78 750 single front disk

[Road Rash]

Hmm, I'll have to go back and look. I just polished up my right side lower and am almost certain there were bosses for the fender mount and nothing else.

[TheCafeKid]

All the GS wheels I've ever had, single disc or not, have been drilled for dual disc applications. Yes, it's under the plastic cover.
The dual discs are smaller than the single disc (which incidentally is the same size as a rear disc on most of the early bikes) but the difference in stopping power is only marginal. That bigger disc and puck padded caliper actually do quite a darn good job if they're bled correctly and you use a stainless line on it.
I was actually surprised that many of the single disc 750s I've had stopped as good or better than their dual disc and later model counterparts.

What's more, the single disc saves some unsprung weight over the dual.
However, if you're wanting to change to dual disc for whatever reason, I have a couple of sets of forks for sale in a thread that are an upgrade to your stock fork. Besides being dual disc forks, they're 37mm instead of the 750s 35mm, and one of the sets has anti-dive system in it as well and is a bit more adjustable for pre-load than the earlier model forks were.

[cowboyup3371]

Besides being dual disc forks, they're 37mm instead of the 750s 35mm, and one of the sets has anti-dive system in it as well and is a bit more adjustable for pre-load than the earlier model forks were.

Not to hijack too much here but what is the advantage of a 37mm fork over a 35mm Josh?

[tkent02]

Not to hijack too much here but what is the advantage of a 37mm fork over a 35mm Josh?

More rigid, in GS days it was the heavier bikes which got the bigger stronger fork tubes. You wouldn't really notice unless you were riding very hard, or on rough broken surfaces. All of the newer bikes have gone to much thicker fork tubes, just as they have gone to more rigid frames. Same idea, better handling is the end result.

[TheCafeKid]

Not to hijack too much here but what is the advantage of a 37mm fork over a 35mm Josh?

Assuming the wall thickness is the same ratio, the simplest benefit is rigidity.
A bigger/thicker fork is going to have more resistance to flex under lateral load.
How much benifit a two mm step up is, I don't know for sure. One of our resident engineers might be able to say. But it was apparently large enough that Suzuki deemed it worthy of fixing their larger, and flagship models with 37mm vs 35mm forks. The other benefit nowadays is that since so many of the popular UJM models used a 37mm fork there are plenty of companies offering upgrade components for these forks and internals. Cartridge emulators for both rebound and compression damping are available for many bikes (I'm not sure that there are compression valves available for ours yet or not) through various manufacturers (which is nice because up until recently only Race-Tech offered emulators and they're somewhat expensive. Now there are a few companies, likely Chinese or assembled in china, that offer cheaper and as effective alternatives). For the street-fighter/cafe racer crowd there are now clip-on bars (actually quite nice ones) being produced where before they were pretty much only doing stuff for 41mm forks and larger. Fork braces, headlamps and headlamp ears etc etc are now being made for this generation of bikes. Likely because the whole cafe thing and this era of bikes has caught fire in recent years where before they were just "old nap bikes" leaning against a wall in someone's garage.

However, the OD of the fork doesn't always equate to being better.
Some of the bikes of the generations after our GSes actually had "softer" forks than what we have because although the outside diameter of the fork was larger, the wall thickness was no greater. Some of the last gen KZs (for instance the KZ1000ST, and 1100ST, their answer to the GS-G models) had at the time "Huge 41mm forks" but they were actually somewhat flimsy. The KZ, being shorter coupled than most GSes, often suffered from "head shake" when putting to spurs to her driving out of an apex. This was caused by both the flexible fork, and the more upright angle of the fork (compared to a GS, which had a longer wheelbase and were in comparison rock solid stable at high speed and quite good at driving out of the corner under heavy acceleration, one of the many reasons that the GSes often won the cycle rag shoot-outs vs Kawasaki. Even though most times the KZ had more peak HP, the GSes tractability made more of its horsepower available in real world situations instead of simple top speed runs)

Anyway, basically the 37mm fork was a better option at the time. Which is why after 1981 models, nearly every GS model 750cc and larger came fitted with them vs 35mm that the 750s and smaller bikes of earlier years were equipped with.

The 82 750 had not only 37mm forks, but also came equipped with the Suzuki Anti-Dive mechanism that the mighty GS1100E, and then the 83 and on GS550, 3rd Gen 750 and 1150s had.

Some people don't like it, some do. I will say when the system is clean, it works quite well, but because the anti dive valves were operated by the brake fluid and were part of the brake system, once the fluid and valves became compromised and dirty, the anti-dive either didn't work well, or (and my personal major complaint about it) became inconsistent. Sometimes it would prevent fork dive on hard braking, sometimes it would not. And myself, I would prefer to know what it's going to do every time. I can deal with the dive, if I know it's going to happen. But when it sometimes happened and sometimes didn't it became more an annoyance than an aid. Many people installed block off plates or simply placed a bolt on the anti-dive valves to cap them off while removing them from the brake system. Many people also complained that the set up caused a "mushy" lever feel that no matter how hard one tried, could not be bled out.

[TheCafeKid]

More rigid, in GS days it was the heavier bikes which got the bigger stronger fork tubes. You wouldn't really notice unless you were riding very hard, or on rough broken surfaces. All of the newer bikes have gone to much thicker fork tubes, just as they have gone to more rigid frames. Same idea, better handling is the end result.

Indeed. But there comes a point where "more stiffness" is actually a hinderance.
One of the things I noticed right off the bat when I went from my GSes to the ZRX was how much more stiff not only the fork was, but the frame as well.
Riding a GS, or any older bike, really hard for a good while, (especially when you're not 150 pounds and 5'10) one of the "quirks" you learn to anticipate and deal with is the flex in the frame and fork. It actually becomes part of the suspension. For example, in a long, high speed sweeper with a road surface like we have around here (full of frost heaves and surface pocks from the freeze-refreeze cycles) you can actually feel the frame/swingarm wallow a bit. You just learn to accept it, and ride with it. The ZRX, while still a tube steel frame, has substantially larger frame tubing and looks like a road racing frame with all the gusseting it has around the head stock, and around the "B" and "C" down tubes and such. It is remarkably stiff. I wasn't really familiar with the bike yet and took it out on one of my little "suspension tuning" routes. Full of chunked and heaved asphalt and many high and low speed corners and multiple "S" curves where you have to get the bike over, up and over the other side quickly and smoothly to be fast.

I hadn't set up the suspension yet as I was trying to get a feel for what needed to be done (aside from setting the sag, the Rex has a full cartridge fork and both compression and rebound damping adjustment front and rear. Something I was still learning about and I wasn't about to just start spinning knobs and clicking adjusters)
The bike literally scared me. I expected it to be a bit soft and wallow a bit in the esses on transition, and leaned over on the undulating road surface. It didn't. The back end chopped and hopped, the bike had a figure eight feedback through the bars as it wanted to stand up and then lay back down. The front end plowed and then pushed through the corners. I nearly tucked the wheel as I tried to trailers front brakes to shave off some of the speed as I certainly didn't feel as comfortable as I did on my beloved but now gone 1100ES that I had spent so much time on making it handle as well as I could.

Back to the "Suspension tuning bible" I went after I got the colour back in my knuckles and my hands to quit shaking lol.

Once you reach a certain point with stiffness, it becomes a fault. The suspension doesn't work as well when heeled over in the corners as the forks and shocks are designed to move up and down. Laid over obviously, bumps go from vertical input to the suspension to almost lateral input. Some of that input is transferred to the frame. On my GS it would soak that input up some. It felt a little loose, but you could actually FEEL what was happening under you. On the Rex, that input that was transferred to the frame became jarring shock. The frame not only didn't absorb it, it almost seem to amplify it, and then smack you in the face with it. Hahaha. Once I got the suspension set up sorted out, it became very very good. And once I got used to this new feeling and feedback, I got quite a bit quicker on my little test route and my little "Germantown TT" course.

Of course, many companies have tried different suspension designs to attempt to eliminate these issues of transfer to the frame. BMWs Telelever design has some pretty good praise for this and it's ability to prevent fork dive under braking.
One of the major reasons Ducati has struggled with their GP effort is one of this very thing.
Both Rossi and Hayden complained of a severe lack of "feel" with their Desmo GP12. The feedback of the front end when cornering on the edge, which these guys rely heavily on to tell them when they go from being on the edge to being on the brink of going down, was not there. They couldn't feel when they crossed the point of amazing lean angle in a corner to washing out the front end and losing it.

Of course, I am not even in the same galaxy as those guys, but after that first real day on the ZRX I completely understood what they were talking about. Lol

[cowboyup3371]

Thanks Josh. I definitely have much to learn about the feel then as I haven't ridden enough different bikes yet. I need to go do some more riding once everything is running well again.

Again, sorry for the hijack

[Road Rash]

Yeah, the right fork lower does not have the mounting bosses for a caliper. Kind of a moot point, if what was said is true about stopping power between dual and single, above.

[tkent02]

Ive never seen a single brake work anywhere near as well as a dual on the bigger bikes.
Adequate, maybe but not as good.

[Jedz123]

My 79 750 and my 81 750L both has single stoppers. The 750L was sketchy at best when applying the single brake... About as good as applying the rear ... First upgrade on my 81 was a complete GS1100E front brake setup...

My 2 cents. Every bike I get my hands on; have or receive a twin disc setup.

[hjfisk]

Indeed. But there comes a point where "more stiffness" is actually a hinderance.
One of the things I noticed right off the bat when I went from my GSes to the ZRX was how much more stiff not only the fork was, but the frame as well.
Riding a GS, or any older bike, really hard for a good while, (especially when you're not 150 pounds and 5'10) one of the "quirks" you learn to anticipate and deal with is the flex in the frame and fork. It actually becomes part of the suspension. For example, in a long, high speed sweeper with a road surface like we have around here (full of frost heaves and surface pocks from the freeze-refreeze cycles) you can actually feel the frame/swingarm wallow a bit. You just learn to accept it, and ride with it. The ZRX, while still a tube steel frame, has substantially larger frame tubing and looks like a road racing frame with all the gusseting it has around the head stock, and around the "B" and "C" down tubes and such. It is remarkably stiff. I wasn't really familiar with the bike yet and took it out on one of my little "suspension tuning" routes. Full of chunked and heaved asphalt and many high and low speed corners and multiple "S" curves where you have to get the bike over, up and over the other side quickly and smoothly to be fast.

I hadn't set up the suspension yet as I was trying to get a feel for what needed to be done (aside from setting the sag, the Rex has a full cartridge fork and both compression and rebound damping adjustment front and rear. Something I was still learning about and I wasn't about to just start spinning knobs and clicking adjusters)
The bike literally scared me. I expected it to be a bit soft and wallow a bit in the esses on transition, and leaned over on the undulating road surface. It didn't. The back end chopped and hopped, the bike had a figure eight feedback through the bars as it wanted to stand up and then lay back down. The front end plowed and then pushed through the corners. I nearly tucked the wheel as I tried to trailers front brakes to shave off some of the speed as I certainly didn't feel as comfortable as I did on my beloved but now gone 1100ES that I had spent so much time on making it handle as well as I could.

Back to the "Suspension tuning bible" I went after I got the colour back in my knuckles and my hands to quit shaking lol.

Once you reach a certain point with stiffness, it becomes a fault. The suspension doesn't work as well when heeled over in the corners as the forks and shocks are designed to move up and down. Laid over obviously, bumps go from vertical input to the suspension to almost lateral input. Some of that input is transferred to the frame. On my GS it would soak that input up some. It felt a little loose, but you could actually FEEL what was happening under you. On the Rex, that input that was transferred to the frame became jarring shock. The frame not only didn't absorb it, it almost seem to amplify it, and then smack you in the face with it. Hahaha. Once I got the suspension set up sorted out, it became very very good. And once I got used to this new feeling and feedback, I got quite a bit quicker on my little test route and my little "Germantown TT" course.

Of course, many companies have tried different suspension designs to attempt to eliminate these issues of transfer to the frame. BMWs Telelever design has some pretty good praise for this and it's ability to prevent fork dive under braking.
One of the major reasons Ducati has struggled with their GP effort is one of this very thing.
Both Rossi and Hayden complained of a severe lack of "feel" with their Desmo GP12. The feedback of the front end when cornering on the edge, which these guys rely heavily on to tell them when they go from being on the edge to being on the brink of going down, was not there. They couldn't feel when they crossed the point of amazing lean angle in a corner to washing out the front end and losing it.

Of course, I am not even in the same galaxy as those guys, but after that first real day on the ZRX I completely understood what they were talking about. Lol

A very good description, but I'll add just a little. If you can't do it yourself and want to get your suspension sorted properly it is well worth the money to get the suspension experts to sort your bike for you . They can set the bike up for your weight and check the geometry for your bike . I have used GMD computrac out of Boston . I had them do my SV race bike and the difference was night and day, I picked up 3 seconds at Loudon almost immediatly . Best money I have ever spent on a bike except for brakes, thats another story.

[MR.G]

You can use a one piece but be careful about mounting it

The up and down motion of the fork can make it saw into your triple clamp

thanks to all that replied. Sorry for getting back so late. Anyway, seems like the original post took a left turn somewhere.

I would like your thoughts on the following. I am not going to a single line, I will stay with the original 3 piece set up. Question - does anyone know of an upper front brake line that will fit a 78 gs750 single disk wire wheel, from another gs but about 15" in length vs the original being about 19". As mentioned in the original post I have lower bars on it and do not want to use the original length that was used for the original higher bars. Thinking I could order a line from another model.

Thanks again Guys, always appreciate your help.

[Tukn20s]

Your best bet is to have lines made. They can make them in any length. You will just need to provide the length and what type of ends you need. As previously mentioned, check BassCliff's site for a possible list of vendors. Otherwise there are many on ebay and I'm sure a google search will provide many more. You may even have a local business in your town that can do them.

[Tukn20s]

Oh and not to hijack your thread again as it already got off track once.....


......can anyone tell me what years/models spoke wheels will accept dual discs? Anyone know the spoke count for the suzukis?

[T8erbug]

78 GS750 has a dual front disc set-up on a wire wheel and 79 has it on a mag wheel