Brake rebuild = need advice

[Guest]

I'm working on rebuilding the front brakes on my 1980 GS-1000-G. I picked up a couple kits with all the rubber bits and have cleaned up the callipers and pistons (Single Pot Callipers). Everything is looking good considering the bike has 207,000 kms. with only one previous brake rebuild back in the early 1990's. The problem is, trying to keep the Inside (lower) rubber seal in place while reinstalling the piston. The new seal fits in the groove and trying to wiggle the piston past it, isn't working, as they are slightly smaller diameter so interfere with the piston. I've tried some of the grease the kit provides. I checked the old seal and it is exactly the same size and diameter. I've heard of people putting the piston in the freezer to shrink it, but that sounds risky to me. Same with the seal being put into hot water to stretch it to fit better into the groove. Neither sounds like a factory way of doing things. Any of you had similar issues? How did you solve them? Being a Pensioner, I can't afford to take the bike to a shop with their current labour rates, and many shops now refuse to work on bikes that are much over 10 years old. HELP !!!

 

[Guest]

First of all, WELCOME.

Next, clean that grease off anything that will eventually be near brake fluid. Then clean it again. The grease is only for the pad/caliper junction, nothing inside.

Try assembling again, but using brake fluid as you lubricant. Yes, it's a snug fit, but it will work.

If you that that is fun, wait until you try fiddling with the dust boot.

 

[Rich82GS750TZ]

Ron
Welcome to the forum.

To search the archives of the forum for any solution to an issue it is advised to use The Advanced Search. When you put in the key word(s) on the next page, change it from Search Entire Posts to Search Titles Only, then click Search Now. This is the only way to get meaningful search results. Just about anything you come up with has been dealt with in the past.

Another very useful resource we use is Bike Cliff's Website, linked in my signature. It's a treasure trove of how-to articles, manuals and wiring diagrams. On that page there is at least one Brake Caliper rebuild article. I'll link the one here that helped me with your same issue, refitting the piston/seal back into the caliper. See if this helps, even if your caliper isn't exactly the same.

http://members.dslextreme.com/users/storagecliff1/images/brake_caliper_overhaul.pdf

This one will be useful as well:
http://members.dslextreme.com/users/cbsaunders/gs/79-Brake_overhaul.pdf

The grease that came with your kit is likely for use on the backs of the pads/shims, and/or the pins that allow the caliper to slide, and probably should not be use on the piston/seal. I believe that only brake fluid in indicated for that use, but not entirely sure. I'd clean that grease off w/ brake cleaner spray before continuing.

Please create a signature with, at least, your bike info in it. That way you'll never have to remember to type it when asking questions. Go to settings at the top right of any page. Signature creation tools are on the left side after the jump.

Also, we like pictures. The forum is a bit finicky w/ pictures. I have written instructions for using Imgur to host images for use on the forum, linked in my signature.

 

[Baatfam]

1980 GS-1000-G...the bike has 207,000 kms.

All those miles yours? Owned since new?
If so, wow.

 

[Rich82GS750TZ]

that's 128,623 Miles. Wow, indeed. Them's Grimly miles.

 

[chris]

Hi, I would make sure the piston leading edge is free of corrosion or build up , assuming you are reusing the old piston. I know the oem kits come with a lube that works really well. I wish I could buy some. Like the other guys said, make sure everything is spotless, but don't contaminate the new seal with any kind of cleaners. The piston should go in with finger pressure, don't force it. I really doubt that freezing the piston would make difference. I have put seals in hot water to aid assembly in industrial hydraulic applications like a 14 inch diameter cylinder but not for motorcycles brakes. Take your time and don't force it. Oh yeah, that piston boot is a supreme PITA .

 

[Guest]

Thanks for the advice. I have the front brakes reassembled and have good feel at the brake lever. I'm now waiting on a new Stator I've ordered, as the electrical system isn't charging the battery. Bike starts easily and runs fine so once I install the new Stator, it's time for some test rides in the area. As per an earlier question, most of the kms were added by myself. Bought the bike with about 60k in '93 from Original owner. Sold it a few years later (ran into financial trouble), New owner found it too small for him, but had rebuilt the engine at around 100,000 kms.Turned out it wasn't necessary as everything inside was still well within factory specs. Bought it back at 130,000k give or take a few, and did the rest of accumulated mileage over the years. Always had other bikes so not my exclusive ride. 39 machines so far, and hopefully still counting. Thanks again for the advice.

 

[Rich82GS750TZ]

I'm now waiting on a new Stator I've ordered, as the electrical system isn't charging the battery.

You may already know this, but it is almost a certainty that a failed Reg/Rec killed your stator. But you certainly should do your own testing. Countless stories in the archives of this occurring regularly with Suzuki GSs. My saga is linked in my signature. You may want to skim through it. I've asked all the dumb questions, so you don't have to.