Date: Sat, 16 Nov 1996 17:59:28 +0000 (GMT)
From: Philip Pick
Having followed the recent thread about brake fluid the list may be interested in this article, written some 5 or 6 years ago. The contents were approved by the AP Racing management, before it was first published the Open Megga, the inhouse magazine of the Classic Motorcycle Racing Club.
Hydraulics
While staying in the Isle of Man, at Classic TT time, I happened to be accommodated in the same hotel as the Lockheed brake representative, Mr Ron Hammond. Although I have known Mr Hammond for a number of years, it is quite amazing how much better you get to know a business contact over a few evening's conversation. Our evening discussions were wide-ranging. Mr Hammond had some interesting stories about his years of servicing Lockheed equipment in the racing world, and had some strong words to say about the standard of brake equipment used at Classic events.
Some of the equipment used on Classic bikes is now 20-years old, and a great deal is in poor condition. The majority of problems can be traced back to the simplest of maintenance procedures, the changing of the brake fluid. Mr Hammond's recommendations here are very specific. For a machine that is paraded only, change the fluid before the season's use, and again before winter storage. Always store with the system filled with fluid. For a machine used for racing, change the fluid, as above, and also monthly during the season to ensure 'as new' performance.
The brake fluid used should be either DOT3, high boiling type, e.g. Lockheed 550 racing; or the high boiling type Lockheed 600. DOT5 fluid is not approved by Mr Hammond. DOT5 fluids may be either silicone based or conventional synthetic formulation. Silicone fluids are not approved by most brake manufacturers for a variety of reasons. In competition their compression and expansion characteristics at racing temperatures render them less suitable than conventional type of fluid. Special (racing) DOT3 or DOT4 fluids are likely to have higher boiling points than the DOT5 non-silicone fluids currently marketed.
Brake fluids are hygroscopic. This means they absorb water and if the fluid is not changed a water level may be reached at which the fluid's corrosion inhibitors become ineffective. Mr Hammond told me that one year during his stay in the Isle of Man he stripped and overhauled a system and he found that the fluid was 75% water!!
Until two years ago, the pistons used in the brake calipers were hard-chromed steel. These are prone to rusting, especially where the piston is exposed to air, behind the brake pad. When a piston has started to rust, this can 'travel' under the hard-chrome, which can then flake off. When new pads are fitted, this damaged area of piston can be pushed through the piston seal, causing damage. A brake caliper should be stripped regularly for overhaul. The body of the caliper is fairly trouble free, but must be kept clean. The only available recommended cleaning agent is methylated spirits. Petrol must be kept away from the seals, as it causes the seals to swell. There is no excuse for seized or damaged unions or bleed nipples.
Much the same is true of master cylinders, both front and rear. Unless the fluid becomes contaminated, the bore of the master cylinder is quite long lived, but water in the fluid can again cause corrosion to the piston. If the exposed end of the piston is rusty, it is a good indication of the internal condition of the piston. Also, the covering 'boot' should be intact. The practice of fitting adjuster screws to the levers of master cylinders should be avoided. The piston of a master cylinder should be allowed to return to its rest position. If this rest position is altered, it is possible for the brake to 'lock on' with disastrous results.
So, to sum up, a little more thought towards brake systems, especially where bikes are only rarely used, will pay dividends in terms of life of the components and braking efficiency. Overhaul kits for all variations of Lockheed equipment are available and are not particularly expensive and pistons for calipers and master cylinders are also available.
Please feel free to contact me on 0181-478-4807 if I can offer any further advice or supply components.
Philip Pick, Triple Cycles, 228 Henley Road Ilford Essex IG1 2TW England
Telephone +44 181 478 4807 Fax +44 181 478 4807