Trans pops out of gear on decel...

[EricB]

Last Friday on the way in to work I noticed that on deceleration the trans started popping out of gear... it did it at the freeway offramp, then again and several times in bumper to bumper traffic on the way home that night...

Because the timing was about right mileage-wise I changed the tranny fluid over the weekend, looked for any obvious issues and didn't see anything wrong... didn't really drive the car the remainder of the weekend.

This morning coming to work and going to lunch just now it did it again several times. I noticed that when in fifth when I get on and off the gas the shifter jerks forward and rearward quite a bit - fifth gear is probably the gear it slips out of easiest although out of second is pretty common too...

I've never taken this car to the race track.

I've never done any kind of burnout or dropping of the clutch with this car.

Basically I've babied both the car and the 78 5spd on the car the whole four years I've had it with never any problems... and now this out of the blue...

Any clues?

Ideas? Recommendations?

-e

[jurven240z]

Back in 1994 my 71 4 speed took a dive so went in a had a 78 5sp put in. The price was the same for the 4sp so why not upgrade. Well after one year and less than 5 thousand mile the 5th gear would pop out a few second after ingaging it. Took it in as it was under warranty and was told that some pin had come lose/broken after only 5 thousand miles. They replaced it in one day. Had no problems with the tranny to this day. Replaced it with a rebuilt 83 a year ago getting ready for the 4:11 upgrade. Sorry could not be more technical trannys are not my favorite.

[EricB]

hmmm... well I do have a spare 82 5spd... given to me by a friend of mine... but it has no reverse... maybe i need to open that up and fix it in case this 78 gets worse... it's just so weird cause there was no bang, no grinding no nothing, it just sort of started happening last friday

-e

[2ManyZs]

Before you pull anything apart, just for the heck of it, you might want to double check your shifter bushings and the pin that holds the shifter in place.

Little bit of play in one or both, and you won't be putting it fully in gear. I've even seen on shift lever that had worn enough that it needed to be replaced. Not only at the pivot, but at the bottom as well can wear.

There's so many little things that can cause this, it's almost impossible to figure it out till you open it up, worn shift rail, bent roll pins, the list is a pretty long one.

[EricB]

hi keith

as far as shifter bushings go, i did replace the two sleeves on either end of the pin... as for the little cup that goes on the end of the shifter (the end that goes in the tranny), well with it in place it meant that the hole through the shifter for the pin did no longer line up with the ears on the end of the tailstock it is supposed to go through... so I did away with it.. .

it seemed like the cup i was given was too thick on the end ...

the reason i replaced them to begin with is that when i did the engine swap some months ago i noticed i practically had no shifter bushings left at all in there.... but the Z had been shifting fine... go figure...

-e

[2ManyZs]

I think you just found your own problem.... Without the cup on the end, you aren't getting the shift forks to go thru the whole travel, leaving the sliding clutch not fully engaged in the gear you select, when you let off the throttle, the friction is lost which allows the sliding clutch to disengage.

You really need that cup on the end of the shifter, not only so the shift forks are going thru their full travel, but also to keep it from being metal to metal at the end of the shifter which is gonna wear it out in short order.

If the cup is too thick at the bottom and you can't line up the pivot pin in the shifter, you could probably sand off a little of the cup on the bottom where it sits into the shift rail. I've never had a problem with any of the bushings like what you describe, maybe I've been lucky... :surprised

Although there were times when I had to jam it in gear to get the pivot pin to line up with the shifter pivot.

[EricB]

right on keith... will do...

-e

[sblake01]

There are different cups depending on the transmission you have. Make sure you use the right one.

[EricB]

...aaahhh...Zs....

Dont you just love them?

"When it rains it pours"....

So guess what happened when I got off the same freeway onramp to get to work THIS morning... now all of a sudden the nearly new (6mo?) throwout bearing just developed a loud whine.... all of a sudden just like that...

Ugh.... guess I'm going by the jyard and looking for a tranny so I can fix this one in the meantime....

-e

[EricB]

btw... just figured out... it ain't the throwout bearing... oooh no. it's one of the bearings for either mainshaft or lay shaft... youch... parked the Z now time to rebuild the tranny...

-e

[ksls94]

when you pull it apart check the nut on the main shaft it is common for it to back off causing all the problems you talked about even the noise like bearing noise.