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What does a bad synchro look like?

tektic

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ronkonkoma, ny
How can I tell if a synchro is worn out? where would the damage show and what should be measured or inspected?
 

mitsuturbo

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The inside part that rides on the cone will be smooth if it's really bad. It's often harder to "see" it than it is to feel it. Take a synchro and try to push it onto the cone and turn it. It shouldn't want to move. If they're REALLY bad, no amount of pushing the 2 pieces together will generate any resistance.
 

tektic

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ronkonkoma, ny
Would scoring on the top cause issue?

I want to swap a gsx 5th set on to a gst. The synchros are obviously different right? I have a whole set anyway . I'll check the inside. Thanks.
 

mitsuturbo

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Also, you're supposed to measure clearance from the back of the synchro to the gear. If it's under 1/2mm, it's supposed to be replaced.
 

tektic

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I just removed the end cover of a fwd km210 trans and there is no place for a synchronize to ride on the cover. Is this missing or just not a part of this transmission? This is revers or 5th gears syncro? I'm assuming it's just missing. I was about to do a 5th gear swap from an awd trans. Is this going to be a problem? I only stopped because it has red lock-tight on the end nuts. I will have to heat them tomorrow.
 
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FlyingEagle

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I think you are missing a wavy pressure spring that sits on the round spot on the cover.

Click me and scroll down to the pic of the cover off

It should be there and I have seen it in person. Fifth is the one with a syncro, as most reverse did not have syncros in the early years. Straight cut gears for whine effect too!

The syncro is build into the gear set you see held in by the nut. When the fork is moved over, that forces the mesh internally of the dog teeth to mesh with the syncro and allow the slider to fully engage the gear for power transmission. I think I mostly stumbled through that power transmission test at school and now here. Nothing pushes out past the nut at the end of the gear set, but if the nut is loose, it allows slop at the shifter and or the gear pops out or will never engage/stay engaged.
 

tektic

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ronkonkoma, ny
Thanks for the picture. As I expected the metal piece that screws to the case and holds the wave spring is missing and the last brass syncro that rides on it isn't present. I'm going to try to assemble a complete awd trans from all the parts I have and remove the input shaft and install a welded center differential. Supposedly these km210s shift very poorly anyway. Other option is remove the locktight and swap an awd 5th and reverse gear on there.
 

donniekak

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surprise az
I don't believe that the km210 uses a reverse synchro. There is probably a plate on the hub that keeps the synchro springs and keys in place.
 

FlyingEagle

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I don't think any Mitsu trans from this era has a reverse syncro; at least not from the factory. I could be wrong, but it's like every Honda of the era and all others before that.

I have some pictures for you taken from the Mitsubishi service manuals.

Link provided to the manual for you to have at'er, and or for reference sake.

http://www.lilevo.com/mirage/Manuals/FWD%20Manual%20Transmission%20F4M21-F5M2X-F5M3X-W5M3X%20Series%20PWEE8902-ABCD%2022A.pdf

Nearly all the manual transmissions repair manuals are located there. I uploaded all I could find from around the globe. This will help more than just our OP.

Spring update on that one.




I did post a pic of the F5M33 FWD trans end case, so you could see what that one looks like. The F5M31 is listed in the manual whenever you get to pics like above, it just doesn't list it in the titling of the manual and chapters, as such.
If you don't find what you are looking for there, it likely doesn't exist. I doubt that your FWD transmission will be any different than the ones printed in this 1989 copy of the factory repair manual.
 

FlyingEagle

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I have two KM210's sitting in the garage with the end case facing up. I can remove one and show you what should be there. I assume I put everything back in place when it was apart but I am pretty sure they have just a wavy flat spring in place then the cover. I don't remember the triple screw center piece being there on either the F5M33 FWD DSM trans I had built up, or the F5M31/KM210's that I had apart to inspect 5th and or use for parts when they came out and I needed pieces like the oil channel tube (long black plastic guide), when I lost mine somewhere in the shuffle and fit right into the F5M33!
Both transmissions I have should be 1989 MY 4g61t transmissions. Same trans "should" be in the Sonata 2.4L SOHC.
 
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FlyingEagle

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Pictures inbound. It turns out I have an early and late model transmission pair. It will illustrate the end cases per the picture above. There is not an extra assembly bolted/screwed to the case end cover however, so be prepared for that.









 
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tektic

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ronkonkoma, ny
My end cover says f5m33 and the bell housing says km210 so its very similar to the second one you posted. I guess it didn't come with the reverse syncro and plate.

How did that trans shift? I'd relay like to figure out what trans I want to use out of the 4 I have. I think the 93 nt trans in the car would be my best bet until I build a turbo bottom end. I did like the idea of the awd 5th gear swap on the fwd turbo trans. The car is going to be used mostly for commuting.

p.s. thank you for taking the time to show me that !
 
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FlyingEagle

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Mar 5, 2005
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THE Ottawa
I think the FWD's had interchangeable end covers to a certain degree, within certain frames.

My two transmissions shown were (the one with the end guts missing) the 1989 Plymouth Colt (C53A turbo KM210) as original to the car as far as I know, with nearly 183,000kms and very worn fibrous syncros in second and third, and secondly the other KM210 came from Virginia and was reported to be a turbo Mirage trans) but had the different end cover plate thing. Neither had the wave spring I was looking for, so it must have been the F5M33 FWD DSM trans that I have now installed that was coming back from my memory.

The 89 Colt/Mirage trans should have fibrous syncro liners which are great for holding/slowing engagement of the syncronizer and gear, so easier on the shifting persons arm but they do wear out faster given a high abuse over long term type scenario. 90 DSM transmissions were like this too. When I had the fifth gear syncro for my original trans out (the one with guts missing) I noticed it had the grooved style syncro and no fibre ... so it is leaving me kinda perplexed!

Keep in mind that a 1993 FWD DSM transmission if turbo, will have switched to a 27 spline count open differential. You can swap in any differential FWD or AWD to the transmission, so that part is good, but the AWD uses ball and cage and requires a substantial amount of shimming, so food for thought before you go that route. I run the AWD front diff setup in my FWD trans, and it works great and as I suspected it would after I had a local trans shop set the preloads and shim the center differential. AWD Galant and CSM's share the 25 spline count axles for front axles. DSM turbo axles switched at 92.5 MY or production date.
 

FlyingEagle

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Mar 5, 2005
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Oh, and you are welcome. I figured it was the least I could do with just a few bolts to remove on the one and the others were loose from having been in there already. I keep tripping over them in the corner of the garage, and no one around here is building anything like our cars; no one! So, every time I drive down the road, I am reminded of just how unique these cars are in my neck of the built up woods.
 
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