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A One Inch Diameter Brake Master Cylinder for the S30 Z Cars


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After having my 1" Wilwood master on the shelf for about 2 years I finally did this swap about a week ago. I have the modern motorsports rear disc package with the Toyota fronts and had the 7/8 OEM master.  It seemed like it worked pretty good that way so wasn't in rush. 

 

Followed the procedure here and it worked with no surprises. Just had to adjust my brake rod out a bit. My Wilwood 1" master had check valves in both ports so removed them. My OEM master did have the check valve in the rear port (never seemed to drag at all though). 

 

I don't think its a major difference but is definitely noticeable. Pedal effort is about the same but it wants to grab harder. Seems to make the rear discs work better at first impression. Certainly looks better with the rest of the new parts under the hood.

 

I now have a Nabco 7/8 master in the parts pile.

Edited by Aero Z
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My 1" Wilwood seems to have low pedal.  I think I need to revisit my booster pushrod.

Running race pads and fresh fluid but with the booster the pedal is just lower than I want it.

 

Guess I would need to max out all the adjustments to get the most upright pedal I can?

 

I have the 1 inch Wilwood MC with Toyota solid calipers on the front and 240sx calipers on the the rear with all adjustments, including the push rod,  verified and no air in the lines. I have a long slightly squishy  pedal  which becomes firm after about one inch of travel.  Many other people have made this same complaint.

 

The long pedal is a pain, so I researched the 240SX caliper design. The 240SX caliper has a low drag design (look it up) which means that the seals are designed to pull the piston away from the rotor which means that moving the piston takes a bit more fluid volume to bring the pads  in contact with the rotor. I verified this by looking at 240SX master cylinders and sure enough they are of the  "fast fill" step bore design as indicated by the bulge on the side.  The"fast fill" MC provides an initial additional volume of fluid to push the piston out of the caliper to reduce time for the pads make contact with the rotor.

 

I now believe that this may explain why there are many complaints about a long pedal or squishy pedal by people who have done the 240SX rear caliper swap.

 

I have been researching  the pros and cons of installing a 2psi residual pressure valve on the rear brake line coming out of the MC to offset the lag time (volume) required to bring the piston out of the bore.  Some hot rod blogs make this recommendation to fix the long pedal issue common to drum to caliper swaps: http://www.hotrodders.com/forum/low-drag-caliper-replacement-110823.html

 

 

I am still researching the viability of installing the 2psi residual pressure valves. 

 

Note: The first two Wilwood MCs I bought both leaked internally out of the box. So far the third MC has held up for three years.

Edited by Miles
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Hmmm...interesting. I have the vented S12-W on the front and the 240SX solid on the rear. After fighting an issue with the reaction disc in the booster - I have it sorted. Reaction disc now glued into place....I can't tell the difference in pedal between my stock 78 setup and the Yota setup. You may have a little more adjustment to do with the booster rod AND/OR your pedal travel/adjustment at the pedal itself. It's in there....mine works perfectly....you just gotta futz with it a little bit. Solid pedal from initial push.

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  • 3 months later...
  • 2 months later...

Yes ^ the spring and the valve gets removed. Mine only had the check valve and spring in the rear cylinder. Doesn't speak too well about Wilwood quality control if some boxes ship without the valves, some are installed in both cylinders and some in only the rear. 

 

 

DUMB QUESTION: how the heck do you guys bench bleed the master cylinder and then install it in the car without getting fluid all over the place? Drip drip drip drip drip

Edited by thedarkie
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Yes ^ the spring and the valve gets removed. Mine only had the check valve and spring in the rear cylinder. Doesn't speak too well about Wilwood quality control if some boxes ship without the valves, some are installed in both cylinders and some in only the rear. 

 

 

DUMB QUESTION: how the heck do you guys bench bleed the master cylinder and then install it in the car without getting fluid all over the place? Drip drip drip drip drip

 

You can use small black rubber stoppers available at the hardware store or you can buy brake line plugs with the correct threads and inverted flare shape.

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Fair suggestion, I'll try to find some before I install it. 

 

Another question: has anyone tried installing it and bleeding according to Wilwood instructions? Their documents specifically say to install the cylinder and hook up the lines prior to bleeding, and then to run a hose from the bleeder screws into the reservoirs and bleed the cylinder in that manner. Not sure why the discrepancy between that and a more standard bench bleed procedure.. 

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thanks smoorenc and Miles for the replies

 

I've got the master in, the front side works fine, bled fine, and seals fine. The back brake line leaked. I bought a new line with flared ends and bent it to shape, installed...... and it still fuggin leaks at the flare. 

 

Has anyone used conical copper washers for the flare seal? I really don't wanna keep buying new brake lines if they're all gonna leak. I used the Brakequip BQ50 fittings on the master to accept 10x1 metric threads... it worked fine for the front brake portion so I know the adapter is good. 

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Update, and confirming a few tips for future reference. 

 

You don't have to bench bleed this master cylinder. Wilwood's instructions state that it should be installed and hooked up, and then the bleeders on the cylinder used to do the initial bleeding. I did it this way and it worked just fine. I went on to bleed the brakes and very very little air came out of only one of the 4 calipers.

 

Also, if you're flaring your own lines, or buying a pre-flared one and bending it to suit... make damn sure that the bends are accurate and there's no sideways tension on the brake line, otherwise it won't seal. If you can't get the nut to thread without much effort, there's something wrong and it will leak. 3 lines later and a bunch of brake fluid (and cursing) my setup is finally up and running. 

 

Lastly, the BQ50 fitting from brakequip is what you'll want if you don't have an old master cylinder with adapters that fit the wilwood. 

 

Cheers

Edited by thedarkie
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  • 2 weeks later...

I wasn't happy with the 1" Wilwood Master.  Pedal still had too much travel.

I installed the Strange B3359TA 1.125" master and now the pedal is perfect. 

S12W with DTC60 pads front / early style 280zx rear caliper with DTC70 pads.

Good ducting and good fluid and I can push pavement for days without fade.

 

Love this new setup.

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I wasn't happy with the 1" Wilwood Master.  Pedal still had too much travel.

I installed the Strange B3359TA 1.125" master and now the pedal is perfect. 

S12W with DTC60 pads front / early style 280zx rear caliper with DTC70 pads.

Good ducting and good fluid and I can push pavement for days without fade.

 

Love this new setup.

 

What booster are you using?

 

I thought of doing the same thing, but was concerned that it would increase pedal effort or the brakes would have a wooden feel.

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I wasn't happy with the 1" Wilwood Master.  Pedal still had too much travel.

I installed the Strange B3359TA 1.125" master and now the pedal is perfect. 

S12W with DTC60 pads front / early style 280zx rear caliper with DTC70 pads.

Good ducting and good fluid and I can push pavement for days without fade.

 

Love this new setup.

Also curious about the booster.

Now I've gone for a very similar setup: s12w, early 280zx rears, but am running a late 280zx booster and 1" nissan pickup master. Luckily I'm now the horizontal master style, so I could got to the 1-1/16" z32 one if need be.

 

I'd prefer a softer than firm pedal (closer to a modern car), so we'll see how it goes.

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  • 4 weeks later...

Finally getting to finish my brake rebuild but after chasing leaks (all new Stainless steel lines) I bled the MC and all four corners (wilwood 6/4 setup) the pedal is still soft and goes to the floor. I would expect it be firm and not allow for full travel. Is this a booster rod adjustment? Also using the 280Z booster

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  • 3 months later...

I picked up Wilwood 260-8794 from amazon and there are no residual pressure valves in either front or rear. I've looked through documentation on wilwood's site and they talk about installing inline pressure check valve adapters that are external to the unit. Can someone confirm if the new design eliminates pressure check valves from the MC itself, or am I just missing something really simple?

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Could be poor quality control. I had two of the Wilwood 260-8794 MCs leak internally right out of the box. I now bench test Wilwood  MCs before installing them. Another member complained that the bleeder fittings appeared to be damaged. 

 

We remove those anyway for disk brake applications.

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I have talked with Wilwood engineers in the past.  They were very responsive helpful.  Give Wilwood a call. It would be interesting to see if they stopped including the residual pressure valves for some reason.

 

When I did the Wilwood 1 inch install a few years ago I ran the the car with the valves in place for a month and then without the valves for a month and there was no difference. At the same time I looked at some old 280ZX MCs and there were residual pressure valves in the front and rear outlets.

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