>The brake M/C on the '72 Spit currently being restored is a single line.
>Looking at the manuals, it seems it should be a dual line. All the brake
>lines and fittings appear to be correct for a single line system, although
>the m/c itself appears to be about the same size as the clutch m/c. Any
>ideas ? Looking at the cost of a dual m/c and a PD fitting, I would like to
>stay with the single line system if possible, but not if it really needs a
>dual system. Help...
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If your car is a USA spec car, then it definitely should be a tandem master
cylinder. Some other markets were single line system, even for some of the
MK4/1500's, but the USA had tandems from about '68 on. If it is a US spec
car, and has a single line system, then somebody removed the tandem system
and installed a single line probably from an earlier Spitfire. The master
cylinder (cast reservoir) on a single system should be larger than the
clutch however, so they may have just used the same clutch master cylinder
- At any rate, I would definitely change it to a proper setup, be it
single or double. In my opinion there is nothing "wrong" with the correct
single line system, and while the tandem is "supposed" to be safer by
effectively having two separate braking systems, one for the front, and one
for the rear, I for one, haven't seen it work like this. In the event of a
failure of the lines or wheel cylinders of one system, the other should or
is supposed to still work. It's been my experience that when you have a
failure, it's total. I have never been able to figure out how it works in
practise. In theory it looks good, but in practise, I have never seen it
work as described. When I had a failure (leaving my driveway) it was
total, pedal to the floor, no brakes. (and the poor girl walking her dog
right then in front of my car, thought I was trying to hit her :-}, got a
nasty look!) When bleeding brakes, isn't this the equivalent of a failure
in one line? The pedal, on EVERY tandem system I've bled (and I've done
quite a few) always goes to the floor during bleeding. I would think this
is akin to failure in one line. I even tried on several occasions stomping
on the pedal (simulating a panic situation if this happened while driving)
just to see, and still, very little if no resistance. The pedal just went
to the floor, so the jest of this admittedly long winded explanation (sorry
'bout that) is whether you leave it single or convert it to tandem, make
sure you've got the PROPER bits that were designed for whatever system you
choose.
Barry Schwartz (San Diego) bschwart@pacbell.net
72 FI, V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (long term project)
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