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Re: Brake drums

To: "Power British Performance Parts, Inc." <britcars@powerbritish.com>
Subject: Re: Brake drums
From: "T. R. Householder" <trhouse@greenapple.com>
Date: Mon, 10 Jan 2000 09:32:33 -0500
Cc: triumphs@autox.team.net
References: <3879D36A.10E4@buffnet.net> <3879E78C.5B0C5350@powerbritish.com>
I don't feel this is entirely true. By design the Brake shoes are
mounted in a configuration that they float.?????????????????

Reference the following....(even slight errors)

> If the center bore was mis-matched, and so were the wheel stud holes, it
> would be
> humanly impossible to properly center the drum upon reinstalling the
> wheel.  As you
> say, even slight error would result in pedal pulsation, if not brake
> overheating from
> continually dragging for part of each rotation.
> 

Power British Performance Parts, Inc. wrote:
> 
> J&E wrote:
> 
> > Taken from 1-10-00 TR Digest List
> > >Hi Karl,
> > I'm copying this to the list as it may be unclear for others as well.
> >
> > If the center bore was mis-matched, and so were the wheel stud holes, it
> > would be
> > humanly impossible to properly center the drum upon reinstalling the
> > wheel.  As you
> > say, even slight error would result in pedal pulsation, if not brake
> > overheating from
> > continually dragging for part of each rotation.
> >
> > Actually, the center bore that fits over the axle nut is the same for
> > both drums, and
> > there is no problem with drums locating on center for either
> > combination.  The
> > difference is in the shank of the wheel stud.  While both cars take the
> > same 7/16 - 20
> > lug/stud, the shank on the solid axle cars is stepped to about 9/16 at
> > the hub and the
> > holes in the drum for the studs are correspondingly larger.  With that
> > in mind, if you
> > were to install a TR-4 drum onto a TR-6, the drum would locate properly
> > on the hub's
> > center, but you'd have axial shift about the extra clearance in the stud
> > holes.  In
> > this situation, the only positive location for the drum would be the
> > retaining
> > screws.  True, friction between the drum, hub, and wheel would and
> > should probably
> > keep it from shifting.  But if it doesn't, the drum may slip, especially
> > in a panic
> > stop the forces involved are quite high.  If the drum does slip, all the
> > panic-braking
> > force would be transmitted throught the locating screws and the they
> > might shear under
> > such stresses.  This could result in potential damage to the drum or
> > hub.
> >
> > Of course, you could run the combo without the screws, and just allow
> > the drum to
> > shift on the clearance around the stud holes, but I sure wouldn't want
> > to take any
> > chances like that with my brakes. Regards,  -Brian Schlorff <
> > -----------------------
> > Hi List!
> >         Question: Why can't some type of "pipe or tubing" be installed as a
> > "sleeve" to take up the space between the wheel stud & drum hole for the
> > wheel stud. Thus being a "bushing" of some type? Also, if this was to be
> > done would Stainless Steal be an accpetable material? If not, then what
> > material would be accpetable? Wouldn't I be a good idea to coat the
> > inside & outside of this material with an anti-seize grease coating for
> > easy removial of the drum? -Cosmo Kramer
> 
> Yes, sleeves could be made up if you really had to run a TR-4 drum on a TR-6, 
>but just
> be very clear that it is marked in some way so if someone else takes the drum 
>off,
> they know to look for the spacers and not to overlook them on reinstallation. 
> The
> only time this would be an issue is if you were to put TR-3/4 drums on a 
>TR-6.  Again,
> I strongly urge you not to take ANY chances with brakes and just get the 
>right drums.
> TR-6 drums are very easy to find.  The only time I could see a real need for 
>this
> procedure would be if you were to get a set of Alfin's that were once on an 
>early car
> and you are now trying to fit them to a late car.  If you're doing that, just 
>have
> them drilled for the correct size stud at a 45 degree offset - then you'd 
>effectively
> have dual pattern drums.  Alternatively, you should be able to find a machine 
>shop to
> weld the holes up and redrill them to the correct size.  If you get the 240Z 
>drums,
> they'll be the smaller size to begin with and you can just machine them to 
>fit your
> particular application.
> 
> Regards,
> 
> Brian Schlorff    '61 TR-4     '64 TR-4     '72 TR-6     '79 Spit
> ---------------------------------------------------------------------
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