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slave cylinder issues


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#1 spdcrazy

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Posted 08 March 2017 - 10:00 AM

71 Datsun 521. short 5spd transmission. clutch slave cylinder is from a 78 620. stock clutch master.

 

everything was running and working fine until I pulled into a gas station, hit the cluth and had nothing. looked in the res, and it was empty. looked under and could see fresh clean fluid coming from the boot on the slave. all lines were dry.

 

I walked 3.3 miles, bought a new slave, and installed. went to bleed the system and about when I was done, while my helper was pumping the clutch, I heard and saw a pop. and fluid started leaking form the boot on the new one.

 

I am curious why I am having this issue and why now when its been running fine for months of daily driving.

 

my thought is this, the slave cylinder rod is adjustable and maybe vibrated to the point of trying to over engage when I put my foot on the clutch, which then bottoms out on the clutch and the slave still attempts to push more?

 

anything else I should be looking at? clutch functioned before without any issues.



#2 Stoffregen Motorsports

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Posted 08 March 2017 - 10:42 AM

Aside from the fact you say it was working fine for months, I would have a look at the pedal freeplay. If the pedal does not have freeplay to the clutch master, then the fluid will "pack up" and never release all the way, kind of like a ratchet. Every time you pump, it will keep a small amount of pressure and multiply until either the slave pops out, or as in the case of brakes, the brakes lock up.

 

It's worth checking.



#3 banzai510(hainz)

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Posted 08 March 2017 - 10:42 AM

what type clutch fork you have?? a CUP or one with a hole?

The stock 521 had a threaded rod adjustable type set up.

The later 5 speed used a cup on the FORK. so when you oder a new slave it comes with a NON threaded rod that is ussauly sized for that transmission.

 

I will assume your over extending the slave rod out to where the rubber cup goes out.

 

 

so you have to give more infor. What motor is in there. a L 16 or a L16 as they can have diffent diaphrame heights and cause this if wrong TO bearing sleeve installed.

Datzenmike is more knowelgable on this or the other truck guys Daneil and Wayno

 

 

what Stroffren said.

One has to assume if a new Cluctch slave was ever installed that the rod length there was correct also as I notice all my brake masters I have to cut. But I never notice on the clutch master where I had this proplem. I had the Rachet happen on my brakes once but I just replaced the whole master cyl. it would keep pumping up and not release. I had to hit the brake bleed screw on side of the road to get home w/o cooking the brakes


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#4 spdcrazy

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Posted 08 March 2017 - 11:14 AM

the ratchet idea is a possibility, but it would have been a very small amount of fluid to hold each time, as I drive 30min each way to work. 4 days a week. but I think you are right in the lack of freeplay. I always put the clutch all the way down to the floor, but it was engaging about half way or so. usual feel for the truck.

 

its an l20b with a fork that has a hole. the threaded rod is a separate piece on my setup. and of course adjustable.

 

the transmission, clutch collar, and fork all had to be pieced together until it worked. but then it worked for months, so the collaboration of parts should be correct, just misadjusted somehow.



#5 banzai510(hainz)

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Posted 08 March 2017 - 11:52 AM

i WILL ASSUME WHEN YOU HAVE THE SLAVE ADJUSTED WITH THE THREADED ROD.That you have that ball out as far as it can with about a 1/16 play at the fork. so most of that thread rod is pushed in. Or make sure its pushed in when you hit the blled screw. then lock it and adjust the play. and shouldnt take much to push the clutch in to work.

 

dont know if you have a 200mm or 225mm set up as that would have a big offset on TO bearing sleve length


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#6 d.p

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Posted 09 March 2017 - 09:44 AM

i WILL ASSUME WHEN YOU HAVE THE SLAVE ADJUSTED WITH THE THREADED ROD.That you have that ball out as far as it can with about a 1/16 play at the fork. so most of that thread rod is pushed in. Or make sure its pushed in when you hit the blled screw. then lock it and adjust the play. and shouldnt take much to push the clutch in to work.

 

dont know if you have a 200mm or 225mm set up as that would have a big offset on TO bearing sleve length

 

Is it normal for the fork to be tight against the slave no matter where the ball is?   I watched mklotz video and he is able to push the threaded rod into the slave which I cannot do.  the only adjustment I have is turning the threaded rod or the ball to move the fork forward or back.  



#7 banzai510(hainz)

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Posted 09 March 2017 - 12:19 PM

NO its not normal to have tension unless for the clutch wear then it will get tight. then you adjust for the wear and put the 1/16 in play.

 

on the 5 speeds trans with the fork cup they seem to have alwasy been tight that I noticed. But I dont have any of those. Mine are all 510/521 with the threaded rod and hole in Trans Fork

 

 

 

open the bleed screw and the threaded rod should push in.  I think theres a spring in there also.

 

Since he has a threaded rod and a 510 521 Fork to should be EZ to adjust.   Unlock the Jam nut then turn the half moon nut out toward the back of the trck till it takes up the slack till it almost hits the fork with about 1/16  inch play in fork(wiggle)


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#8 spdcrazy

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Posted 15 March 2017 - 08:52 AM

yes the slaves have a spring ins. mine came apart, so I removed it, cleaned it thoroughly, let it dry, then put it back together and installed. as long as the inside walls of the body is smooth, it should hold just fine.

 

also, I figured out my issue, for future searches, it vibrated to tight and then allowed the throw to be to far out of the slave body, adjust back to specs and all is well again.



#9 Sslatham

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Posted 20 March 2017 - 09:48 AM

Hello all I am new to the site and am in need of some help.
I bought a 69 patrol out of Colorado a few years back and am looking to get it up and going . The engine runs great. I had to replace the rear axle with one from a Toyota Land Cruiser. Now I am stuck trying to find a clutch slave cylinder mine is rusted and pitted extremely bad. Any one know where I can find one or if any other Nissan vehicles run the same part ?

#10 Doctor510

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Posted 20 March 2017 - 02:11 PM

Google



#11 banzai510(hainz)

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Posted 21 March 2017 - 05:30 AM

look on here there is a guy in Texas that has a Patrol


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#12 banzai510(hainz)

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Posted 21 March 2017 - 05:31 AM

look under

OTher Datsuns and Nissans on this site

Theres a guy from Texas that has a nice Patrol

 

Is is that black white zebra colored Patrol?


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#13 datzenmike

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Posted 21 March 2017 - 05:37 AM

The slave looks like the same from any 521/620. If rusty pitted maybe the early ones were steel. Later ones are cast aluminum. It should work.


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#14 Stoffregen Motorsports

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Posted 21 March 2017 - 07:50 AM

There's a guy here on Ratsun that does a ton with Patrols - http://community.rat...ser/41788-rmpo/ He's in Wyoming.

 

There's also that gal in Orgeon that sells vintage Datsun parts. I think she's in OR. Most of you Pac NW guys probably know who I'm referring to.



#15 datzenmike

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Posted 21 March 2017 - 12:53 PM

Tana the Datsun lady.... vindats 1

 

or vindats@yahoo.com


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#16 Sslatham

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Posted 21 March 2017 - 12:53 PM

Doc I have googled it and have came up with one in Australia.
Unfortunately they won't ship it to me . As for here in the states I have had no luck. Thank you everyone for your advice I will follow up on the tips and see where that gets me thanks again.

#17 datzenmike

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Posted 21 March 2017 - 12:57 PM

Well I have a picture (sort of) and it looks like the 521/620 with the inlet and bleeder on the end to clear the torsion bars. Car ones are on the side at the back. I'm 90% sure a truck one will fit. 


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#18 Lockleaf

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Posted 21 March 2017 - 01:58 PM

We have Australian rats on here. You could see if one of them would take delivery from the Australian company and reship it you.

Half Pint ('71 510 Goon) http://community.rat...agon/p?=1269361

 

Audrey ('69 Roadster 1600) http://community.rat...rey-the-ratster

 

Tiny Havok ('85 720 DIY built Crewcab 4x4) http://community.rat...ache/?p=1395455

 

720 Shenanigans http://community.rat...20-shenanigans/