Bob,
The TR rotors are 15 yr since being drilled and still going strong. If the
holes are 3/16 to 1/4in diam and spaced apart and assuming you don't have to
hollow it out significantly, the integrity of the rotor is not affected.
You should start with good, unskimmed rotors or get new ones, which might
solve the problem anyway. Definitely check the other suggestions like wheel
and tire trueing, suspension and steering ball joints, shocks and mountings.
They can all have an effect. Have someone drive alongside and behind to see
if the wheels are shaking, bouncing or showing runout.
On my 100M with either the RS5's on 48 spokes which I trued, or the 185/70
Vred's on 72 spokes, all just statically balanced on a bubble balancer with
the weights on the inside for appearance, the car is completely smooth and
shake free up to xxxmph. If you have serious scuttle shake, there has to be
a reason and quite likely it is the wheel/tire combination but not always
necessarily.
Happy hunting,
Peter Davis
----- Original Message -----
From: Bob Spidell <bspidell@pacbell.net>
To: PETER DAVIS <paddymck@peoplepc.com>; healeylist <healeys@autox.team.net>
Sent: Saturday, July 24, 2004 7:33 PM
Subject: Re: Balancing Rotors
> Thanks, Peter.
>
> I was wondering if this would help the scuttle shake, which no
> amount of wheel balancing will solve.
>
> Not sure about drilling into the rotor edge, though ... wouldn't
> that weaken the rotor (like turning too thin)?
>
>
> bs
> ********************************************
> Bob Spidell San Jose, CA bspidell@pacbell.net
> '67 Austin-Healey 3000 '56 Austin-Healey 100M
> ********************************************
>
>
>
> > Bob,
> >
> > I have done it successfully on my TR rotors when having a persistent
front shake at 60-65mph and the wheels were
> balanced. The unmachined section around the hub can be off center or
irregular shape and create out of balance forces.
> Remove the wheel, slacken off the bearing (preferably wipe out most of the
grease for the purpose of the test), then let
> the rotor go from different rotational positions and see if it
consistently stops with the same spot at the bottom, the
> heavy point. Drill radial holes, about 0.25in diam worked, in the center
of the rotor edge thickness, spaced about
> 0.375in apart, going in towards the stub axle about 1in. Stop when the
rotor no longer has a tendency to turn when
> released from any position. Regrease and re-adjust the wheel bearing.
> >
> > You can make a reasonable job of balancing wheels the same way with the
bearing slackened off.
> >
> > regards,
> >
> > Peter Davis
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