Fork Swap

[Mr.humbucker]

I have a GS550T that i am in th final stages of restoring. Stock forks come with a single disc brake. I would like to upgrade this to a double disc. Does anyone know what other fork configurations with a double disc front wheel/break assembly would be interchangable? I would assume that it would involve changinging the triple tree too?

[Lorenzo]

Hello, not an exhaustive list, but something to strart with:

GS 650 E 81- 82
GS 750 77 - 83

[cowboyup3371]

I have the gs750e forks on mine that have to be raised about 15mm above the top triple tree to have the bike sit properly when on the center stand. It rides fantastic though.

[Mr.humbucker]

Thanks for this. I would assume you have to use the triple tree from the 750 for the spacing to fit the twin discs?

[Lorenzo]

They share the same stearing stem bearings.
Do not know if the stem is same length but, with a bit of luck you should be on top.

Anyway, way do you want to augment the gyroscopic effect, on the front-end while negotiating a curve?

Perhaps, you could improve on the efficiency of the brake department (master cylinder overhaul, bleeding of the system, new/braided lines).

Ciao

[Mr.humbucker]

I will take your advice and do an overhaul on the master cylinder first to see if that improves the braking!

[8ball]

I put an 83 550M set on. I bought forks, rotors and calipers from an eBay seller. The forks fit in the stock triples and Suzuki was nice enough to drill and tap the original hub for the other rotor. Braking is vastly improved.

Oh, and any difference in gyro effect is hardly noticeable. The dual discs are lighter and smaller in diameter. Even though the two may weigh a little more, the smaller diameter lessens the affect on inertia. So the inertial effect is a wash.

[tkent02]

Another option is Saltymonk's brake on just one side, it works very well on my '78 550. No fork swappage required. You could do it on both sides but it would be way overkill. One finger braking is plenty good enough, and be careful with that one finger.

[salty_monk]

I would use the original triple trees with the same 35mm forks for simplicity - steerer stops, ignition mount etc differ between models.

[Mr.humbucker]

Good suggestion. My concern was there was a difference in diameter of the fork tubes. I think i will start with a rebuild of the existing brake system and see what kind of performance improvement I get from that. It likely needs it being 35 years old!

[8ball]

The 83 550M has dual discs and the same diameter fork tubes. As I said before they slot right in the original triples. You just need the rotors and calipers that go with the 83 forks. There is probably a plastic dust cap on the right side of your front hub that is covering threaded holes for the extra rotor.

[Lorenzo]

Braided lines might help

[Mr.humbucker]

I am not that familiar with rebuilding brakes so I am curious what difference do braided lines make?

[8ball]

Braided lines have less expansion under pressure than standard rubber hose....particularly 30 year old rubber hoses...., so they tend to have a more direct feel at the lever.