Gen 1 Sumitomo calipers

[Nibsy]

Hi all,

I have a ‘92 Gen 1 with standard brake setup. My brakes have always been crap with the lever coming pretty much all the way up to the bar. I have just overhauled my master cylinders and calipers, all new pistons and seals, also fitted braided lines………you guessed it, they are still crap!; added to that I have just noticed something truly horrifying . When i’m squeezing the brake lever I can see the calipers flexing on the joint between the two halves and a small weep of fluid coming out. I have tried replacing the caliper bolts with high tensile strength replacements but still no joy. If you watch between the blue brake line and the bleed nipple on the attached video you can see the flexing as I pump the lever. What the heck is going on here?

 

[Fire-medic]

A bad O-ring or a warped body.

Split the two halves and place the inner halves on a piece of glass, and check w/a thin feeler gauge all the way around to see if you can slip the feeler gauge in anyplace.

 

[Nibsy]

A bad O-ring or a warped body.

It’s happening on both sides. Both calipers have new O rings, although they are not OEM as that little O ring between the two halves is not listed on the Yamaha fiche.

 

[Fire-medic]

Measure the depth of ea. side of the caliper recess for the O-ring, and try to locate the correct size to have it compress when the halves are re-assembled. Try McMaster-Carr.

 

[Nibsy]

Measure the depth of ea. side of the caliper recess for the O-ring, and try to locate the correct size to have it compress when the halves are re-assembled. Try McMaster-Carr.

A thicker O rings might cure the leak but to my mind there should be no flexing at all

 

[wayne billings]

Hello nibsy I ran into the same thing, not getting the seal ring that fits in between the 2 halves. As you said , it is N.L.A. everywhere you look, even the factory manuals say not to separate the calipers. Any way I found kits that have them, Brake crafters.

 

[Nibsy]

A thicker O rings might cure the leak but to my mind there should be no flexing at all

Yes I agree. They shouldn’t flex at all.

 

[Nibsy]

Hello nibsy I ran into the same thing, not getting the seal ring that fits in between the 2 halves. As you said , it is N.L.A. everywhere you look, even the factory manuals say not to separate the calipers. Any way I found kits that have them, Brake crafters.

Thanks for this info. I don’t want to buy more kits just to get the O ring as I have already paid out on new pistons and seals…….also I’m in the UK so shipping and customs fees would break the bank. I’m thinking I might go for the Yamaha blue spot calipers and ****-can these ones.

 

[gentsvmax]

Thanks for this info. I don’t want to buy more kits just to get the O ring as I have already paid out on new pistons and seals…….also I’m in the UK so shipping and customs fees would break the bank. I’m thinking I might go for the Yamaha blue spot calipers and ****-can these ones.

+1 the blue dot, better yet check with Sean for a bolt-on conversion.

 

[CaptainKyle]

Blue spot are not a direct bolt on for a 92

 

[lajo666]

I fully recommend the blue spot conversation much better feel and breaking look for R1 or fz1 calipers you can get the adaptors online

 

[Nibsy]

Blue spot are not a direct bolt on for a 92

Yes I understand I need adapter brackets for the blue dots.

 

[lajo666]

Yes I understand I need adapter brackets for the blue dots.

Definitely worth looking at gonna put the correct master cylinder on mine now one I've got now is coming too close too the bar years of riding sports bikes I'm more used too 2 finger breaking

 

[Nibsy]

Definitely worth looking at gonna put the correct master cylinder on mine now one I've got now is coming too close too the bar years of riding sports bikes I'm more used too 2 finger breaking

Yes the brakes are absolutely *****. I feel I’m too far down the road now though as I’ve bought all new pistons, seals, pads, braided lines, spent ages stripping paint and respraying!!!! I really wish I’d gone down the blue dot route now right from the get-go. You live and learn I guess.

 

[lajo666]

Just see how it goes hopefully if you can pick the adapters up cheap may be worth looking into later n I agree breaks are shocking for a heavy muscle cruiser

 

[one2dmax]

You need the busa upgrade kit I offer for the 85-92's (I have other kits for these years and the 93-07's too).

 

[Nibsy]

You need the busa upgrade kit I offer for the 85-92's (I have other kits for these years and the 93-07's too).

Fair play they look great! Alas, shipping costs to the UK and being clobbered with customs fees would make it a very expensive venture.

 

[one2dmax]

The brackets only are easy to ship and not bad on import duties. Then you can get the busa calipers and 93-07 larger Vmax rotors there easily enough.

Fair play they look great! Alas, shipping costs to the UK and being clobbered with customs fees would make it a very expensive venture.