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521 clutch master cylinder OK?


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#21 wayno

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Posted 26 April 2017 - 08:50 PM

All I did was remove the rear brake line from the "T" and plug that hole, I then made a new brake line to the rear because mine had rusted thru, but I initially cut the rear brake line and put a metric fitting on it and then double flared the end of the line, I then installed it on the new master brake cylinder, but as I said it was rusted and blew a hole in the line while bleeding the brakes so I made a new one.

 

I also had to make a new front circuit line from the master to the "T", as the master is metric, I have the tools to make my own brake lines.

 

I also used spacers to hold the brake master out a quarter of an inch, I also slotted the brake master mount holes to fit the 320 bolt pattern, you cannot just bolt a dual master into one of these trucks.


 

 


#22 difrangia

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Posted 27 April 2017 - 05:16 AM

If the 620 master is what you end up using, you'll have to deal with the operating rod length issue that Mike pointed out and the slotting of the mounting holes of the master that Wayno mentioned. Also the hole in the firewall is too small to accept the rear snout of the 620 master and will need to be opened up something like 1/16-3/32". I did away with the plumbers nightmare on the cowl and used a small brass T near the master to split the front circuit to left & right wheels and used all new line on the front system. Used the original rear line, as it was in good nick and just put a loop in it near the master to take up excess length (snipped off the flare to change from SAE to metric fitting and reflared the line). 

 

The 620 clutch master bolts in after slotting the holes in master an changing out the op-rod to use the original from the 320 master. Still in the plumbing process in this photo:

 

New%20Master%20Cylinders_zpslot6olu0.jpg


Better to have a bottle in front of me than a frontal lobotomy !!


#23 difrangia

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Posted 27 April 2017 - 05:20 AM

Rubber%20Skirt%20Left%20Re-Pop%20Install


Better to have a bottle in front of me than a frontal lobotomy !!


#24 320 Newb

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Posted 10 June 2017 - 11:11 AM

I'm doing a rebuild on my clutch master and slave cylinders. Once I've replaced the pistons and rubbers can I bleed both from the slave bleeder back to the reservoir using a long piece of tubing? 

 

*edit: The slave rebuild was a fail. I couldn't get the piston loose which I'm guessing means the cylinder is pitted. I tried soaking all afternoon in PB Blaster and using forced air to blow it out. No dice. I just bit the bullet and ordered one for $100 off eBay. Apparently the 2 3/8" bolt spacing means I get to pay more than twice what the 2" spacing slaves cost. 



#25 Charlie69

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Posted 10 June 2017 - 05:07 PM

In my opinion it is never a good idea to push brake fluid through a system and return it to the master.  I will bet it will come out dirty at first and then clean up.



#26 320 Newb

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Posted 10 June 2017 - 09:22 PM

^^At this point I'm redoing the whole clutch hydraulic system so it'll be all squeaky clean fluid top to bottom. Also I don't plan to run a tube back to the master but rather into partial bottle of new fluid. I think I have to do it that way since I'm bleeding it by myself. 



#27 Stoffregen Motorsports

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Posted 11 June 2017 - 09:48 AM

The clutch system is very simple and it is possible to gravity bleed it by opening the bleeder over a catch can and just walk away. Make sure the reservoir is full and the cap is off so it won't hold a vacuum. You can prime the system by pumping it a few times after the bleeder is opened, to get things moving. Don't let the reservoir run out of fluid or you'll have to start over.

 

If you have a helper, you can just bleed it the old fashioned way.



#28 320 Newb

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Posted 11 June 2017 - 04:52 PM

Forgive me if this is a stupid question but can you use a brake master as a clutch master? To my inexperienced eye they look like they do the same thing. 



#29 Stoffregen Motorsports

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Posted 13 June 2017 - 07:36 AM

They do the same thing, but the size of the bore and stroke may be different.



#30 320 Newb

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Posted 13 June 2017 - 01:59 PM

The bore is definitely different. 3/4 on the brake, 5/8 on the clutch.