checkmate1996

Sharks,

AFTER replacing my clutch hose (black one on the bottom of car), the stick now wants to randomly pop out of 2nd gear. It only seems to be 2nd gear also. Again, prior to changing clutch hose, I had no problems here. What gives? Air bubbles in line still??

GregBBRD

Nothing you did with the hydraulics in the clutch would have anything to do with the transmission popping out of gear.

Check the shift linkage. Check the transmission and motor mounts. While the engine and transmission, as well as the gearshift linkage are all hooked together and essentially floating in one piece (unless you are one of the suckers that has one of Colin's incredibly bad design shifters witch is mounted to the chassis while the engine moves back and forth), if the mounts move so far that the shifter handle hits the chassis, the contact with the chassis can pop the transmission out of gear.

mark kibort

does it only do it under no load (neither accel or decel conditions)? This is a key question. if so, its the synchros. If it does it when you are, even slightly, accelerating, then it could be mechanical like the linkage.

I i did something really stupid with my set up. putting in the transmission the new one had a perfect boot over the rear coupler. well, instead of putting it over the mechanism, i left it all bunched up. thiis created a perfect rubber spring load trying to pull the shifter OUT of 2nd gear (and 4th too). in the end, and over time, it just wore out the edges of the synchros that keep it in gear. with any kind of load, no problem. as soon as you go equilibrium.... it pops right out.

GregBBRD

The engaging teeth on the gear and the teeth on the slider have the "negative" backcut to interlock the pieces in order to keep them in gear. The syncro plays no role in this....it has "teeth" on it, strictly for alignment purposes.

mark kibort

so that was a guess on my part, so is my theory correct, but ive identified the wrong piece as being worn? How do those teeth on the slider wear then. You don't think it was due to that boot putting pre-load on the gear selector shaft on the top of the transmission?

checkmate1996

Guys, thanks for the replies.

To give some additional context...
The transmission is a completely rebuilt transmission.
I had just put over 1000miles in June and July and absolutely NO problems. The car was running great. Took it sharks in hell ... and back!
Car sits for two weeks while I find the time to replace clutch hose.
Replace hose.
Problem starts.

That being said, it does seem to happen on load. I will double check the shift linkage, boot and motor-mounts. It's really quite bizarre...

AO

My $0.02 is that it's unrelated to your hose job!

Check linkage as suggested. I'm sure you'll find the issue.

GregBBRD

Yes, the teeth actually are shaped with what I call a negative rake.....on both the gear teeth and the teeth on the slider. There's an "entry angle", which slopes down to the actual tooth. The tooth is "undercut" so that it is smaller at the bottom than the top.

When the two pieces are "engaged", the top of one tooth is locked into the bottom of the other tooth...this is all that keep the transmission in gear.

Once the transmission starts to pop out of gear, that edge wears away, ever so slightly. Once this happen enough, there is no longer anything to hold the two sets of teeth together and they pop out of gear....usually when the load is removed.

This stuff is really difficult to see and judge. Common for rebuilt transmissions, where the rebuilder didn't know there was a "popping out of gear" issue, to completely miss this.

I worked my way through college rebuilding VW transmissions, which have the "Borg Warner" syncro design. You could put a brand new slider in and still have a worn enough gear to allow the transmission to pop out of gear. A real pain in the butt! Apparently, the VW's had teeth that were more prominent that other teeth and you could remove the worn teeth and shift the load to teeth that had never had much load on them. I never had to do this....gears were so cheap, back then, that I just put in new gears.

mark kibort

I hate to hijack..... so, is there a way i can grind the edges of the synchos to keep this from happening . you know, with a dremel???

GregBBRD

Unfortunately, "rebuilt" has many different interpretations....and is an extremely overused term.

I see many things which are supposed to be "rebuilt" and got billed out like they were "rebuilt", which are barely "repaired".....and in many cases, are not repaired!

I'm not saying that the OP's problem is inside the gearbox (although that is a possibility), I'm just saying that the hydraulic part of the clutch has absolutely nothing to do with the transmission staying in gear.

GregBBRD

I think you missed the important part.

The syncro has nothing to do with the "locking angles" that keep the transmission from coming out of gear. I took a couple of pictures to show you the angles on the gear and the slider, which keep the two pieces locked together.

You could leave the syncro completely out and it would have no affect on the slider and the gear teeth interlocking and staying in gear.





Pretty easy to see how the two pieces interlock and stay locked together.

You will need a new hub and gear teeth.....minimum

checkmate1996

Greg,

Fortunately, I oversaw most of the rebuild. We totally stripped down the box and the only thing that wasn't replaced was 4/5 gear. it was about $5k repair job and took about 9 months to source all the now NLA parts.

Ok, so I put it back on the rack today and checked all the linkage points, (which I totally rebuilt as well from the top of the TT all the way back) and everything looked just fine. I put it back on the ground and ran it again. It only popped out one time this time under load in 2nd gear. It's so strange because again before this, it never happened ONCE. Sometimes these cars make me want to poke my eyes out!!

GregBBRD

What year is your transmission?

checkmate1996

Greg, IIRC 82 ROW with 2.54 gear ratio. I'm starting to think it's a linkage thing since now that the car has been on the ground for a couple of days the problem seems to have gone away...strange...

GregBBRD

I'd agree.

Not very common for transmissions to pop out of gear under load, because of wear. Almost always occurs when load is removed.

Sounds like it might not be getting all the way into gear.

I'd remove the shift boot and see if the lever is contacting anything at the extremes of fore and aft movement. You can also check to see if the "throw" to 2nd gear is "shorter" than the throw to 4th gear....the amount of travel should be the same.