Another quick question, about 1st gear popping out

[XC92]

I'm going to be dropping my trans within a month or so now that it's warming up here in the NE, and finally try to fix the issue it's had where it pops out of 1st gear. I had hoped to fix this last year, but for various reasons I wasn't able to and had to reinstall the trans before I could get to it.

Anyway, I'll hopefully know what's causing this and what else needs to be fixed once I open it up. But in the meantime, I'm just wondering what's the most likely cause, given the specific way in which it pops out.

Sometimes, it doesn't pop out at all and stays in until it's time to shift into 2nd.

Sometimes it tries to pop out but if I hold it in it'll stay until it's time to shift to 2nd.

And sometimes it pops out no matter how hard I hold it in, and I have to start in 2nd, which is not good because I have to slip the clutch so as to not stall the engine. Major pain in stop and go traffic.

At no point do I hear or feel any grinding. There was some grinding a while back, but that was because the clutch didn't fully disengage, and I've fixed that (temporarily, but that's another matter). There's no problem getting into 1st with the clutch fully disengaged. It just doesn't stay in most of the time.

Does this sound like a shift fork or detent ball/spring issue? Maybe these aren't the right words for them. I mean whatever keeps the trans in a given gear once the synchros have done their thing and the gear, sleeve and hub are fully engaged and under load. Could it be as simple as these being worn out or broken, which I believe is a much simpler fix than a bad synchro, hub, sleeve, key, etc.?

There was no play in the input out output shafts and the locknuts are tight.

I'm not looking for an actual blind diagnosis, of course, just what these symptoms likely point to.

 

[92AWDHX40]

Popping out of gear sounds internal, like ok my older 91 i had. Simply worn out gears.

 

[XC92]

Well obviously it's internal. I'm just wondering why it's happening THIS way. But if the gears are worn out, why would it pop out sometimes but not other times? Wouldn't gear slipping and grinding be more likely if the gears were worn out, and I'm not hearing any of that?

 

[92AWDHX40]

I never heard anything it just popped out. I'm no expert but you haven't torn into the transmission right.

 

[pboglio]

Mine did that. It didn't grind much either, just would randomly pop out. The shifter fork detent spring isn't going to hold the gear in place. It's the hub slider spring and key that does that along with the friction of the dog teeth on the side of the gear and hub. If you had a worn synchro, then the dog-teeth wore out and it's "camming" the hub-slider back off the side of the gear under load, nothing you do is going to keep it in place. Think of trying to hold (2) cones in place, not possible. The dog teeth normally cones near the lead-in with flats for the engagement. Worn synchros round these dog teeth down to nubs basically, then the popping out starts. At best the synchros need replacing, the hub-slider, keys & spring. The 1st gear itself depending on the condition of the dog-teeth but it might need replacement too.

I used TRE but Shep or Jacks tranmission can help you out. I highly recommend shot peening the gears, the difference in strength and durability is amazing.

 

[AWD-Tony]

This smaller gear is what holds it in place. Idk what it’s called. If it’s popping out, it’s worn

You must be logged in to view this image or video.

 

[pboglio]

That is the dogteeth on the gear flank, it's cast into the gear although it looks seperate....it's one piece. See the "arrowhead" shape, well that get ground to a nub when the synchro wears out and doesn't properly slow the engagement. The synchro is sitting in-line with it ready for the hub-slider to lock both dogteeth/gear and synchro together to the hub-slider which is splined to the shaft. The synchro obviously slows the engagement then the hub-slider rides right over the top of it and engages the dogteeth on the gear flank and they lock together with the shaft. That's a great pic, I have a good one of a shattered 3rd gear.....great memories coasting the car down a hill into the parking lot at work.

I should point out something. What actually might have happened is the shift fork pad wore out, shortened the throw and providing only limited dogtooth engagement. That is what happened on mine now that I remember. This isn't like a worn synchro, but you wear the tips of the dogteeth this way. The entire shift fork is basically wasted and needs replacement, which is typical for a standard rebuild. If that happened and you don't drive on it too long, the gear could very well be re-used, but the slider would automatically get replaced for reliability on the rebuilds.

 

[XC92]

Thanks all, very, very useful info. Of course I won't know for sure what's going on till I take it apart, but I want to understand how it all works and be prepared for what awaits me ahead of time.

It does sound like the dog teeth are worn and maybe spring or key, as the synchro just gets everything synced up, thus the name, and then it's just sort of there, along for the ride but not doing anything (from what I understand, that is). The gears are getting synced up (meaning the gear, sleeve and hub), or else there'd be grinding. They're just not staying in place (usually, sometimes they just do and it all works as it should).

Hopefully only 1st gear parts are shot, as this could get expensive fast. I'm guessing that I'll have to replace other parts too, though, like bearings and spacers. Whatever needs to be replaced, will be replaced. No point in taking it apart and doing half a job.

I wonder what could have caused this given that the car has less than 78k miles on it. I do know that the clutch wore out several months after this started happening, and there's a good chance that the infamous clutch lever slop issue cropped up before either happened. Could the clutch not fully disengaging, due to the pedal lever slop, cause this, by putting excessive pressure and wear on the synchro, which in turn would wear out the dog teeth?

I know that some people have the view of "just fix it, whatever the cause", but I like to know, to the extent possible, what likely caused a given issue, to better avoid it repeating. I'm also better appreciating the value of a good mechanic, who probably could have seen this coming and told me how to prevent it. Oh well, you live and learn.

 

[pboglio]

That's a good guess as well. Keep in mind the shift fork and how it works tends to squeeze out any lubrication, not totally surprised they wear out. Resting your hand on the shifter wears the shift fork pad, which is aluminum riding on the steel hub slider groove which rotates within it. It's kinda normal. The upgraded shift forks I believe had a teflon pad or bronze pad brazed onto it to stop this from happening. Mine went at about 100k miles, could have been earlier.

The clutch not being adjusted properly can cause some serious problems. I had some clutch drag at very high rpms which clearly was an indication I didn't adjust the release point correctly. Then the ACT clutch seemed to have launched a spring out the transmission case.....fun stuff. Possible you could rebuild a transmission yourself, highly recommend you don't but it's doable for a novice. When I was at TRE for my rebuild he used a Magnaflux to check for gear cracks. He threw out half the transmission while I stood there and watched in disbelief.

It's best to simply visit their websites (Shep, Jacks transmission, TRE) and simply replace everything they replace as a start. The rebuilds they do are about $1800 and it's worth every penny to have them do it unless you want to learn. You have to nail the case/gear preloads which is the trick to increasing the torque capacity, and all that stuff. Too much work for me.

 

[luv2rallye]

pboglio in post 8's 2nd paragraph is a very likely and common senerio. I've rebuilt my 99 tranny 3 times myself for that very thing except mine was 4th gear popping out (due to shift fork wearing down not pushing the slider over far enough).

 

[XC92]

That's a good guess as well. Keep in mind the shift fork and how it works tends to squeeze out any lubrication, not totally surprised they wear out. Resting your hand on the shifter wears the shift fork pad, which is aluminum riding on the steel hub slider groove which rotates within it. It's kinda normal. The upgraded shift forks I believe had a teflon pad or bronze pad brazed onto it to stop this from happening. Mine went at about 100k miles, could have been earlier.

The clutch not being adjusted properly can cause some serious problems. I had some clutch drag at very high rpms which clearly was an indication I didn't adjust the release point correctly. Then the ACT clutch seemed to have launched a spring out the transmission case.....fun stuff. Possible you could rebuild a transmission yourself, highly recommend you don't but it's doable for a novice. When I was at TRE for my rebuild he used a Magnaflux to check for gear cracks. He threw out half the transmission while I stood there and watched in disbelief.

It's best to simply visit their websites (Shep, Jacks transmission, TRE) and simply replace everything they replace as a start. The rebuilds they do are about $1800 and it's worth every penny to have them do it unless you want to learn. You have to nail the case/gear preloads which is the trick to increasing the torque capacity, and all that stuff. Too much work for me.

I'm sure it's worth it and then some, but that's more than I can justify at this point, especially given how much I've already spent on restoring the car and have yet to spend. But mostly I want to do it myself. It's not currently my DD so it can sit for as long as it takes for me to figure out what's wrong, order the parts, and slowly and carefully install them, a month or longer if need be.

But based on what I've read here and elsewhere, it doesn't sound like the damage is TOO bad, and mostly if not entirely restricted to the 1st gear, with maybe some 2nd gear parts that could stand to be replaced while I'm at it. I'll know when I take it apart, and if it seems too overwhelming, then I'll send out the stacks. Hopefully that would save me some money.

But if I can do it, I'd really prefer to do it myself, and not just save the money but gain some skills and have the satisfaction of having done it myself. Everything else I've done on the car and several others has worked out well, so I think I can do this. I'll look into having the parts Magnafluxed and shot peened locally, though, to make sure I address all issues and do it right.

As for what caused all this, I strongly suspect that clutch lever play leading to insufficient disengagement wore down the synchro and gears as well as the clutch itself, which only had around 40k miles on it. All because of a poorly designed $40 part. Needless to say I will address this issue as well. I've already replaced the clutch, PP & slave.

pboglio in post 8's 2nd paragraph is a very likely and common senerio. I've rebuilt my 99 tranny 3 times myself for that very thing except mine was 4th gear popping out (due to shift fork wearing down not pushing the slider over far enough).

All of these potential scenarios are actually making me more eager to open it up, see for myself, and fix it myself. I've always been a tinkerer and this is totally in line with that.

And yes, I'm careful, methodical and patient. I don't cut corners.

 

[luv2rallye]

Internal tranny worn bearings, worn hubs (https://www.dsmtuners.com/attachments/thrustwear-jpg.103934/), loose 36mm shaft end nuts can also cause pop-outs. Here's some more (http://www.wcengineering.com/articles/popout.html).

Want to fix the tranny yourself? See this: http://web.archive.org/web/20100627174759/http://www.twingles.com/ideck/rebuild3/dretranny.htm. Even though it's for a 99 tranny, it will help.

 

[XC92]

Thanks, but shaft nuts were solidly on, no shaft play, bearings felt ok when rotating shafts by hand. Looks like the gears, hubs, synchros, etc., and shift fork.

I've been reviewing many of these older threads to educate myself and be prepared for all sorts of situations, but in this thread I had a specific question about my specific set of symptoms.

Btw your first link is to an image, not a thread. The second doesn't take me anywhere. The third I'm familiar with. It's kind of slow so I've been downloading images.

 

[pboglio]

Keep in mind you have to measure the gear preload, little bit tricky but you have to nail it. If nothing changes, the same size shims can be used.....maybe. You start pressing bearings in and off and you may need to resize the bearing race shims. Just saying. Any slop in the gear stacks means serious weakening of the gears in the mesh, and breaking stuff. Not rocket science, but I let TRE do mine with shot preening which seriously increased strength in the input shaft failures I was having and 3rd gear breakages. Up to you.

 

[pauleyman]

You won't know until you get in there but as for common cause.
Resting your hand on the shifter.
Clutch drag issues wearing the gear/hub/synchro etc.
worn/broken synchronizer keys/springs etc.
Worn shift fork
At a minimum if I were going into a trans with 80k I would replace 1/2 shift fork. 1-4 synchronizers, 1/2 hub and sleeve/springs/keys. Check the 1st gear carefully for wear since you had a popout.
All non replaceable parts, all seals etc.
That is the MIMINUM I would say given those I've torn apart. There is a spec for synchros so measure them and check the teeth. Any rounded teeth on the sleeve/synchro and gear will be headed for trouble.

The last one I did for myself I did all the bearings, center diff shims, 3/4 hub/sleeve and synchros etc.

If you ever wanted the double synchro 2nd this is the time to do it. You will need the proper 2nd gear synchro and a new 2nd gear.

 

[92AWDHX40]

Tre here for me jon did shot peened my gears and gear detail he went over the trans with me hes only 30 minutes from me and when i needed a rebuild 15 years ago. I went to him i was in doubt so he did the work it was done, i didnt spend time with other stuff knowing it was going to be rebuilt right the first time. So send it off for a rebuild or try it yourself.

 

[92AWDHX40]

pbgolio, good to see your still on the forums.

 

[luv2rallye]

Before you take anything apart I recommend you test the syncros: https://www.dsmtuners.com/threads/2...d-second-gear-problems.406668/#post-152697045

 

[pboglio]

pbgolio, good to see your still on the forums.

Yeah, I check-in from time to time. Any of my DSM knowledge is foggy these days but it's coming back. Bought an EVO X back in 2016 so kind of enjoying being back in a Mitsubishi. That's my summer only car but it moves pretty good, about 340 w.h.p. From time to time I wish I could get a DSM again but I'd done that for about 21 years, so time for new things and experiences. Agree though, TRE all the way. I'm respecting the DYI mentality of the OP, no doubt. I was at the point I was already breaking the TRE transmissions left and right, even with the standard Stage 3 new built transmissions. Only when Jon started shot peening the gear stacks was I able to hold the transmission together at about 400 w.h.p. level. There would have been zero chance had I rebuilt it myself using a 100,000 mile transmission core. Anyhow, the OP will see what he needs to do once the cases are cracked open and the gears stacks spreadout.

 

[92AWDHX40]

Yeah I agree once he opens it up. And sees what he has to work with .love my tre transmission gonna have fun once real soon this dsm is fully rebuilt just about everything is done

 

[XC92]

Keep in mind you have to measure the gear preload, little bit tricky but you have to nail it. If nothing changes, the same size shims can be used.....maybe. You start pressing bearings in and off and you may need to resize the bearing race shims. Just saying. Any slop in the gear stacks means serious weakening of the gears in the mesh, and breaking stuff. Not rocket science, but I let TRE do mine with shot preening which seriously increased strength in the input shaft failures I was having and 3rd gear breakages. Up to you.

By preload are you referring to axial preload, which is set with the proper thickness shims, or radial preload, which is actually also set with shims from what I understand? I have all the right sizes of solder for the former, and a decent 1/4" torque wrench for the latter.

Either way I realize that this has to be done right, for a given HP range.

As for shot peening, is that really necessary if I'm running stock with no intention of upping it any time soon, and if I do it would likely be no more than 300HP, and more likely 250HP? I also don't race or have any intention of doing so. At most "spirited" DD.

 

[XC92]

You won't know until you get in there but as for common cause.
Resting your hand on the shifter.
Clutch drag issues wearing the gear/hub/synchro etc.
worn/broken synchronizer keys/springs etc.
Worn shift fork
At a minimum if I were going into a trans with 80k I would replace 1/2 shift fork. 1-4 synchronizers, 1/2 hub and sleeve/springs/keys. Check the 1st gear carefully for wear since you had a popout.
All non replaceable parts, all seals etc.
That is the MIMINUM I would say given those I've torn apart. There is a spec for synchros so measure them and check the teeth. Any rounded teeth on the sleeve/synchro and gear will be headed for trouble.

The last one I did for myself I did all the bearings, center diff shims, 3/4 hub/sleeve and synchros etc.

If you ever wanted the double synchro 2nd this is the time to do it. You will need the proper 2nd gear synchro and a new 2nd gear.

Resting hand on shifter, check. Clutch drag due to pedal slop, check. Not necessarily the greatest shifting skills in the world, check. Excessive downshifting to engine brake, check.

Yeah, between the pedal slop and my shifting, I'm pretty sure I know what caused this (and what needs to be done to prevent it recurring in the future). But that's all past and at this point there's nothing to do buy open is up and see what's going on, and do whatever has to be done.

By "non replaceable parts" I assume you meant all parts that are supposed to be replaced when you take the trans apart, like springs, detent balls, pins, etc., right? I already have new seals, all OEM, except the input shaft seal, which I need to order, also OEM.

Aren't the cone bearings usually destroyed when you take the stack apart, and so have to be replaced as well? What about the needle bearings and their sleeves?

And why would I want to put in a double synchro on the 2nd? Isn't that more for higher HP setups and for folks who race?

 

[92AWDHX40]

Its for a reason thats why its done, its not about hp, i dont race mine im looking for 500 hp easy but i didnt it done for hp .

Here look at this you dont have to do it, you can rebuild your own transmission and skip shot peening. My TRE Trans | DSMtuners
DSM AWD Transmission Rebuild Services - TEAM RIP

Shot Peening - TEAM RIP

It seems like your bent on doing it yourself then, dont worry about it. just rebuild without the all the extras.

 

[XC92]

I have the time & tools (mostly), will order and replace whatever new parts I need, am very patient, thorough and deliberate, and will do it right, to the best of my ability. If I have questions, which of course I will, I'll ask, and hopefully get answers.

At worst, if I'm stuck, I'll send out at least a part of the job. But I'm guessing that I won't need to. Everything I've fixed, tends to work well.

My only real concern is, since I have no other place to work on the car at present than the street in front of my home, it'll have to sit there for at least a few weeks, and most likely a month or more, between taking the trans apart to see what's going on, ordering the right parts, waiting for them to arrive, and installing them properly, including the shimmiig process, etc.

The concern is that they finally decide to tear up the street and put in new asphalt, since we're overdue for it, or some other repairs have to be made to the street right where the car is parked. I can probably push the car into a neighbor's driveway for the duration, but it would be a pain.

I also need to find a decent press. Buying one would be a challenge, as I've nowhere to store it once the work is done, and I won't need it for a long time after. Perhaps I can buy a used one then sell it when I'm done, or find a neighbor or friend who has one.

Alternately, I was wondering if there are pullers and presses that use a forcing bolt or screw that might work, similar to wheel bearing presses. Or, I could possibly built my own press with a 6 ton bottle jack I have. Do you have thoughts about either of these options?

Sorry about all the questions, but prep work, which includes research and having everything you'll need in place, is half the job, in my experience, if not more so.

 

[92AWDHX40]

Sound like you need to get a place work and get the tools you need, to do what you want with it. Im assuming you need to do that before tackling this job.