R100GS Nissin 4-piston caliper conversion

OK, first here is the picture that made me think "why can't I do this?, I'm really cheap and this looks very doable!" (picture from an ADVR member Steve in NZ...)

Here is what you need to buy, and where I got my stuff:

Nissin 4-piston caliper conversion for R100GS<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

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DISCLAIMER:<o></o>

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I am not a mechanic, engineer, or expert in any way in any issue related to brake conversions. I do not know if this conversion is safe, or even a good idea. Proceed at your own risk! This may be a really bad idea! Just because I did it doesn't mean you should even consider it!<o></o>

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Parts list

**EDIT added 03/17/2008***

ADV Member HPMGuy is producing the adapter that is mentioned below. Please send him a PM or email if you are interested in one... the plans are below for any "do-it-yourselfers".... Guy's work is first rate **end edit***

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Caliper: Nissin 4-piston fitted to Suzuki GSXR's 92-93 600cc, 88-93 750cc and 89-92 1000cc. As these are mounted behind the fork leg on the GSXR's, and in front of the legs on the BMW be sure to buy the left front caliper as you will be turning it around to mount on your BMW. Got mine off eBay for $5, expect to pay up to $25<o></o>

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Stainless brake line: The stock BMW line to the steel hard line won't work. I bought a 50"? ss line off of eBay for $25. I think one as short as 45"? may be fine. This length allows for the line to be run through the fender like the stock line and routed right up to the stock master cylinder.<o></o>

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Brake Pads: I bought a set of EBC FA145's, and believe the other options are: <o></o>

SBS624, Vesrah VD 343, DP DP213 and Ferrado FDB557. <o></o>

Check to make sure. I got two sets of EBC's off ebay for $25.<o></o>

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Hardware:<o></o>

Upper bolt to attach the caliper to the fork leg I used the stock BMW caliper bolt and tapped the aluminum chunk for it. M10 x 1.5 (30mm)<o></o>

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Upper bolt to hold the alum adapter to the upper caliper mountNo stainless Allen-heads available in this size says my source. The only choices were black Allen-heads that seem to rust if shown a picture of water and what you see in the picture. M10 x 1.25 (40 mm)<o></o>

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Lower bolt to hold the lower caliper mount to the fork leg&shy; - No stainless Allen-heads available in this size says my source. The only choices were black Allen-heads that seem to rust if shown a picture of water and what I bough see picture. M10 x 1.25 (25mm)

I have all of the specs for the adapter available in a PDF that another ADVR converted to a usable and attractive drawing... if you want it send me a PM.

**NOTE** I had to machine the caliper mounting "ears" to remove 0.0625". This moves the caliper to be approximatley centered in on the rotor... you should do your own measurements for this one!

**EDIT added 03/17/2008***

Member HPMGUY is producing the adapter that is mentioned below. Please send him a PM or email if you are interested in one... the plans are below for any "do-it-yourselfers".... Guy's work is first rate **end edit***

And machining the word "Nissin" off of the caliper is optional.... now if I could just figure out the CNC mill to add "BMW" to the caliper I'd be set...

Here is my version... (not made by HPMGuy, his is much nicer looking!)

and one more photo...

and one more...

My test ride home was about 4 miles in the pouring rain, needless to say I dont have idea if this is a huge improvement yet. My initial thoughts are that the lever position is a bit further out then with the BMW caliper when brought completely "home" and the feel is strong an progressive. The newness of the pads and the wet weather didn't allow me to get an idea if this will make a great improvement, but the change does make a noticable difference.

I suspect that it is making a difference because I noticed a significantly greater amount of front end drive when braking....... until just now I was writing it off to changing my fork oil from 15w to 10w before doing the caliper change, but now I'm reconsidering that judgement and thinking it's from the caliper conversion.

Hope to ride in Friday and give it some more testing....

I considered fitting a Nissin 4-pot to my airhead GS until I measured the diameter of the Nissin caliper, worked out the surface area & found that the two large diameter GS pistons had a greater surface area than the Nissin caliper (off a GSX-R750/1100).

It could be though that Nissin pads have a greater pad area?

Steve,

I'll repeat the same measurement and also check the pad area. All I can say it that the change does make a noticible difference (rode in today). I am still working through a slight ridge that the stock set-up left at the top of the rotor where the stock pads didn't touch, but that is mostly gone this morning!

I suspect that the different sized bores for the Nissin pistons makes a difference as well in the "feel" component of this change.

Let's see what my measurements say!

SL

The Nissin pads are bigger..........

I recently converted my 80G/S to a Harrison six piston and had a similar experience - more brake dive. But the increased travel at the master cylinder gave a different feel, besides it started leaking. It didn't like the conversion and decided to give up the ghost. But I came to the same conclusion that I must have increased braking as evidenced by the increased brake dive.

Yeah, I'd like to get more braking power from the GS. Most of the stuff I've read on Horizons Unlimited and UKGS'er suggest that going to a bigger rotor makes the most difference. Anyone figured out a cheap(er) way to do that?

Thought I saw a post around here of a guy that hung a K11RS??? rotor on his airhead.... doing this Nissis mod may be enough though.

Hi Solo...that would be me. I'll post the pic again, and your right the caliper is from a K1100RS. Also posted is a Spiegler (german) rotor and caliper on a friends GSPD. It is an amazing brake (2 fingers will do the job)...but you get what you pay for and the whole assy including SS line is about $1000 USD. ouch.

Comparing your nissis mod to my 4pot brembo i see the similarities. We both
only gained a small amount of stopping power. It was enough to make it 'noticeable' and therefore worth the time and effort for the small amount of $ we invested. That small but still signifigant amount of stopping power just may be enough to prevent whacking something hard one day...we hope.
...good job Solo and thanks for sharing


4pot brembo on a GSPD



Speigler (german) on a GSPD

Just rode a '92 R100GS with a Harison 6 that was fully beded in (around 4k miles??). It was super-dooper!, when my Nissin has more miles on it I expect it will be 85% of a Harison...... no single finger front wheel lock ups, but much improved over the stock.


More to come as I ride it more!

Good news Solo.
Sorry for being a bit too judgemental in my last post.
Like a fine wine it needs to age. I'm likeing your mod
more and more. I was never totally satisfied with my 4 pot brembo, just seems like it could have been better. And i'm not convinced that if i upgrade to a 15mm Magura master cylinder that it will improve mine.
Anyone here use a 15mm mc on their airhead? I'm lucky if mine improved 30%...but any improvement is better than that anemic 2 pot stock brembo. The twin disc on my Africa Twin has spoiled me.
regards.

If I was worried about being judged, I wouldn't be here, no worries.


I haven't heard about anyone using the 15mm, but I believe that my last bike a 1995 R1100RS has a 20mm or 21mm master cylinder piston. Isn;t the rule the large the bore, the higher the fluid pressure and therefore greater braking? (with some potential loss of "feel"?)

Im using this front brake system:

320mm MAP Eng. disk, bracket & SS line
Stock 2 pot Brembo caliper 42mm pots
Black Galfer pads
and 15mm Magura master cyl.

I was always annoyed at the large amount of lever travel on the GS ('88 R100). Repeated bleeding with the pistons retracted, speedbleeders, rebuilding the caliper, making sure that the caliper was reasonably centered on to the disk only helped a little. The SS line was the best improvement of all this.

Started thinking about mc to caliper bore ratios and vintage brake publishes a chart. According to their chart the 13mm in right for the 13mm master with the 2 42 mm caliper pistons.

Then I spoke to a racer engineer friend who quickly did an excel chart showing that vintage brake is just off, and that I should use a 15 or a 16 mm master cyl., both of which are available at the dealer.

After years of just too much lever travel the 15 just works. No pinched fingers, the ability to modulate the gas while braking, if some power was lost it was regained by the larger disk. Galfer green were a little to grabby, the blacks have less bite more gradual.

On the Galfer greens: too thick and forced the floating disk to be asymmetrical in the caliper and keeping a piston retracted.

Thanks for the great input Paolo. Maybe its time to source me a 15mm Magura. Speigler USA had them at a blowout price
awhile back on their website, but now i don't see them there anymore.[/QUOTE]


Got to use the BMW master by Magura if you want a 15mm because in the GS (all I think) the MC is integral to the switchgear, it is not a standard clamp & 2 bolt mount.