Gearbox Grinding When Put in Reverse

Hi,

I have a mk3 jetta tdi and i just put in a VR6 clutch and pp with a ton of other front end suspension and axle stuff. I have got the shift linkage as dialed in as i can get it (I think), but the gearbox still grinds when i put it in reverse. this can be remedied by putting in the clutch, put it in second then first gear, then put it in reverse, then there is only a mild clunk and no grinding. Is this because i have not gotten the shift linkage perfectly in tune, or has the reverse synchro died?

Thanks

Did it grind before you did the work? I have to do shift into second prior to reverse as well.

Determine that the sound was after the install.

Have any strange hydraulic issues lately? Did you open your clutch system when you did the install (did you open the clutch master or just move it away).

Do you experience any problems shifting in 1st from a dead stop? This can help you determine if it's a non disengaging clutch.



This is a clutch job that went horribly wrong. Possibly because of the wrong clutch fork, or the thicker disc that replaced the thin stock one. Though, your clutch slave is self adjusting and should have taken care of a thicker disc. Could mean my flywheel needed a specific cut into it, but that was not figured out till it was all too late.
http://forums.tdiclub.com/showthread.php?t=277217&highlight=sbc

There are no syncros with reverse. You need to let the gears stop spinning after putting in the clutch and before shifting into reverse.

If its grinding or clunking no matter what you do then you could have some issues that require the transmission to come out. Some of the items that come to mind:

Bad throwout bearing (gets indented where it contacts the pressure plate)
Bad clutch release lever/fork (can bend/flex)
Wrong clutch release lever (the 02J and 02a levers are slightly different)
pressure plate fingers contact area is worn
Improper flywheel machining

before pulling the transmission I would try making the slave cylinder engagement rod a tad longer....get creative

Thanks for the responses!

Before I pulled the transmission, reverse would go in fine only when at a dead stop (no rolling) and sometimes then it wouldn't go in nicely, so I would push on it and it would pop in. Now it grinds, even at a dead stop, unless I put it in 1st and 2nd a couple of times, then reverse only 'clunks' (the engine jumps under the hood, but the car doesn't jump forward or backward). When the car is off, it will go into reverse with some trouble, I have to push on the stick kind of hard the first time, then if I take it out and put it back in reverse, it goes in easier.

As for 1st, what I have to do is put a little pressure on the stick forward, wait a second or two, then the transmission will go into first gear with varying degrees of difficulty, sometimes it goes in halfway and I have to push on it to get it in the rest of the way, sometimes it slides in smoothly. All the other gears go in more or less smoothly when the car is stopped.

I replaced the pressure plate and the throwout bearing, and the clutch does feel like it is disengaging fully because it only starts to 'grab' halfway through the clutch pedal travel. I didn't touch any hydraulic stuff, and all the other gears are fine, except for reverse.

My best guess is that I either messed up reverse when I pulled the transmission out (though unlikely I think), the shifter is not adjusted correctly (though I tried adjusting it in all directions and where I have it now feels best, and it is where it was before), or I damaged the shifter (it did pop off its track when I was trying to adjust it, but I popped it back on). The shifter on the transmission end does seem sloppy, so I may try replacing that and see if it works.

Clutch is not fully releasing. Putting in second uses the synchro to stop the input shaft rotation. Putting in reverse (without synchro) will grind if input shaft is spinning.

1999Jetta said:

Thanks for the responses!

Before I pulled the transmission, reverse would go in fine only when at a dead stop (no rolling) and sometimes then it wouldn't go in nicely, so I would push on it and it would pop in. Now it grinds, even at a dead stop, unless I put it in 1st and 2nd a couple of times, then reverse only 'clunks' (the engine jumps under the hood, but the car doesn't jump forward or backward). When the car is off, it will go into reverse with some trouble, I have to push on the stick kind of hard the first time, then if I take it out and put it back in reverse, it goes in easier.

As for 1st, what I have to do is put a little pressure on the stick forward, wait a second or two, then the transmission will go into first gear with varying degrees of difficulty, sometimes it goes in halfway and I have to push on it to get it in the rest of the way, sometimes it slides in smoothly. All the other gears go in more or less smoothly when the car is stopped.

I replaced the pressure plate and the throwout bearing, and the clutch does feel like it is disengaging fully because it only starts to 'grab' halfway through the clutch pedal travel. I didn't touch any hydraulic stuff, and all the other gears are fine, except for reverse.

My best guess is that I either messed up reverse when I pulled the transmission out (though unlikely I think), the shifter is not adjusted correctly (though I tried adjusting it in all directions and where I have it now feels best, and it is where it was before), or I damaged the shifter (it did pop off its track when I was trying to adjust it, but I popped it back on). The shifter on the transmission end does seem sloppy, so I may try replacing that and see if it works.

Click to expand...

You need to adjust your shift cable.

If that does do it then your shift cables might need adjusting:

from the www.corrado-club.com website:

CABLE "A" (Driver side): if pushing down and to the side on the shift lever to go into reverse, and it gets hung up on the reverse lockout, then this cable needs to be adjusted. Note the position of the cable end to the transmission lever on the transmission. Loosen the bolt and slide the cable toward the front of the car in small increments until the lever does not hang up on the reverse lockout. Retighten the bolt to 18ft/lbs. CABLE "B" (Passenger side): if 1st or 5th gears are hard to get into, then this cable must be adjusted. Note position of cable end on transmission lever. Loosen the bolt and slide the cable rearward in small increments for better alignment for 1st gear. Slide the cable forward for 5th gear alignment. Retighten the bolt to 11ft/lbs.


Now go in the car and pull up the plastic part that the shift boot comes out of. You might want to untwist the shift knob and get it out of the way so you can inspect the shifter mechanism. Move it around and look for obvious issues. A common problem is that the clip that goes on the driverside of the shift rod falls off and when shifted into 1st and reverse it will slide off the shaft. There is a clip on the end of the shaft that keeps the plastic mechanism on the shaft.

Yes, after some thought it does seem that the clutch is not fully releasing. Would adjusting the clutch slave cylinder help with this even when it seems that the clutch only grabs halfway through the travel of the clutch pedal? If my reasoning is correct, if you adjust the slave cylinder to press the clutch out farther, then the clutch will start grabbing later in the clutch pedal travel, and possibly not reach full clamping force if it is adjusted too far? The old clutch did not have this problem, it didn't show too much more wear (if any) than the new one and the old clutch grabbed sooner when I released it than the new one.

As for adjusting the shift mechanism, 1st will just slide in no problem sometimes, but I will try to fine tune it. Also, sometimes if I put a lot of force to move the stick left, then push forward, it feels kind of like it is going into reverse, then I pull the shifter back and push forward again and it goes into reverse. Maybe it is adjusted too far left? but 5th is easy enough to get in.

Thanks for the responses!

There is no adjustment for the slave. My offering is a complete hailmary before pulling the transmission.