[DeTomaso] Mushy brakes

MikeLDrew at aol.com MikeLDrew at aol.com
Sat Mar 15 22:37:15 EDT 2008


In a message dated 3/15/08 5 57 39, wkooiman at earthlink.net writes:


> 4. Removing the proportioning valve - you can switch to a gutted valve if
> you want the stock look.  I was going to add an adjustable prop valve, but I
> didn't need it.  No prop valve was just right.  I removed the shuttle valve
> at the same time, but I think removing the prop valve did the trick - not
> the shuttle valve.
> 

This is a common myth, I think.   Removing the proportioning valve results in 
much more front brake application, sooner.   This gives the illusion of 
better braking, when in fact (I believe) all that is happening is that the front 
brakes are now coming on substantially sooner than they would otherwise, for a 
given amount of pedal effort.   This does not make the braking system work 
better--in fact overall it makes it work worse.   Sure, for light stops, it takes 
less pedal effort to stop the car.   But I bet that under heavy use you would 
lock the front brakes long before the rear brakes started doing anything 
meaningful.

Brake systems are just that, SYSTEMS, and the front and rear components need 
to work together.   That proportioning valve is there for a very good reason.  
 Now, I'm not necessarily advocating sticking with the stock one; if there 
was any doubt as to its serviceability (i.e. if it was leaking)I would plumb an 
adjustable valve into the front line, and actually test the brakes under 
severe use, restricting more and more pressure to the front brakes until the rear 
brakes lock up first, and then back off the restriction so that the front 
brakes lock only slightly before the rears.   This is the only way to get optimal 
performance from the stock calipers.

Mike


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