TL
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| posted on 7/11/03 at 10:34 PM |
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VENTED DISC CONVERSION
This may be of interest to only a very few of you, but I would like to share my recent experience with you, as some of it might be useful.
Also, if you've got bags of money and no access to a lathe & pillar drill, you might as well stop reading now. If however you have access to
a machine shop and, like me, have no money, read on:
I've converted my Spitfire to vented 266mm discs (standard = 229mm solid).
The normal conversion for a spit is Capri 2.8i discs, but I found these very expensive. I am using 14" revolutions ( so I could use bigger
diameter discs), and GT6 uprights, which have bolt on caliper brackets, as opposed to the Spitfire ones which have the caliper mount holes cast into
the upright. Bolt on calper brackets give you more flexibilty in the position & type of caliper you can use.
My biggest hurdle was to find a disc which fitted the following criteria:
a) Large enough dia. to make the conversion worthwhile.
b) Small enough dia. to fit without caliper/rim contact.
c) Correct working thickness (most vented discs seem to be in the 20-25mm thick range).
d) Correct overall height (i.e. working thickness + height of boss where it bolts to hub).
e) Ideally, a perfect match in terms of disc/hub bolt PCD and dia of central locating hole.
Notes on above points:
a) I dont want to get involved in the "You don't need big/vented discs on such a light car" argument. I wanted them - end of
story!(plus I am going V8)
b) Obvious
c) Obvious again, but you still need to make sure your calipers are wide enough, or your spacer kit makes them wide enough.
d) This is the tricky one. As we all know, most modern cars (e.g. Sierra) have the discs fitted on the outside of the hub; This allows them to be
changed without the need to remove & refit the hub from the upright, but they tend to be relatively "tall" (e.g. Sierra = about 58mm I
think). Old cars (Spit & Escort & Cortina) have the disc fitted to the back face of the hub, and the disc tends to have a much lower profile
(Spit = about 26mm I think). This is presumably why the 2.8i conversion is used on the Spit This is the main reason for this post, because I found 1
or 2 other discs which are worth considering: MKI Golf GTI = 240mm dia & is about 30mm thick; BMW 320i (E30) = 260mm dia x 35mm high; Pug 206 =
247mm x 35mm? IF YOU ARE INTERESTED, PLEASE DOUBLE CHECK THESE DIMS FOR YOURSELVES, AS MOST OF THEM ARE FROM MY FAILING MEMORY, AND THEY VARY
DEPENDING ON ENGINE/TRIM LEVEL. What I opted for was Citroen Berlingo / pug 306 discs (266mm x only 28mm high). Depending on the height of your chosen
disc, you might have to turn a few mm off the back face of the hub to get the disc in the correct axial position relative to the caliper.
e) I had to bore out the central hole slightly and drill new disc/hub bolt holes (Ijust clamped my old GT6 disc VERY concentrically to the new
disc and drilled through the old holes) Hence the need for lathe & drill.
Lastly, but by no means least, I removed the bolt on caliper brackets from the uprights, and used these as a pattern to allow me to make 2 new
brackets, identical except that the caliper mounting holes are about 15mm further out to accomodate the larger disc dia. I have the luxury of access
to a full machine shop, which I know most mortals don't have. But that's life; I am a humble engineer: If I wasn't, I could afford
to buy all this kit at great expense!
The joke is that I was quoted about £90 for 2.8i discs, and my Berlingo discs (Bendix) cost £31.81 inc VAT for the pair from German & Swedish. The
Golf GTI discs were about the same price.
Good sources for dimensional info I used
- I borrowed a Brembo catalogue from my local ARE branch.
- Look up Quinten Hazell website www.qha.com. They have online catalogues.
CONCLUSION:
i) Escort & Cortina brakes are similar to Spitfire, but you may be limited in disc dia by the fixed points of your caliper mounts.
ii) With a lot of time & effort you can get big brakes for little money.
I hope this is useful to someone, as it's taken me bloody ages to type it!
Disclaimer: Please double check all these facts & figures for yourselves and for your particular installation. Also, don't blame me if your
wheels fall off!
[Edited on 8/11/03 by TL]
Cheers,
Terry
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Alan B
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| posted on 7/11/03 at 10:42 PM |
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Terry,
Although I'm building neither a V8 spit nor a regular locost that kind of detailed info . is invaluable.
Like you I have a decent shop, but very little cash to spare....this kind of stuff is great to read.
Cheers,
Alan
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TL
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| posted on 7/11/03 at 10:50 PM |
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Alan,
Thanks for the compliment. I'm glad you enjoyed reading it. Incidentally, I think your meerkat is great. Did I read somewhere that it is a
one-off, not a bought kit?
Cheers,
Terry
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andyps
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| posted on 8/11/03 at 08:02 AM |
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Hi Terry,
I don't have access to machining facilities but it is great to read your contribution to see what I would regard as the "true spirit of
the locost" at work.
In my view, this sort of thing is well worth reading as it really shows what can be done with time and determination (and a good set of tools).
Cheers
Andy
An expert is someone who knows more and more about less and less
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