Wilwood Dual Chamber Brake Master Cylinder

[Sam Buchanan]

52 minutes ago, James_Douglas said:

I do not know who did the work. I happen to have a Logan gear cutting lathe, but fine threads are fun to do...

 

Any good general machine shop should be able to cut the threads without any issue.  I just happen to like the design as it screws right into the back of the MC and does not need any modifications to anything else.

 

Maybe I will ask my local shop what he would charge me on his big ass CNC to design up the program and run a couple off for me.

 

James

 

 

Be prepared to pay!!  ?

[sjaakslinger]

@Sam Buchanan

 

I see this is an older thread, but I'm considering going this route as well to upgrade to a dual master setup for my stock drum/drum brakes.

 

I was wondering though how this 1" master cylinder performs better than the previous 1" you tried in another thread. Wouldn't a 1 1/8" bore like the original mc be a better match? How is the braking experience after the installation of this setup?

 

Thanks.

 

Dennis

[Sam Buchanan]

I suggest a 1 1/8" bore, the 1" bore of the Wilwood I have works fine but I think the pedal would be firmer with the larger bore. However, I am running disks on front so my experience might not match what you find with drums on front. Once we start mixing non-standard cylinders and brakes we are in the experimental realm.

[sjaakslinger]

I'm wondering if an aftermarket 1 1/8" bore mc displaces enough brake fluid. The original mc has a pretty large stroke, so I suppose that should be matched on an aftermarket one when sticking to drums/drums. 

 

Anyone here who stuck to drums/drums with a dual mc setup?

[rcl700]

I have never seen this post and feel it's a great option. Im considering sams setup for my p15. I'm not loving the idea of single pot for front and rear. My stock MS needs to be replaced so this my be a good option. 

Edited February 1 by rcl700

[sjaakslinger]

@Sam Buchanan

 

I read your first post again. I'm considering this same setup. I wrote Wilwood for advice on the 1" and 1 1/8" bore. The 1" bore version you used is, acc. to them, an oem mc used on multiple applications. That's why that mc is around 188 dollars and the 1 1/8" version 300. According to them the 1" should work fine indeed, also on drum/drum. They also adviced looking at an underfloor brake and clutch pedal unit from classicperform (CCP). That would eliminatie the stock mc and pedals, but will probably need some fabricating. 

 

Do I understand correctly you initially had this setup with drums/drums and switched to discs at a later stage? If so, any recollection on the braking with this setup with drums/drums? Did you use the built in residual valves or external ones?

 

Thanks.

 

Dennis

[Sam Buchanan]

1 hour ago, sjaakslinger said:

@Sam Buchanan

 

I read your first post again. I'm considering this same setup. I wrote Wilwood for advice on the 1" and 1 1/8" bore. The 1" bore version you used is, acc. to them, an oem mc used on multiple applications. That's why that mc is around 188 dollars and the 1 1/8" version 300. According to them the 1" should work fine indeed, also on drum/drum. They also adviced looking at an underfloor brake and clutch pedal unit from classicperform (CCP). That would eliminatie the stock mc and pedals, but will probably need some fabricating. 

 

Do I understand correctly you initially had this setup with drums/drums and switched to discs at a later stage? If so, any recollection on the braking with this setup with drums/drums? Did you use the built in residual valves or external ones?

 

Thanks.

 

Dennis

 

Dennis, I converted to the Wilwood m/c at the same time the disc brakes were installed so have no experience with the cylinder/drums combination. My comment about the 1 1/8" was due to the pedal on my car not being as firm as I expected. As a rule of thumb a larger bore will move more fluid but require more pedal effort. But my brakes work fine and I think your installation will be fine. When we move away from original equipment we sometimes have to be willing to experiment a bit. 

[sjaakslinger]

Ah, ok, thanks. Yeah, I'm inclined on using the 1 1/8" bore from Wilwood, but $300,- is a bit steep. I'll give it some more consideration.

 

Dennis

[Sam Buchanan]

I don't know which requires more fluid volume to be moved, drum wheel cylinders or disc pistons, so I don't have a definitive answer on which Wilwood master cylinder is optimum for our application. I added a proportioning valve to the rear brakes but don't see any difference in pedal pressure regardless of how the valve is adjusted. I'm satisfied with the brakes especially when considering the limited traction allowed by the bias-ply tires I use.

 

I failed to address your question about residual valves. I don't have any external valves installed and don't think they are needed. However, I have disc brakes, don't know if that makes a difference.

Edited February 14 by Sam Buchanan

[Los_Control]

Not sure if relevant here .... My chebby truck with disk front drum rear. The smaller MC chamber feeds the rear drums.

The MC is divided into 2/3 front 1/3 rear.

Disk requires more fluid because the calipers are larger and more volume then drum wheel cylinders.

 

FWIW my dual circuit Toyota MC shares 1 bowl for both circuits .... is that the same as a single circuit? 🤔

 

My limited knowledge, I remember a larger bore will move more volume, smaller bore will deliver more pressure.

Like the tip on a pressure washer, the smaller the diameter tip the more pressure.

So it is a fine line to get enough volume for larger disk, too much volume and get a soft pedal.

Too little volume and need to pump to fill and get firm pedal

This makes my head hurt    😆

[sjaakslinger]

I think disc pistons. They do have a larger volume chamber on master cylinders. I guess the 1" bore should work fine on my stock drums/drums. If I reason correctly, a smaller bore mc means more force at the wheel cylinder (at same pedal force). Apparantly not so wise when using bias ply tires I read, but I'm running radials.

 

I did some research on the tandem master cylinders. Seems the one you have has built in residual vaves for drums. The more expensive ones in variabele sizes would need external residual valves when using drum brakes.

[Los_Control]

2 hours ago, sjaakslinger said:

I guess the 1" bore should work fine on my stock drums/drums. If I reason correctly, a smaller bore mc means more force at the wheel cylinder (at same pedal force).

That's the way I understand it also .... I feel the engineers spent a lot of time to figure out what is needed for these cars.

 

If you were building a custom race car with huge disks and 4 piston rotors .... you will need to be a engineer and calculate all the necessities.

2 hours ago, sjaakslinger said:

Seems the one you have has built in residual vaves for drums

That is true, they do have residual valves built in for proper fluid disbursement .... same time, with a single reservoir we kinda lose the security of a dual chamber MC.

If a rear wheel cylinder blows and drains the single reservoir ... no brakes work.