cloudsipper
New Member
I'm replacing the master cylinder on my Taifun motorglider. The current system uses a BMW motorcycle M/C (master cylinder) mounted behind the baggage compartment, about 2 feet down (not very accessible) The rubber diaphragm( it's a DOT-4 system) self destructed already, and one of the o-rings on a caliper failed. I'm trying to replace the entire system with a more conventional aircraft master cylinder (l Have a used M/C looks like a Cleveland model 10-5 (id plate missing) and has a parking brake lever)
The current linkage uses a bellcrank at the end of the Spoiler(Airbrake) pushrod travel. I don't think I want to crawl back and try to use it. The Spoiler lever has about a 15" rearward travel and I'd like to put the brake at the last 3 or 4 inches of deployment. The spoilers, flaps, and trim controls are in a central console (about 18" deep) made of fiberglass/foam sandwich. see attached pic.
A couple of troublesome areas:
1)Fabricating and installing a mounting bracket to foam sandwich
2) Restricting the brake actuation to the final part of the spoiler lever travel.
On the fabrication side, do people cut up aluminum angle/ square tube, or do they weld up something in weldable steel? I believe the mechanical advantage of the brake lever needs to be around 2:1, with the actual M/C piston travel on the order of 1"- 1.5" . The calipers are standard Cleveland 30-9 5" caliper. (the O-rings are currently EPDM to withstand the DOT-4, but I will be replacing them with Nitrile/BUNA and changing the fluid to Mil-Spec 5606).
I would also love to hear about successful brake line flushing methods.. I'll be going from DOT-4 (Glycol based) to MilSpec 5606 Mineral oil based. I think I will try Acetone using the existing EPDM O-rings and then change everything after flushing.
The current linkage uses a bellcrank at the end of the Spoiler(Airbrake) pushrod travel. I don't think I want to crawl back and try to use it. The Spoiler lever has about a 15" rearward travel and I'd like to put the brake at the last 3 or 4 inches of deployment. The spoilers, flaps, and trim controls are in a central console (about 18" deep) made of fiberglass/foam sandwich. see attached pic.
A couple of troublesome areas:
1)Fabricating and installing a mounting bracket to foam sandwich
2) Restricting the brake actuation to the final part of the spoiler lever travel.
On the fabrication side, do people cut up aluminum angle/ square tube, or do they weld up something in weldable steel? I believe the mechanical advantage of the brake lever needs to be around 2:1, with the actual M/C piston travel on the order of 1"- 1.5" . The calipers are standard Cleveland 30-9 5" caliper. (the O-rings are currently EPDM to withstand the DOT-4, but I will be replacing them with Nitrile/BUNA and changing the fluid to Mil-Spec 5606).
I would also love to hear about successful brake line flushing methods.. I'll be going from DOT-4 (Glycol based) to MilSpec 5606 Mineral oil based. I think I will try Acetone using the existing EPDM O-rings and then change everything after flushing.
