1978 GS750 braking issues

[The1970's]

Since I bought my 1978 GS750 it's had some small braking problems and figured i'd just sum it all up in one post. Starting with the easiest: my front caliper retaining plate and the associated bolt have fallen off. I can see this part on the parts fiche but it doesn't list a part number for the plate, only the bolt and washer. any idea where to get one?

The biggest issue I'm having is a brake shudder on the front. When I first bought the bike I noticed it and figured it was a warped rotor. After putting around 4000 miles on it I no longer thing its the rotor. Since then I have replaced the pads, brake lines, wheel bearings, steering head bearings and when I first got the bike I took the caliper off disassembled and cleaned the whole thing and then put it back on with the new pads. This seemed to help the shudder but it soon came back. At this point I can't tell for sure but I think the shudder might be the forks actually compressing intermittently under braking. My bike came with a non-factory master cylinder that also had some very old fluid/dirt in it and it has also been cleaned out. But I have not rebuild the master cylinder nor the caliper with new seals.

[GSXR7ED]

Hello fellow GSer,

I suggest a rebuild. Not difficult but tedious to clean out the caliper and Master Cylinder.


Ed

[The1970's]

Hello fellow GSer,

I suggest a rebuild. Not difficult but tedious to clean out the caliper and Master Cylinder.


Ed

I'm happy to rebuild. In fact I probably should have already. But I can't seem to find a part number on my master cylinder to order a rebuild kit and a new factory one runs almost $400 if I can even find one. Is there anyway you know of to figure out what it is?

[Big T]

Post up a picture

[The1970's]

The front side
20171021_003447.jpg

[The1970's]

20171021_003453.jpg

As you can see the unit has seen better days. If anyone knows of a aftermarket master cylinder for the bike that isn't too far overpriced I may just replace it all together

[chuck hahn]

First of all its the wrong master for a 78 750. All the 77 and 78s used the round one. Shudder can be from things such as worn carrier pins..which rareley happens, bad orings on a carrier pin, warped rotor, or the lines themselves are weak and swell as the pressure builds.

http://www.partsoutlaw.com/oemparts/a/suz/50d3fffef8700230d8b4e18c/front-master-cylinder-gs750ec

[chuck hahn]

Let me go to the storage unit and see if I have a body in th brake parts box that the bore is good. If so you can still by the oring and reservoir new and rebuild kits arent all that expensive. You can rehab one for way way less than 400 bucks!!!

[GSXR7ED]

I cleaned up/soaked the main components (MC & Capilers) and bought new gasket and braided line, brake pads on mine for less than $100. You'd be surprised how much better it operates once all the gunk is cleaned out.


Ed

[The1970's]

First of all its the wrong master for a 78 750. All the 77 and 78s used the round one. Shudder can be from things such as worn carrier pins..which rareley happens, bad orings on a carrier pin, warped rotor, or the lines themselves are weak and swell as the pressure builds.

I cleaned up/soaked the main components (MC & Capilers) and bought new gasket and braided line, brake pads on mine for less than $100. You'd be surprised how much better it operates once all the gunk is cleaned out.
Ed

I am aware that it is not the factory master cylinder but I believe it has the same bore size. I wouldn't mind going back to the factory unit if I can find a rebuildable core I just figured it would be cheaper to rebuild what I have.

I've just put on SS line and was hoping that would fix it. So now I'll order the rebuild kit for the caliper, I just can't find that darn brake pad retainer anywhere.

[chuck hahn]

Nothing in my boxes..sorry. Few rear calipers and some front brake caliper bodies though

[The1970's]

Nothing in my boxes..sorry. Few rear calipers and some front brake caliper bodies though

I do appreciate you looking. No chance with that brake pad retainer on one of the calipers?

[chuck hahn]

No..i used it on my 1000 project a few weeks ago

[The1970's]

No..i used it on my 1000 project a few weeks ago

Ah, no problem thanks for looking. I've put in a PM with a couple guys parting out early 750's in the parts section to see if I can get ahold of a rebuildable master cylinder and that retaining plate. In the mean time i'll keep looking around to see if I can figure out what my current MC is off of and possibly rebuild that.

[chuck hahn]

Heres a 1000 one..which is the same dual disc one that the 750 uses. Not a bad price as it has a lever, mirror vibration dampner, and a really nice cap with it.

https://www.ebay.com/itm/1978-Suzuki-GS-1000-Brake-Master-Cylinder-With-Lever-/162719712940?hash=item25e2d9c6ac:g:m7EAAOSwai1Z6iIH&vxp=mtr

I did find a pad retainer this morning. Its the round metal one. Do you need the round one or the plastic one with that notch deal in it??? I ask as I dont know if yours is a stock 78 one or not...Round metal one as seen here......

http://www.partsoutlaw.com/oemparts/a/suz/50d3ff8cf8700230d8b4dfa9/front-caripers-gs750ec