So its a slow day and this problem caught my curiosity. I am going to throw this out there but I have never seen this so I cannot vouch for it. The combination valve may be failing in such a way that it it holding pressure on the front brakes. Found a couple of instances on a couple sites were the stock one was replaced and it solved the problem. So you understand what I am talking about when I say combination valve it is the brass block that has the proportioning valve and shuttle valve in it and also has a switch in it that illuminates the brake light in the dash if you have a failure.
Most know all of this below is when swapping over to SN95 brakes on a Fox and most know this but just in case.
Typically when installing the SN95 brakes on a Fox the factory proportioning valve side of the combination valve is gutted and a solid plug is installed.
This is one place to get the plug:
After gutting the proportioning valve side of the combo valve a manual proportioning valve for the rear brakes is installed at the union that is on the firewall or at least that is a super convenient place to put it.
Factory Union
Aftermarket Manual Proportioning Valve Installed
You can get the manual proportioning valve from several different places but again MM has them. You will need the SAE one as the factory union has 3/8-24 threads. The other thing you will need is a 3-2 conversion kit so you can tie the three lines from your old Fox 3 port master cylinder to the 1993 Cobra or SN95 2 port master cylinder.
You can eliminate the combination valve all together. This will require the 3-2 kit, a manual proportioning valve, and a combination valve elimiantor kit. You install the 3-2 kit with a 1993 Cobra MC or SN95 MC, install the eliminator kit, install the manual proportioning valve for the rear brake line, and then properly bled the system.
All of the Fox to SN95 parts can be found here:
Or you can do what this guy did:
The reason I ask is I've stripped my stock prop valve when changing the master cylinder and the OEM piece is proving to be difficult to find. Also, my brakes are still stock. Has installed these with the stock brakes? If anything, I think it will look better under the hood. Edit: I realize...
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