Hey guys, first time posting on this forum, hoping I could get some help. I've been working on my 1995 Integra GSR's transmission (it has an imported JDM trans with clutch type LSD), trying to install the Synchrotech Carbon Lined rebuild kit (version that comes with synchros, sleeves, springs, bearings, and seals) as well as MFactory's longer ratio first gear (3.07 ratio). I have used several videos and a service manual to help me complete the rebuild as it's my first time, but when I tried to test it on the bench I couldn't get it to spin in anything but third gear and neutral. The problem persists despite me taking apart and rebuilding both shafts two times apiece. I've since narrowed the issue down to third gear not wanting to spin free on the main shaft once you install the bearing on top. No matter what gear it's in, even if you manually place it in neutral, it always acts as if third gear is fixed in place. Obviously when it's already in third it won't spin when I shift to fourth or any other gear. Based on the service manual, nothing seems to be out of spec, however third and second are tight enough on the mainshaft that I can't even get a 0.0381 mm feeler gauge between them, which I assume is the issue. Does anyone know what might be causing this, or what part to replace? It's my first time working on a transmission, so any input would be very helpful. It should be noted that the reason I am doing this work is that the bearing that holds the mainshaft in on the bottom (if you have it open sitting on the table) exploded, but so far I have noticed very minimal damage cased by this incident in the transmission itself.


This is my third gear, synchro is new. It has some minor damage but nothing I thought was major.

Third attached on mainshaft. It will spin without anything else installed, and the needle bearing is in there (just can't see this angle).

Full mainshaft assembled. Note: in this state, third either won't spin at all, or takes significant effort.

One final angle for the connection of third and second. I think these are maybe too tight somehow? It feels to me like there should be a piece between them but I didn't see anything in the service manual or videos, looked like you just pushed them together like this.

 

So, at what point does 3rd no longer want to freespin? You are trying to spin the gear freely on the shaft right? The synchro doesn't spin inside the sleeve, it's held inside the hub and only rotates a little bit forward and backward. In your test photo gravity is pulling the sleeve down onto the 3rd synchro causing it to try to bite, are you holding the sleeve up so it's not pushing down on 3rd synchro? Does 3rd synchro move loosely back and forth in the hub?

If we are on the same page and it's the gear that's being stuck, at what point durring the assembly does it become stuck? If you drop the components onto the stack one by one, what one causes the bind?

 

Thanks for responding! I have tried holding it up while spinning, as well as assembling both shafts and the forks to have it held up by them. Usually I can get it to spin easily when it's just third gear on the mainshaft, and once I put fourth and or fifth on it'll still spin, but it's much tougher. The real problem is once I seat the bearing. The video I've been watching ( ) says you can do it by tapping it in with a hammer and an oversize socket, though the manual suggests a shop press. I've tried both methods, and once I get that bearing set the way it's supposed to be the gear won't spin at all, even with a good bit of strength behind it. I don't know much about transmissions, but I was thinking possibly third gear needs replaced? I measured it with calipers and it seemed a little bigger than what the manual suggested it should be, though I'm a little confused since the car ran fine before I took the transmission out.
The only part that noticeably needed replaced was the bearing I mentioned which caused it to pop out of certain gears (mostly second and fifth), but third gear worked fine before taking it apart.

This picture isn't perfect since I had to hold my phone in one hand, but I measured it with both hands after and got almost the exact same measurement, give or take .01 mm

Unfortunately I'm at college over the week so I don't have the shaft on hand, but the synchro seemed to spin properly. A bit tighter than the old one, but that's to be expected given the old one was worn down. Pretty sure I tested with the old one in there and it was having the same issue.
Come to think of it, do you think the synchros being new and a little thicker is causing excess pressure? It would be a little odd since the guy in the video is installing the exact same kit, but just a thought.