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#1
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Tost Disk Brake rebuild?
I discovered that my Nimbus 3D had lost it's wheel brake Saturday.
Fortunately, I still fly with the assumption that it, like many gliders of the past don't have wheel brakes. No damage done other than a Long push back to the tiedown area. Upon examination of the system, (and the puddle) it appears that it's time for a rebuild of the caliper. Who's got some advice on the process? Any tricks?? Thanks for the advice in advance Paul Ephrata, WA |
#2
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Tost Disk Brake rebuild?
On Apr 14, 10:29*am, Paul Cordell wrote:
I discovered that my Nimbus 3D had lost it's wheel brake Saturday. Fortunately, I still fly with the assumption that it, like many gliders of the past don't have wheel brakes. * No damage done other than a Long push back to the tiedown area. Upon examination of the system, (and the puddle) it appears that it's time for a rebuild of the caliper. * Who's got some advice on the process? * *Any tricks?? Thanks for the advice in advance Paul Ephrata, WA Tost calipers on DG's and I assume many sailplanes are made by Cleveland and parts are available through AircraftSpruce.com. The only differance is that Cleveland uses an O-ring compatable with hydraulic oil and DG uses one compatable with brake fluid. The O-ring shown on the Aircraft Spruce parts list is the one for use with hydraulic oil but the correct O-ring material (EPDM) for poly-glycol brake fluid can be purchased from mscdirect.com. The size of the O-ring used on current DG's is 1/8 diameter, 1 ¼ I.D and 1 ½ O.D. and it is available as part# 31953284 for $8.76 (box of 50). Your Nimbus may use a differant size. |
#3
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Tost Disk Brake rebuild?
It's Done!
Thanks Dave Nadler and Uncle Hank for the off-line notes. This Soaring community is always surprising. I talked to Monty@ M & H Soaring this morning about the spec's for the Pads and O-ring. Then went over to Aircraft Spruce to get the parts. After I looked at their web site, I still had some questions about the rivets. I called a buddy that is an ex '20 owner and RV-7 builder to ask about the rivets. He lives about 100 miles away. As we talked, he walked out to his Hanger and went thru some stuff on his work bench. He had exactly the parts I needed. When would you like to do this he asked?? I told him that if he wanted to "help", it would be on his schedule........He responded, I'll be there in an Hour. He was and did the whole job as I "supervised". Cleaned and polished, pads and ring with a full bleed and new fluid. The system in general was in good shape. Just slight corrosion and some gunk. I supplied him with 1 soda for all the trouble. He'll be back next weekend for a test flight. Paul |
#4
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Tost Disk Brake rebuild?
Paul,
As Gary Evans mentioned, there are basically two brake fluids used in gliders. The "red stuff" Mil Spec 5606 oil (which most GA aircraft use) and DOT # automotive type fluid. 5605 wants to have Buna-N seals and O-rings while the DOT fluid uses EPDM rubber. You mentioned corrosion and this raises some flags. Cleveland parts, that Tost uses - changing the rubber parts to EPDM, were never really intended for use with DOT fluid. The problem is that DOT fluid is hygroscopic and whatever moisture gets into the fluid can corrode the bare aluminum surfaces of the caliper and piston (later pistons were anodized and this helps some). To find out if the piston is anodized, see if it conducts when touched with the leads of an ohm meter as the anodize surface is an insulator. If you have corrosion in the caliper bore or in the O-ring groove of the piston, you will likely have leakage again, probably sooner than later. One fix is to have the caliper bore machined and brass sleeved along with anodizing the piston. If anyone needs a free EPDM O-ring (for DOT fluid) for the Cleveland 300 series caliper, contact me via email (bumperm at att dot fish net) - remove the scaley thing) to get the address to send a self-addressed stamped envelope. bumper Quiet Vent - reduces vent noise by 10 dba "Paul Cordell" wrote in message ... It's Done! Thanks Dave Nadler and Uncle Hank for the off-line notes. This Soaring community is always surprising. I talked to Monty@ M & H Soaring this morning about the spec's for the Pads and O-ring. Then went over to Aircraft Spruce to get the parts. After I looked at their web site, I still had some questions about the rivets. I called a buddy that is an ex '20 owner and RV-7 builder to ask about the rivets. He lives about 100 miles away. As we talked, he walked out to his Hanger and went thru some stuff on his work bench. He had exactly the parts I needed. When would you like to do this he asked?? I told him that if he wanted to "help", it would be on his schedule........He responded, I'll be there in an Hour. He was and did the whole job as I "supervised". Cleaned and polished, pads and ring with a full bleed and new fluid. The system in general was in good shape. Just slight corrosion and some gunk. I supplied him with 1 soda for all the trouble. He'll be back next weekend for a test flight. Paul |
#5
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Tost Disk Brake rebuild?
Why does Tost change the parts to use DOT fluid?
Which glider manufactures use brakes that take the red stuff, and which use DOT fluid? bumper wrote: Paul, As Gary Evans mentioned, there are basically two brake fluids used in gliders. The "red stuff" Mil Spec 5606 oil (which most GA aircraft use) and DOT # automotive type fluid. 5605 wants to have Buna-N seals and O-rings while the DOT fluid uses EPDM rubber. You mentioned corrosion and this raises some flags. Cleveland parts, that Tost uses - changing the rubber parts to EPDM, were never really intended for use with DOT fluid. The problem is that DOT fluid is hygroscopic and whatever moisture gets into the fluid can corrode the bare aluminum surfaces of the caliper and piston (later pistons were anodized and this helps some). To find out if the piston is anodized, see if it conducts when touched with the leads of an ohm meter as the anodize surface is an insulator. If you have corrosion in the caliper bore or in the O-ring groove of the piston, you will likely have leakage again, probably sooner than later. One fix is to have the caliper bore machined and brass sleeved along with anodizing the piston. If anyone needs a free EPDM O-ring (for DOT fluid) for the Cleveland 300 series caliper, contact me via email (bumperm at att dot fish net) - remove the scaley thing) to get the address to send a self-addressed stamped envelope. bumper Quiet Vent - reduces vent noise by 10 dba "Paul Cordell" wrote in message ... It's Done! Thanks Dave Nadler and Uncle Hank for the off-line notes. This Soaring community is always surprising. I talked to Monty@ M & H Soaring this morning about the spec's for the Pads and O-ring. Then went over to Aircraft Spruce to get the parts. After I looked at their web site, I still had some questions about the rivets. I called a buddy that is an ex '20 owner and RV-7 builder to ask about the rivets. He lives about 100 miles away. As we talked, he walked out to his Hanger and went thru some stuff on his work bench. He had exactly the parts I needed. When would you like to do this he asked?? I told him that if he wanted to "help", it would be on his schedule........He responded, I'll be there in an Hour. He was and did the whole job as I "supervised". Cleaned and polished, pads and ring with a full bleed and new fluid. The system in general was in good shape. Just slight corrosion and some gunk. I supplied him with 1 soda for all the trouble. He'll be back next weekend for a test flight. Paul |
#6
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Tost Disk Brake rebuild?
On Apr 16, 8:46 am, Greg Arnold wrote:
Why does Tost change the parts to use DOT fluid? Which glider manufactures use brakes that take the red stuff, and which use DOT fluid? bumper wrote: Paul, As Gary Evans mentioned, there are basically two brake fluids used in gliders. The "red stuff" Mil Spec 5606 oil (which most GA aircraft use) and DOT # automotive type fluid. 5605 wants to have Buna-N seals and O-rings while the DOT fluid uses EPDM rubber. You mentioned corrosion and this raises some flags. Cleveland parts, that Tost uses - changing the rubber parts to EPDM, were never really intended for use with DOT fluid. The problem is that DOT fluid is hygroscopic and whatever moisture gets into the fluid can corrode the bare aluminum surfaces of the caliper and piston (later pistons were anodized and this helps some). To find out if the piston is anodized, see if it conducts when touched with the leads of an ohm meter as the anodize surface is an insulator. If you have corrosion in the caliper bore or in the O-ring groove of the piston, you will likely have leakage again, probably sooner than later. One fix is to have the caliper bore machined and brass sleeved along with anodizing the piston. If anyone needs a free EPDM O-ring (for DOT fluid) for the Cleveland 300 series caliper, contact me via email (bumperm at att dot fish net) - remove the scaley thing) to get the address to send a self-addressed stamped envelope. bumper Quiet Vent - reduces vent noise by 10 dba "Paul Cordell" wrote in message ... It's Done! Thanks Dave Nadler and Uncle Hank for the off-line notes. This Soaring community is always surprising. I talked to Monty@ M & H Soaring this morning about the spec's for the Pads and O-ring. Then went over to Aircraft Spruce to get the parts. After I looked at their web site, I still had some questions about the rivets. I called a buddy that is an ex '20 owner and RV-7 builder to ask about the rivets. He lives about 100 miles away. As we talked, he walked out to his Hanger and went thru some stuff on his work bench. He had exactly the parts I needed. When would you like to do this he asked?? I told him that if he wanted to "help", it would be on his schedule........He responded, I'll be there in an Hour. He was and did the whole job as I "supervised". Cleaned and polished, pads and ring with a full bleed and new fluid. The system in general was in good shape. Just slight corrosion and some gunk. I supplied him with 1 soda for all the trouble. He'll be back next weekend for a test flight. Paul I've wondered myself - Possibly for compatibility with the master cylinder components scavenged from motorcycles ? Beringer systems use DOT fluid (and work extremely well, and are light). I had an HP that used the red stuff. I don't know about other glider hydraulic brakes out there. The Cleveland adaptations are, um, a bit problematic... See ya, Dave |
#7
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Tost Disk Brake rebuild?
On Apr 15, 10:55 pm, "bumper" wrote:
Paul, As Gary Evans mentioned, there are basically two brake fluids used in gliders... Well, pretty much. But: When I was cobbling together a brake for my HP-18 a few years ago, I found it really convenient to use a Yamaha TZ250 master cylinder (left over from my misspent youth) with a Cleveland wheel and brake. The motorcycle parts like the DOT 3 fluid, and the Cleveland stuff likes the 5056. I ended up using a silicone-based brake fluid, similar to what they now sell as DOT 5 (also left over from the roadracing days) that worked fine with both ends of the system. It also had enough color that I could see it through the walls of the 1/8" OD Nylaflow tubing that connected the two. The whole system worked great, never leaked, and was trouble-free. And since the master cylinder is diaphragm-vented as motorcycle brakes so tend, it didn't drip at all when I turned the fuselage upside-down. Thanks, Bob K. |
#8
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Tost Disk Brake rebuild?
On Apr 16, 7:59*am, Bob Kuykendall wrote:
On Apr 15, 10:55 pm, "bumper" wrote: Paul, As Gary Evans mentioned, there are basically two brake fluids used in gliders... Well, pretty much. But: When I was cobbling together a brake for my HP-18 a few years ago, I found it really convenient to use a Yamaha TZ250 master cylinder (left over from my misspent youth) with a Cleveland wheel and brake. The motorcycle parts like the DOT 3 fluid, and the Cleveland stuff likes the 5056. I ended up using a silicone-based brake fluid, similar to what they now sell as DOT 5 (also left over from the roadracing days) that worked fine with both ends of the system. It also had enough color that I could see it through the walls of the 1/8" OD Nylaflow tubing that connected the two. The whole system worked great, never leaked, and was trouble-free. And since the master cylinder is diaphragm-vented as motorcycle brakes so tend, it didn't drip at all when I turned the fuselage upside-down. Thanks, Bob K. That's a good solution except for my extreme (and possibly mistaken) paranoia when 'silicone' and composites are allowed close proximity. |
#9
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Tost Disk Brake rebuild?
Bob
Any time spent on a TZ as a "Youth" is not mispent! (At least I keep telling myself that) I started on the DS-7 before moving to the TZ 250 and ending up on the 750! Leathers, beer and women! Now I hang out with old guys who dress funny. Life is strange! Bob |
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