GL1100 Master Cylinder upgrade

9693 Views 22 Replies 14 Participants Last post by TBear, Oct 2, 2009

84GrayWing

Discussion Starter · Sep 29, 2009

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Ok, I've read some about the front brakes on the 1100 not being the best in the world. I'm guessing that the weak link would be the master cylinder. What I'm thinking about doing is going with a more up to date master cylinder on the bike. I would like to try and use the master cylinder from an ST1300 or the GL1800. Is this possible? I know the newer bikes have linked systems but I was thinking I could still go direct to the front caliper on the 1100 because it is just a hydraulic system that applies fluid pressure wherever the lines are routed correct? I'm ready for any flaming I may get but I dig old school stuff with new school safety.

Jeff

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Sakryn

· #2 · Sep 29, 2009

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Since I have to change an old cracked leaky master cylinder on my bike I would love to know this as well. If it isn't possible I guess I will have to try and find one to replace over the "non-riding" season.

Blaine

William_86

· #3 · Sep 29, 2009

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it doesn't have to be new.. it must be bigger

Bschofield

· #4 · Sep 29, 2009

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William_86 wrote:

it doesn't have to be new.. it must be bigger

to clarify, the plunger must be bigger, not necessarily the fluid reservoir..correct?

84GrayWing

Discussion Starter · #5 · Sep 29, 2009

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The reason I mentioned ST and GL1800 is they are both fairly heavy bikes and seem to be able to stop on a dime and give you 9 cents change. I don't know what bigger means in the master cylinder sense. I don't want to link my brakes, I think that would be a little over my realm of talent.

jeff

84GrayWing

Discussion Starter · #6 · Sep 29, 2009

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If this works I may do the 1200 too, it has the mushiest brakes I've ever had. The only thing that bothers me about that bike.

Jeff

peterbilt

· #7 · Sep 30, 2009

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my dad has an 07 fat boy and his front master cylinder isnt any bigger than mine the only thing i noticed is that his lines are brand new and dont "flex" under a brake action

on mine they flex alittle but im going to put stainless hoses on mine this winter rember alittle flex means pressure lost i dont think changing the mastercylder from one to another would really matter too much they all put out about the same pressure im sure they differ alittle but basically they are all the same try better brake pads or try racing rotors with relief holes drilled in them lol but if you need those on a wing your goin WAYYYYYYYYYYYYYY too fast

DaveO430

· #8 · Sep 30, 2009

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There is more to it than the master cylinder. If everything is working right you will have decent brakes but the older bikes didn't have enough friction area to have the braking power of the newer ones. You could make improvements with new brake lines and a different master cyl. but it actually would have to be a smaller piston or different fulcrum point for the lever to apply more pressure to the calipers. Calipers with larger pistons and/or larger pads and larger rotors would be great if you could find something that would work.

Bagmaster

· #9 · Sep 30, 2009

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Stainless steel brake lines seem to help a lot of folks on the older bikes. My brakes on my 82 feel real good so I haven't up-graded the lines yet but may do so next year if I still have this bike.

Big Port Jimmy 6

· #10 · Sep 30, 2009

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I have a CBR 600F3 Master on mine. I am satisfied with it so far, I unlinked the brakes and will change out the "small" caliper with one from an 82 this winter. New stainless lines will help also. Dave has it right above, a larger piston diameter means only more volume not pressure, a smaller bor will increase the pressure. Upgrading your pads will also make a difference. Jay

goldtop

· #11 · Sep 30, 2009

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Yup. for me the satinless brake lines are the best bet. I also stick to my beloved EBC organic pads tried and trusted.

The caliper upgrade is one route I have been thinking of too. When I find a pair of twin pots in the bike breakers I will give them a try.

William_86

· #12 · Sep 30, 2009

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peterbilt has a point, old wings hoses are the weak point of brakes.. if you change to stainless steel lines brakes will feel totally different. thats probably all you need

GSMacLean

· #13 · Sep 30, 2009

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I agree. My front brakes were quite mushy - I could squeeze the lever all the way to the grip.

I replaced my brake lines with stainless lines from Vencowings last spring (along with rebuilding the master cylinder and caliper), and the brakes are rock solid, knife-edge sharp now - a thousand times better than they were.

I would recommend going with the stainless lines first, and then decide if you still think they need improving.

William_86

· #14 · Sep 30, 2009

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Even using a bigger/newer master cylinder with the old hoses you will see no improvement at all.

garyft

· #15 · Sep 30, 2009

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In point of fact, a master cylinder with a SMALLER bore will give you better braking force as it will increas the hydraulic advantage. Picture it like a kickstand pad. The kick stand has the same amount of weight on it no matter what it's sitting on (force). But if the ground is soft, it may sink in, so you use a pad, or a piece of wood or something. This increases the surface area, thereby reducing the pressure. If you increase the diameter of the plunger, then the force you apply to the brake lever is spread over a larger area and actually decreases the amount of pressure in the brake line for the same amount of force applied to the lever. Randakk's has a very good explanation, as well as an upgraded master cylinder for the GL1000 (don't know if it will fit the GL1100, or if it will be an upgrade for the 1100). But at least the theory I'm trying to convey is explained better on this page:

http://www.randakks.com/Brake%20Parts.htm#1

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TBear

· #16 · Sep 30, 2009

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OK not an engineer, but brave experimenter. Sometimes no other choice. That said I have tried a GL1200 front master cylinder on my 83 Aspy GL1100 and had no problem. No difference in braking or feel. I recently aquired a New in the box gL1500 master with some other parts I bought. Looked it over and thought "why not" so for the last month have been riding my 83 Aspy with The Gl1500 master cylinder. It does have a slightly smaller bore and smaller reservoir. Lever pulls about a quarter inch more than stock one did but real solid. Actually seems to brake a bit better. Of course with the smaller reservoir will have to keep a closer eye on fluid level as pads wear.

84GrayWing

Discussion Starter · #17 · Oct 1, 2009

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Well you have all probably saved me a ton of money going in the wrong direction. I'm in touch with Lopeha "Andy" and he's going to set me up with the new brake lines and I'm going to try and just do a 1200 master cylinder, it's all metal housing seems a bit more durable than the plastic one on the 1100. Thanks for the help, this is a great forum.

Jeff

redbaron

· #18 · Oct 1, 2009

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One last note...Several months ago Broke Winger found NEW front master cylinders from this company they come either power coated or chrome ......Any one needing a new front master cylinder might check these guys out.....

http://cgi.ebay.com/ebaymotors/FRON...ries?hash=item20ad73a415&_trksid=p3911.c0.m14

Just a thought...Broke really liked his and when he complained that the lever had a defect ..They sent him another one and told him keep the defective one......

Claude

William_86

· #19 · Oct 1, 2009

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just remember, 1500 and 1200 front master cylinders are mean to work with a single caliper (rear brake operates one of the front), 1100 front brakes are dual caliper.

TBear

· #20 · Oct 1, 2009

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William,early 1100's were dual on the front but late 1100's were linked front and back and front master cylinder just worked a single caliper. on my 83 Aspy it only works the front left caliper

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