If the master brake cylinder is not functioning properly, the seal rings (gasket) must be replaced.
Drain brake fluid reservoir.
Unscrew brake pipe and plug up hose ends.
Dismantle operating lever A.
– Type 3 and 4: Dismantle seal collar C with operating arm.
– Type 6 and 7: Press in piston B completely to remove washer E from the inside of the bore.
Pull out piston B by hand.
Turn piston spring F clockwise to loosen it.
Remove the old seal rings by hand. Do not use metal tools and take care not to damage the piston.
Clean all arts with alcohol and check them for damage caused by wear or by improper usage or handling.
Finally, brush parts with brake fluid.
Install new seal rings G and H, see sketch for position. Since July 2012 seal ring H is a two–part seal. First position the o–ring in the groove, second slide the seal onto the o–ring.
Grease sliding parts and rubber parts with “ATE” brake cylinder paste before assembly.
– Type 3 and 4: Install piston, taking special care of cup leather.
– Type 6 and 7: Place seal D and washer E on 10 mm diameter of piston and push in together.
Press washer E into place with pipe tool (25Ø x 2.5 wall x 60 long).
History of TOST
TOST has more than 60 years of experience in the development and manufacturing of aviation safety equipment. It's a family business – run in the fourth generation – they stick to the motto: Conserving the well–proven system – Developing forward. The cornerstones of their corporate policy are: Service
Customer satisfaction is their highest goal. The customer is the king – he should like to come back – and not like to send the product back. Quality
Since 1969 TOST holds a LBA approval as Design and Production Organization. (LBA= German Aviation Authorities). In the meantime, all approvals are issued by the EASA. In yearly audits through the aviation authorities, the compliance with quality standards is checked and kept record of. Over and above those official regulations, they live the quality thought in their every–day work. Sustainability
Modern manufacturing techniques, economical resource management and the long lifetime of TOST products are their contribution to the protection of the environment. Gliding is an ecologically friendly sport. Continuity
Long standing relations to their customers, suppliers and employees stand for the continuity in their company.
TOST Gasket Set price varies depending on selection. Use above dropdown box for selection and final price.
General Maintenance
Regular Operating Checks
• Regularly check the brake fluid level in the reservoir. The level must never drop more than 10 mm below the maximum fill level. For topping up use only brake fluid specified for the system. Do not open the brake fluid can until just before topping up.
• Do not use old brake fluid for topping up!
Annual Checks
• Check wear on dist pads and replace if wear has exceeded 2.5 mm.
• Check disk surfaces for deep grooves and if necessary install new genuine brake disks. Disk thickness (new disk) = 5 mm, wear limit = 4.3 mm
• Completely drain brake system, fill with new brake fluid and bleed brake system as described on this page.
• Never use mineral oil or grease!
Maintenance
Rules for disassembling any part of the disk brake system
Before dismantling any parts thoroughly clean the outside of the brake system with alcohol and a clean brush.
Unscrew hydraulic pipes and carefully close off pipe end with stoppers to prevent dirt from getting into the pipes.
Clean all dismantled parts, including those made of rubber, with alcohol using a fine brush and let them dry in a dust–free area.
Using other cleaning agents such as petrol, diesel, petroleum or trichloroethane is strictly prohibited, as these will irreparably damage the rubber parts!
Handle precision metal parts (alloys) carefully to avoid damage.
Brush cleaned parts with brake fluid to inhibit corrosion.
Grease sliding parts and rubber parts with “ATE” brake cylinder paste before assembly.
Description
The master cylinders are die–cast alloy housings, comprising the reservoir that holds the brake fluid, the brake lever mechanism and the cylinder.
The hydraulic piston has two seal seats, one at the front for holding the pressure collar, one at he back for holding the guide seal (since July 2012 a two–part seal us used as spare part). The top of the piston is milled to seat the return spring. On the rear there is a pan–shaped recess (type 3 and 4) into which the operating arm off the brake lever fits.
The exact position of the piston is determined by the setting of the manual brake.
To unsure that the hydraulic circuit is always supplied with brake fluid, the slack of the manual brake lever (travel between rest and working position) must be 3 to 4 degrees.
The master cylinder must be mounted in such a way that it is always above the brake yoke even under unfavorable operating conditions.
Filling or bleeding the hydraulic system is simpler from below using a TOST brake fluid gun or with TOST vacuum filling and bleeding pump.
Topping up Brake Fluid in Disk Brake Systems
Loosen bleeding screw on brake yoke by one turn.
Fill master brake cylinder reservoir with brake fluid and pull manual brake lever repeatedly full travel until brake fluid starts to flow through the bleeding screw on the brake assembly.
Tighten bleeding screw.
Continue to operate the manual brake lever slowly until a distinct shortening in the travel of the brake lever is observed.
Bleeding the Hydraulic Disk Brake System
Pull manual brake lever.
Slowly loosen and re–tighten bleeding screw before reaching full travel with the manual brake lever.
Repeat bleeding process until the brake fluid flowing through the bleeding screw is completely free of bubbles.
Fill brake fluid reservoir to about ¾ of total capacity and carefully replace closure cap.
