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Old 04-25-2021, 03:02 PM   #1
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transmission difficult to shift

ok I did search through here and found some good info but nothing gave me a good answer. So basically my transmission is very hard to shift, through all the gears, to the point where i have to put all of my weight on the shifter. reverse is especially bad, itll grind every time you have to pretty much jam it in there if you want to use it. This problem started a couple months ago, it wasnt all of a sudden but more of a progressive thing. so far ive adjusted the pedal, replaced the clutch fluid, bled it, replaced the slave, none of that did anything. today I dropped the trans, hoping to find a messed up fork or throwout bearing, nothing at all. everything seems fine with the the fork and the clutch as well(all springs are intact). so at this point what could the problem be? I replaced the master cylinder about a year ago I find it hard to believe thats the problem. The slave cylinder is extending all the way as well. I also cant see it being the synchros as theres difficulty in every gear especially reverse which doesnt even have synchros. at this point im stumped, probably going to do the shifter bushings and the master cylinder for the hell of it, but besides that does anyone have any ideas of what the problem could be? I was thinking maybe the soft line portion of the clutch line is expanding causing the clutch to not disengage all the way. if anyone has any ideas please let me know!!!
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Old 04-25-2021, 04:28 PM   #2
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Hmm interesting

I?m going to keep an eye on this thread

It?s not on my 240 but it?s something I feel on my Infiniti G20

I changed the tranny fluid and made sure I used GL4 fluid which nobody had in stock and had to order it online

Did notice a little bit of difference more of an improvement

Did you use the right fluid??


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Old 04-25-2021, 04:52 PM   #3
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used redline mt90, however i did notice the level was a little low probably due to the leak in the rear seal. You think that could be part of the problem? it wasnt super low probably half an inch under the fill plug. Now that I think about it that would explain the slow onset on symptoms. still dont know how that would explain it being so rough into reverse tho. When i put it back in this weekend im doing all new fluid maybe thatll make a difference.
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Old 04-27-2021, 08:03 AM   #4
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i have found that royal purple 75w-90 works great...maybe its the weight of the oil you are using? when you had the trans dropped were all the spring fingers an equal height? is there oil on your clutch/flywheel? if you have someone push the clutch in make sure the disk actually releases and doesn't stick otherwise
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Old 04-27-2021, 08:39 AM   #5
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does the trans shift smoothly with the engine turned off?
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Old 04-27-2021, 10:58 AM   #6
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i have found that royal purple 75w-90 works great...maybe its the weight of the oil you are using? when you had the trans dropped were all the spring fingers an equal height? is there oil on your clutch/flywheel? if you have someone push the clutch in make sure the disk actually releases and doesn't stick otherwise
spring fingers look good, from what i could tell the clutch was bone dry. Oil being on the flywheel behind the cutch i feel like could be possible, when i put it back in Im going to have someone watch through the fork hole while i push the clutch in
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Old 04-27-2021, 11:01 AM   #7
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does the trans shift smoothly with the engine turned off?
when you first turn it off, it doesnt. however after Ive gone through all the gears a few times is starts to be smooth again. im not really sure what that means but i feel like it might be a significant piece of the puzzle
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Old 04-27-2021, 01:48 PM   #8
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Did you ever check how the transmission shifts when you had it out of the car and were inspecting the fork and such? Sounds like you may have to remove the front and rear housings from the transmission and see what's going on there. Sounds daunting, but it's not too hard to do.
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Old 04-28-2021, 07:09 AM   #9
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Did you ever check how the transmission shifts when you had it out of the car and were inspecting the fork and such? Sounds like you may have to remove the front and rear housings from the transmission and see what's going on there. Sounds daunting, but it's not too hard to do.
i did actually, and it seemed to shift fine. Im gonna twist the input shaft tho and try it again and see what happens. if its shifting rough again imma crack the case open and update with my findings. THANK YOU FOR THE RESPONSES EVERYONE!!!
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Old 04-28-2021, 02:53 PM   #10
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If its hard shifting through ALL the gears, it makes me think its a disengaging issue. Have someone press the clutch in while you look to see how much the clutch fork is moving. If the fork isn't pivoting much it'll not release your clutch fully causing the hard shifting.

Also see if you can shift through the gears when the engine is off. (Which I see someone has asked)

Basically if you are able to shift through the gears while the engine is off, then it definitely leads to an disengaging clutch issue. But you said "once you first turn it off, it doesn't" until after you shift it a few times (I'm assuming because it's still spinning a bit before fully stopping).

Just to make sure you can shift through easily with the engine off, have the car lifted from the rear and spin the rear tires a bit and then try shifting through the gears again. Repeat a this a couple times. If you're constantly getting hard shifts at first and then smooth, I would think your gear teeth/hub teeth are pretty bad and rounded throughout the tranny. (bad/worn dog keys within the trans can also cause this since it won't provide a decent range for the syncho hub teeth to align with the gear teeth. - requires rebuild)

fyi: reverse gear will always be the worst worn out gear out of all of them so that's normal even in decent working transmissions.

after reading through the thread, I would most likely think its a disengaging issue first.
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Old 05-29-2021, 06:53 PM   #11
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UPDATE: due to some delays caused by the end of the school year it took me a little longer to get everything back in than I thought it would, but I finally got it all buttoned up. Unfortunately theres still no change. I have verified everything is working mechanically in the disengagement portion of the clutch, and I replaced the slave/master cylinders with oem units straight from the stealership. I also replaced the rubber softline going from the hardline to the slave with an aftermarket braided line to ensure no type of expansion/loss of travel is happening. At this point the only explanation is that theres something wrong with the internals of the trans like some of you have been suggesting. I was really hoping it wouldn't come to this but I dont see any other option besides dropping the trans again and cracking it open. if the dog keys/gears Tieny mentioned are alright and all I need is a synchro rebuild, I plan to do it all myself. Seeing as these transmissions are so rare these days I'll probably do some kind of writeup on it since buying a new one isn't so easy or inexpensive. All of this right as I get my kouki front end :'(((( thank you again for all the help I'll probably update this thread again once I crack the trans.
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Old 05-29-2021, 10:16 PM   #12
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Ok sorry to hear and yeah waiting to see a write up from you

Thanks for the update


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Old 06-03-2021, 12:38 PM   #13
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When you dropped the tranny, did you check the pilot bushing?

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Old 06-05-2021, 08:05 PM   #14
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When you dropped the tranny, did you check the pilot bushing?

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I didn't, however I installed a new one about a year ago so I figured theres no way i could be bad. Ill take a look at the pilot bearing tomorrow along with the clutch again
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Old 06-05-2021, 08:23 PM   #15
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update: pulled the trans trans today and cracked the case. I have to say I'm very disappointed, I was hoping to see something catastrophically wrong with it but unfortunately I didn't see anything I thought was too crazy. I'll admit though I have no idea what im looking at so i took a few pics, gonna include them here maybe you guys have some ideas.

https://drive.google.com/file/d/1-8g...ew?usp=sharing

First gear^ besides reverse this gear has given me the most trouble by far. you can't see the synchro in the pic but the teeth on it look alright, similar to the other gears.

https://drive.google.com/file/d/1YNi...ew?usp=sharing

second gear^. out of all the synchros this one looked the most ragged.

https://drive.google.com/file/d/1gG2...ew?usp=sharing

reverse^ apparently reverse does have a synchro. You can see the teeth on the gear here are pretty messed up. explains why it always grinds in.

Thats all I got for pics atm, if anyone wants me to post more im happy to share. gonna check out my clutch again tomorrow
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Old 06-06-2021, 11:10 AM   #16
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besides the synchro's, check for bearing play, check the fluid that you drained for any kind of particulate or material (check with a flashlight, put it through a paint strainer)

How long have you owned this transmission/how many miles have you put on it? It's a bit odd that the teeth on the hub for reverse are worn so badly, but the synchro for it looks like it hasn't taken any abuse...I'd think it would be the other way around, but maybe I'm wrong about that.
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Old 06-07-2021, 10:54 AM   #17
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besides the synchro's, check for bearing play, check the fluid that you drained for any kind of particulate or material (check with a flashlight, put it through a paint strainer)

How long have you owned this transmission/how many miles have you put on it? It's a bit odd that the teeth on the hub for reverse are worn so badly, but the synchro for it looks like it hasn't taken any abuse...I'd think it would be the other way around, but maybe I'm wrong about that.
trans came with my sr motor, I really don't think it has many miles at all I'd guess around 100k. I also found the reverse gear/synchro strange, as I watched a video which says gear wear like that points to a disengagement issue.

this brings me to my next point... I think I found I may have found the real problem. the other night as I was staring at my trans, I started absentmindedly scraping stuff off my input shaft. And I dont mean grease, but actual metal burrs that had accumulated between the splines(possibly from wear/clutch kicks?). I had to actually scape them off with a pick. somehow the back inch or so of it was all jammed up with it. My guess is that theres actually nothing wrong with the transmission at all... I think the shit on the input shaft wasn't allowing my clutch to fully disengage, as the clutch needs to slide along it. This also matches up with all my symptoms(happened slowly over time, affects all gears, feels like disengagement problem). At this point i'm crossing my fingers and putting everything back together. hopefully it'll be done by tomorrow night and I'll have an update.
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Old 06-07-2021, 02:14 PM   #18
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that could be your smoking gun. Just try and track down where those metal shavings are coming from.
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Old Yesterday, 09:52 AM   #19
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how did the reassembly go? Just saw the update and didn't get a chance to give a reply til now. Yep, the worn reverse gear teeth is pretty common. That's what happens when people don't completely stop before switching to reverse. The synchro prevents the grind but a lot of stress is still put on it. Like after getting out of 1st gear and you try to putting it back, (especially at higher speeds), you can do it if you keep pushing the gear in but the synchro works hard as shit to get it to slow in.

The teeth on your lower gear synchros do look pretty worn though. They should be straight on the sides and then taper up to a point. Check out the 5th gear syncho, that gear is usually less worn out if you want to compare.

If you have burrs on your input shaft, it could cause the clutch to seize on that burr while trying to disengage which would cause your issues. Do you have any photos?
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Old Yesterday, 01:05 PM   #20
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I rebuilt 3 different SR transmissions. They make some with reverse synchro and some without.

The input shaft, throwout bearing, fork, all need a healthy coating of molybdenum disulfide grease. The FSM specifically says this so check it out.

Yes debris accumulated on the splines directly contributes to the clutch disengagement and this could well be the major issue. Honestly there isn't much that I've seen that can actually go wrong with these transmissions beyond an obviously broken shaft or gear. Seems like they last forever if you just clean them up and use the right grease.
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