PLEASE HELP diagnose trans problem.

[mattrobertsxn]

lately (past month) my 91 s13 has had problems shifting gears, first starting off as it being hard every once in a while to shift into first, then turning into everytime i get into my car i have to use excessive force and pop it into first. I then replaced the trans fluid, which helped slightly, but nothing huge, but soon returned to normal a couple days afterwards. I then replaced the slave, which helped, but returned to how it was again, and now i just bled the clutch after putting in a new master cylinder. It was shifting SO perfect after i replaced it, and i was so happy, but now its slowly returning to how it was. Also now when i put it into reverse, it makes some weird ass sounds i couldnt even describe but theyre loud. I know the clutch is grabbing still because if i put it in first and hold the clutch in and rev it up to around 5k i can start rolling forward....

This is my daily and first 240 please help im not sure what to try next because i have a bad feeling my syncros are getting trashed and im not capable of rebuilding my entire trans. Its starting to be sloppy shifting into other gears too, not a smooth transition from 2 to 3rd or 3rd to 5th etc.

Thank you if you need a video of the sound for reverse to help diagnose what to do next ill get it uploaded


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[derass]

i just bled the clutch after putting in a new master cylinder. It was shifting SO perfect after i replaced it, and i was so happy, but now its slowly returning to how it was.

I know the clutch is grabbing still because if i put it in first and hold the clutch in and rev it up to around 5k i can start rolling forward....

Its starting to be sloppy shifting into other gears too, not a smooth transition from 2 to 3rd or 3rd to 5th etc.

There is air leaking into your clutch release hydraulics, and so you are not able to fully disengage the clutch. Either from a dead-stop, or during gear changes.

You said you replaced the master and slave. So I would look at the flex hose, and hard line next. They might be either cracked or rusted through from old age.

I would have also said to check the bleeders, but I assume the new master and slave came with new ones.

[mattrobertsxn]

flex hose goes from master to slave? where is the flexhose / hardline? And if the problem was air leaking into clutch hydraulics, wouldnt i be losing a lot of pressure in my pedal? Or atleast over time? I guess time will tell but im very uncomfortable driving my car because if i toast the syncros ill have to buy a new trans.


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[mattrobertsxn]

There is air leaking into your clutch release hydraulics, and so you are not able to fully disengage the clutch. Either from a dead-stop, or during gear changes.

You said you replaced the master and slave. So I would look at the flex hose, and hard line next. They might be either cracked or rusted through from old age.

I would have also said to check the bleeders, but I assume the new master and slave came with new ones.



^^ forgot to press reply but i responded above this


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[derass]

flex hose goes from master to slave? where is the flexhose / hardline?

Yes, the flex hose that's in between the slave cylinder and hard line. The hardline runs from the master cylinder, across the firewall, and down to the clutch damper.

Which I actually forgot about: the clutch damper attached to the frame rail. That also needs to be bled, or may even be faulty. I ended up deleting mine because the rusted bleeder broke off.

And if the problem was air leaking into clutch hydraulics, wouldnt i be losing a lot of pressure in my pedal? Or atleast over time?

If it's a rusted-out pinhole in the metal hardline, it will let in air very slowly. The system will still work like this, but with degrading performance until the air pocket becomes so large that the hydraulics will no longer release the clutch at all.

You even said this is happening in you original post.

...i just bled the clutch after putting in a new master cylinder. It was shifting SO perfect after i replaced it, and i was so happy, but now its slowly returning to how it was.

[mattrobertsxn]

Yes, the flex hose that's in between the slave cylinder and hard line. The hardline runs from the master cylinder, across the firewall, and down to the clutch damper.

Which I actually forgot about: the clutch damper attached to the frame rail. That also needs to be bled, or may even be faulty. I ended up deleting mine because the rusted bleeder broke off.



If it's a rusted-out pinhole in the metal hardline, it will let in air very slowly. The system will still work like this, but with degrading performance until the air pocket becomes so large that the hydraulics will no longer release the clutch at all.

You even said this is happening in you original post.



You know i did see a divit in my flex hose that looked like it could be leaking air into it. I think im just going to have to rebleed EVERYTHING again and replace the flex hose which is a huge ass pain but i dont have a choice really. What do you think? Flex hose, see if it works, then check hardline?


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[derass]

I would check both things at the same time. The hard line is likely to be rusted out where it's held by the plastic clips. Moisture gets trapped in there, and then the metal rusts, possibly to the point that a pin-hole develops. Check / bleed / delete the clutch damper as well.

There's certainly no harm in replacing your 26 year old rubber flex hose. They're cheap to replace, whether it be a new rubber one, or steel braided.

[Zenki_559]

If your hardlines are rusted/damper box broken/flex line punctured, it would probably be beneficial to just get a new steel braided line that goes straight from the master to your slave cylinder. It would remedy all of your issues, and deleting the damper box would increase clutch feel. Also makes it easier to bleed since air wont get trapped in the damper box.

https://www.enjukuracing.com/products/isr-performance-auto-to-manual-conversion-clutch-line-nissan-240sx-89-98.html?gclid=EAIaIQobChMI5PXKsf_m1wIVEkwNCh0sFAum EAQYASABEgLbd_D_BwE

[mattrobertsxn]

If your hardlines are rusted/damper box broken/flex line punctured, it would probably be beneficial to just get a new steel braided line that goes straight from the master to your slave cylinder. It would remedy all of your issues, and deleting the damper box would increase clutch feel. Also makes it easier to bleed since air wont get trapped in the damper box.

https://www.enjukuracing.com/products/isr-performance-auto-to-manual-conversion-clutch-line-nissan-240sx-89-98.html?gclid=EAIaIQobChMI5PXKsf_m1wIVEkwNCh0sFAum EAQYASABEgLbd_D_BwE



Any insight on deleting damper box? Is it pretty difficult or what. Thank you so much for the help.


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[Zenki_559]

Any insight on deleting damper box? Is it pretty difficult or what. Thank you so much for the help.


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Its super easy. Buy a braided line, drain your clutch fluid, undo your hardline from the clutch master cylinder, install one side of the new line to the clutch master cylinder, undo whatever line is going to your slave cylinder, and install the other side of the new line to your slave. Refill clutch fluid, bleed, and be done. After that, you can just unbolt the damper box from your frame rail, and pull the old hardline and damper box out as a single piece.

[Zenki_559]

You can also undo the hardline from where it goes into the damper box, CAREFULLY bend the hardline and screw it into the rubber line coming off your slave. But if your hardline is what is messed up, its easier just to buy the new line and be done with it.

[derass]

You can also undo the hardline from where it goes into the damper box, CAREFULLY bend the hardline and screw it into the rubber line coming off your slave. But if your hardline is what is messed up, its easier just to buy the new line and be done with it.

This is what I did. I used a hand-held tubing bender to bend the line without kinking. Turned out perfect.

[mattrobertsxn]

Ok so is enjuku the only vendor that sells those braided lines because thats a lot of $$ for a hose


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[Zenki_559]

Ok so is enjuku the only vendor that sells those braided lines because thats a lot of $$ for a hose


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There are definitely others on the market. On my last S14 i used the DIF one from FRSport. They are all going to be around $30 though. Cheaper than buying any of the OEM clutch pieces. And it would suck to replace your damper box, and have it be your hardline thats messed up, or replace the hardline and have it be your damper box thats screwed. I know everyone has differing budgets, but $30 is a pretty cheap price to pay for something that will remove all doubts about which of your pieces is broken and give you a little peace of mind.

[mennermafia]

I literally just went through (October 27th this year). I replaced the master, the slave, etc. chasing the same issue you have. After getting the ISR line I have not had a single issue since the day I bled the fluid.

It's cheap insurance, just do it, put it on, bleed again, never worry again until you bleed the lines again for maintenance.

Also, if you use the braided line you will need to find a way to mount it to the firewall so it's not loosey-goosey flapping around in there. The factory plastic mounts on the firewall will not hold the diameter of the new line, but need retained for brake lines coming out of the brake master cyl.

I came up with a similar solution to this (except metal):

https://www.securecableties.com/4-inch-black-miniature-push-mount-cable-tie-100-pack

See how the one area will press into the firewall, the "zip tie" portion will wrap around the new clutch line and hold the line in place once you tighten it. I recommend finding a metal version of this rather than plastic (it is a hydraulic line that runs pressure through it), but the plastic one in the link above will be effective enough in theory (I mean the factory holder is made out of plastic, right?).

GL with the project.

[mattrobertsxn]

Its super easy. Buy a braided line, drain your clutch fluid, undo your hardline from the clutch master cylinder, install one side of the new line to the clutch master cylinder, undo whatever line is going to your slave cylinder, and install the other side of the new line to your slave. Refill clutch fluid, bleed, and be done. After that, you can just unbolt the damper box from your frame rail, and pull the old hardline and damper box out as a single piece.



Did practically exactly what you said, once i bled it my clutch felt new again, wasnt letting me movewhile in 1st clutch in 5000 rpms but then slowly started to come back the same day. Harder to shift, softer pedal. What in the world is putting air in my system? Im about to rebleed it, i just got everything set up. I double checked the hose connections to the master and they are tight however i am going to see what the slaves looking like after i jack it up. Please magically get fixed lmao🤞🏾


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