Transmission jumping out of 4th gear

[grannyknot]

One of the two close ratio 5 spds that I rebuilt last winter jumps out of 4th gear on deceleration. It was rebuilt using the correct

rebuild kit and I'm sure it all went back together properly.

I want to open it up again this winter to try and fix it but I really don't what I would do differently, any ideas?

Thanks,

Chris

[Mikes Z car]

Like I know anything about transmissions but I am curious, if you are going down the highway in 4th gear and you push in the clutch and then pull the shift lever out of 4th into neutral is it easier to pull than pulling it out of the other gears into neutral under similar conditions?

[EuroDat]

Hi Chris.

Is it only doing it in 4th, not 3rd? Does it kick out with a lot force or can you hold it in gear with light finger pressure on the gear knob?

There are a couple of things you should check before pulling the transmission. Jumping out of gear is often caused by poor adjustment in the shifter components.

Some simple checks you can do:

1. Remove the center console and rubber transmission tunnel boot. Take it for a test drive and see if it still does it. The boot or console could be pushing on the gear lever knocking it out of gear. I have seen someone pull the transmission and replace components just to discover that the rubber transmission boot was pushing it out of gear.:stupid:

2. Check the shift lever bushes (2 side and end cap) for excessive play. Remove the rubber selector boot and visually check it for play.

3. Check the spring and the check ball for the 3rd/4th selector rod. Its the top one on the side of the adapter plate (The bottom one is 5th/reverse). Compare the springs for wear and tension. It could be worth swapping them to see if it improves.

Do each check one at a time. That way if you solve the problem, you will know what caused it.

If its not there than it could be wear in the center shaft bearing between the input and main shaft. You probably already replaced the neddle rollers, but they are not the only components that wear. The shaft contact surfaces can be worn.

Or it could be the coupling sleeve, the synchronizer hub or the coupling teeth (teeth the coupling sleeve locks onto) on the gears for 3rd and 4th. If the teeth wear which can happen to forth when the bearings are worn and the alignment is off, that can cause this problem. I would expect that with a 4 speeds because it needs to be in forth a lot to get that much wear.

Good luck

Chas

Edited July 6, 2014 by EuroDat

[grannyknot]

I wish I had asked this question before I removed the offending tranny and installed the spare one.

The shift lever bushes and end caps are all new as are the bearings and syncro rings however I did re-use the check balls and springs so that is a good place to start.

I could easily hold the shift knob in place with two fingers on deceleration

but I remember it was very easy to shift out of 4th so the check ball could be the problem.

Chas, how important do you think the countershaft front bearing shim thickest is?

I didn't have anyway of measuring it so re-used the shim that was installed when I dismantled.

Thanks,

Chris

[EuroDat]

Chas, how important do you think the countershaft front bearing shim thickest is?

I didn't have anyway of measuring it so re-used the shim that was installed when I dismantled.

Thanks,

Chris

Hi Chris. It is important, but not for the problem your having. It won't have much if any effect on forth gear.

The shim is to adjust the end play in the counter shaft. Too much end play you cause clunking sounds when the counter shaft moves forward and backward. I don't mean rotation, I mean its virtually moving towards the front or the back of the car. Occurs when you acelerate and decelerate.

Don't get too excited and throw in an extra shim for good measure. The extra thrust pressure on the bearings can cause them to overheat and collapse.

Pitty the tranny is out of the car. The tests I mentioned are quick and easy to do with it still in there.

The way your going, you will be a specialist in Zed transmissions;)

[grannyknot]

Well I don't know about that but I sure am glad I opened one up, very intimidating at first but after spinning it and playing with for a few hours you come to realize that it's a very simple mechanism.

Hey Chas, you remember that rattling sound coming from my stick shift that I have been chasing around for two yrs? The rattling sound that I rebuilt a perfectly good working 5 spd tranny (that now drops out of 4th) and a driveshaft that also didn't need to be rebuilt or balanced?

Well, the problem turned out to be the cheesy MSA stickshift knob, the threads that mate with the stickshift lever were over sized and although tighten up still rattled at a high fequencey then were amplified by the 1"dia hole drilled through the wooden knob and the thin metal plate on top with the 5 spd diagram on it acted as a drum skin and made it very loud.

The fix was accomplished by wrapping the the shift lever threads with plumbers teflon tape, stuffing the echo chamber inside the knob with foamy earplugs and reattaching the 5 spd diagram plate with flexible sealant.

The car is quiet now and that is beautiful!

I sure hope this trick helps someone else, it was hard won.

Chris

[EuroDat]

Well I don't know about that but I sure am glad I opened one up, very intimidating at first but after spinning it and playing with for a few hours you come to realize that it's a very simple mechanism.

Hey Chas, you remember that rattling sound coming from my stick shift that I have been chasing around for two yrs? The rattling sound that I rebuilt a perfectly good working 5 spd tranny (that now drops out of 4th) and a driveshaft that also didn't need to be rebuilt or balanced?

Well, the problem turned out to be the cheesy MSA stickshift knob, the threads that mate with the stickshift lever were over sized and although tighten up still rattled at a high fequencey then were amplified by the 1"dia hole drilled through the wooden knob and the thin metal plate on top with the 5 spd diagram on it acted as a drum skin and made it very loud.

The fix was accomplished by wrapping the the shift lever threads with plumbers teflon tape, stuffing the echo chamber inside the knob with foamy earplugs and reattaching the 5 spd diagram plate with flexible sealant.

The car is quiet now and that is beautiful!

I sure hope this trick helps someone else, it was hard won.

Chris

WOW would never have thought a gear knob would make so much noise. Great to hear you found it:)

Chas