Clutch, Transmission

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
Hal_Armes
Posts: 12
Joined: Fri Sep 02, 2016 7:00 am
Car: 1984 Nissan 720

Clutch, Transmission

Postby Hal_Armes » Mon Oct 02, 2017 7:59 am

My 84 Nissan 720 with 5-speed manual transmission has a problem that I believe to be with the hydraulic clutch, but either the clutch or transmission for sure. The master and slave cylinders were both replaced last year and should be good, but it is of course possible they were faulty and have gone bad. The clutch lines do not seem to be leaking, if so it would be a pinhole leak but I really don't think it is a leak. In the past when I've had a clutch friction plate go out I never experienced a problem shifting, the clutch just started slipping while I was driving til the engine stopped turning the transmission and it acted like it was in neutral, never experienced any grinding gears or other symptoms. I tried bleeding the cylinders the other day but that didn't help much if any, but they didn't seem to expel as much fluid as I thought they should. WHAT IT'S DOING: I have to pump the clutch considerably to get it to shift into a different gear except for 5th. There is sometimes a little resistance. If I don't pump it enough the gears grind and it won't go into the next gear. Also if the engine is running with it in gear and I have my foot on the clutch it doesn't take long before the gear it's in starts grinding and I have to take it out of gear and pump the clutch some more before I try to shift it back into gear. My question is whether this is likely a problem in the hydraulics such as a faulty master or slave cylinder or does anyone know if it is more likely to be a worn-out clutch plate??? Before I go to pulling the transmission to change the clutch I want to make sure it really needs changed rather than the problem being in the hydraulics. The engine was rebuilt about a year and a half before I got it and one would think the clutch would have been changed then and should still be good, but no guarantee it was changed when the engine was rebuilt. Anything anyone can tell me about their experiences with these symptoms and the likely causes will be appreciated.


mannyboricuad21
Posts: 2
Joined: Thu Oct 05, 2017 11:35 pm
Car: 1995 Nissan Pickup Standard bed/D21

Re: Clutch, Transmission

Postby mannyboricuad21 » Fri Oct 06, 2017 12:01 am

I know this is old as hek but I'm having the same problem with my D21. I recently had the clutch changed and the idiot who did it didn't tighten criss cross applesauce and now I got a bolt missing. Since I cant seem to find them anywhere for sale, my next best option is to look at Home Depot or something. Ive been driving it without pressing the clutch for the past week. I can barely shift into first, and when I do the whole truck feels like a 7.0 earthquake while I let off the clutch from a stop. I can feel and hear the trans run quite rough. when I let off the gas in 1st 2nd and 3rd and I kid you not it sounds like a straight piped 18 wheeler downshifting and when I put it into 4th it always grinds. does anyone know the dimensions to those bolts to a 95 pickup? its a 4cyl 5 speed. I only trusted this mechanic because my family mechanic who moved away said he would leave me in good hands but I that turned out to be a load of bull >.>

any help is appreciated. Thanks in advance!

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centralcoaster33
Moderator
Posts: 2772
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

Re: Clutch, Transmission

Postby centralcoaster33 » Fri Oct 06, 2017 12:57 pm

Hey Manny, don't threadjack if you can help it. You both have clutch issues, but the trucks are 11 years apart and yours is due to shady mechanic work while his seems to be hydraulics. I replied to your other post in the other thread, which really isn't a good place to get feedback on your specific issue either. It is okay to make your own thread. Welcome to NICO.

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centralcoaster33
Moderator
Posts: 2772
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

Re: Clutch, Transmission

Postby centralcoaster33 » Fri Oct 06, 2017 1:10 pm

Hal, what you describe does sound like issues in the hydraulics. There's not that much to the system, so I'd give the whole thing a 'once over', um again I suppose. Use the FSM as you go. Inspect the hydraulics, tighten all nuts, bolts, flanges and fittings, etc. then bleed the clutch properly once more. You may have a bent fork. It might be possible for you to peek into the whole where the fork is and see if that is the case or not. You might even see if it wiggles in strange ways. That would be a sign that maybe it's off the pivot ball or off of the throw out bearing carrier. Try and peek into the bellhousing. A bent or dislodged fork will limit the movement and not allow full clutch disengagement. You may have the incorrect Master cylinder. I bought a new one online for my 240 and the input shaft was much shorter than stock, so the pedal never got full travel and it didn't work. I had to throw away that master cylinder. You may have the incorrect slave cylinder. If the piston on that isn't long enough to push your fork all the way, you won't get full clutch disengagement.

If your clutch worked properly for a while and now isn't working properly, then you probably don't have to worry about the parts being the wrong length. If they were wrong parts, you'd have this problem the whole time since installation.

Your experience with normal clutch wear is typical and I agree with your assessment.

Here's the the best I've got for a Service Manual: http://www.nicoclub.com/service-manual? ... e%20Manual


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