Rear master cylinder predicament


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maintainer
Posts: 291
Joined: Sun Mar 22, 2015 11:39 am
Location: Houston, Texas
Motorcycle: 1977 GL 1000
1982 GL 1100 Interstate (Sold)

Rear master cylinder predicament

Post by maintainer »



On my GL 1000 project bike, I am getting down to the short lists. One item was to go thru everything on the rear brakes and pedal pivot etc.
The single thing I lack doing is rebuilding the rear master cylinder, it was in just awful condition. (corrosion)
The rear master cylinder which is very similar to but not exactly like the GL1100 one on the forums video tutorial.
Problem is, evidently the piston is stuck in the bore.
I have soaked it in PB blaster, tapped on it hoping it would spring outward, shot compressed air to the back side of it.

Nothing has worked. I'm to the point of drilling into it and using an ease out bit.

Any idea's before I go all radical on it?????


1982 GL 1100 Interstate SOLD
1977 GL 1000 Standard (naked can be good, who knew?)

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spiralout
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Motorcycle: 1975 GL1000 (gone)
1980 GL1100I (with '77 1000 engine)
1996 GL1500 SE

Re: Rear master cylinder predicament

Post by spiralout »

If the banjo fittings are the same size, take your front brake line off the splitter, bolt it to the rear master and use the front to pump it out.

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maintainer
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Location: Houston, Texas
Motorcycle: 1977 GL 1000
1982 GL 1100 Interstate (Sold)

Re: Rear master cylinder predicament

Post by maintainer »

spiralout wrote:If the banjo fittings are the same size, take your front brake line off the splitter, bolt it to the rear master and use the front to pump it out.
Nope, rear line is a thread in line with no banjo fitting.
My fronts are all new and rebuilt but I haven't added and brake fluid or bled them out yet.
1982 GL 1100 Interstate SOLD
1977 GL 1000 Standard (naked can be good, who knew?)

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spiralout
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Motorcycle: 1975 GL1000 (gone)
1980 GL1100I (with '77 1000 engine)
1996 GL1500 SE

Re: Rear master cylinder predicament

Post by spiralout »

Yep, I was thinking of the 1100 rear master, sorry :cry:

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ankgrays
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Motorcycle: 1981 GL1100 interstate

Re: Rear master cylinder predicament

Post by ankgrays »

I had a similar problem with my '81

Someone suggested taking out the brake bleeder and putting on a compressed air hose as tight as

you can hold it on. Then hit the air lever...popped right out.

Be careful to have the piston aimed at something soft so as to keep it from shooting across the floor.

Good Luck!!
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maintainer
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Location: Houston, Texas
Motorcycle: 1977 GL 1000
1982 GL 1100 Interstate (Sold)

Re: Rear master cylinder predicament

Post by maintainer »

ankgrays wrote:I had a similar problem with my '81

Someone suggested taking out the brake bleeder and putting on a compressed air hose as tight as

you can hold it on. Then hit the air lever...popped right out.

Be careful to have the piston aimed at something soft so as to keep it from shooting across the floor.

Good Luck!!
Sounds like an idea.
So just so I understand, I shouldn't look down the bore at the top of the piston and apply high pressure air to it? :P :D
1982 GL 1100 Interstate SOLD
1977 GL 1000 Standard (naked can be good, who knew?)

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maintainer
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Location: Houston, Texas
Motorcycle: 1977 GL 1000
1982 GL 1100 Interstate (Sold)

Re: Rear master cylinder predicament

Post by maintainer »

Ok I went radical and got it out with no damage to the bore.
1. I carefully drilled a pilot hole in the top of the piston.
2. I followed up with a larger bit which wedged in and spun the piston, and out came all the guts.
Cleaned up the mucky nasty bore.
Ready for rebuild kit.

It's a shame a rebuild kit with a piston some rubber bits and a spring are $50. :shock:
1982 GL 1100 Interstate SOLD
1977 GL 1000 Standard (naked can be good, who knew?)

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spiralout
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Location: Alabama
Motorcycle: 1975 GL1000 (gone)
1980 GL1100I (with '77 1000 engine)
1996 GL1500 SE

Re: Rear master cylinder predicament

Post by spiralout »

maintainer wrote:Ok I went radical and got it out with no damage to the bore.
1. I carefully drilled a pilot hole in the top of the piston.
2. I followed up with a larger bit which wedged in and spun the piston, and out came all the guts.
Cleaned up the mucky nasty bore.
Ready for rebuild kit.

It's a shame a rebuild kit with a piston some rubber bits and a spring are $50. :shock:
Agreed. I think I paid 35 bucks to vtcustoms ebay store for the rear master kit for my '80, and that was about $20 too much for what it is, in my opinion.

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maintainer
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Motorcycle: 1977 GL 1000
1982 GL 1100 Interstate (Sold)

Re: Rear master cylinder predicament

Post by maintainer »

Here's a couple of pictures of the carnage.




1982 GL 1100 Interstate SOLD
1977 GL 1000 Standard (naked can be good, who knew?)

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redial
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Location: Labrador, Queensland, Australia
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Re: Rear master cylinder predicament

Post by redial »

That drill does not look too radical! But some of the other bits look somewhat sad! :shock:
Len in Kapunda

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gc33
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Location: Perth Western australia
Motorcycle: 1981 Gl1100 naked.

Re: Rear master cylinder predicament

Post by gc33 »

Same problem with my 1100. and of course scarce as hens teeth. And it would seem every wing from 1000's to at least 1100's have had same problem with the rear master cylinder. Im currently looking for a replacement fuel tank (there are quite a few on ebay..its the shipping that hurts me) and almost every one I look at has the paint missing in that same area the master sits.
Anyway, Ive bought a new cyl off ebay, its not a wing one, its one of those kinda generic type ones that can go on any bike.But at $16aus I figured id give it a go. If it works great, if not, its only $16. As you guys have mentioned, the rebuild kits are pretty ridiculously priced, as are caliper rebuild seal kits and as I cant seem to get anything here in Australia I have to get from UK or USA. And again, between exchange rates and shipping its a killer. brake crafters are $32US for a rear cyl rebuild kit, thats $50 in our money. and about the same for front rebuild kit.
I have been told, and Im yet to investigate true or not, and how much, but apparently there is a brake place here in perth WA that will re-sleeve the cylinder with a stainless sleeve. I have a feeling its gonna be in the $80 mark to have done. Expensive but trying to replace that master is almost impossible. One of the parts suppliers I was in contact with in USA reckoned he could sell 1 a day...Kinda tells me the cylinders a a bit crappy if everyone wants them..same problem I guess.

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pidjones
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Motorcycle: 2006 GL1800A
1978 GL1000 w/'75 engine (project)

Re: Rear master cylinder predicament

Post by pidjones »

Please pull that new Chinabay MC apart, clean thoroughly, and assemble properly with brake fluid lubricating it before use. I bought both a front and rear to adapt and use on a CB750F, and they were both filthy inside. After cleaning and proper assembly they worked fine, however.



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