Shaving pounds to add performance, ? on component weight

[Chuck78]

Postman Pat, I'd love to hear what you and others would have to say about the weights of the different varieties and diameters of rotors. I wonder if a 260mm GS snowflake style (appears to be all steel) would weigh much more than the alloy center GS550E style? And if a lightweight modern style of floating rotor as listed above in a 275mm diameter would be as light as the 260mm 83-86 GS550 rotor?

It's REALLY HARD for me to pass up the bargain of using my existing caliper bracket and a low cost used GSX1100 275mm rotor, as I would imagine they weigh about the same as the 260mm GS550E rotor, no? Looks like the same or probably slightly less steel in the brake surface (slightly thinner, larger diameter but inside is scalloped out a lot), and definitely less aluminum, but is the GS550E rotor's much stiffer appearing build going to benefit braking performance? 7mm less aluminum on the shorter hanger bracket if going with the 260mm GS550E etc setup would probably put them at about equals overall I am guessing.

Maybe I should combine two suggestions and bleed a little helium into the brake lines to make the rear less touchy and save a few grams of weight!

[postman_pat]

These rotors are the only lightweight front rotors that are a direct fit onto the rears of our bikes that I can find:


fits 84-86 GS1150, 84-93 GSX1100. these are an exact fit, down to the 56mm center hub opening. 275mm 21.5mm offset 78mm pcd etc

An excellent choice at the rear and by the looks of it, quite light too. Also, they're a floating design so you can use them on the twin piston caliper at the rear. If you put two on the front as well, you'd match all round!

to rehash, 83 GS750E_ and 85 GS700E_ front right rotors are a good lightweight 260mm swap for the rear rotor using the rear caliper hanger bracket from those two exact year/models, and the front right rotors off of 83-86 GS550E__ models are the same as well, but the rear rotor and caliper hanger are not compatible.

That's right. That's what I'm using on my GS750 at the moment. I chose that set-up only because I wanted my bike to look as close to factory standard as possible.

I also JUST found that these guys have several rotors of interest, including the exact EXACT fit snowflake style in 260mm AND 275mm:

Don't use this design at the rear. In my experience they are not rigid enough for an opposed piston caliper - they will deform. I know that MetalGear are selling these for application at the rear - but I have my doubts that MetalGear have tested them in that application.

They also have THIS exact fit (but 275.5mm?) lightweight floating rotor $beauty that I would love to have on mine... I am amazed at their selection of 3 or more rotors in the correct offset, PCD, EXACT hub opening diameter, etc. wow:

Oooooh, shiny! And gold! You go for it!

BTW, as promised, I tested out the GS500E calipers on the earlier style brackets. Unfortunately they don't fit.

[postman_pat]

... And if a lightweight modern style of floating rotor as listed above in a 275mm diameter would be as light as the 260mm 83-86 GS550 rotor?

Yes, it probably would be. Unfortunately I don't have any of those floating discs to make a comparison.

It's REALLY HARD for me to pass up the bargain of using my existing caliper bracket and a low cost used GSX1100 275mm rotor, as I would imagine they weigh about the same as the 260mm GS550E rotor, no? Looks like the same or probably slightly less steel in the brake surface (slightly thinner, larger diameter but inside is scalloped out a lot), and definitely less aluminum, but is the GS550E rotor's much stiffer appearing build going to benefit braking performance? 7mm less aluminum on the shorter hanger bracket if going with the 260mm GS550E etc setup would probably put them at about equals overall I am guessing.

I think that, under the circumstances, that would be the wisest choice. The main reason being that you can get the floating style discs NEW from aftermarket suppliers. When you say GSX1100, I assume you mean the GSX1100F Katana from the late 80's onwards. Yes, I reckon those Katana discs would be comparable in weight to the GS550 disc I am using.

[limeex2]

saving weight

Ok. I am totally confused. I have a GS1100 swingarm on my GS1000. Going with the upgraded front brakes, calipers and brkts from this site. Looking to get lighter rears. What is the combination for a floating rear brake system? There is one listed on this thread for a non-floating style that would look good with my new fronts. Thanks for the help.

[postman_pat]

Ok. I am totally confused. I have a GS1100 swingarm on my GS1000. Going with the upgraded front brakes, calipers and brkts from this site. Looking to get lighter rears. What is the combination for a floating rear brake system? There is one listed on this thread for a non-floating style that would look good with my new fronts. Thanks for the help.

Then you would go with the front brake disc from the GS1150 (1984-87) or the later GSX1100F Katana. These are "floating" style discs, 5mm thick, and they would bolt onto the standard GS1000 rear wheel. You can then keep your standard GS1000 rear caliper and mounting bracket.

[limeex2]

Cool. Thanks. But the old caliper is butt ugly....So many choices. I made swiss cheese out of my original disc. It is light and is harder to lock up with so much material removed. But it is butt ugly also...

[Chuck78]

I just ebay'd a 2006 GS500 caliper that I believe will fit directly onto my 77 GS750 caliper hanger bracket. 89-2010 GS500 calipers are the exact same caliper as the 83-86 GS550E, which most likely would interchange with our older bigger bikes I assume, so I am guessing that this caliper is a direct bolt on. up to 2002 looked like this:

and 2003-2010 GS500 calipers look like copies of those with a not as smooth casting and a different name on the end, exact same shape though.

This is the early & mid 1980's caliper (try GS650 in the search, this came on those and other GS's) that is an improvement on the older very bulky style:


and this bulky dinosaur is what came stock on our bigger older GS's, note line connection comes out rear at angle, different configuration than the two above, and much wider (longer) front to rear than the two lighter versions:

[Steve]

I must say, ... there is certainly a lot of FAITH going on here.

I just ebay'd a 2006 GS500 caliper that I believe will fit directly onto my 77 GS750 caliper hanger bracket. 89-2010 GS500 calipers are the exact same caliper as the 83-86 GS550E, which most likely would interchange with our older bigger bikes I assume, so I am guessing that this caliper is a direct bolt on. ...

.

[Chuck78]

Well for $20 for a 6 year old caliper from a bike with 1,024 miles, I figured I'd be the guinea pig

[John Kat]

I'm very interested to see if it works
Look at my side stand idea I posted here:http://www.thegsresources.com/_forum...d.php?t=204392
Another weight saving potential

[Toasty]

Btw, if anyone wants to try fitting a 2006 R6 rear caliper you can have it for free just pay shipping. It comes with the bracket as well.

[Chuck78]

Well, the second gen version of the GS500 caliper ('02 or '03 to 2010) arrived today, same diameter pistons, all mounting specs match up with the big Tokico GS1100E caliper that I have sitting here (came with my 81-83 GS1100E swing arm) EXCEPT that the mounting bolts are smaller diameter and are 75mm center distance, the big caliper is 80mm.

I suspect that the GS650 type smaller Tokico caliper is probably the 75mm spacing, but looking for someone to confirm. Ebay photos seem to indicate to my eyes that the GS650 caliper brackets have the smaller bolt diameter as the GS500 caliper, so I think I am on to something.

If anyone else (Pat?) could measure the GS650 type caliper mounting bolt spacing, that would be awesome, as the winter just hit us hard today and the GS650G is outside at the local VJMC junkyard if they still have it (I stripped half the bike down months ago).

I will try and get a set of digital refrigerant gas tank scales from work that I use in AC season so that I can start weighing these parts as I can.

[TheCafeKid]

Chuck I've got a stock GS rotor for the rear that has been drilled.
I'd say just by comparing with my "hand scales" that it's about 1/2-2/3 as heavy as stock. And it's thick enough that it won't deform or warp at all. It's far from perfect, but if you'd like it let me know.

[limeex2]

gs diet plans

These posts are great ideas for saving weight. How about fastners? I am currently doing a ground up restoration and have been derusting nuts and bolts. When lumped all together like this for cleaning i have found them to be very heavy. any idea's?

[TheCafeKid]

These posts are great ideas for saving weight. How about fastners? I am currently doing a ground up restoration and have been derusting nuts and bolts. When lumped all together like this for cleaning i have found them to be very heavy. any idea's?

I'd be careful changing out fasteners simply because enough of them are specific tensile strength for the application. Any load bearing or area of stress or torque I'd not change. Which is nearly everything on a bike lol.
You could go with Titanium bolts and a few companies offer them but they're bloody expensive, and you have to take care to use anti-seize compound everywhere to prevent galling.
Certainly there are some bolts that can be substituted for lighter ones but I don't think that it's enough to make a substantial difference.