Jump to content


Photo

521 clutch master cylinder OK?


  • Please log in to reply
29 replies to this topic

#1 KFunk740

KFunk740

    Advanced Member

  • Members
  • PipPipPip
  • 270 posts
  • Location:Athens, Ohio
  • Cars:1965 Datsun L320, 1974 BMW 2002, 1992 Mazda Miata, etc.

Posted 19 April 2015 - 10:41 AM

I can't find any parts listing for 320 or 520 on RockAuto, but the 521 clutch master pics look exactly like the one in my 320 that appears to be leaking.  

 

I had previously thought it was the slave (and didn't have any luck with the 520/521 slave cylinder bolting right up without mods).  Now I do see wetness around the master clyinder shaft, so I was probably on the wrong track with that anyways.



#2 Charlie69

Charlie69

    Senior Member

  • Senior Member
  • PipPipPipPipPip
  • 6,177 posts
  • Location:Tolleson, AZ
  • Cars:1966 520, 1985 720 ST King Cab, 1986 720 King Cab

Posted 19 April 2015 - 11:00 AM

Clean up you master cylinder and take it apart.  Look at the bore if it is not badly pitted hone it lightly go to NAPA and take your parts with you.  See if they can match up the the parts with a rebuild kit.  It probably just needs new rubbers.



#3 KFunk740

KFunk740

    Advanced Member

  • Members
  • PipPipPip
  • 270 posts
  • Location:Athens, Ohio
  • Cars:1965 Datsun L320, 1974 BMW 2002, 1992 Mazda Miata, etc.

Posted 19 April 2015 - 11:52 AM

It's only $20 to $30 for a new one, and a lot less hassle than finding time to get to town while NAPA is open and explaining what I want to them.  

 

The one that's on the truck looks brand new (maybe a 521 one), as the PO appears to have replaced many parts like that.  But, I think it's a crapshoot these days getting parts like these.  They're probably all chinese made, and a good percentage are bad from the start.  I had a front wheel cylinder leaky from the start right after I bought one.  



#4 KFunk740

KFunk740

    Advanced Member

  • Members
  • PipPipPip
  • 270 posts
  • Location:Athens, Ohio
  • Cars:1965 Datsun L320, 1974 BMW 2002, 1992 Mazda Miata, etc.

Posted 04 May 2015 - 08:54 AM

The 521 clutch master worked just fine.  I did have to swap the control (push?) rod from the other master cylinder, as the 521 rod was too long.  I think whoever replaced it on the truck before did the same thing.    



#5 320 Newb

320 Newb

    Advanced Member

  • Members
  • PipPipPip
  • 248 posts
  • Location:Tucson
  • Cars:Datsun 320

Posted 23 April 2017 - 12:03 PM

Sorry to revive such an old threat but both my brake master and clutch master are leaking on the cab side of the firewall so I need to replace both. 

 

I see from the post above I've got swap the push rods. Is there any trick to it? Do they just thread into the cylinder body?

 

Any other tips or advise?



#6 banzai510(hainz)

banzai510(hainz)

    L motor God

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 15,058 posts

Posted 23 April 2017 - 12:22 PM

I don't know the older trucks but all the 521 masters I buy all need to be cut as the rod is too long. As one mounts the master the rod is getting pushe by the pedal.

 

So one needs to cut about 1/2 so there is not pressure on the rod.

 

I guess one can swap the rods but I seen a nice 510 get smashed as a rod was swapped out and later fell out and rear ended a car


Throw on some Weber sidedrafts, Rising Sun hood.... call it good

#7 wayno

wayno

    Datsunahaulic

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 12,995 posts

Posted 23 April 2017 - 01:10 PM

You need to swap the 320 rod into the 521 master as I recall, they are both held in by spring clips again as I recall.


 

 


#8 Stoffregen Motorsports

Stoffregen Motorsports

    Datsun Mechanic

  • Senior Member
  • PipPipPipPipPip
  • 3,901 posts
  • Location:Cool, CA
  • Cars:http://www.4wdandsportutility.com/features/rover/0611_4wd_1957_range_rover/viewall.html

Posted 24 April 2017 - 06:55 AM

Before you do any "rod swapping", measure the length from the 2 bolt mounting flange to the centerline of the pushrod clevis hole. Make the new measurement the same when installing the rod in the new master.



#9 KFunk740

KFunk740

    Advanced Member

  • Members
  • PipPipPip
  • 270 posts
  • Location:Athens, Ohio
  • Cars:1965 Datsun L320, 1974 BMW 2002, 1992 Mazda Miata, etc.

Posted 24 April 2017 - 06:50 PM

I can't really remember that well, but don't think there were any tricks and pretty easy to figure out.  Don't think there was any difference in the length at all on the master cylinder itself once you remove the part that gets swapped.  It's been on the truck 2 years, and no problems.  Just hauled home a load of mulch today.

No idea about the brake master cylinder, haven't touched that one yet.  



#10 KFunk740

KFunk740

    Advanced Member

  • Members
  • PipPipPip
  • 270 posts
  • Location:Athens, Ohio
  • Cars:1965 Datsun L320, 1974 BMW 2002, 1992 Mazda Miata, etc.

Posted 24 April 2017 - 07:06 PM

OK, banzai got me paranoid so I ran out and looked.  Still had the 521 rod on my shelf too for comparison.  The 521 rod has a lot of room for adjustment, but at its shortest its like 1/2 to 1" longer than what was in my 320.  

I had just swapped the entire rod, so the length will be identical as before.  To do this, you need to take the rubber boot off the firewall side of the master cylinder.  Then there's a little triangular spring clip on the inside, and you can fish it out with an o-ring pick or a tiny screwdriver.  Replace rod with your 320 one, put spring clip back,  and all is back as it should be.  



#11 HOGIE

HOGIE

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 1,603 posts
  • Location:Springfield, Or
  • Cars:70 521, 64 NL320

Posted 24 April 2017 - 07:25 PM

I just did the 'rod swap' on both brake and clutch master, granted only the clutch has been bleed and the truck hasn't moved since install, but it worked fine.

#12 320 Newb

320 Newb

    Advanced Member

  • Members
  • PipPipPip
  • 248 posts
  • Location:Tucson
  • Cars:Datsun 320

Posted 24 April 2017 - 07:32 PM

Thanks everyone for chiming in, I'm feeling fairly confident in the project. 

 

Once I do the swap can I bleed the masters installed with a bleed kit by running a tube from the outflow port back into the reservoir by pumping the pedals? Will I have to bleed the lines too?



#13 Stoffregen Motorsports

Stoffregen Motorsports

    Datsun Mechanic

  • Senior Member
  • PipPipPipPipPip
  • 3,901 posts
  • Location:Cool, CA
  • Cars:http://www.4wdandsportutility.com/features/rover/0611_4wd_1957_range_rover/viewall.html

Posted 25 April 2017 - 07:20 AM

You should "bench bleed" the master by the method you stated. I usually do this in a vice before I install it in the car as it can be quite messy. You don't want to get the brake fluid on your paint.

 

But yes, after you install the master, you will need to bleed the entire system. If it has old brake fluid in the lines, blow them out with air first (wrap a rag over the end of the line so the fluid doesn't go everywhere), or just run a quart (or so) of fluid through the master when bleeding. Bleed until the fluid runs clear to be sure you got all the old fluid out.



#14 difrangia

difrangia

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 1,019 posts
  • Location:SE Oklahoma
  • Cars:78 620 Longbed, '63/64 NL320, '64 Beetle Type 117 Ragtop, 61 FIAT 500D, 3 Vespa Scooters

Posted 25 April 2017 - 01:00 PM

In the course of the 'Mighty Mouse' 320 project, over the past couple years, I've gravitated to juicing up the hydraulic systems from the slave cylinder back toward the master. It's a one person job. As Matt added, If you're adding new equipment upstream ( master, Proportioning valve, etc.) the old lines should be flushed to avoid introducing old fluid/crud into the new machinery upstream. 

Steve



#15 320 Newb

320 Newb

    Advanced Member

  • Members
  • PipPipPip
  • 248 posts
  • Location:Tucson
  • Cars:Datsun 320

Posted 25 April 2017 - 07:02 PM

Does anyone know what size stock 320 brake lines are? 



#16 datzenmike

datzenmike

    KING RAT

  • User Administrator
  • 70,327 posts
  • Location:Vancouver Island
  • Cars:'74 710 sedan, '76 710. prevoius... '78 620, '71 521, '68 510 new '76 B-210

Posted 25 April 2017 - 07:17 PM

Or make a spacer for the fire wall and shim the master outward. Aluminum is easy to work with.


Posted Image

#17 Stoffregen Motorsports

Stoffregen Motorsports

    Datsun Mechanic

  • Senior Member
  • PipPipPipPipPip
  • 3,901 posts
  • Location:Cool, CA
  • Cars:http://www.4wdandsportutility.com/features/rover/0611_4wd_1957_range_rover/viewall.html

Posted 26 April 2017 - 07:28 AM

I'm pretty sure the lines are 3/16" tubing. Stock had 3/8" SAE inverted flare fittings on the 320.



#18 320 Newb

320 Newb

    Advanced Member

  • Members
  • PipPipPip
  • 248 posts
  • Location:Tucson
  • Cars:Datsun 320

Posted 26 April 2017 - 04:27 PM

Thanks! I'm thinking through the project and if I'm considering upgrading to a dual brake master. If I have to bleed the whole system anyways it seems like doing a little extra brake line work might not be that big of a deal. 

 

 

 

I'm pretty sure the lines are 3/16" tubing. Stock had 3/8" SAE inverted flare fittings on the 320.



#19 datzenmike

datzenmike

    KING RAT

  • User Administrator
  • 70,327 posts
  • Location:Vancouver Island
  • Cars:'74 710 sedan, '76 710. prevoius... '78 620, '71 521, '68 510 new '76 B-210

Posted 26 April 2017 - 04:36 PM

Dual system is the way. My first car was a '64 Dodge. Single master. I wouldn't even get in one today. ANY leak in the system and the brakes go out. When I was a kid it was common to hear on the news 'the accident was caused by brake failure'. You almost never hear this now.


Posted Image

#20 320 Newb

320 Newb

    Advanced Member

  • Members
  • PipPipPip
  • 248 posts
  • Location:Tucson
  • Cars:Datsun 320

Posted 26 April 2017 - 06:45 PM

Can anyone who's done a dual master upgrade on a 320 post a pic of how you T'ed off your brake lines? My stock set up goes to a 3-way T in the middle of the firewall where the master comes in one side and lines go out the other two, one line to passenger side and one line to the driver side.