Alternate brake plumbing

Gunner · #1 (**permalink**) 10-30-2009, 09:01 AM

Nearly all modern cars have dual master cylinders that control the brakes in criss-cross "safety" fashion - front right and left rear on one circuit, the others on the other circuit. The notion is that if one circuit fails, the other will give a measure of normal braking.

Cobras use the master cylinders front and rear. I understand this gives more control for mechanical brake proportioning and balance, but as with so many other "original vs. maybe-better" choices... has anyone ever routed their brakes in safety fashion? It would be a nearly undetectible change as far as originality goes.

Thoughts?

Tommy · #2 (**permalink**) 10-30-2009, 12:58 PM

My non-expert opinion is that the criss-cross arrangement makes a lot of sense for a car with anti-lock brakes, as all modern cars have. But on a car like my Cobra without antilock brakes, its not as good a choice. If either system failed on my car, the weight on the remaining two tires would remain close to the same during hard braking, so it's unlikely that I would lock up just one of the remaining tires. However, if I had criss cross plumbing with one system failed, I'd likely lock up the brake on the one good rear tire leaving me with only one effective tire for braking. That would also make steering difficult. ... At least thats what I think until someone offers a better explanation.

Gunner · #3 (**permalink**) 10-30-2009, 01:31 PM

Cars have had opposite-corner braking long before ABS was common.

I can't see that having brakes fail on ANY two wheels is a fun situation. Having corner brakes at least ensures some modicum of control and less absolute certainty that you'll spin.

xlr8or · #4 (**permalink**) 10-30-2009, 04:09 PM

The problem is that with two master cylinders typically used in Cobra's are of different size for front and rear. This would cause the car to pull violently under braking as the front wheels would be under different fluid pressure as would the rears.

Gunner · #5 (**permalink**) 10-30-2009, 06:39 PM

Quote:

Originally Posted by xlr8or

The problem is that with two master cylinders typically used in Cobra's are of different size for front and rear. This would cause the car to pull violently under braking as the front wheels would be under different fluid pressure as would the rears.

I'm assuming that significant replumbing would be required, not just switching a line here and there. Equal-sized masters would be a start.

It seems like someone must have tried it, especially on one of the donor-part models.