[DeTomaso] Trying to diagnose weak brakes

Sat Feb 17 10:35:16 EST 2018

Thanks Mike.  I may go ahead and swap the master.  I definitely have rear brakes as that's where most of the brake dust seems to accumulate - much more than the front wheels, but there's much bigger hoop surface to collect it.

What recommendations from you and the rest on a master cylinder?

Mike Thomas

-----Original Message-----
From: Mike Drew [mailto:MikeLDrew at aol.com] 
Sent: Friday, February 16, 2018 9:00 PM
To: Mike & Elizabeth Thomas <mbefthomas at comcast.net>
Cc: Paul Timko <thedrol at pobox.com>; List DeTomaso Forum <detomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] Trying to diagnose weak brakes

Mike,

Either a bad master cylinder or mega air in the lines. 

A failed booster gives a hard pedal, feeling just like when the engine isn’t running. 

I hope your proportioning valve isn’t gutted. If it is, you effectively have no rear brakes.....

Mike

Sent from my iPad

> On Feb 16, 2018, at 20:56, Mike & Elizabeth Thomas <mbefthomas at comcast.net> wrote:
> 
> There is probably 3-4 inches of travel at the pedal on the first pump and no change to the second or beyond.  It's hard after those 4-5 inches, does not feel like it's bleeding down.
> 
> Mike
> 
> -----Original Message-----
> From: DeTomaso [mailto:detomaso-bounces at server.detomasolist.com] On 
> Behalf Of Paul Timko
> Sent: Friday, February 16, 2018 7:38 PM
> Cc: List DeTomaso Forum <detomaso at server.detomasolist.com>
> Subject: Re: [DeTomaso] Trying to diagnose weak brakes
> 
> How does the pedal feel with the engine off just sitting in the garage?
> Does it take a lot of movement before it catches?  What about the second pump?  The pedal should have no give after the first press. High and hard.
> 
> Paul #9270
> 
>> On Fri, Feb 16, 2018 at 8:51 PM Mike & Elizabeth Thomas < mbefthomas at comcast.net> wrote:
>> 
>>   I've been working through trying to figure what seems like a weakness
>>   in my brakes on 6328.
>> 
>> 
>>   How do they feel now?  There seems like a fair bit of pedal travel
>>   before they start to hook up.  Once they hook, they're fine when I'm
>>   just in normal traffic and stop and go.  If I have to stomp down on
>>   them, it just doesn't seem like they're biting very well.  If I have to
>>   really stomp on them, I can't get any wheel to lock up at all.
>> 
>> 
>>   Current setup:  the brakes are stock Girling, rebuild in 2004. they've
>>   been fully bled at Les Schwab 6 months ago with DOT 3 (they wouldn't
>>   use DOT 4 as it was not spec).  Yes, they were aware that there were
>>   two nipples on the front, the tech that handled me has 2 or 3 Panteras
>>   that come in through the year.  The flex lines were replaced with
>>   stainless lines in 2004 when all of the calipers were rebuilt.  The
>>   vacuum line from the engine to the tube and tube to booster is recent,
>>   about 3-4 years ago.  So far as I know, the proportioning valve has
>>   been gutted, but not really sure nor know how to be sure.  The master
>>   is an early `80's GM/Cadillac replaced about 10 years ago, the same was
>>   in the car when I bought it in `04.  I've just replaced the Porterfield
>>   R4S pads.  It was rather cold day when I went out to burn them in so
>>   first speculation is that they are not fully `seasoned'.  However, they
>>   feel about the same as the previous 10-yr old R4S's, and that wouldn't
>>   explain the pedal travel.  The booster is original so far as I know.
>> 
>> 
>>   First question, how much pedal travel should there be before the pedal
>>   feels resistance the brakes start to take up?
>> 
>> 
>>   So, what else can I check/do out to figure out why my brakes seem so
>>   lazy.  I will try to re-season them when the weather gets warmer, but
>>   that won't deal with pedal travel.  When brake booster starts to fail,
>>   how does that happen?  Gradually or all at once?
>> 
>> 
>>   Your input is appreciated and eagerly awaited.  I'd like to get this
>>   figgered before the season starts as everything else is running a well
>>   as it ever has.
>> 
>> 
>>   Thanks
>> 
>>   Mike Thomas
>> 
>>   Pres., Panteras Northwest
>> 
>>   206-795-3302
>> 
>>   Yellow '74 #6328
>> 
>>   [1]www.panterasnorthwest.com
>> 
>> References
>> 
>>   1. http://www.panterasnorthwest.com/ 
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