Running four front calipers?

Hi Ulix

The front does have the two lines coming out of the master cylinder for the front calipers. I just plug one of them by welding the tubing end of the fitting and screwing it back into the master cylinder port. The other master cylinder port goes to the safety valve so I run a line from the output of the safety valve to a proportioning valve then out of the valve to a 3 way block with one port going to one front wheel and the other port to the other front wheel. I use a Wilwood proportioning valve. You can't use a Tilton valve on the front because it is a duel pressure valve that reduces pressure at a certain point. The Tilton is for the rear brakes where the pressure is reduced as weight transfer increases. There are more complex valves that connect to both front and rear lines but that is more complex to plumb and I don't see any advantage with our cars given the small rear brakes. Remember this setup will increase the braking pedal effort but it also stops the premature front lockup. I leave the valve under the dash close to master cylinder so I can reach under the dash and make any adjustment as needed but only while stopped. If you want to make adjustments while the car is moving then the valve will need to be placed where it can be reached while the car is moving.

Good luck
Charlie
 
Alterations to the brake master front caliper ports are the same as if the exxe cylinder is used on the Lancia Scorpiacarlo, one of the ports is plugged off. Another way to plug the port is to use a copper sealing washer with a small head M10x1.25 screw not much longer than 10mm, ball bearing between the port seat and tube nut has been reported as another way by some of the Lancia folks, bubble flared tube with a brazed in plug on the end of the tube would be another way.

Adding the front limiting valve was done when the pedal box on the 74' was rebuilt. Details are here:

http://xwebforums.com/forum/index.php?threads/25800/

Part two:

http://xwebforums.com/forum/index.php?threads/25869/



Bernice
 
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With all the discussion on MC compatibility I thought I would mention that on my track day 128 I had WHOA brakes (Wilwood calipers) on the front and 124/128/X front calipers on the rear. Initially it would easily lock up the rears but of course this was a front wheel drive car with NO weight on the back. I installed an adjustable bias valve on the rear line and got the balance good. This was with a stock 128 MC (actually the same as a 124 MC) and the brakes worked fine with excellent pedal feel even though I now had four piston calipers up front and front calipers on the rear (replacing the drum brakes).

Theory is great but sometimes you just have to get out there and try things in real life.
 
Great job Repunzel

Pretty much the same as I did except mine is not as involved and not nearly as pretty as yours. I did make one change though. I put my proportioning valve after the pressure safety switch where yours is before the safety switch. The reason was that I didn't know what differential of pressure between front and rear brakes was required to operate the safety switch and was concerned that reducing the front pressure might operate the safety switch. I assume that your setup didn't operate the switch so I was probably over cautious.

Good job
Charlie
 
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