Twinpot Brake upgrade on 78 Skunk

[Chuck78]

so far when I stopped researching it, 275 was the smallest diameter I could find in a 6 bolt rotor with a similar PCD. I would be thrilled to find a slightly smaller diameter floating rotor that was easily adaptable to our hubs, then we could make caliper bracket adapters or new brake caliper hanger bracket to fit the proper modern calipers to match the rotor, with longer swept area.

[Chuck78]

Very nice! It should be possible to fit one of the Honda front rotors to the rear which would match up the look as the PCD is the same on both front & rear Suzuki wheels from memory.

this would definitely save on weight! Using the GS caliper would probably require removing some of the brake pad friction material towards the inside using a Dremel, as I believe, don't quote me, that the friction surface is taller on the GS rotor. you would then have some very touchy rear brakes! using the stock GS pad as I said would help with making it not lock up as prematurely.

I upgraded the rear on mine just to drop weight and ditch the 295 rotor.I was told the caliper used on the GS 650 rear and other models, cross reference it, is slightly lighter than the caliper that came on my bike, GS1100's and 1000's, and others. I went with a newer hanger for the 275 rotor, a GS1150 caliper which requires extensive brake stay modification, and something along the lines of a front right 1989 through 1991 1100 katana floating rotor with the correct 22.5mm offset and 275mm diameter. this used the same bolt circle diameter, but the bolt holes ended up being 10 mm, so I had to redrill the pattern a half hole off with 8mm holes. this style of rotor is harder to come by, but substantially lighter than the GS set up.

upgrading to a caliper with a longer swept area on the brake pad would be much more beneficial, as that is what is really outdated on our stock brakes. The longer the pads, the better the stopping. A taller pad with the same surface area as a longer skinny pad will not grip as well as the long skinny pad on similar diameter rotors. The long skinny pad has more leverage because it is gripping at the outer part of the rotor entirely, where the diameter & leverage force advantage is greater, instead of half of the surface area of the pad gripping in a smaller rotor diameter area more toward the inside.

[salty_monk]

Haha - I've done that too... In the year plus that I ran these wheels not one person noticed.

True, but I'd like to research the idea just to keep the looks symmetrical....think how a cycle would look with different front and rear rims - that's my thought line on it.

[salty_monk]

Very nice! It should be possible to fit one of the Honda front rotors to the rear which would match up the look as the PCD is the same on both front & rear Suzuki wheels from memory.

I don't know what the offset (or dia) of the rear rotor is. Assuming Chuck78 is correct above you'd need the 77 caliper hanger (hopefully the axles is the same dia) for a 295mm rotor and some hub spacers to make it work. - I'd have to look at it. From a performance standpoint I would be very surprised if you need any more rear end performance.

[Chuck78]

Salty's recommended & very well researched front brake upgrade makes our bikes (with suspension valving/spring upgrades & excellent tire selection) fully capable of very spirited (aggressive) riding in the most fun terrains possible, such as the nonstop Appalachian foothills in the SE corner of Ohio near West Virginia, like this Labor Day ride we just did through a segment of Wayne National Forest & surrounding State Forests (about 230 miles of BIG smiles plus 70 travelling there):



Never ending big hills everywhere densely packed, and me picking the route with the absolute most & tightest curves. try to find a straight road on that entire map! They don't exist! I have absolutely no problem and no complaints ever with my brakes' capability while riding aggressively in this terrain, as well as Northeast West Virginia mountains.

[Chuck78]

the stock rears usually do pretty darn well, if you look at most modern sport bikes, they might have a 2 piston sliding caliper in the rear, but the rotor diameter is substantially smaller. If you did a lot of heavy loaded touring and needed more rear brake, get a rear rotor and the caliper hanger bracket off of a 1977 GS 750 (in 78 I believe they downsized the rear rotor slightly from 295 down to 275 mm). The stock rear was on my 77 when I got it, and it was way too much rear brake, very easy to lock up the rear. Some people intentionally leave some air in the lines just to give the rear brake a little more feel and cushion on the stock setup. Your bike is heavier, so maybe that might warrant not doing so. The opposed piston caliper and 275mm rotor is adequate for mine with aggressive riding on a lightened 485lb GS750. any more substantial caliper and swept brake pad area and you would definitely need to downsize the rotor diameter again.

I absolutely love the stopping power of my 296 millimeter dual twin pot front set up. riding in the most tightly packed nonstop twisties this past weekend on a 300 mile backwoods Appalachian round trip, I was reminded how I basically only need one finger the majority of the time when properly judging my speed going into turns at least. A few surprises over blind rises led to me reaching a second finger in to panic stop/brake check.

[kingofvenus]

I'm a convert!...well, I'm going to be soon.
I welcome the added front stopping power for my old girl, heavy as she is - user name is my bike {how clever, I know} - but what I have to question is this; what is every one doing for the rear brakes? It's opposed singles back there, but couldn't that be improved?
I know, the majority of stopping is done on the front{s}, but wouldn't it be even better for a rear brake upgrade as well?...and to have it "match" too?
My main concern for the upgrade was improved stopping power, but let's be honest here, it looks good {win/win} and runs nearly the same cost as twin oem rotors but better stopping.
I sort of worry about the looks of the back end.....since I'm guessing that even though mine weighs more, my buddy on his CB750 will be getting a good look at it from that view. {unless he gets a jug kit, then I'm in trouble}....seriously though, rear kit?

I have the fronts done on my '79, stock rear is plenty just the way it is.

I'm a convert!...well, I'm going to be soon.
I welcome the added front stopping power for my old girl, heavy as she is - user name is my bike {how clever, I know} - but what I have to question is this; what is every one doing for the rear brakes? It's opposed singles back there, but couldn't that be improved?
I know, the majority of stopping is done on the front{s}, but wouldn't it be even better for a rear brake upgrade as well?...and to have it "match" too?
My main concern for the upgrade was improved stopping power, but let's be honest here, it looks good {win/win} and runs nearly the same cost as twin oem rotors but better stopping.
I sort of worry about the looks of the back end.....since I'm guessing that even though mine weighs more, my buddy on his CB750 will be getting a good look at it from that view. {unless he gets a jug kit, then I'm in trouble}....seriously though, rear kit?

[salty_monk]

Nice! - Thanks for the pic

[Thumper88]

Thanks for the brackets Dan! Just got back from a spirited ride--huge improvement.

[salty_monk]

Looking good!

Here is a picture of mine with the brake mod fitted.

bugad gs.jpg

[salty_monk]

Yes could be!

There are still a few sets of brackets here and I have one full kit with some 2006 Concourse calipers (the very last year you could get these calipers on anything)

[Chuck78]

Well we sorted that out... We now know how to fit them to the 85 550E! No change in parts but slightly different configuration.

I do have some more brackets here if anyone is in need.

I believe the solution that you came to is probably the same fitment that is needed to use this brake mod on the GS 1100 GK with its 204 mm center to center 41mm diameter fork legs, much wider & thicker than most GS's. the brake mounts on the fork legs set in much further and are much thicker, but still, that bike was a very special beast all on its own.