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Anything and everything Spitfire.
Section : Rear Axle
Rear axle, brakes, wheels and tyres.
Posted By : Lindsay Dearing, 06-Dec-2002,
05:57pm
Following a 3 year restoration of my 1500, at the Test Centre the brakes scored the following on the dynamometer: Near side Front 300 rear 200. Off side
Front 400 rear 300. Apart from the obvious disparity between the sides can anyone tell me what the readings SHOULD be and what could be wrong. I have
renewed EVERYTHING during the restoration and yet the brakes are awful,(but road legal apparently as it passed the test!) I have even got the new Kevlar
pads at the front, and the pedal is firm. They are single circuit with silicone fluid. Any ideas out there?
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Posted By : Daniel James, 07-Dec-2002,
01:43pm
I was under the impression that silicone brake fluid was not as good, as it's more compressable then the normal kind, meaning some of your effort is
going into compressing the fluid rather then pushing the pads against the discs.
If you have just renewed everything I would give the pads etc a while, I renewed my brakes last year (including fitting braided hoses, which made a
bigger difference than I thought possible) and it took a while for them to bed in.
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Posted By : Lindsay Dearing,
07-Dec-2002, 08:41pm
Daniel... I have heard lots of stories concerning silicon brake fluid (DOT5) but in my experience it works just fine. I fitted some in a friends
Stag 20 years ago and it is still performing well with no brake problems!
I have also fitted the aeroquip type hoses to restore any compressability effects and have completed over 500 miles of road travel (and very scary
they were too!). If I cannot resolve it I will have to bring them up to modern standards with 4 pot calipers and a servo BUT I do not wish to go
down this route if I can possibly help it. I do not remember Spitfire brakes as being all that bad; but modern cars tend to spoil you! Any more
input out there?
Lindsay
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Posted By : Malcolm Coulson,
07-Dec-2002, 10:28pm
Hi Lindsay,
I wouldn't upgrade the brakes on the Spit, this would take away a lot of the fun of driving it. I agree that modern cars spoil you, but as you
are aware, you have to drive a Spitfire and that is why they are so much fun. My MkIII is 34 years old and the brakes are original, and good.
(when you get used to them after not driving it for a few days)
Pete's Stag looks good, as a matter of interest, which car do you think is more fun to drive?
Regards
Mal
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Posted By : Lindsay Dearing,
08-Dec-2002, 01:25pm
Mal....Totally agree with you regarding original Spitfire brakes: but mine just are not right. I dare not use the performance of the car to
its fullest because I cannot stop within a safe distance for modern traffic conditions. As regards Stag/Spit: No contest: Spit every
time-pure unadulterated pleasure. The Stag makes a good touring car with its V8 and is still good by todays standards, but it is'nt as much
FUN as a Spitfire!
Lindsay
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Posted By : Malcolm
Coulson, 08-Dec-2002, 09:25pm
Hi Lindsay,
Glad you agree regarding Spits; regarding your brakes I can't think of anything you havent done already, apart from take it easy and
see if they bed in.
Happy Spitty'ing.
Mal
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Posted By : Colin
Wake, 11-Dec-2002, 11:19am
You could try fitting some cheap and nasty pads as the kevlar ones may not be taking to the shape of the discs very quickly. Give
them a good bedding in and see if that helps. I fitted Kevlar green pads 2 years ago, still trying to bed them in. The figures from
the brake tester seem good, so don't worry, the adrenalin rush will help you to brake if needed!!
Colin
(who still get scared when the ABS fails to kick in on his Spitfire...)
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Posted By : Mike
Crewes, 20-Dec-2002, 07:40pm
Lindsay
If you have a soft pedal, this can be the silicon fluid, fitting braided hoses will make a significant difference. If it is
still soft, then there is air in the system somewhere.
If the pedal is hard and there is diminished retardation, it is probably the pads. Hard pads. like Kevlar, work best at high
temperature (that's what they're designed for). This means high speed with sustained hard braking, like racing. At low speed
they will not develop enough heat to work properly. Try swoping the pads for a standard set, bed in and see how it feels. Our
Spit has been tuned a bit and gets about 100 bhp, we run on silicon fluid, braded hoses and standard pads - no problem.
If you try this, let us know how you get on. Softer pads may be the answer.
Mike Crewes
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Posted By : Lindsay Dearing, 22-Dec-2002, 09:22pm
Thanks Mike and Colin for the insight into Kevlar pads. I really think you have something here and I will be changing the
pads for standard ones over the Holiday. It is interesting to note in all the hype about Kevlar that this glaring
deficiency is not noted and that the practical experience by we users is the only ultimate guide to a products true worth.
Thanks again, and to all the contributors to messageboard. I will let you know how I get on.... I have just got to sort out
my STIFF steering rack now!
Lindsay
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Posted By : Oliver Smith, 10-Jan-2003, 01:50am
There is also the fact that you may have damaged the pads in an attempt to get them to work properly, in my experience
with kevlar pads on my MkIV Spit, if you try too hard to brake early on they will never give good performance. Check to
see that there isn't a glazed appearance to the surface of the pads and that there isn't a whiteish line below the
surface where the top layer of the pad has hardened. My brakes actually got a lot better after the mot as the tester
gave them a good workout on the rollers. recommended use is light braking for the first 150 miles.
Oli
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Posted By : Stephen Airey, 10-Jan-2003, 03:14pm
You could also try cross drilled brake discs on the front - they help a bit.
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Posted By : Graham Lawson,
03-Feb-2003, 01:08pm
I understand that you may not want do alter your Spitfire for fear of altering its character. But, as a Spitfire owner for 10 yrs, I found
that too many times somebody would pull up sharpish in front of me and I would apply the brakes and think "Oh no, I'm not going to stop."
and end up standing on the brake pedal. The truth is that standard Spitfire brakes are just not up to scratch if you plan to drive the car
on modern roads. My feeling is that safety comes above fun of driving . If some-one steps off the kerb in front of you - even at a distance
- the chances are that standard Spitfire brakes will not stop you in time.
The 4-pot caliper made my brakes more responsive and gave me brakes that I could rely on.