stuck and move with the shifter and will act like that.
Jack

 

[kayakersteve]

@viperwolf - sent pm about kick down shaft.

 

[Viperwolf1]

@viperwolf - sent pm about kick down shaft.

It's supposed to look like this.

 

[kayakersteve]

Wow ..... I'm missing everything except the shaft. So, the rest is in tranny somewhere?

 

[FlogginHarvey]

Might have already been mentioned but we just had the C4 rebuilt in mine and was stuck in 1st and 2nd... Went over it again with a beer in my hand and noticed the vacuum line had wiggled off... Put it back on and and was fine for a few miles then started missing 3rd again. It turned out the vacuum line was cracked. So replaced and now is all good to go...

 

[kayakersteve]

No, this isn't a vacuum issue...broken kickdown shaft unfortunately

 

[kayakersteve]

here's what mine looks like:

The inner portion is completely missing....somewhere inside my tranny

 

[kayakersteve]

Help gain

I'm trying to steal the shaft out of my spare c4. Got VB off, but shaft hits inner drum and wont slide in any more. Do I have to go deeper to get it? I hope not!

 

[kayakersteve]

Assembly question

So I have to slide new shaft on from inside the tranny and am wondering if I should put o-ring on shaft and then slide in or leave off and slide the O-ring on the part of the shaft that sticks out by shift linkage??

 

[Viperwolf1]

The o-ring goes on the part that sticks out. Theres a recess in the manual lever shaft for it under the kickdown lever that attaches with the nut.

Make sure you get the manual lever and kickdown lever oriented correctly at the valve body. When the manual lever is in place you should have all 6 lever positions and should see the manual spool valve move with each one. The kickdown lever should have spring tension in the CCW direction against the downshift valve. If either one of these is not right drop the valve body and try it again. It almost requires 3 hands to get it all lined up.

 

[kayakersteve]

Still no third gear...

So, I switched in a new kick down shaft and actually have it hooked up. It works great kicking tranny down from 2nd to 1st gear. The tranny still wont go into 3rd manually or auto. Any other ideas???? All other gears work well and there is no slippage.

 

[Viperwolf1]

So, I switched in a new kick down shaft and actually have it hooked up. It works great kicking tranny down from 2nd to 1st gear. The tranny still wont go into 3rd manually or auto. Any other ideas???? All other gears work well and there is no slippage.

Looks like we went full circle. Refer to post #2.