GS 750 Single to dual front disc brakes

[Guest]

I have a 78 GS 750 with a single front disk. I intend to convert to dual disk and do the salty monk conversion. I was shopping ebay today and I was wondering if I buy just the right fork leg lower what years are compatible? For the different lengths they only changed the upper fork leg right?

[allojohn]

You're safe with just the lower leg off '78 & '79 750's, there may be others.

[Nessism]

You need both outer tubes. Check the parts fishe and compare the part numbers between the GS750 and GS750E.

http://www.alpha-sports.com/suzuki_parts.htm

[Steve]

I have not done this conversion, but if I remember reading others' tales about it, the single disks and double disks are different diameters (the dual disks are smaller). If you use the smaller disk on the fork intended for a single disk, the caliper will not be in the right location to properly squeeze on the disk.

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[SVSooke]

I did do this conversion on my 78 1000 and Steve is right.Because the disc rotors are different sizes you need both legs.If you're doing a Salty Monk conversion to I'd go with better rotors to.

[Dizzixx]

I did do this conversion on my 78 1000 and Steve is right.Because the disc rotors are different sizes you need both legs.If you're doing a Salty Monk conversion to I'd go with better rotors to.

Thank you, exactly the information I needed. I remember reading the rotors were different sizes but failed to connect that to the fact that the mounting points would therefore be different also. I will look at the parts fiche and see what years the lowers are cross compatible. I am guessing all 750's with dual rotors from 77 to 83 maybe later but I will have to check....

[tkent02]

No, only through '79 unless you want to mess with geometry changes.

[Dizzixx]

No, only through '79 unless you want to mess with geometry changes.

This agrees with my parts fiche findings. The parts numbers for the left and right fork outer tubes are:

51140-45031 - OUTER TUBE, LH
(Replace with 51140-45032)

51130-45031 - OUTER TUBE, RH
(Replace with 51130-45032)

Though I think it is worth pointing out it is not clear on the parts drawings or descriptions that the right is necessarily with or without the brake mount. The geometry should be the same though either way so it is kind of a moot point. Anyways these outer tubes are used on the following bikes:

1977

GS550 /E
GS750 /B/C/EC/EN/N

1978

GS550 /E
GS750 /B/C/EC/EN/N

1979

GS550 /E
GS750 /B/BC/EC/EN/N

And also in 1980 the 45032 part version was used in the 550:

1980

GS550 /E

Also I found the following site useful in quickly cross referencing parts use:

http://www.suzukipartspitstop.com/

[tkent02]

There's another way, Saltymonk's brake on just the one side works great on my 550, no buying different fork legs required. It would probably be enough on a 750 with good pads and lines:



You have to use slightly a bigger diameter disc for it to work on the single brake forks, I think it was a Blackbird disc or something like that.

I know the 750 is a lot heavier but depending on how strong you like your brakes it might work for you. On my 550 it's mostly a one finger brake, unless you really have to haul it down then you would want to use two. With better pads and lines two fingers would not be neccesary. I'd do it on my 750 too but it's going to be an 1100 soon, and it already has dual brakes, so I'll do the dual brake twin pot conversion.

[Dizzixx]

There's another way, Saltymonk's brake on just the one side works great on my 550, no buying different fork legs required. It would probably be enough on a 750 with good pads and lines:



You have to use slightly a bigger diameter disc for it to work on the single brake forks, I think it was a Blackbird disc or something like that.

I know the 750 is a lot heavier but depending on how strong you like your brakes it might work for you. On my 550 it's mostly a one finger brake, unless you really have to haul it down then you would want to use two. With better pads and lines two fingers would not be neccesary. I'd do it on my 750 too but it's going to be an 1100 soon, and it already has dual brakes, so I'll do the dual brake twin pot conversion.

Anyone done an upgraded single on a 750? Roughly how much does the rotor and caliper weigh? Like many others my biggest complaint has been the front brakes on this bike. Other than brakes I have been superbly happy with the way it rides even with only basic progressive suspension upgrades front and back.

[salty_monk]

The rotor & caliper combine are much lighter than stock as the inner spider is Aluminum.....

TKent has a Blackbird rotor which is 310mm but there is a 900RR rotor that is 320mm that should be better suited. I don't know the year 900RR but I know it exists because I bought one by accident years ago (the guy told me it was a 295mm rotor..).

[tkent02]

Will that 320mm rotor fit my 550 with no other changes? Might be all I need to leave that second finger on the grip forevermore.

[Dizzixx]

The rotor & caliper combine are much lighter than stock as the inner spider is Aluminum.....

TKent has a Blackbird rotor which is 310mm but there is a 900RR rotor that is 320mm that should be better suited. I don't know the year 900RR but I know it exists because I bought one by accident years ago (the guy told me it was a 295mm rotor..).

Since you are here now I might as well ask these things here....

In the long salty monk thread I have the following notes:

Kawi twin pot calipers 87-97 (early years I think were the ninja 750 and later like 93-97 or something they were the ninja 6's? What about the little 250's do they use the same calipers?)
Kawi master cylinder (dont know I believe the ninja 6)

Rotors:
(single caliper setup 295mm, dual caliper setup 274mm)

CBR F3 Rotors
CBR900RR Fireblade rotors (must be 296mm and not 310mm...?)
Honda GL 1500 Valkyrie rotors (1997-2003)

And if I recall correctly the F3 requires re-drilling new pattern, the Fireblade requires opening up the holesize of the existing pattern, and the Valkyrie is a direct bolt on part?

PS - you have a PM Salty

[salty_monk]

Will that 320mm rotor fit my 550 with no other changes? Might be all I need to leave that second finger on the grip forevermore.

Yes.. it's essentially the same just a slightly bigger dia. I caution to add though that I have NEVER seen another one & this was at least 6 years ago when I saw it. I think it was advertised as a 98.

[salty_monk]

I will add in below with *** as it's easier.

If you PM me your email I can send you a list of compatibles that I have pulled off here over the years.

Since you are here now I might as well ask these things here....

In the long salty monk thread I have the following notes:

Kawi twin pot calipers 87-97 (early years I think were the ninja 750 and later like 93-97 or something they were the ninja 6's? What about the little 250's do they use the same calipers?)

**** The newest ones are Concourse 2000-2004. The EX250 had them about 2000-2006 but only on one side. The Ninja is 86-90 from memory.

Kawi master cylinder (dont know I believe the ninja 6)

**** I use the modern EX650 master. Looks like it fits, has a mirror mount & an adjustable lever. They are cheap.. from $20 on Ebay in my experience.

Rotors:
(single caliper setup 295mm, dual caliper setup 274mm)

**** You need 295mm for dual.

CBR F3 Rotors -
**** F4 fit as well. Send me links & I will tell you if they are the right ones. Lightest is an F4 rotor with 7 Rivets.

CBR900RR Fireblade rotors (must be 296mm and not 310mm...?)

*** The 310mm works on the single sided upgrade but the pad hangs off the edge of the brake surface. A 320mm would be better. I have not seen one but I believe there is also a 320mm Aprillia rotor that should work.

Honda GL 1500 Valkyrie rotors (1997-2003)

*** Yes - one guy did this for the dual setup. Looked good.

And if I recall correctly the F3 requires re-drilling new pattern, the Fireblade requires opening up the holesize of the existing pattern, and the Valkyrie is a direct bolt on part?

*** They all require the use of the spacer. Yes F3 needs re-drilling to a new Bolt circle but the spacer is also a drilling jig so it's very easy.

PS - you have a PM Salty