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Speed Merchant makes "adapters" (11.5" & 13" rotor versions) to allow a radial
caliper (108mm bolt spacing) to be fitted on a Sportster. You can also find
cheaper versions from China on AliExpress. Here's a link to the Speed
Merchant 11.5" rotor version.
Looked into a variety of the suggestions here, and the wallet has been opened.
I really fancied the idea of a complete front end swap, but when I looked at parts prices for decent gear, it started to pile up fast. Ł250 would get me a good set of forks from something like a Transalp with twin discs. Another Ł100 for a wheel, then Ł100 to get a donor lower yoke to rob the steering stem out of to get swapped into the new front end. Was quoted Ł150 to do that ( which isn;t bad all things considered). Then the brakes, master cylinder and sorting out the fact that all the likely donor front ends use 22mm bars, not 1/2".
Wildwood calipers were looked at, but are just not available in the UK. Pads also. But...there was a UK made alternative.
So, a 4 pot Harrison Billet caliper in black anodised finish ( Harrison advised that as I use the bike in all weathers. They also come in a polished ally finish...but I know what winter will do to that! Ł360 with pads, fittings, banjo bolts and new crush washers. That's posted to my door.
Not wishing to dip toes in political waters, but slapping trade tariffs on the world is resulting in increased prices, made worse by our incompetent leadership over here. So being able to source local stuff worked. Plus the range of pads available was better. Including my preferred EBC items.
Could have gone for 6-pot, but to be fair...it's not a fat front tyre, and I have moved from a twin pot sliding caliper setup to a 4 pot. A desing choice that should mean moreeven pad pressure, and no issues with sticking sliders, even if you do strip and clean them every spring.....and autumn. Can;t wait to bolt this thing on and see how it does!
A bit late. I’d look into a TC bros caliper bracket, like previously mentioned-
Brembo M4 Monobloc calipers for maximum performance (sold separately) but they can also work with just about any 108mm radial caliper (Beringer, Tokico, etc.) with proper shimming. For the budget minded customer, these brackets pair very well with factory takeoff 2005-2016 Suzuki GSXR 600/750 Tokico calipers commonly found used online.
Yet, I have read that the 19" spoked wheels to caliper clearance can be an issue.
Other co-members may have insights to the need for a master cylinder swap.
Welp .... had the Harrison billet 4 pot caliper on for a few weeks, and I have to say I am very happy with it.
Had a different feel to stock, and at first I thought I hadn't bled it properly as it felt a little spongy, but it was certainly working as it should. Bike stops a LOT better now. Decent feel too, once I was used to not having to put so much force into the lever. Picks up nice and progressively
Re-bled it after a week, and no air was visible, and the lever feel was unchanged. Now I have got accustomed to it, it's like its always been there.
For UK riders looking for a locally sourced item I can definitely reccomend it. I wasn't able to source Wildwood units and would have to have had them imported with the extras cost associated. Plus the same issue with pads.
Harrison also do 6 pot units, and you can get them polished or anodised. I went with black anodised as, again, I ride all yewar round in all weathers and the finish is pretty thick and looks durable.
Heres the dumb question - Ive owned many sporties and never had a complaint about the brakes. Are you certain that the lines, the master cylinder and everything else are up to spec?
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