Late 60's/early 70's Clutch Master Cylinder Tech

[cruiseroutfit]

Alright, I've been banging my head against the wall on this one today.

The 9/1966-7/70 4x Series (OE# 31410-60021 our part# CLN60021N) clutch master cylinder appear nearly identical to the 7/1970-1/75 4x/5x (OE# 31410-60022 our part# CLN60022N) cylinder, both have this shaped casting:

(31410-60022 variant shown)

Differences are the reservoir style and apparently the hard line junction, bolt and washers/gaskets shown here:

Question 1: So about that bolt, gaskets (copper washers) and union. The EPC parts references are showing the earlier variant as 11mm and the late 7/70+ as 10mm. Can anyone confirm the earlier model uses the 11mm. Is it 11 x 1.0mm or 11 x 1.25mm?
(Update: I'm quite confident it is 11x1.25 in the casting)

Question 2: So the hard hydraulic line that attaches to the union: The 7/70+ is the standard 10mm flared fitting and I'm 60% sure the 9/1966-7/70 4x Series union uses the 9mm found on the brake components of the same vintage. Does this jive? Or does the older union use the 11mm fittings like some of the early clutch slaves? Anyone have one handy to inspect & measure against a known 10mm brake flare fitting?

As the main cast and bore are essentially the same. It might be possible to source a union that has the 10mm bolt but the 9 (or is it 11mm) fitting as to allow use in a 9/1966-7/70 4x Series

 

[Poser]

The early clutch master is like the early brake master on the 06/70 and earlier 40s, and the 11mm line threads into the adapter fitting on the end of the master cylinder, like the brake unit has the 9mm line adapter.

Pretty sure Mike Davidson detailed all this in the 25 section some time ago.

 

[Landpimp]

Yes, you can use the brake master(I know OEM is available) with line that exits out front as a clutch master, just change the 9mm end cap with the 11mm cap and leave out 1-2 parts per the 25 post. if you use the style you show, the stock hard line won't work(at least up to 65)

Funny I just picked up a pile of NOS OEM parts for mid 60''s, new tin cup brake master, both new 9mm and 11mm hoses, all rebuild kits, 9mm cylinders , slaves etc. just a month before I redid it all with SOR parts and what OEM I could get.

 

[Landpimp]

Early clutch master tin cup type

 

[lc69hunter]

I still have my original 09/69 clutch master on (rebuilt several times), but have one sitting on the shelf from a 72. You have me curious. sometime in the next couple of days I will check.

 

[cruiseroutfit]

The early clutch master is like the early brake master on the 06/70 and earlier 40s, and the 11mm line threads into the adapter fitting on the end of the master cylinder, like the brake unit has the 9mm line adapter.

Pretty sure Mike Davidson detailed all this in the 25 section some time ago.

Mike did a great job detailing the retrofit. The E-9/66 clutch master is like the E-7/70 brake master and the two can be retrofitted but the 9/66-7/70 clutch master is different (pictured above). I'm confident the thread in the cast is 11x1.25mm for the 60021 and 10x1.00mm for the 60022. What I'm really curious on is the size of the hard line going into the union. I've seen references for both 11x1.0 and 11x1.25. I do have a union on order from Japan, we'll see if they actually fulfill it. I'll update when I get it.

 

[cruiseroutfit]

I still have my original 09/69 clutch master on (rebuilt several times), but have one sitting on the shelf from a 72. You have me curious. sometime in the next couple of days I will check.

Sweet

 

[Conrad67FJ40]

I found these parts from Exedy.
MC294 - EXEDY OEM Clutch Master Cylinder - EXEDY Globalparts - Performance and OEM Clutches and Flywheels
says it fits a 67-70 clutch master cylinder. also on amazon
https://www.amazon.com/gp/product/B0049U04E4/ref=od_aui_detailpages00?ie=UTF8&psc=1
I'll let you know how it fits.

 

[S4Cruiser]

Not sure if this was ever concluded @cruiseroutfit

I was assembling the clutch components on my early FJ40 yesterday (early 67 style with the all metal dash). I am using a replacement clutch master and slave from you guys and was attempting to salvage my original hardline.

Unfortunately since I converted the brakes to a geo metro boosted setup, the OG clutch hardline won’t work as it hits the booster.

I was able to get the hardline fitting removed from the union and the female fitting for the union is NOT m10. A m10 tube nut is too small. M11 for sure but the threads aren’t clean enough to say if they a m11x1.25 or x1.0.

The male end (m11x1.25) of my city racer reproduction hose threads into the union easier then threading the tube nut I removed from the union into the female end (m11-1.0) of the city racer hose.

Since I already have a new master, slave and hose that match, I’m going to try and reuse my original tube nuts and bend up a new hose (1/4” tube vs the 3/16” used for brake lines).

Is there a source for the union at the master cylinder and m11x1.25 tube nut? My interwebs searches show squat.

 

[Luckyguy33]

Just reviving this thread to try to gain some knowledge and help, in the middle of rebuilding my OG 9/66-1/75 clutch master. and parts fell over the counter lost sequence to how cylinder cup part 16……which direction does it go into the master cylinder body…..is it flat washer, cylinder cup facing out towards front or in towards firewall. The pictures aren’t very clear I believe I have it correct but want to make sure before reassembly. Thanks for any help!!

 

[Pighead]

Just reviving this thread to try to gain some knowledge and help, in the middle of rebuilding my OG 9/66-1/75 clutch master. and parts fell over the counter lost sequence to how cylinder cup part 16……which direction does it go into the master cylinder body…..is it flat washer, cylinder cup facing out towards front or in towards firewall. The pictures aren’t very clear I believe I have it correct but want to make sure before reassembly. Thanks for any help!!

Pretty sure that you want the cup towards the fluid outlet

 

[Luckyguy33]

Pretty sure that you want the cup towards the fluid outlet

View attachment 3704462

Thank you, double checked and all was correct, installed and bled ready to go!,

 

[nachohouse]

Thank you, double checked and all was correct, installed and bled ready to go!,

I’m embarking on the same project for my 2/70 master cylinder. Where’d you source a rebuild kit? Did you replace the slave? How’s your pedal feeling now? Mine feels like stomping in a bowl of oatmeal right now.

 

[Luckyguy33]

I’m embarking on the same project for my 2/70 master cylinder. Where’d you source a rebuild kit? Did you replace the slave? How’s your pedal feeling now? Mine feels like stomping in a bowl of oatmeal right now.

For starters, I rebuilt due to it leaking out the rear of the master into the cab along the plunger rod, pedal had decent pressure before and wanted to get the leak taken care of. Sourced the rebuild kit from Cruisercorps, ordered it then worried if my body was too pitted to accommodate the new seals as apparently this can be a big issue with the old cast masters, it wasn’t and Slave was fine and reused. Did a little painting to refresh parts while waiting for my rebuild kit, added all parts and even ensured with the help of the comment above for placement of seals as the diagram doesn’t really identify it well. Bench bled and installed master, with the help of the young lad pumping the pedal and bleeding at the slave all went well. It’s takes about a 1/4 more force to push the pedal down before and all works well and has amazing pressure now. I’d suspect if yours is just mushy then it’s most likely the plunger seal that’s toast allowing the oil to revert to the rear of the master around the seal. But best of luck!!