Tilton Dual MC Setup

Arthropraxis wrote:Has anyone set this up yet that can give feedback on the pedal feel for the hole being drilled .75 vs 1.1"?

968ls1.

Dawgz83948 wrote:Priceless!!!!!

+.75" MC pushrod relocation:
6:1 Ratio:
________________________________

+1.1" MC pushrod relocation:
7.6:1 Ratio:

This modification (1.1") will yield a softer pedal, better suited to daily street driving. Track applications
using the +.75" pivot point will experience a firm pedal, especially when upgrading to larger rotors
and calipers.

I think 968ls1 will confirm this.

For the track, 1.1" may be too much pedal (too soft, and longer pedal movement).
Street cars will not likely experience brake-fade conditions, but the 3/4" modification is proven to work well for both street & track applications.

Who has done this? How do you like it?

Has anyone completed this yet? Any reports on performance? Can the tires be locked up if stomped on?

All the fittings I posted above bolted up 100% and keep the lines away from the header. I did move the larger Diameter (1") MC to the bottom so the split-tee 1/8-27 NPT to double -4AN could screw into the .70" Wilwood and the 90 degree lines exit beautifully. The stock Brake MC and Clutch MC share only one Reservoir, so I went with the Large one Provided in one of the Wilwood MC kits and made sure the top-off level was above the highest point in the feed-lines....

While looking for formulas to size master cylinders... stoptech.com, pedal setup-dual master cylinder-install guide. It's a pdf file that's not on the tech info list, but came up on a Google search.
That kind of math makes my head hurt.

Must be nice, I need to startup a brake company. I spoke with Jason at Tilton and he recommended 5/8" masters front and rear. While the rears are rock hard, the fronts go to the floor and do no stopping. He's blaming the calipers, I told him the calipers stopped just fine before and the only thing that has changed is the Tilton setup. Apparently you can recommend incorrect sizes and once installed they don't give a rats left nut about you. $90 down the tube, now he tells me to order a larger master. Anyone need a 5/8" tilton for a good price. It has never stopped a car in motion.......

Tim, I thought that Tilton had told you the wrong master size from the get-go since I was told .7 front and 1.0 for the RX7 calps and I am thinking even the .7" MC for the 4x42 calps are a little small in volume for the Tilton stroke......... That is pure B.S.

I called Wilwood and they specd out 7/8. The issue with that is 7/8 is damn close to the 23mm that stock is (.905). And we all know how well that stopped w/o power. So now I'm totally confused and have no clue what to do. Tilton also said I can try 3/4, well I can keep trying till my wife kills me since they are not returnable once installed. My machanic suggest Residual Line Pressure valve @ 2psi may work.

If you are running 944 Turbo calipers on the rear with the Lexus 4 pots on front, a 13/16" (0.8125) for the Lexus calps is what I am thinking.

Just remember, you said that the front Lexus circuit was spongy and bottoming with the 5/8". If you increase the MC diameter the pressure will decrease in relation to the volume increase, but the 4x42 piston chambers will fill much quicker and not bottom out. It really is strange, but it's called fluid dynamics....It's kinda like Obamanomics...screwy

xpost from RL thread about rotors:

"Has anyone used the LS430 fronts and decent rears in conjunction with the manual tilton dual set up yet in practice? I know Tim is working on it, I am just wondering if I should consider this my answer, or keep looking at assisted options."

This may be useful, it is a link to a spreadsheet for braking bias. Click on the link to computer spreadsheet on the bottom of the page. I need to know the distance between the MC pushrods and the distance from the MC rod to brake pedal. I put in 3 and 1.5. Does anyone have the correct numbers?

http://sports.racer.net/brake_bias.htm#Master%20Cylinders

another link with some good equations for determining MC bore size for piston area and other useful info.

http://www.pirate4x4.com/tech/billavista/Brakes/#MasterCylinders

I'm finally at the point where I am ready to bolt in the dual M/C mount, I've been wresting with ideas to seal up the hole. I think XChop said he was going to use a piece of rubber, or the old bellows from the vacuum booster. What have others here done? I thought I had a tie rod bellow from a Golf laying around that might work, but couldn't find it. Any thoughts would be appreciated.

Just a few questions
1)How much PSI of hydraulic pressure is required to lock up street tires? The best I could find is 1000-1200 PSI.
2) Does anyone have the distance between the MC rods on the tilton or wilwood?
3) Last question, what is the distance from the MC rod to brake pedal?
I am trying to use a spreadsheet that gives an idea of the correct MC size. Thanks.

1) Haven't researched that one yet.
2) Distance between the MC rods on the Tilton 72-610 is ~2.75".
3) Distance from the MC rod to brake pedal varies, as the distance from pivot to pivot (balance bar to pedal) is adjustable from 7.75 - 8.75". Overall length from MC piston to brake pedal pivot is 12.5 - 13.5".

If you need other dims, I have the 72-610 and Wilwood master cylinders here, but haven't installed them in-car yet.

Thanks, I am not sure what the last measurement is asking for. If I put in 1.5 the numbers come out to be about what is expected. If I put in a larger amount the results get smaller. Leads to another question, of course. What is the acceptable/desireable master cylinder movement?

Wilwood lists stroke for the compact remote series @ 1.12".
That may be what was meant by "Distance Front M.C. Rod to Brake Pedal=".

EDIT:
I entered 1.12 first, then changed it back to 1.5, and now I don't trust that spreadsheet.
Big difference between the two.



Based on Tilton's "conservative" sizing, specs for an '86T brake system, and what I expect from the DMC balance bar, I will be using a .625 front and .75 rear MC setup. Also, the pedal ratio becomes 6:1 if moving the pivot up the pedal .75".

Yeah, not sure what they want there. It seems to give accurate numbers (same as expected from manually doing the formula) if you stay with 1.5. It does give an idea for the brake balace front to rear and the MC stroke that would be used with different MC sizes. Somwhat usefull if not entirely accurate. The other link has the formulas and a table for MC size.

Wilwood states 1.1" stroke when I've measured all 3 (including clutch master upgrade) to be 1.25. I'm sure it's like every other spec in the auto industry....a little on the conservative side. So you have better room for error. I bleed the rear RX7 calipers this weekend and I am very happy with the firm pedal feel.

Was anyone aware of this product?
http://www.kokeln.com/dual_master_cylinder_kit.php

The knowledge and information being exchanged here is so cool!

Make me almost want to get ride of my hydroboost brakes because it does go over the drivers side valve cover and makes it hard to check and refill the oil.

Found another good post for dual MC sizing and another calculator worksheet.

http://www.hotrodders.com/forum/c4-corvette-brake-questions-80515.html

AP racing has compact MCs that have a 90deg or 60deg mounting flange.
http://www.apracing.com/info/products.asp?product=Offset+Flange+Type+%3Cimg+border%3D%222%22+src%3D%22http%3A%2F%2Fwww.apracing.com%2Fpics%2Fproductpics%2Foffset_flange.jpg%22%2F%3E-CP4623+Type_2390_2389

so, who here is now running dual cylinders, on the stock pedal?

Found these on another site from someone that has installed a dual master setup:

I have a tilton dual master setup and am EXTREMELY HAPPY with it. the bore sizes I was using was 3/4' front and 5/8' rear with big reds in front and stock front calipers in the rear. I have a balance bar inside the car. I must stress that this is a street car that I do 5-10 track days a year in, and I have no problems with pedal effort at all.The difference in brake feel and ability to modulate threshold braking is every bit as communicative as the skip barber formula cars in which I normally race(and were the inspiration for the removal of the booster.) This upgrade was very reasonable in cost (<1000) and I
REALLY like it.

and another about a year later by the same person

I have a tilton dual master cylinder setup that was mounted to the firewall with a bracket welded up from flat bar stock. The adjuster is just a threaded rod that varies the amount of pressure applied to each master cylinder by changing the distance of the brake rod from the center of the balance bar, a really simplistic but very effective mechanism . I'm using 7/8" front and 3/4" rear bore sizes with big reds front and '86 front calipers in the rear. I spent less than 700 on this setup and as far as bias goes, you brake hard in a straight line at threshold and keep moving the bias to the rear until you reach a point where the rears just start to lock up first... and then move the bias back to the front a little. This may change depending on track conditions, how much trail braking you have to do, etc... I really love this setup and wouldn't go back to using a booster/stock arrangement, at least on this DE car


I think the stock front calipers that he put on the rear were are 86 turbo front brakes.

Has anyone checked this out? http://www.gorillaperformance.com/
It uses a balance bar setup that attaches inside the car at the stock pedal. The master cylinders mound directly to a two piece mount that sandwiches the firewall. Looks like it would save a lot of space under the hood.