Adapting Rear Master Cylinder from GL1800 to GL1100

cross over parts from other wings, hondas, or any other parts sources that can be used on our wings.

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Adapting Rear Master Cylinder from GL1800 to GL1100

#1

Post by Easter »

I am rebuilding/customizing a GL1100 and have been working through a long list of issues but one of the more frustrating has been the rear brake master cylinder. I have three now and although perhaps it is a reflection of my skill level I have not been able to get any of them to work properly. Since these parts are now 30+ years old and often left unused for decades they are often thoroughly gunked up to say the least.

I decided to look for something newer that could be substituted and decided to try the GL1800 series since they are only a few years old and plentiful and often cheap. I bought a nice clean one from a 2009 bike complete with hydraulic fluid for $35 including shipping. Less than the price of a rebuild kit.

It turns out the conversion is quite simple. The GL1800 has a slightly larger piston and the mounting tabs are in different locations and the threaded shaft must be cut down but a reasonably skilled person with ordinary hand tools can make an adapter and install the new master cylinder in a couple of hours. Some hand fitting is required and this gets tedious with a fully assembled bike.

After a test ride through town today, I am quite satisfied with the function and do not feel the larger piston/cylinder will create any problems.
Attachments
A comparison of the GL1100 to the GL1800 MC. The shaft has been shortened already and electrical hardware removed from the 1800.
A comparison of the GL1100 to the GL1800 MC. The shaft has been shortened already and electrical hardware removed from the 1800.
IMG_2063.jpg (65.09 KiB) Viewed 4260 times
The adapter is made from small bar stock and serves to give you a second mounting point since the one closest to the rod will not be accessible because of the frame rail. Washers are placed between the cylinder and the adapter to make it similar in thickness so the mounting bolts do not twist. After trial fitting a third hole is drilled between the other two to keep the MC oriented properly under pressure from the petal. This step is best accomplished by drilling through the frame web and at least part way into the adapter to be sure of alignment.
The adapter is made from small bar stock and serves to give you a second mounting point since the one closest to the rod will not be accessible because of the frame rail. Washers are placed between the cylinder and the adapter to make it similar in thickness so the mounting bolts do not twist. After trial fitting a third hole is drilled between the other two to keep the MC oriented properly under pressure from the petal. This step is best accomplished by drilling through the frame web and at least part way into the adapter to be sure of alignment.
IMG_2067.jpg (134.41 KiB) Viewed 4260 times
To mount the cylinder first attach the banjo bolt finger tight. The new mounting location causes the line to twist slightly and it will be very difficult to attach after the cylinder is bolted down. Next connect the brake pedal to the threaded shaft, unless you have three hands a wooden block is a big help in holding the brake lever in the proper place. Next, bolt up the top mounting tab by passing the bolt through the frame, through the adapter plate and through a couple of washers before threading into the cylinder. This gets a little tedious but can be done. Next drill a new hole through the frame web and on through the new bracket as far below this mounting point as possible. I used allen head bolts to give me as much spread as possible.
To mount the cylinder first attach the banjo bolt finger tight. The new mounting location causes the line to twist slightly and it will be very difficult to attach after the cylinder is bolted down. Next connect the brake pedal to the threaded shaft, unless you have three hands a wooden block is a big help in holding the brake lever in the proper place. Next, bolt up the top mounting tab by passing the bolt through the frame, through the adapter plate and through a couple of washers before threading into the cylinder. This gets a little tedious but can be done. Next drill a new hole through the frame web and on through the new bracket as far below this mounting point as possible. I used allen head bolts to give me as much spread as possible.
IMG_2087.jpg (125.2 KiB) Viewed 4260 times
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#2

Post by Easter »

Unfortunately, I forgot to photograph the reservoir in place but it is unchanged from the original configuration. The GL1800 hose is about a 1/2 inch shorter but the mounting adapter on the cylinder itself is long enough that the tube can be slid off a bit to create more length. The original GL1100 reservoir must be used since the mounting angle is different for the GL1800 and the tube comes out of the side rather than the bottom as on the 1100. It is also smaller in diameter but I was able to push the 1100 reservoir onto the tube without much trouble. A larger clamp is required so put it on first or you will be taking it back apart as I did!

It was relatively easy to prime. I left the banjo bolt loose until I had fluid seeping out, then tightened it and opened the bleeder valve at the caliper. A small tube placed over the bleeder valve goes into a can of brake fluid to prevent suction from pulling air back into the line. In a few minutes I had the brake bled and was ready for a ride. After a few miles warming up the pads and seating them, the rear brake felt just fine.
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#3

Post by CYBORG »

nice job
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#4

Post by Sagebrush »

Good to know. Nice work.
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#5

Post by Brant »

Good info, thanks.
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#6

Post by chewy999 »

Useful to know for when the time comes. :partytime
Previous Rides,
1980 CB250N Good to learn on
1981 CX500 good mid range tourer, went to Austria on it!
1983 GL1100C Pride and joy, sold when I bought my 1st house, big mistake
1985 GL650 Silverwing another mistake, horrible bike
1986 CBX550 Good commuter
1989 Suzuki GS750 (1976) cheap and cheerful until a dog ran out in front of me on Xmas Eve, 1991
Current bikes
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#7

Post by westgl »

Hey Easter,

You have had some time to test ride and get a good under standing as to the Pro's & Cons, of going to this conversion.

1. Do you get any brake lockup, Front or Rear?
2. What about panic stop, can you lock either wheel larger piston means more brake power?
3. Any problems that you have encountered?
4. How does the foot brake feel now? any excess foot pedal play?
5. Are the brake similar to the way they were stock?

I have a 1983' GL1100 with linked brakes That i will be testing this on.
Easter wrote:I am rebuilding/customizing a GL1100 and have been working through a long list of issues but one of the more frustrating has been the rear brake master cylinder. I have three now and although perhaps it is a reflection of my skill level I have not been able to get any of them to work properly. Since these parts are now 30+ years old and often left unused for decades they are often thoroughly gunked up to say the least.

I decided to look for something newer that could be substituted and decided to try the GL1800 series since they are only a few years old and plentiful and often cheap. I bought a nice clean one from a 2009 bike complete with hydraulic fluid for $35 including shipping. Less than the price of a rebuild kit.

It turns out the conversion is quite simple. The GL1800 has a slightly larger piston and the mounting tabs are in different locations and the threaded shaft must be cut down but a reasonably skilled person with ordinary hand tools can make an adapter and install the new master cylinder in a couple of hours. Some hand fitting is required and this gets tedious with a fully assembled bike.

After a test ride through town today, I am quite satisfied with the function and do not feel the larger piston/cylinder will create any problems.
1983 GL1100I Beige was an Interstate, Now Naked, Refresh & needs repaint
1984 GL1200A Naked 4Cyl.Valkyrie, Single Valk. seat & Valk. Gas Tank
1986 GL1200 Naked Hotrod with some old school in the mix (Completely gone through) Better than new
1988 GL1500 76 k miles, Naked 6cyl. building into a HotRod trike. (Under Construction)
1999 GL1500 45K miles Runs excellent
2006 M109R 1800cc Naked Reverse Trike
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#8

Post by spiralout »

Wish I'd come across this post before spending months and $125+ hunting down an original that only took 5 days of soaking to get the circlip and washer out so I could start on the old frozen piston... :( :( :( .
westgl wrote:Hey Easter,

You have had some time to test ride and get a good under standing as to the Pro's & Cons, of going to this conversion.

1. Do you get any brake lockup, Front or Rear?
2. What about panic stop, can you lock either wheel larger piston means more brake power?
3. Any problems that you have encountered?
4. How does the foot brake feel now? any excess foot pedal play?
5. Are the brake similar to the way they were stock?
I'm curious about these, too. How's it working out, Easter?
Chris
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#9

Post by jimmyz3286 »

Nice write up if I can work it in I may have to do this since I am in the middle of a build.
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#10

Post by irishcarbomb »

I just did this...took about an hour and works great. Used a master from a 2001 gl1800 same as pictured in this thread.

I never rode with stock brakes so I cant compare the feel, but its pretty close to what my sportbike is like. If not better. I wish I would've just done this instead of hunting down a second M/C...cost about the same as a rebuild kit.


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1983 GL1100 Fuel Injected Turbo Build Thread
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#11

Post by 82aspy »

Easter wrote:I am rebuilding/customizing a GL1100 and have been working through a long list of issues but one of the more frustrating has been the rear brake master cylinder.
what year 1100?
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100-83 i

#12

Post by 82aspy »

i know of one (& only) other recent 83 conversion that i don't think has been tested much, comments are in this thread
I just did this...took about an hour and works great. Used a master from a 2001 gl1800 same as pictured in this thread.

I never rode with stock brakes so I cant compare the feel, but its pretty close to what my sportbike is like. If not better. I wish I would've just done this instead of hunting down a second M/C...cost about the same as a rebuild kit.

Pics in my build thread.
http://ngwclub.com/forum/viewtopic.php?p=562670#p562670

westgl wrote:Hey Easter,

You have had some time to test ride and get a good under standing as to the Pro's & Cons, of going to this conversion.

1. Do you get any brake lockup, Front or Rear?
2. What about panic stop, can you lock either wheel larger piston means more brake power?
3. Any problems that you have encountered?
4. How does the foot brake feel now? any excess foot pedal play?
5. Are the brake similar to the way they were stock?

I have a 1983' GL1100 with linked brakes That i will be testing this on.
Easter wrote:I am rebuilding/customizing a GL1100 and have been working through a long list of issues but one of the more frustrating has been the rear brake master cylinder. I have three now and although perhaps it is a reflection of my skill level I have not been able to get any of them to work properly. Since these parts are now 30+ years old and often left unused for decades they are often thoroughly gunked up to say the least.

I decided to look for something newer that could be substituted and decided to try the GL1800 series since they are only a few years old and plentiful and often cheap. I bought a nice clean one from a 2009 bike complete with hydraulic fluid for $35 including shipping. Less than the price of a rebuild kit.

It turns out the conversion is quite simple. The GL1800 has a slightly larger piston and the mounting tabs are in different locations and the threaded shaft must be cut down but a reasonably skilled person with ordinary hand tools can make an adapter and install the new master cylinder in a couple of hours. Some hand fitting is required and this gets tedious with a fully assembled bike.

After a test ride through town today, I am quite satisfied with the function and do not feel the larger piston/cylinder will create any problems.
"there is a Darwinian element"
Yoda said, "There is no try or not try; there is only do or don't do."
=====================
ngw quotes anim-cheers1 - \ "I will strip the beast" \ "the swingarm is just a hunk of metal" \ "gonna maybe ...dunno yet" \ "It's never done, thats the fun." \ "something about this site brings me back"
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#13

Post by Brant »

Ok so I got an 1800 master cylinder and want to do this swap/upgrade. But the hard line that goes in to the 1100 rear master on my 83 has a line nut on it. How do I swap it to a banjo fitting? I'm guessing I cut the hard line and slip a rubber brake line with a banjo fitting on the end end, over the hard line and secure with a clamp of some type??

Well I just checked a couple places here in town and they said they can't do it. Don't have the banjo fitting. NAPA said they can't crimp the fittings to the lines, a DOT thing.
83 GL 1100 bagger Ugly Betty
ALL WE WANT TO DO IS DRINK OUR ESPRESSO, RIDE OUR MACHINES, AND NOT BE HASSLED BY THE MAN
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#14

Post by CYBORG »

I'm not a fan of clamps on brake line fittings. I would have a new line made, with the correct ends
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Re: Adapting Rear Master Cylinder from GL1800 to GL1100

#15

Post by Brant »

Found a couple on line places. Guess I'll get it done but thought it would be a little quicker swap. Shoulda checked it out a little more first.
83 GL 1100 bagger Ugly Betty
ALL WE WANT TO DO IS DRINK OUR ESPRESSO, RIDE OUR MACHINES, AND NOT BE HASSLED BY THE MAN
Owning a motorcycle is not a matter of life or death. It's much more important than that.
"Don't sweat the little things, guys, take care and appreciate all that you have around you!" - Fewman
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