Subject: Re: [Fot] Rear brake help needed

From: Greg Blake via Fot <[email-masked]>
Date: Fri, 7 May 2021 17:10:12 -0500

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Bob that is a hydraulic bias adjustment essentially all it does is dial back=
 the pressure available to the rears.=20

Sent from my iPhone

> On May 7, 2021, at 5:03 PM, Bob Kramer <[email-masked]> wrote:
>=20
> =EF=BB=BF
> Greg
>=20
> When we looked at it at the track the knob for the bias was way in the bac=
k on the driver shaft tunnel. I'm sure it is a smooth run from there up unde=
r the bonnet to the bias bar but maybe the cable arrangement could hold a cl=
ue. Might it hang up somehow causing the rears to change to dragging while g=
etting off and on the peddle? Running with it disconnected would tell a stor=
y.
>=20
> Bob Kramer
>=20
>=20
>> On Fri, May 7, 2021 at 3:01 PM Greg Blake via Fot <[email-masked]> wr=
ote:
>>=20
>>> =EF=BB=BF
>>> Fellow racers and breakers of parts,
>>>=20
>>> =20
>>>=20
>>> This past weekend we had wonderful racing at Eagles Canyon Raceway.  Own=
ership turned over a couple years ago and they have finished a multi-million=
 dollar renovation of the track, it is truly amazing now.  ECR has always be=
en high on my list because of its potential with the natural terrain, but th=
e lack of good construction methods had held it back since it opened.  That h=
as all been corrected now and it is truly amazing=E2=80=A6well enough on tha=
t for now.
>>>=20
>>> =20
>>>=20
>>> My problem
>>>=20
>>> For the past two years I have not been able to finish a race weekend w/o=
 completely destroying my rear brakes.  Usually related to heat build up tha=
t manifests as a blown wheel cylinder or brake shoe linings that start crack=
ing and chuncking off the shoe causing further rapid wear.  This last weeken=
d, I had a total rapid failure of the rear brakes when the right rear cylind=
er let go under hard braking from 100+ mph, I may have blown another seal in=
 the drivers compartment when that happened, but will spare those details.  L=
uckily, my dual masters allowed me to get the car slowed reasonably with jus=
t the front brakes.  For any of you that have had this happen before, you un=
derstand that with a balance bar setup, you don=E2=80=99t end up with full b=
rakes when one end fails.  The balance bar rotates significantly to the side=
 that has zero resistance.  In my case I=E2=80=99d estimate that I had about=
 20% of my front brakes available to slow the car, like I said, interesting e=
xperience that I=E2=80=99d rather not repeat again.
>>>=20
>>> =20
>>>=20
>>> My setup
>>>=20
>>> Twin Wilwood 0.7 master cylinders with a custom balance bar.  Stock fron=
t TR6 calipers and stock 9=E2=80=9D TR drums with 0.75 wheel cylinders (I=E2=
=80=99ve tried everything from 5/8 up to 7/8=E2=80=9D).  I also run a hydrau=
lic proportioning valve to be able to fine tune the rear hydraulic pressure.=
  I was running with the aluminum rear drums until I destroyed the linings l=
ast year in one of the incidents when the rear shoe linings cracked and brok=
e completely off allowing the shoe to cut groves into the drum linings. My r=
outine setup is to put the car on jack stands to adjust the brakes.  I start=
 by running the rear drum shoe adjusters in until I perceive slight drag, th=
en back off two clicks.  Then I adjust the rear mechanical bias with the bal=
ance bar until I have the front and rear brakes engaging (dragging) at appro=
ximately the same point of pedal travel.  I then fine tune the adjustment to=
 dial back the rear bias until I can threshold brake at speed and lock the f=
ronts slightly before I lock the rears.  This allows me to trail brake with c=
onfidence that I=E2=80=99m not going to swap ends because of too much rear b=
rake.
>>>=20
>>> =20
>>>=20
>>> I have used stock, portifield, and TSI drum linings all with the same re=
sults.
>>>=20
>>> =20
>>>=20
>>> I=E2=80=99m looking for a couple things from the group (no disc conversi=
on ideas please):
>>>=20
>>> What is wrong with my rear brake setup and adjustment approach?
>>> What is your setup and adjustment approach?=20
>>> Do you like the amount of rear brake you get with your approach or is it=
 a compromise to keep the brakes from failing?
>>> Lastly, I hate our wheel cylinders, its is a terrible design and I think=
 we have real junk on the market today.  I have a theory that the sliding wh=
eel cylinder assemble is part of the root cause of my failures, along with h=
eat.  The piston and seal are dealing with some severe side loading once the=
 cylinder starts sliding around to do its job and I don=E2=80=99t think it i=
s up to the task, especially what we get these days.  Has anyone modified th=
eir backing plates and shoes to use a modern day twin piston wheel cylinder t=
hat is bolted to the backing plate?  Or has anyone ditched the TR drums all t=
ogether for another 9=E2=80=9D or 10=E2=80=9D drum backing plate and guts fr=
om another source.  I=E2=80=99m open to all drum brake ideas at this point. =
 I=E2=80=99m really tired of not racing because of rear brake failures.=20
>>> =20
>>>=20
>>> Sorry for the long post and thanks in advance for your ideas.=20
>>>=20
>>=20
>> Greg=20
>> _______________________________________________
>> [email-masked]
>>=20
>> http://www.fot-racing.com
>>=20
>> Donate: http://www.team.net/donate.html
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mail.com
>>=20
>>=20

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto">Bob that is a hydraulic bias adjustment ess=
entially all it does is dial back the pressure available to the rears.&nbsp;=
<br><br><div dir=3D"ltr">Sent from my iPhone</div><div dir=3D"ltr"><br><bloc=
kquote type=3D"cite">On May 7, 2021, at 5:03 PM, Bob Kramer &lt;rkramer56@gm=
ail.com&gt; wrote:<br><br></blockquote></div><blockquote type=3D"cite"><div d=
ir=3D"ltr">=EF=BB=BF<div dir=3D"ltr">Greg<div><br></div><div>When we looked a=
t it at the track the knob for the bias was way in the back on the driver sh=
aft tunnel. I'm sure it is a smooth run from there up under the bonnet to th=
e bias bar but maybe the cable arrangement could hold a clue. Might it hang&=
nbsp;up somehow causing&nbsp;the rears to change to dragging while getting o=
ff and on the peddle? Running with it disconnected would tell a story.</div>=
<div><br clear=3D"all"><div><div dir=3D"ltr" class=3D"gmail_signature" data-=
smartmail=3D"gmail_signature"><div dir=3D"ltr">Bob Kramer</div></div></div><=
br></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmai=
l_attr">On Fri, May 7, 2021 at 3:01 PM Greg Blake via Fot &lt;<a href=3D"mai=
lto:[email-masked]">[email-masked]</a>&gt; wrote:<br></div><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px s=
olid rgb(204,204,204);padding-left:1ex"><div dir=3D"auto"><br><blockquote ty=
pe=3D"cite"><div dir=3D"ltr">=EF=BB=BF

<div>
<p class=3D"MsoNormal">Fellow racers and breakers of parts,<u></u><u></u></p=
<p class=3D"MsoNormal"><u></u>&nbsp;<u></u></p>
<p class=3D"MsoNormal">This past weekend we had wonderful racing at Eagles C=
anyon Raceway.&nbsp; Ownership turned over a couple years ago and they have f=
inished a multi-million dollar renovation of the track, it is truly amazing n=
ow.&nbsp; ECR has always been high on my
 list because of its potential with the natural terrain, but the lack of goo=
d construction methods had held it back since it opened.&nbsp; That has all b=
een corrected now and it is truly amazing=E2=80=A6well enough on that for no=
w.<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>&nbsp;<u></u></p>
<p class=3D"MsoNormal"><b>My problem<u></u><u></u></b></p>
<p class=3D"MsoNormal">For the past two years I have not been able to finish=
 a race weekend w/o completely destroying my rear brakes.&nbsp; Usually rela=
ted to heat build up that manifests as a blown wheel cylinder or brake shoe l=
inings that start cracking and chuncking
 off the shoe causing further rapid wear.&nbsp; This last weekend, I had a t=
otal rapid failure of the rear brakes when the right rear cylinder let go un=
der hard braking from 100+ mph, I may have blown another seal in the drivers=
 compartment when that happened, but
 will spare those details.&nbsp; Luckily, my dual masters allowed me to get t=
he car slowed reasonably with just the front brakes.&nbsp; For any of you th=
at have had this happen before, you understand that with a balance bar setup=
, you don=E2=80=99t end up with full brakes when
 one end fails.&nbsp; The balance bar rotates significantly to the side that=
 has zero resistance.&nbsp; In my case I=E2=80=99d estimate that I had about=
 20% of my front brakes available to slow the car, like I said, interesting e=
xperience that I=E2=80=99d rather not repeat again.<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>&nbsp;<u></u></p>
<p class=3D"MsoNormal"><b>My setup<u></u><u></u></b></p>
<p class=3D"MsoNormal">Twin Wilwood 0.7 master cylinders with a custom balan=
ce bar.&nbsp; Stock front TR6 calipers and stock 9=E2=80=9D TR drums with 0.=
75 wheel cylinders (I=E2=80=99ve tried everything from 5/8 up to 7/8=E2=80=9D=
).&nbsp; I also run a hydraulic proportioning valve to be able to
 fine tune the rear hydraulic pressure.&nbsp; I was running with the aluminu=
m rear drums until I destroyed the linings last year in one of the incidents=
 when the rear shoe linings cracked and broke completely off allowing the sh=
oe to cut groves into the drum linings.
 My routine setup is to put the car on jack stands to adjust the brakes.&nbs=
p; I start by running the rear drum shoe adjusters in until I perceive sligh=
t drag, then back off two clicks.&nbsp; Then I adjust the rear mechanical bi=
as with the balance bar until I have the
 front and rear brakes engaging (dragging) at approximately the same point o=
f pedal travel.&nbsp; I then fine tune the adjustment to dial back the rear b=
ias until I can threshold brake at speed and lock the fronts slightly before=
 I lock the rears.&nbsp; This allows me
 to trail brake with confidence that I=E2=80=99m not going to swap ends beca=
use of too much rear brake.
<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>&nbsp;<u></u></p>
<p class=3D"MsoNormal">I have used stock, portifield, and TSI drum linings a=
ll with the same results.<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>&nbsp;<u></u></p>
<p class=3D"MsoNormal">I=E2=80=99m looking for a couple things from the grou=
p (no disc conversion ideas please):<u></u><u></u></p>
<ol style=3D"margin-top:0in" start=3D"1" type=3D"1">
<li style=3D"margin-left:2.25pt">What is wrong with my rear brake setup and a=
djustment approach?<u></u><u></u></li><li style=3D"margin-left:2.25pt">What i=
s your setup and adjustment approach?&nbsp;
<u></u><u></u></li><li style=3D"margin-left:2.25pt">Do you like the amount o=
f rear brake you get with your approach or is it a compromise to keep the br=
akes from failing?<u></u><u></u></li><li style=3D"margin-left:2.25pt">Lastly=
, I hate our wheel cylinders, its is a terrible design and I think we have r=
eal junk on the market today.&nbsp; I have a theory that the sliding wheel c=
ylinder assemble is part
 of the root cause of my failures, along with heat.&nbsp; The piston and sea=
l are dealing with some severe side loading once the cylinder starts sliding=
 around to do its job and I don=E2=80=99t think it is up to the task, especi=
ally what we get these days.&nbsp; Has anyone modified
 their backing plates and shoes to use a modern day twin piston wheel cylind=
er that is bolted to the backing plate?&nbsp; Or has anyone ditched the TR d=
rums all together for another 9=E2=80=9D or 10=E2=80=9D drum backing plate a=
nd guts from another source.&nbsp; I=E2=80=99m open to all drum
 brake ideas at this point.&nbsp; I=E2=80=99m really tired of not racing bec=
ause of rear brake failures.&nbsp;
<u></u><u></u></li></ol>
<p class=3D"MsoNormal"><u></u>&nbsp;<u></u></p>
<p class=3D"MsoNormal">Sorry for the long post and thanks in advance for you=
r ideas.&nbsp;</p></div>

</div></blockquote><br><div>Greg&nbsp;</div></div>__________________________=
_____________________<br>
<a href=3D"mailto:[email-masked]" target=3D"_blank">[email-masked]</=
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