[DeTomaso] Fun w/ brakes and questions

[Szwab,Konrad,HOUSTON,IT]

Thank you for the advice. What do I use to force the pistons out, compressed air ?

From: JDeRyke at aol.com [mailto:JDeRyke at aol.com]
Sent: 2011-04-11 13:50
To: Szwab,Konrad,HOUSTON,IT; detomaso at realbig.com
Subject: Re: [DeTomaso] Fun w/ brakes and questions

Konrad, if you can locate a copy of the August 2002 POCA News, I went thru a street-rebuild of all 4 calipers, with illustrations. You're right- its not difficult nor do you need special tools or an assistant. It IS incredibly messy and will take most of one Saturday to do all 10 pistons. The pistons collect varnish from not changing brake fluid each Spring, and hang up in the bores. All thats needed is to check for leaks, then force one piston at a time out, wipe it clean with a mildly abrasive Scotch-brite pad and reassemble. If the slightest leak is seen, the seal inside the casting is a single square o-ring and replacements are available from the vendors.
The only bad thing is, some caliper leaks are not fixable by replacing the seal. European brakes are made with nickel-plated mild steel pistons. Which rust in old water-loaded brake fluid (yet another reason to change fluid each Spring!) A rust-pitted piston cannot be re-sealed. U.S brakes- including Wilwoods- use stainless steel pistons and do not suffer this problem. I know of no replacements for these Girling pistons. You can strip the plating, smooth the steel and re-plate a pitted piston at vast cost, or make duplicates from stainless bar stock if you're handy. Most guys look around for a useable used caliper from someone who'se upgraded his brakes. Note there are two different sized pistons in front brakes; the trailing-edge piston is smaller than the leading edge piston- a racing feature from Dallara, I suspect.
While you're digging around in there, I'd replace the stock lines with stainless AN lines. Best is dash-3 which are smaller diameter and thus react faster to pedal force, but dash-4 are common, cheaper and work better than stock rubber. I also recomment Speed-bleeders on all bleed ports including the clutch slave, to save from having to beg a helper to spend his/her Saturday sitting in the car pumping the pedal for you. Finally, I recommend Porterfield R-4-S pads front & back. They stop the car quicker than stock pads and last nearly as long. They are not 'racing' pads- they need not be heated up to work wonderfully well. Good luck- J Deryke

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