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Resolved What else causes reverse pop out?

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Fooxz

Probationary Member
12
1
Nov 21, 2009
Milwaukee, Wisconsin
Problem: reverse gear pops out under load. If you baby it and feather the clutch it will reverse SLOWLY on flat land. Attempting to back up an incline of any sort causes the gear to pop out and grind. Stopping and not touching the shifter causes it to go back into reverse following the same symptoms as above.

Apologies upfront for the wall of text, I've tried everything I can find information on and need a sanity check.

My 1991.5 Talon TSi AWD has a W5M332-WQNK. It has had the correct secondary gear swapped (kindly worked on by @twicks69 about two years ago.) to allow it to work with this car's original transfer case and rear. It has been driven for 25K+ miles with all of the forward gears working beautifully. 91 shifter cables, base, shifter bracket and both shift levers are used. The trans came with a shorter shift selector lever which I tried but it makes it nearly impossible to move far enough over to get to 5th/reverse unless you lean your entire body on the shifter.

This was my fathers car but he hasn't had time to work on it so he's made me the new owner.

Reverse originally worked when the trans was first installed. It slowly started having problems where it would pop out but just when backing up a hill until it got as bad as it currently is.

Exhaustive list of things I have tried or checked:
  • Pulled trans and replaced reverse synchro, cone, wave spring, 5th/rev synchro keys and springs, with new end nuts. (Problem almost feels worse now like even less load is needed for pop-out)
  • End nuts were not loose and had not moved from their staked locations.
  • Reverse idler looks beat up and rounded (likely due to the repeated attempts to use reverse)
  • With the trans apart and standing on the bell housing end, the reverse idler gear will fall into place under its own weight with no issues. (obviously this doesn't tell us anything since the idler shaft is not secured and probably moves some to the benefit of engagement.)
  • I used a dremel with various stones and sandpaper rolls to detail the leading edge of the idler teeth to make them less round.
  • Adjusted both shifter cables in extremes each way in an attempt to rule shifter cables out. They are now adjusted correctly per the manual.
  • Tricks such shifting from "X" gear before reverse, pumping clutch, letting clutch out as going into reverse, starting the car in reverse, going into every gear before reverse...
  • Adjusting clutch pedal to bring full disengagement further from the floor, as it had been too low per spec from manual.
  • Solid shifter bushings on trans side of cables, and on shifter base
  • Reverse switch has an aluminum washer and no visible damage from contact with shift rail
  • Reverse idler bolt is installed and torqued to spec, with an aluminum washer
  • "Restrict Ball Assembly" bolt is installed and torqued to spec, with an aluminum washer
  • Interlock plunger is present in the reverse shift lug
  • Springs and poppet balls are present and clean for all three rails
Clutch is ACT 2100
Clutch slave has an extended rod
Clutch fork does not touch bell-housing but it is probably close
There is no clutch drag as far as I can tell

It does not feel like the clutch pedal assembly is worn, but I am pulling it today to make sure, and will repair if needed or might anyways so it's good for the foreseeable future.

I am uncertain if the shift fork and ball were replaced or not. I believe a new ball was installed, but I doubt a new shift fork was used. We likely used whichever "best" one we had at the time.

I know the next step is probably pulling the trans again and replacing the reverse idler gear and 1-2 slider but I am curious if anyone else has any ideas about what actually causes reverse pop out.
 
You weren't joking when you said extensive list of things checked!!!
I'd be curious to see what the reverse idler gear would do for your issue. You'd be surprised how worn that gear can get when you compare it to a new one.
You said there was a noticeable difference in how reverse performed when you did the detailing work. I think you were onto something
 
Yeah it's starting to drive me a bit crazy.

Turns out I do have clutch drag at around 6200RPM. Clutch fork was positioned to the left of center, so I pulled the trans again to check my flywheel step height and take a closer look at my fork and pivot ball. I may toss a single washer shim on it to see if it makes a difference.

But truth is clutch drag shouldn't affect going into reverse before starting the car which it also pops out from.

I picked up two spare transmissions last weekend and already broke them down, one had a reverse idler in good condition so I may swap it out and see if it helps since I can't find anywhere to buy the idler new.

I'm starting to nit pick stuff, like how the reverse idler support bolt's hole in the case is larger than the bolt so you can tighten it down without being certain of how the shaft is positioned, ie left right high or low, or if that even matters. I question this because reverse drops in easily when it's all apart but could the small difference in angle of that shaft cause an issue?

I think I'm gonna get real good at pulling the trans trying these little different things.
 
Finally made some actual progress.

Transmission is on my bench with the end case and intermediate plate sections off. It is resting on the bellhousing side so gravity is helping reverse fall into place. If I shift into reverse while watching reverse from above it doesn't fully mesh. Probably barely half way like the top of the reverse idler is at the same height as the tallest point of the 1-2 slider. If I slowly unscrew the restrict ball assembly then reverse idler continues to fall and engages further to the point where the leading "synchro" tips on the slider are fully above the gear.

If I add two additional aluminum washers for that restrict ball assembly bolt (the approximate distance that I unscrewed it before the gear stopped moving further into engagement) and attempt to shift into reverse again, the reverse idler appears to fully engage.

What did I just discover? Is just adding the washers the correct fix or is there some issue with the reverse shift lug or reverse shift lever for the reverse idler? How would I go about checking something like that?

Normal partial engagement:
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Engagement after unscrewing restrict ball assembly bolt
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Said restrict ball assembly bolt with three total washers:
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Is the plastic select shoe present on the trans shift assembly? Reverse should be a direct positive shift just like any other gear. You can see how the levers move and when the reverse idler drops into place it's a direct shift lever move just like any other. It shouldn't go halfway or partway etc.
 
Yup the plastic shoe was new when the trans was rebuilt and is not worn yet. It fits without much play. When the transmission is in the car all hooked up shifting into reverse feels like its gone fully into gear. The shifter moves as far back in reverse as 4th and 2nd gear. It feels right and correct when you shift into reverse, but then it just pops out and grinds.
 
Given that's a straight cut gear it makes little sense. Are there any Marks inside the bellhousing? Bolts tight on the reverse arm holding the actual gear? Is that arm bent?
 
Thus you understand my plight. No marks on the bellhousing, bolts on the reverse lever tight, arm straight as far as I can tell. One washer on reverse switch, same for the restrict ball bolt but I will be trying it with one and two more once its back in the car just to see.

I will break down the trans further and check the reverse arm lever against some spare core transmissions I have.

Thanks for your time, I appreciate more eyes on the problem.
 
I'm not going to rule out motor mounts, other than it has to also be something else because removing the shifter cables and manually shifting into reverse and starting the car it still pops out.
 
I have a suspicion that the improperly adjusted clutch caused the wear to the idler gear due to incomplete disengagement, eventually leading to the idler gear's reduced engagement not holding and popping out.

So hopefully the increased idler travel/engagement and a properly adjusted clutch will fix this. I've got the trans reinstalled but not entirely back together so I haven't had a chance to test it.
 
make sure you have correct shift rails for the case your using. In this case I would probably sacrifice a mid case, and cut a hole in it so you can see what's going on in there.
Cut a hole???? No way. Jesus you have to drop the trans anyway. Open it assemble shafts and rails and watch it work
 
make sure you have correct shift rails for the case your using. In this case I would probably sacrifice a mid case, and cut a hole in it so you can see what's going on in there.

I was considering drilling and tapping holes in certain places so I can fit a scope in to see, then just plug it when i'm done. I do have a second trans I can sacrifice parts of to make larger inspection holes if needed too. I had two extra trans, one had sheared teeth enough to ruin parts of the case so I scraped that one keeping parts that were good enough, but both trans supposedly have bad synchros (or so i'm told) and I'd rather keep the JDM trans with the EVO close-ratio gears.

I agree, yes way on sacrificing case parts because this issue is driving me nuts. Continuing to checking things and them being correct/OK yet there still being a problem is going to make me insane. If actually seeing what's going on inside with the trans installed can help me even in the slightest then I say it's worth it.

I will be finishing getting the trans back in the car this weekend, and will report back if shimming the pivot ball with adjusted clutch pedal and an extra washer or two on the restrict ball assembly fixed the issue or not (crossing fingers)

I had thoughts about the shift rails too, how do I determine which rails i have? I see there are different numbers/positions of rings on the shafts but I don't know how to identify what they are beyond that. I have three sets in total I can swap around and try if needed.

Cut a hole???? No way. Jesus you have to drop the trans anyway. Open it assemble shafts and rails and watch it work

The shift rails move too much without the bearing plate (or whatever it's called) installed because it holds the other end of the shift rail shafts. If you shift into reverse without that in place you have to physically push down on the 5th/rev shift rail to get it out of reverse. Plus not having the 5th/rev fork pinned on that shift rail rotates so you have to manually hold it in place or keep rotating it back into place in order to shift into reverse on the bench. You could *maybe* assemble the trans without the center case but it would be so flimsy you might as well cut up a junky trans.
 
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I was considering drilling and tapping holes in certain places so I can fit a scope in to see, then just plug it when i'm done. I do have a second trans I can sacrifice parts of to make larger inspection holes if needed too. I had two extra trans, one had sheared teeth enough to ruin parts of the case so I scraped that one keeping parts that were good enough, but both trans supposedly have bad synchros (or so i'm told) and I'd rather keep the JDM trans with the EVO close-ratio gears.

I agree, yes way on sacrificing case parts because this issue is driving me nuts. Continuing to checking things and them being correct/OK yet there still being a problem is going to make me insane. If actually seeing what's going on inside with the trans installed can help me even in the slightest then I say it's worth it.

I will be finishing getting the trans back in the car this weekend, and will report back if shimming the pivot ball with adjusted clutch pedal and an extra washer or two on the restrict ball assembly fixed the issue or not (crossing fingers)

I had thoughts about the shift rails too, how do I determine which rails i have? I see there are different numbers/positions of rings on the shafts but I don't know how to identify what they are beyond that. I have three sets in total I can swap around and try if needed.



The shift rails move too much without the bearing plate (or whatever it's called) installed because it holds the other end of the shift rail shafts. If you shift into reverse without that in place you have to physically push down on the 5th/rev shift rail to get it out of reverse. Plus not having the 5th/rev fork pinned on that shift rail rotates so you have to manually hold it in place or keep rotating it back into place in order to shift into reverse on the bench. You could *maybe* assemble the trans without the center case but it would be so flimsy you might as well cut up a junky trans.
A junk case yes but I wouldnt sacrifice a known good one. I have a USB borescope. Wonder if that would slide through the bearing plate holes
 
A junk case yes but I wouldnt sacrifice a known good one. I have a USB borescope. Wonder if that would slide through the bearing plate holes

Should fit good if you leave the oil guide out, that hole is pretty large and in the right place to check the reverse idler, the smaller oil guide hole might be big enough to check the shifting stuff.
 
Reverse friggin works now.

So all I really did was add ONE more aluminum washer (total of two, I can measure the thickness if anyone is interested) to the restrict ball assembly bolt that is on the top of the case under the ends of the shifter cables when the trans is in the car. Reverse now has a MUCH more solid "click" into gear, and it is tougher to get into but once it is in reverse it didn't pop out backing up my driveway which would have been laughably impossible to do before.

I also shimmed the clutch pivot ball and welded my clutch pedal assembly with a bronze bushing but as I still have some clutch drag I still have some adjustment to do, but it is probably about the same amount of clutch drag as I had the previous time.

I don't know why the one washer wasn't enough, and there wasn't any more wear on the restrict ball assembly bolt or the reverse shift lug that the ball rides on. So it was really only by chance that I saw how weak the engagement of the reverse idler gear was that led me to unscrew that bolt some.

I am so relieved to finally have this problem solved. Thanks everyone for your input.
 
Maybe there was a hodge podge of parts in that transmission that needed human input to get things set right? an example would be a spring that is the wrong length in that reverse detent assembly.
 
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