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#21
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Grob 103 Twin II Brake Master Cylinder
What do you mean by "swap over the lever"?
Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? Did anyone mention why it needed replacement? My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. If this is the case, there are places that will bore the cylinder and sleeve it with either stainless steel or brass. It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. |
#22
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Grob 103 Twin II Brake Master Cylinder
the new master cylinder may not have the brake lever installed.. (attached)
as most replacement motorcycle parts do not either, the master cylinder is separate part number from the external brake lever handle. BT "Mike McCarron" wrote in message ... What do you mean by "swap over the lever"? Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? Did anyone mention why it needed replacement? My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. If this is the case, there are places that will bore the cylinder and sleeve it with either stainless steel or brass. It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. |
#23
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Grob 103 Twin II Brake Master Cylinder
At 04:50 24 October 2008, BT wrote:
the new master cylinder may not have the brake lever installed.. (attached) as most replacement motorcycle parts do not either, the master cylinder is separate part number from the external brake lever handle. BT "Mike McCarron" wrote in message ... What do you mean by "swap over the lever"? Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? Did anyone mention why it needed replacement? My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. If this is the case, there are places that will bore the cylinder and sleeve it with either stainless steel or brass. It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. |
#24
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Grob 103 Twin II Brake Master Cylinder
At 10:15 24 October 2008, Don Johnstone wrote:
At 04:50 24 October 2008, BT wrote: the new master cylinder may not have the brake lever installed.. (attached) as most replacement motorcycle parts do not either, the master cylinder is separate part number from the external brake lever handle. BT "Mike McCarron" wrote in message ... What do you mean by "swap over the lever"? Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? Did anyone mention why it needed replacement? My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. If this is the case, there are places that will bore the cylinder and sleeve it with either stainless steel or brass. It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. Look on the bright side, at least he isn't in the UK. I'm pretty sure BMW don't supply brake cylinders with EASA release certificates. I can imagine: 1. Brake cylinder from BMW: £100 2. Identical BMW brake cylinder the man from EASA has sprinkled magic pixie dust on: £350 3. ?????? 4. Profit |
#25
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Grob 103 Twin II Brake Master Cylinder
On Oct 24, 4:30*am, Andrew Warbrick
wrote: At 10:15 24 October 2008, Don Johnstone wrote: At 04:50 24 October 2008, BT wrote: the new master cylinder may not have the brake lever installed.. (attached) as most replacement motorcycle parts do not either, the master cylinder is separate part number from the external brake lever handle. BT "Mike McCarron" *wrote in message ... What do you mean by "swap over the lever"? Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? *Did anyone mention why it needed replacement? *My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. *If this is the case, there are places that will bore the cylinder and sleeve it with either stainless steel or brass. *It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. *And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. Look on the bright side, at least he isn't in the UK. I'm pretty sure BMW don't supply brake cylinders with EASA release certificates. I can imagine: 1. Brake cylinder from BMW: £100 2. Identical BMW brake cylinder the man from EASA has sprinkled magic pixie dust on: £350 3. ?????? 4. Profit After replacing the master cylinder on our ship we found that the problem was with the brake line linking the two cylinders. When we replaced it the problem of poor braking was solved. Must have been unobservable expansion within the OE line! |
#26
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Grob 103 Twin II Brake Master Cylinder
Where did you find a brake line to purchase that would fit the Grob? Mike At 12:42 24 October 2008, haven wrote: On Oct 24, 4:30=A0am, Andrew Warbrick wrote: At 10:15 24 October 2008, Don Johnstone wrote: At 04:50 24 October 2008, BT wrote: the new master cylinder may not have the brake lever installed.. (attached) as most replacement motorcycle parts do not either, the master cylinder is separate part number from the external brake lever handle. BT "Mike McCarron" =A0wrote in message ... What do you mean by "swap over the lever"? Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? =A0Did anyone mention why it needed replacement? = =A0My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. =A0If this is the case, there are places that will bore th= e cylinder and sleeve it with either stainless steel or brass. =A0It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. =A0And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. Look on the bright side, at least he isn't in the UK. I'm pretty sure BMW don't supply brake cylinders with EASA release certificates. I can imagine: 1. Brake cylinder from BMW: =A3100 2. Identical BMW brake cylinder the man from EASA has sprinkled magic pixie dust on: =A3350 3. ?????? 4. Profit After replacing the master cylinder on our ship we found that the problem was with the brake line linking the two cylinders. When we replaced it the problem of poor braking was solved. Must have been unobservable expansion within the OE line! |
#27
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Grob 103 Twin II Brake Master Cylinder
At 13:45 24 October 2008, Mike McCarron wrote:
Where did you find a brake line to purchase that would fit the Grob? Almost any motorcycle shop will make one up for you. If you get one that has a steel braid outer you will, as a previous poster said, get rid of the problem of brake line expansion. I have to say that while brake pipe expansion is a problem with mootor cycle brakes, given the very short line on the Grob I am surprised that was a problem. |
#28
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Grob 103 Twin II Brake Master Cylinder
On Oct 24, 6:45*am, Mike McCarron wrote:
Where did you find a brake line to purchase that would fit the Grob? Mike At 12:42 24 October 2008, haven wrote: On Oct 24, 4:30=A0am, Andrew Warbrick wrote: At 10:15 24 October 2008, Don Johnstone wrote: At 04:50 24 October 2008, BT wrote: the new master cylinder may not have the brake lever installed.. (attached) as most replacement motorcycle parts do not either, the master cylinder is separate part number from the external brake lever handle. BT "Mike McCarron" =A0wrote in message ... What do you mean by "swap over the lever"? Mike At 22:00 23 October 2008, Don Johnstone wrote: At 13:00 23 October 2008, Jim Beckman wrote: This thread started with the necessity of replacing the brake master cylinder, right? =A0Did anyone mention why it needed replacement? = =A0My first guess is wear or corrosion in the cylinder bore causing it to leak pressure. =A0If this is the case, there are places that will bore th= e cylinder and sleeve it with either stainless steel or brass. =A0It's done all the time for old cars. On the other hand, I don't know anything about the legality of doing that for an aircraft brake system. =A0And on the Gripping Hand, I would probably do it that way myself. Jim Beckman Old cars normally have steel brake cyliders, the BMW part we are talking about is aluminium. Putting a steel or brass sleeve in will almost certainly cause corrosion (disimilar metals). A new part is available and is not expensive. All that needs to be done is to swap over the lever. Look on the bright side, at least he isn't in the UK. I'm pretty sure BMW don't supply brake cylinders with EASA release certificates. I can imagine: 1. Brake cylinder from BMW: =A3100 2. Identical BMW brake cylinder the man from EASA has sprinkled magic pixie dust on: =A3350 3. ?????? 4. Profit After replacing the master cylinder on our ship we found that the problem was with the brake line linking the two cylinders. *When we replaced it the problem of poor braking was solved. *Must have been unobservable expansion within the OE line! As I remember, it came from Grob in Bluffton, OH but now they are out of the parts supply business ?! |
#29
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Grob 103 Twin II Brake Master Cylinder
Everyone has covered the topic well but I'll add my 2 cents having
repaired our 103 brake. Yes, it is a Magura master cylinder as used on BMWs. All they did was cut off most of the brake lever and mount a cable to the stub to actuate it. Yes, bleeding from the bottom of the system (slave) works best. Here's a little trick - any marine supply depot sells a plastic pump for replacing bottom end oil in outboard motors. It looks like a shampoo or epoxy pump and screws onto a standard oil, or coincidentaly, brake fluid bottle. Screw it on the bottle, push the tubing onto the cracked open caliper bleed nipple and pump slowly. It forces the brake fluid up. Have someone at the master cylinder with a towel wrapped around it to take care of overflow. It is always easier to force air bubbles upwards in a hydraulic system then to force them downwards. It is faster then from the top and a whole lot let frustrating. Another hint ... don't worry about replacing the entire master cylinder, Just go into a BMW motorcycle dealer and buy a rebuild kit (about $75). It includes a new piston, spring and seals. (I can't recall the bore size but these kits care reasonably universal - all you need to do it confirm the size at the parts desk.) Use a very fine emery cloth or wet sandpaper to gentle hone the cylinder and put it all together. Usually the problem is the seals, not pitting of the cylinder. Total job takes about 1.5 hours including removing and replacing the cylinder. |
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