75 GT500: How to repair/restore front brake system?

[GT500-2stroke]

1975 GT500:

How to repair or restore front brake system?

My goal is to make the brake system work properly and reasonably clean.
( It does not have to be perfect looking, at least for now)

Bike came with extra brake system ( partial ), which includes broken master cylinder and
the pipe/cable.

In addition, the is brake system on the bike which is not working.

I need to decide which one to work on?
How to decide which one to work on?
( Attached some pics below)

Once that is decided, I need to know:

1. Where do I start?
2. Which parts of brake system to replace?
3. How should I proceed in terms of what tasks are to be performed?

Appreciate all/any help.

[GT500-2stroke]

More pics..

[Craig380]

You can easily restore the caliper - the seals and pistons are still available from Suzuki for rebuilds.

For the master cylinder, I wouldn't bother trying to restore what you have. It's fiddly and the working bore of the m/c is probably screwed with corrosion.

Just buy a used Suzi m/c from eBay. On my GT380 (same brake set up as the GT500) I fitted a good used m/c from a Suzi RF600 (Suzi used the same type on loads of different bikes, from the Bandit to the GS500 etc etc). The black all-metal m/c body looked fine on the bike and the larger internal piston made the brake much more effective.

[GT500-2stroke]

You can easily restore the caliper - the seals and pistons are still available from Suzuki for rebuilds.

For the master cylinder, I wouldn't bother trying to restore what you have. It's fiddly and the working bore of the m/c is probably screwed with corrosion.

Just buy a used Suzi m/c from eBay. On my GT380 (same brake set up as the GT500) I fitted a good used m/c from a Suzi RF600 (Suzi used the same type on loads of different bikes, from the Bandit to the GS500 etc etc). The black all-metal m/c body looked fine on the bike and the larger internal piston made the brake much more effective.

Great!

Will work along these lines..Thanks a lot for your input!

Appreciate it.

What about the brake line?
Will it need a good cleaning from inside/outside?
I would think it will be good idea to clean it inside, correct?

How do I clean it from inside?
What cleaner should I be using?
Can I just use any parts cleaner like WD40?

[GT500-2stroke]

You can easily restore the caliper - the seals and pistons are still available from Suzuki for rebuilds.

For the master cylinder, I wouldn't bother trying to restore what you have. It's fiddly and the working bore of the m/c is probably screwed with corrosion.

Just buy a used Suzi m/c from eBay. On my GT380 (same brake set up as the GT500) I fitted a good used m/c from a Suzi RF600 (Suzi used the same type on loads of different bikes, from the Bandit to the GS500 etc etc). The black all-metal m/c body looked fine on the bike and the larger internal piston made the brake much more effective.

Could not find a used m/c on ebay.
Found a new m/c on eBay.

https://www.ebay.com/itm/Suzuki-GS500-G ... 4085!US!-1" onclick="window.open(this.href);return false;

Will this need modification to brake line ?
( Not that mind any modification if needed, just want to make sure that it is doable with relatively ease )

Will this be a good choice?

Thanks.

[Craig380]

I can't say if that m/c is a good choice or not, as it is a pattern part and not genuine Suzi, but it's not expensive.

I would definitely not re-use the old brake line: simply purchase a new stainless steel braided hose with banjo fittings at both ends from a bike shop, and fit it using new copper washers. The best stuff for cleaning up the caliper bore and seal grooves etc is proper brake cleaner, which leaves no residue. It's dirt cheap.

Clean out the seal groove really carefully as it will no doubt be full of white furry corrosion. A Dremel with a soft wire brush is ideal.

[dorT500]

.......What about the brake line?
Will it need a good cleaning from inside/outside?
I would think it will be good idea to clean it inside, correct?
How do I clean it from inside?
What cleaner should I be using?
Can I just use any parts cleaner like WD40?

God forbid, you might kill a pedestrian, yourself and/or a passenger with thinking like that. That brake line may be 40+ years old.

From your pic, it looks like it may have already been leaking at one time.

Go with the the upgrade of a new stainless steel braided line as suggested.

[johnakay]

I remember someone years ago fitted a brembo caliper off an MZ motorcycle.
and they claimed it work a hell of a lot better.
I did own an MZ and I can tell you these do work brilliantly.

[sportston]

I would definitely not re-use the old brake line: simply purchase a new stainless steel braided hose with banjo fittings at both ends from a bike shop, and fit it using new copper washers.

+1 on that. Stainless braided hoses aren't too expensive and can make a huge difference. They will usually fit a majority of master cylinders, so should be fine with your new later model m/c.
I also agree that a modern replacement caliper would also be a worthwhile addition. I got one off an old GS750 to fit my GT380, but with a Salty-monk adaptor you could fit something much better and more modern if you can afford it.

[jabcb]

The salty-monk upgrade requires a slightly larger brake disk.
For the GT250/GT380 you need to use a disk that’s for a GT500/GT550/GT750. On our GT250 cafe build we used an EBC VMD disk that they sell for the GT750.

For a GT500/GT550/GT750 you need to use a disk that’s larger than any that Suzuki used. On our T500 cafe build we are using an EBC disk that they sell for an obscure Honda — we haven’t gotten very far on this project so the results are TBD.

[GT500-2stroke]

I can't say if that m/c is a good choice or not, as it is a pattern part and not genuine Suzi, but it's not expensive.

I would definitely not re-use the old brake line: simply purchase a new stainless steel braided hose with banjo fittings at both ends from a bike shop, and fit it using new copper washers. The best stuff for cleaning up the caliper bore and seal grooves etc is proper brake cleaner, which leaves no residue. It's dirt cheap.

Clean out the seal groove really carefully as it will no doubt be full of white furry corrosion. A Dremel with a soft wire brush is ideal.

Before I purchase, just want to make sure.

Found one on eBay. This should work for me, right?
Where do I get copper washers from?
You mean any bike/hardware store?

Could you please have a look at this and confirm.

https://www.ebay.com/itm/60cm-90cm-120c ... 0005.m1851" onclick="window.open(this.href);return false;

[Craig380]

That's the right type of line, make sure the fittings (banjo and securing nut) are stainless steel too. On cheap hoses they can be alloy, which is not strong enough for brake systems. Any bike shop should sell packs of the copper washers.