David Salama

I have a cracked rotor from overcooking my brakes at the last DE, so I decided to get a set of Big reds. Does anyone have an adjustable brake bias valve that can explain how it is hooked up, if it's in the cockpit, and if it's easy to set up correctly. Whare did you get yours from, and about how much are they? I am thinking about putting my front calipers in the rear as well to take advantage of the larger pistons. Given this, I am not sure how much rear brake bias I will need.

David Salama

Bump--anyone?

Dave E

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, but of course I would be put in GT 3 or something if I tried to race this car, and then I'd be a back marker due to the competition. P.S how do you like the Cobra seats? I'm looking at a pair of those (Imola GT) now.

David Salama

Dave,

I have never heard of doing dual master cylinders before. Very interesting however. Is there a reason you went with 86 front rotors instead of your 89s. Is there a fitment issue? The Cobra seats are top quality and look great. They are nicely paded, but not overly padded. They are lighter and cheaper than the equivalent Sparco seat. They are made of Kevlar instead of fiberglass. With the sliders and side mount, they are fairly high. I'm 5'9" and find them perfect. If you are any taller, you would have to skip the sliders to mount them lower.

Dave E

I used the '86 front calipers in the rear due to their larger bore sizes compared to the stock '89 rear calipers. This provides a better balance front to rear, but I do have to be careful to change the pads a little earlier so the pistons don't come out of the bores too far. I haven't actually had this happen but I think it might be possible so it's more of a preventive action than anything else.

David Salama

Dave,

My question was actually why you used the 86 front calipers instead of your 89 front calipers in the rear? Thanks.

Danno

"but I do have to be careful to change the pads a little earlier so the pistons don't come out of the bores too far"

You can make a shim from some old brake-pad backing plates to make up the differences in rotor thickness.

"My question was actually why you used the 86 front calipers instead of your 89 front calipers in the rear"

Because of the mounting. The '89 rear calipers mount axially just like the '86. However, the '89 front calipers are radially mounted.

An adjustable bias valve is the same as the fixed-value one that came on the car with an inlet and outlet port. Any shop that has brake-line flaring tools can fit it into the stock location.

Here's a Tilton adjustable prop-valve for $60 from TrueChoice:

<a href="https://secure.vbcomm.net/store/detail.asp?part=A0707+BLACK" target="_blank"> <img src="https://secure.vbcomm.net/storephotos/A0707BLACK.jpg" alt=" - " /></a>

<a href="https://secure.vbcomm.net/store/detail.asp?part=A0707+BLACK" target="_blank">https://secure.vbcomm.net/store/detail.asp?part=A0707+BLACK</a>

jabbadeznuts

Kokeln makes a dual master cylender for the 944. It seems that a dual set up would make bias REALLY easy to adjust.