About Us

spb350 · 01-10-2012, 07:50 PM

I just got my newly rebuilt m21 installed and it is popping out of every gear on de-acceleration. It wasn't doing that before I pulled it out. The shop replaced the synchros and sliders and supposedly checked evrything else. Before I installed it in the car I mounted the original Hurst shifter and aligned the linkage with a drill bit. I rechecked the alignment after I drove it and its still lined up. What could be the problem? How can I find out if its the shifter or tranny? If its the tranny what did the shop possibly do wrong? Thanks

spb350 · 01-10-2012, 07:51 PM

This is in my 73 TA if that matters

JoePapa · 01-10-2012, 08:55 PM

Check to see if you have a stop on the shifter. Some Hurst shifters will have a bolt that is on either side to prevent over extending the shift. If the shifter stop is poking out too far, you won't engage the gear all the way.

spb350 · 01-10-2012, 09:12 PM

Nope, no stop bolts the original ones didn't have them.

GRX · 01-10-2012, 09:34 PM

4th gear perhaps? Could be the slider is not maintaining engagement with the driven gear. Have the stock sliders been replaced with Tork Loc sliders?

Lemans64 · 01-10-2012, 10:02 PM

I,ve had a few of those apart and the only thing I can think off that would do that is possibly a broken or missing rear snap ring on the output shaft, were it goes through the midplate. Output shaft has to be moving too much. Just my thoughts. I would think it must come out to verify concern though.

spb350 · 01-10-2012, 10:07 PM

There was no mention of the Tork Loc sliders so I'm assuming they just used stock sliders. The only thing I changed from the time I pulled it out to the time I put it in was a slight adjustment to the linkage arms and I lubed up the shifter really good, other then that everything is the same. I'm thinking they must have done something wrong. I think tomorrow I will pull it into the street, put it in 2nd gear and then disconnect the linkage and see if it still pops out, if it does I would assume its the tranny and not the shifter

Lemans64 · 01-10-2012, 10:15 PM

I would think u are on the rigth track, if u made adjustments to it, it wouldn't make it come out of every gear, maybe one but not all 4. keep us updated.

Rick

pfilean · 01-10-2012, 10:40 PM

Long time ago it was standard wisdom that if a tranny popped out of gear (usually high)there maybe some foreign material between the bellhousing and the tranny case. Also sometimes to correct poor machining, shims were strategically placed between the bellhousing and tranny to get proper alignment and prevent popping out.
If everything you did rejects that theory then maybe on rebuild some of the roller bearings between the clutch gear and the main shaft got lost. Some transmissions had two rows of bearings and some only had one row. I don't know which you have but if some of those are missing then movement between the clutch gear and the mainshaft can cause popping out of gear.
I'll assume that as you had no problems before rebuild that the pilot bearing is OK.

Half-Inch Stud · 01-11-2012, 09:01 AM

...long-ago I rebuilt a M21 HD with all new "Blocking rings" and it would pop-out of 4th gear, just like BEFORE the rebuild. Got into gear so much better though.

69Customs · 01-11-2012, 03:44 PM

Drive it to the shop that rebuilt the tranny and have them look at it. They messed it up!

Tempest · 01-11-2012, 05:04 PM

Try this. disconnect one of the shifter rods when in neutral, and manually shift the tranny into gear.(doesn't matter which one 1-2, or 3-4) Then, from under the car, see of you can re-attach the rod, if you can't without adjusting the length, then you know your rods need to be adjusted (more than likely, lengthened). This will determine if you have enough 'throw' in the shifter.
This happened to me in 3rd gear during my first test drive, I lengthened the rod, and no problems since. The shifter had enough throw to put in in gear, but not enough to keep it there during deceleration.
Hope this makes sense

2002Z4CSS · 01-11-2012, 05:05 PM

Some times a misaligned input shaft due to a worn pilot bushing will cause this or missing bellhousing dowell pins.

Red Coupe · 01-11-2012, 08:00 PM

Popping out of 4th on decell? I'll bet you will find that one or more of the pre engagment teeth on the main drive gear are worn or broken. Doesn't take much damage to cause this.

It's not that hard to fix yourself. 5speed.com sells a good rebuild CD.

Red Coupe · 01-11-2012, 08:25 PM

Here's an example of bad pre engagement teeth that caused the same problem you have.

spb350 · 01-11-2012, 09:54 PM

Quote:

Originally Posted by Tempest

Try this. disconnect one of the shifter rods when in neutral, and manually shift the tranny into gear.(doesn't matter which one 1-2, or 3-4) Then, from under the car, see of you can re-attach the rod, if you can't without adjusting the length, then you know your rods need to be adjusted (more than likely, lengthened). This will determine if you have enough 'throw' in the shifter.
This happened to me in 3rd gear during my first test drive, I lengthened the rod, and no problems since. The shifter had enough throw to put in in gear, but not enough to keep it there during deceleration.
Hope this makes sense

I can try that but the only problem is if I lengthen the rod for the forward gear its going to shorten it for the reverse gear, 2 gets more, 1 gets less, its popping out of all the gears.

spb350 · 01-11-2012, 09:55 PM

Quote:

Originally Posted by 2002Z4CSS

Some times a misaligned input shaft due to a worn pilot bushing will cause this or missing bellhousing dowell pins.

I put a new bushing in it when the motor was built and it doesn't even have 10 miles on it.

spb350 · 01-11-2012, 10:04 PM

Quote:

Originally Posted by Red Coupe

Popping out of 4th on decell? I'll bet you will find that one or more of the pre engagment teeth on the main drive gear are worn or broken. Doesn't take much damage to cause this.

It's not that hard to fix yourself. 5speed.com sells a good rebuild CD.

The guy that did the work said everything besides the synchros and sliders looked brand new. He also changed the bearings.

I've been searching the net for other cases of this and some have had this problem caused by a missing snap ring which lets the input shaft slide? I wondering though if this would cause all the gears to pop out?

Half-Inch Stud · 01-12-2012, 11:45 AM

Quote:

Originally Posted by spb350

The guy that did the work said everything besides the synchros and sliders looked brand new. He also changed the bearings.

I've been searching the net for other cases of this and some have had this problem caused by a missing snap ring which lets the input shaft slide? I wondering though if this would cause all the gears to pop out?

Inconceivable; only 4th Gear can pop-out due to an input shaft malady.

spb350 · 01-12-2012, 04:48 PM

I took the TA out on a back street today, as I was driving there I checked to make sure that all the gears are still popping out and yes they are. Accelerating it does great, nice and smooth no grinding. So I jacked it up and disconnected the 1/2 shifter linkage. Then I manually put the tranny in 2nd gear got up to about thirty let off the gas and it popped out of gear. So now I know for sure the linkage/shifter has nothing to do with it. The tranny guy is going to come over and drive it for himself but its a bitch because I'm probably going to have to pull it out again. What could he have done or not done to cause this problem? It never popped out of gear before but could it be that the detent springs are week? not on? I'm pretty sure I replaced the pilot bushing when I had the motor rebuilt. Could a really bad pilot bushing cause this problem? Any other guesses?

Menu

About Us