James,
> >
> > Assuming that the shudder to which you refer is a pulsating
> > brake pedal, I would suggest that you have the front brake
> > rotors checked for runout. (Trueness). This is usually an
> > indication of a warped rotor.
>
> Can I check this trueness roughly myself? Is this something I
> am likley to
> have "made untrue" myself when I was fitting my Spax. It was
> a rather rough
> operation at times.
If you have access to a dial indicator, you can check for
any warping of the rotor. You shouldn't have caused any
warping by manhandling the damper/spring combo.
>
> > How much higher tyre pressure are you talking about? On my
> > '73, I try to keep close to the original spec. I feel the
> > ride is much too hard if you go too far over the recommended
> > pressures. I generally keep mine at 22-23 front and 26-28
> > rear.
>
> Well, I did some tests at various psi both front and back,
> and on my new
> tyres, I keep them at 30-32psi all round. The steering is so
> much lighter,
> you just wouldnt believe it was the same car!
>
> Regards the difference (22/26) - this was originally to
> compensate for the
> likley to oversteer with the rotoflex spring on earlier cars
> - I think -
> possibly - whatever - it was to reduce the likleyhood of you
> ending up in
> the middle of a roundabout. Depends on if you like to get the
> tail out on
> roundabouts, but at 30/30 - I can't do it unless I really
> really try... In
> fact, its pretty much impossible if you dont want to do it.
> Although maybe I
> havent tried hard enough, Im yet to light up the tyres with
> this new set...
> <mental note, for the way home tonight>
>
Well, don't know how hard you drive your car, but I usually
push mine. At least on the twisty bits.
> Depends on how you drive your car I guess, but if you
> increase the psi all
> round from the 22/26 base then I guess you keep the understeer
> characteristics.
>
> I didnt find that increasing the pressure to 30-32 psi made
> much difference
> concerning ride hardness - not compared to the steering ease.
> I also tried
> up to 36 - I could detect a slightly more firm ride, but I
> quickly changed
> the pressure as the car was a bit too skitish for my liking.
>
The only time I run my car with the pressure jacked up is
when I am autocrossing it. One of the things that causes
a severe front end lightness is to keep the camber angle
at stock. I used to have mine kicked out to about 2-3 degrees
negative when I used to do a lot of autocrosses. When I
rebuilt the brakes and replaced the bushings a couple of
years ago, I pulled the extra shims and went back to the
stock positive camber. When I get around to it, I am putting
some of the shims back in. The front end is very twitchy at
times. (After I get the Stag driveable).
Cheers,
Doug
--
Doug Mitchell
mailto:dbmitch@peoplepc.com
'73 Spitfire 1500 - about to celebrate 27 years of ownership
'73 Stag - about to celebrate 1 year of ownership
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