'74 GT550 front brake questions

[vdavidoff]

I'm trying to rebuild the front brakes on my '74 GT550 and I have a few questions I was hoping you all could help me answer.

When I bought the bike the brake lever was gutted. I have a master cylinder rebuild kit, which I believe comes with all those guts, but I have no idea how the parts all fit together. Does anyone have a picture or description of this? I have the Tokico master cylinder and caliper.

It is safe to assume I should be able to blow air through both sections of brake line for the front brake? If so, then my bottom section is horribly clogged (not even compressed air seems to make it through). It has soaked in evaporust a few times and is still totally jammed. What's my best bet? Guitar string or something like that?

I'm also having issues getting the old piston out of the caliper, but I found some tips on the forum here and will be trying them shortly.

Thanks for your tips!
Andy

[two-stroke-brit]

i do remember a member having to clean brake lines with a coat hanger repeatedly.
i am all for new braided lines, they are worth the investment if you are going to keep the bike.
mark

[Cliff]

http://www.alpha-sports.com/suzuki_parts.htm" onclick="window.open(this.href);return false;
Check for parts fiches on sites such as the one above for the master cylider.
I changed the brake line to a one piece stainless one this year. Changed the fluid and line and it made a world of difference to the front brake! Can't do a "Stoppie" but I sure can stop now!!
The brake line is 965mm long. I got mine from a supplier here in Ontario, Canada, for $75.00-$80.00.
Here's the link to the site: http://www.motorcycleinnovations.ca/" onclick="window.open(this.href);return false;

[diamondj]

Or you can get a custom made to fit line for your GT550 for a bit less:

http://www.caferacer.net/forum/topic.asp?TOPIC_ID=8828

I have purchased braided lines from Shaun and sent others to him as well and we were all very happy with the price and product. Tell him diamondj sent you and ask if he's still offering the 15% discount for knowing the coupon code "caferacer" but leave the quotes off!

Jim

[vdavidoff]

Thanks guys.

I took a coat hanger to the stubborn hose and it's looking better now, though I still have more work to do. I appreciate the suggestions as far as replacement hose. I'll look into that and might go that route. I don't plan to keep the bike once it's rideable, but I also don't want to put anyone at risk due to skimping on something like brakes. Bad plan.

I'm going to take a torch to the piston and caliper tomorrow. Nothing else I have tried has cause even the slightest budge. I like the idea of using a grease gun to press the piston out, but while I do have a torch handy, I do not have a grease gun and fittings handy.

As far as the fiche goes, I'm not able to make out how the master cylinder parts there align with what I have in this rebuild kit. The fiche doesn't even seem to show a spring, and I have a spring here in my kit. I have attached a picture of the rebuild kit, SGP part number 59600-45821. I don't think I got the wrong kit but I guess it's possible. Does this look right/wrong/anything to anyone?

Thanks again!
Andy

[vdavidoff]

I got the piston out using a torch, and all the lines and ports are now free and clear after jabbing away with a coat hanger for a while. Down to the M/C assembly.

After looking at a bunch of other M/C diagrams, I think I have figured out how this one goes together, but I don't feel 100% about it. I have attached a picture of how I think things go. Can anyone confirm that I have this right?

Everything up to the washer would live inside the cylinder, then the washer and circlip would be just outside the cylinder in a recessed area holding everything in. The boot would slip over the right side of the piston until the right end (which has a lip inside) slips into the groove on the far right of the piston. The right side of the piston would protrude through the boot a bit and would make contact with the brake lever. The lip on the left side of the boot would rest on top of the circlip.

The thing I am most concerned about is that the rubber topper on the right (small) side of the spring doesn't fall into the cylinder like the other parts. It would have to be pushed in and would fit snugly. Which doesn't seem wrong, but I'd rather not snug a part in if it's not how it's supposed to go.

Oh, and one more question: When installing the new piston into the caliper, should it have any sort of grease applied to its sides, or does it just go in dry?

Thanks again.
Andy

[Cliff]

Never use anything but clean brake fluid as an assembly lube!! Mineral based oils/greases will ruin the new rubbers!

[pig9r]

I am also in the process of rebuilding a MC and caliper on a '74 GT550. Looks like you have it right. Lube with brake fluid like Cliff said. Did you have the thin plastic washer and spring clip to hold the dust cover on?

You might notice that the rebuild kit's piston is a little longer but the first cup is smaller than the original, so the overall length is still the same.

[pig9r]

Only thing I can't remember now, or find anywhere, is on the caliper axle bolts, which grooves the two o-rings go on.....

[vdavidoff]

Cool on using brake fluid only for lubrication as necessary.

I do not have the washer and clip to hold the dust cover on. It seemed to me like it might just sort of stay in place because the boot is a snug fit, but I guess I need to keep an eye on that/address it now. Thanks for that. Btw, the pictures you linked to aren't showing up for me in the thread, but I was able to find them at http://www.r3owners.net" onclick="window.open(this.href);return false;.

As for the o-rings for the bolts, I believe they go on the two inner grooves. I think outer grooves are for the little rubber boots that also go on the bolts (2 on each), and I believe those boots go on with each fully open end towards the middle of the bolt, based on diagrams I have found online.

Thanks again all.
Andy

[Coyote]

[tz375]

I would strongly recommend replacing any old rubber brake lines. I think the recommended life is 3-5 years and it's a little past that date.

I'd get black coated braided lines and be safe.

[vdavidoff]

Thanks again to everyone. I have contacted Slingshot Cycles about replacement line, and my master cylinder is now assembled and seems to be functioning properly (though nothing else is back together yet). I'm waiting on putting the caliper back together until I have the new pads, but it looks like there aren't going to be any surprises there.

Andy

[Cliff]

While we're on the topic of brakes, does anyone know of a replacement disc for the GT's? One that will actually stop the bike! When the brakes are applied with the old stainless steel disc it's like trying to grab a hot knife with two sticks of butter! Stopping in the rain with a solid disc? Not going to happen!!

[two-stroke-brit]

While we're on the topic of brakes, does anyone know of a replacement disc for the GT's? One that will actually stop the bike! When the brakes are applied with the old stainless steel disc it's like trying to grab a hot knife with two sticks of butter! Stopping in the rain with a solid disc? Not going to happen!!

go to ians (old japanese bikes) feild guide ,i beleve there is a section on compatable discs in there.

cheers mark