Master Cyl Upgrade Push Rod Build mklotz70

[mklotz70]

Howdy :) I spent some time on this yesterday....thought I'd share a bit. I've been wanting to come out with a master cylinder upgrade kit...biggest thing to figure out first is the push rod....mainly the clevis. I've done a ton of searching and this is what I've come up with for a clevis. I'd love to find the stock style since they have a much deeper reach...so if anyone has a line on them.. :) I need to find a source for new ones. I really don't want to climb under a 100 dash boards, trying to pull clevis'....only to find out they're worn and sloppy and let's not forget dirty! I can get this style brand new, with a pin and clip in whatever quantity I want....nice and new and clean! :) Anyway....if someone has any feedback on this clevis...good or bad, please let me know.

 

Okay....I pulled a pedal assy off the shelf and got busy. First off, I had to open the hole up a bit with the die grinder and a carbide cutter. When I mounted up the m/c, I put a washer between it and the pedal assy to account for the firewall thickness.

 

 

 

 

I quickly realized that the 120mm long push rod I've been sending out is way too long!! OOPS!! Good thing I've been including them for free!!

 

 

 

 

I put the new style clevis on. This one is for an 8mm rod, but the ones I order will be for a 10mm rod. This is good enough for prototyping and proof of concept. I did a bit of measuring, a bit of cutting, a bit of turning on the lathe....I only cut it twice and it came up short both times!! Not too bad...it was only about 5mm shorter than I would have liked, but it was something to work with.

 

 

 

 

 

 

 

 

 

 

[mklotz70]

These pics are more for comparison and double checking than anything else. The new clevis is shorter, so I need to have the rod a bit longer than if it were for a stock clevis. I did another with a 10mm bolt and stock clevis just to see how I liked the 10mm version. I'll make 100mm x 10mm long rods for the new clevis' when they come in. The stock clevis' come with either an 8mm threaded hole or a 10mm, depending on what year of rig you pull it from. I get the 8mm ones from the clutch push rods on the older rig's. The 10mm ones, IIRC, come from the brake push rod on the 720's and HB's...and late 620's too, I think.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

My Granddaughter loves to come out and look around the shop....it's so much brighter than the rest of the house!!! :)

 

 

 

 

I wanted to see how I liked this mod to the clevis. I think I may do it to them before sending them out. If I do, I'll file it at a more shallow angle since it will gain more clearance. The back of the brake pedal arm could be filed a bit too....which may be the better way to go so that the clevis isn't compromised in any way.

 

 

[mklotz70]

Since it's pretty dang hard to do this in the truck, I marked the pedal while it was pushed all the way to the floor and took the assy back out. The concern is that the clevis will meet the pedal arm before the pedal arm meets the floor. I don't want it to be in a bind. The filing adds a bit more clearance so that the push rod ends up below center when fully pressed. Posting this has giving me a couple more ideas to play with today if I have time.

 

 

 

 

 

[mklotz70]

It just dawned on me....I needed a push rod for Mend....so I've actually worked on Mend for the first time in months!!!! Yea!! Two birds with one stone!! :) LOL

[banzai510(hainz)]

My 521 the Beck Arney brand clutch Master the rod is too long.

I put the nut on and cut the a certain amount of threads off then unscrew the nut and it cleans the threads.

 

My Rebestos brand clutch MC has a shorter rod I believe.

 

So not all are the same between brands

[vdubjim]

http://www.mcmaster.com/#clevis-rod-ends/=bqai80

 

cheap

[mklotz70]

My 521 the Beck Arney brand clutch Master the rod is too long.

I put the nut on and cut the a certain amount of threads off then unscrew the nut and it cleans the threads.

 

My Rebestos brand clutch MC has a shorter rod I believe.

 

So not all are the same between brands

 

I just use the clevis, so the rod length doesn't really matter to me :)

 

 

http://www.mcmaster.com/#clevis-rod-ends/=bqai80

 

cheap

 

Thanks. I've actually checked them out. I really want to use an M10 rod. Their clevis for that rod doesn't have an m8 pin hole. I'd say "affordable", but maybe not cheap. If I order 25-50 of them....that's a chunk of change. I do get a lot of bolts from M-C.....they ship really, really fast!!!! Depending on the bolt, they're cheaper than the box price at Tacoma Screw.

 

....but they do have a deeper clevis....if I were to go with the 8mmx1.25 thread and 8mm pin.....but it's over $7ea.

[vdubjim]

http://clevelandcityforge.thomasnet.com/product/all-categories/clevises-2?

 

What if you just made them? Take whatever size nut fits the rod, and use 12ga or whatever, bend it drill it and weld the nut.

[mklotz70]

I enjoy the prototyping.....don't like the production. I'm at the point I'd much rather buy something pre-made. I would enjoy making the tooling to stamp that piece, but if it fails, all the liability is on me.....I'd rather get a pre-made one :)

 

Besides....the amount of fab time that would take for each one.....it would be a lot faster to pull them out of the s/y. The reality is that I could simply provide the rod and let the buyer find his own clevis.....which is how I've been doing it. :) Some guys don't have access to s/y's and trying to buy these by the each's is a pain.

 

Keep trying....you might find me one yet! :)

[Pacific coast Datsun]

Nice R & D work MIke. You have tremendous patience :)

[mklotz70]

Thanks!

 

The r&d is interesting to me.......patience is putting a couple thousand spot welds down when you cut your roof off!!! That I don't really have! :)

[Charlie69]

Mike I am pushing hard right now on my truck, I will get some pictures of the setup I am running and also of the rod you made for me.

 

This is a must when you are doing different assemblies than stock.

 

Thanks again Mike.

[Pacific coast Datsun]

""The r&d is interesting to me.......patience is putting a couple thousand spot welds down when you cut your roof off!!! That I don't really have! :) ""

 

 

 

998 to be exact :D

[]2eDeYe]

""The r&d is interesting to me.......patience is putting a couple thousand spot welds down when you cut your roof off!!! That I don't really have! :) ""

 

 

 

998 to be exact :D

 

 

:lol:

[mklotz70]

****was a waste of reading time. lol

Edited August 15, 2020 by mklotz70

[Charlie69]

This is the rod Mike made for my 66 520.

 

 

 

Using a 620 spacer, a 81 310 booster, and a 81 280ZX master cylinder.

[CoilOVerKid]

Question, I have 15/16 280ZX M/C, I have been using the stock 510 push rod. Should I be using a different push rod? Or is the stock 510 rod good? I've always wondered.....

[DanielC]

"Question, I have 15/16 280ZX M/C, I have been using the stock 510 push rod. Should I be using a different push rod? Or is the stock 510 rod good? I've always wondered....."

 

Does ther car stop when you push on the brake pedal?   If it does, and the brakes release completely, it is probably OK.

[mklotz70]

Question, I have 15/16 280ZX M/C, I have been using the stock 510 push rod. Should I be using a different push rod? Or is the stock 510 rod good? I've always wondered.....

 

Like Daniel said......if it's working.....it must be OK :)

 

The trucks and the 411's has single reservoir m/cs and captured push rods.  The 510 came with a dual reservoir m/c, just like the 280, but they're different bores.  They both have removable push rods and should be pretty similar, even though the 280 had a booster. 

 

When your brake pedal is all the way up, your push rod should have just a little wiggle to it.  When you push the pedal down, that wiggle should go away within the first 1/4-1/2" of pedal movement.

[Charlie69]

Great explanation Mike.  You amaze me Mike, you are very technical and still can put it in words that us average minded people can understand.

[Icehouse]

Mike I don't like how the non captured rods can fall out, it happened to a friends car and his brakes failed.  What I've been doing now is using the original 510 rod with capture washer.  To make it work I pull the guts out of the master that doesn't have the captured washer and machine the piston a washer thickness shorter.  This way the captured rod can be used again and still allows the master to return far enough to release the hydraulic pressure.  

[CoilOVerKid]

Thanks guys

[mklotz70]

That's a lot of work that the average shop guy can't do.  There had to have been something else wrong.  The rod extends into the cup about 3/4" just to make sure that it can't fall out......even if the cup sticks and stays down in the bore.  The clevis end would have to come off the pedal for it to fall out. 

 

So, the stock 510 m/c has a captured (mushroom end) m/c?  I thought I had a post or pics up of the stock pushrod, but I'm not finding them right now.

[mklotz70]

Found a couple with the truck m/c pushrod.  The stock is the one with the mushroomed head on it....bottom in the first pic and second in the top.

 

 

[Icehouse]

Yes the problem was the lock nut of the clevis came loose and the rod was able to thread into the clevis just enough to fall out of the master.  If the rod had been captured in the master it wouldn't have happened.  I know it was only due to a failure of assembly.