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Greg
When we looked at it at the track the knob for the bias was way in the back
on the driver shaft tunnel. I'm sure it is a smooth run from there up under
the bonnet to the bias bar but maybe the cable arrangement could hold a
clue. Might it hang up somehow causing the rears to change to dragging
while getting off and on the peddle? Running with it disconnected would
tell a story.
Bob Kramer
On Fri, May 7, 2021 at 3:01 PM Greg Blake via Fot <fot@autox.team.net>
wrote:
>
> =EF=BB=BF
>
> Fellow racers and breakers of parts,
>
>
>
> This past weekend we had wonderful racing at Eagles Canyon Raceway.
> Ownership turned over a couple years ago and they have finished a
> multi-million dollar renovation of the track, it is truly amazing now. E=
CR
> has always been high on my list because of its potential with the natural
> terrain, but the lack of good construction methods had held it back since
> it opened. That has all been corrected now and it is truly amazing=E2=80=
=A6well
> enough on that for now.
>
>
>
> *My problem*
>
> 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
> that manifests as a blown wheel cylinder or brake shoe linings that start
> cracking and chuncking off the shoe causing further rapid wear. This las=
t
> weekend, I had a total rapid failure of the rear brakes when the right re=
ar
> cylinder let go under hard braking from 100+ mph, I may have blown anothe=
r
> seal in the drivers compartment when that happened, but will spare those
> details. Luckily, my dual masters allowed me to get the car slowed
> reasonably with just the front brakes. For any of you that 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. 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 ca=
r,
> like I said, interesting experience that I=E2=80=99d rather not repeat ag=
ain.
>
>
>
> *My setup*
>
> Twin Wilwood 0.7 master cylinders with a custom balance bar. 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). I also run a hydraulic proporti=
oning
> valve to be able to fine tune the rear hydraulic pressure. I was running
> with the aluminum rear drums until I destroyed the linings last year in o=
ne
> of the incidents when the rear shoe linings cracked and broke completely
> off allowing the shoe to cut groves into the drum linings. My routine set=
up
> is to put the car on jack stands to adjust the brakes. I start by runnin=
g
> the rear drum shoe adjusters in until I perceive slight drag, then back o=
ff
> two clicks. Then I adjust the rear mechanical bias with the balance bar
> until I have the front and rear brakes engaging (dragging) at approximate=
ly
> 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 fron=
ts
> slightly before I lock the rears. This allows me to trail brake with
> confidence that I=E2=80=99m not going to swap ends because of too much re=
ar brake.
>
>
>
> I have used stock, portifield, and TSI drum linings all with the same
> results.
>
>
>
> I=E2=80=99m looking for a couple things from the group (no disc conversio=
n ideas
> please):
>
> 1. What is wrong with my rear brake setup and adjustment approach?
> 2. What is your setup and adjustment approach?
> 3. Do you like the amount of rear brake you get with your approach or
> is it a compromise to keep the brakes from failing?
> 4. 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 wheel cylinder assemble is part of the root cause of my failur=
es,
> along with heat. The piston and seal are dealing with some severe sid=
e
> loading once the cylinder starts sliding around to do its job and I do=
n=E2=80=99t
> think it is up to the task, especially what we get these days. Has an=
yone
> modified their backing plates and shoes to use a modern day twin pisto=
n
> wheel cylinder that is bolted to the backing plate? Or has anyone dit=
ched
> the TR drums all together for another 9=E2=80=9D or 10=E2=80=9D drum b=
acking plate and guts
> from 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.
>
>
>
> Sorry for the long post and thanks in advance for your ideas.
>
>
> Greg
> _______________________________________________
> fot@autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
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> http://autox.team.net/mailman/options/fot/rkramer56@gmail.com
>
>
>
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<div dir=3D"ltr">Greg<div><br></div><div>When we looked at it at the track =
the knob for the bias was way in the back on the driver shaft tunnel. I'=
;m sure it is a smooth run from there up under the bonnet to the bias bar b=
ut maybe the cable arrangement could hold a clue. Might it hang=C2=A0up som=
ehow causing=C2=A0the rears to change to dragging while getting off 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-smartmai=
l=3D"gmail_signature"><div dir=3D"ltr">Bob Kramer</div></div></div><br></di=
v></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr=
">On Fri, May 7, 2021 at 3:01 PM Greg Blake via Fot <<a href=3D"mailto:f=
ot@autox.team.net">fot@autox.team.net</a>> wrote:<br></div><blockquote c=
lass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px soli=
d rgb(204,204,204);padding-left:1ex"><div dir=3D"auto"><br><blockquote type=
=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>=C2=A0<u></u></p>
<p class=3D"MsoNormal">This past weekend we had wonderful racing at Eagles =
Canyon Raceway.=C2=A0 Ownership turned over a couple years ago and they hav=
e finished a multi-million dollar renovation of the track, it is truly amaz=
ing now.=C2=A0 ECR has always been high on my
list because of its potential with the natural terrain, but the lack of go=
od construction methods had held it back since it opened.=C2=A0 That has al=
l been corrected now and it is truly amazing=E2=80=A6well enough on that fo=
r now.<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>=C2=A0<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 finis=
h a race weekend w/o completely destroying my rear brakes.=C2=A0 Usually re=
lated to heat build up that manifests as a blown wheel cylinder or brake sh=
oe linings that start cracking and chuncking
off the shoe causing further rapid wear.=C2=A0 This last weekend, I had a =
total rapid failure of the rear brakes when the right rear cylinder let go =
under hard braking from 100+ mph, I may have blown another seal in the driv=
ers compartment when that happened, but
will spare those details.=C2=A0 Luckily, my dual masters allowed me to get=
the car slowed reasonably with just the front brakes.=C2=A0 For any of you=
that have had this happen before, you understand that with a balance bar s=
etup, you don=E2=80=99t end up with full brakes when
one end fails.=C2=A0 The balance bar rotates significantly to the side tha=
t has zero resistance.=C2=A0 In my case I=E2=80=99d estimate that I had abo=
ut 20% of my front brakes available to slow the car, like I said, interesti=
ng experience that I=E2=80=99d rather not repeat again.<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>=C2=A0<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 bala=
nce bar.=C2=A0 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).=C2=A0 I also run a hydraulic proportioning valve to be able to
fine tune the rear hydraulic pressure.=C2=A0 I was running with the alumin=
um rear drums until I destroyed the linings last year in one of the inciden=
ts when the rear shoe linings cracked and broke completely off allowing the=
shoe to cut groves into the drum linings.
My routine setup is to put the car on jack stands to adjust the brakes.=C2=
=A0 I start by running the rear drum shoe adjusters in until I perceive sli=
ght drag, then back off two clicks.=C2=A0 Then I adjust the rear mechanical=
bias with the balance bar until I have the
front and rear brakes engaging (dragging) at approximately the same point =
of pedal travel.=C2=A0 I then fine tune the adjustment to dial back the rea=
r bias until I can threshold brake at speed and lock the fronts slightly be=
fore I lock the rears.=C2=A0 This allows me
to trail brake with confidence that I=E2=80=99m not going to swap ends bec=
ause of too much rear brake.
<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p>
<p class=3D"MsoNormal">I have used stock, portifield, and TSI drum linings =
all with the same results.<u></u><u></u></p>
<p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p>
<p class=3D"MsoNormal">I=E2=80=99m looking for a couple things from the gro=
up (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=
adjustment approach?<u></u><u></u></li><li style=3D"margin-left:2.25pt">Wh=
at is your setup and adjustment approach?=C2=A0
<u></u><u></u></li><li style=3D"margin-left:2.25pt">Do you like the amount =
of rear brake you get with your approach or is it a compromise to keep the =
brakes from failing?<u></u><u></u></li><li style=3D"margin-left:2.25pt">Las=
tly, I hate our wheel cylinders, its is a terrible design and I think we ha=
ve real junk on the market today.=C2=A0 I have a theory that the sliding wh=
eel cylinder assemble is part
of the root cause of my failures, along with heat.=C2=A0 The piston and se=
al are dealing with some severe side loading once the cylinder starts slidi=
ng around to do its job and I don=E2=80=99t think it is up to the task, esp=
ecially what we get these days.=C2=A0 Has anyone modified
their backing plates and shoes to use a modern day twin piston wheel cylin=
der that is bolted to the backing plate?=C2=A0 Or has anyone ditched the TR=
drums all together for another 9=E2=80=9D or 10=E2=80=9D drum backing plat=
e and guts from another source.=C2=A0 I=E2=80=99m open to all drum
brake ideas at this point.=C2=A0 I=E2=80=99m really tired of not racing be=
cause of rear brake failures.=C2=A0
<u></u><u></u></li></ol>
<p class=3D"MsoNormal"><u></u>=C2=A0<u></u></p>
<p class=3D"MsoNormal">Sorry for the long post and thanks in advance for yo=
ur ideas.=C2=A0</p></div>
</div></blockquote><br><div>Greg=C2=A0</div></div>_________________________=
______________________<br>
<a href=3D"mailto:fot@autox.team.net"; target=3D"_blank">fot@autox.team.net<=
/a><br>
<br>
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<br>
</blockquote></div>
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