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Discussion Starter #1
Hello all, I'm hoping to get some feedback and suggestions on a fork upgrade I've got in the works.

The bike is a '94 CR with the original non-adjustable Showa's. I scratched a slider and killed a seal. Through considering many available options I landed on a set of Ohlins FG837's. This particular pair are based on the early FG43 with the 2 bolt caliper mount and come with an axle, 65mm brake mounts, and the 900ss specific fender adapter. Build date is Feb 2001. The fork/etc is in transit from Germany and I'm trying to line up as much of the rest of the update/upgrade in advance as I can.

Brake options - I currently have a 1098 19x18 brake master on the bike driving the original 40mm 30/34 P4 calipers and like the feel with the Ferodo Platinum pads. The ideal option is to find a 40mm mount for the fork so I don't even have to drain the lines, but they appear to be even rarer than these forks are. Or I can move to the 65mm 2 pin caliper with the same pads. Never wanting to pass an opportunity to upgrade though, I start to wonder about the 4 Pad calipers from the xx9 R bikes. This isn't a track bike, are these worth trying to do?

Wheel options. It appears to be a 20mm axle, even though the fender adapter appears to be for the carb bikes. What's are the pro's and con's of wheel options? New bearings + spacer machined for the original wheel? Using a later 20mm wheel from an ie and adapting/rebuilding the speedometer sender? Is there a simpler option I am overlooking?

Thank you all for any and all suggestions you might have! This is the upgrade I've been looking for since I bought this bike almost two years ago, the leaky fork just gave me permission to do it.

-Brad
 

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Brad
I think you would notice zero difference between the 65mm spaced calipers and what you have now so swapping is easy with only cost in the way. The 4 pad brakes will have the same bite (given the same pads are used ) but better feel. I converted my monster track bike tom a early caliper and my first impression was that it was a waste of time/money, after spending more time with them I discovered the benefit was more under hard use and trail braking as the feel and feedback were much better on the four pad. So I would guess it depends on what you are doing with the bike.

Obviously you do not mind modding the bike so I would swap the wheel to the 25mm axle front wheel as you will have the most options (916, 1999+ supersports, monsters, ST series) . I also see less of the front wheels bent on 99 and newer bikes so they may be stronger. You will need a new axle,speedo drive and possibly spacers for the forks depending on what you get with the forks. If the forks are set up for 25mm parts it is a no brainer. If they are set up for a small axle then I would probably keep it that way as well.
 

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Discussion Starter #4

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Discussion Starter #5
Brad
I think you would notice zero difference between the 65mm spaced calipers and what you have now so swapping is easy with only cost in the way. The 4 pad brakes will have the same bite (given the same pads are used ) but better feel. I converted my monster track bike tom a early caliper and my first impression was that it was a waste of time/money, after spending more time with them I discovered the benefit was more under hard use and trail braking as the feel and feedback were much better on the four pad. So I would guess it depends on what you are doing with the bike.

Obviously you do not mind modding the bike so I would swap the wheel to the 25mm axle front wheel as you will have the most options (916, 1999+ supersports, monsters, ST series) . I also see less of the front wheels bent on 99 and newer bikes so they may be stronger. You will need a new axle,speedo drive and possibly spacers for the forks depending on what you get with the forks. If the forks are set up for 25mm parts it is a no brainer. If they are set up for a small axle then I would probably keep it that way as well.
Thanks for the input, I appreciate it. I don't mind modding it at all, it's a CR with a shady history that was on the verge of being a basket case - I've been having a good time bringing it back to being a really good rider. Maybe more expensive than finding a decent SP, but much more rewarding in the long run.

As I'm not a 10/10th rider and keep my street riding to a spirited 7/10th I'm guessing I really won't be taking advantage of the 4 pad calipers. I'll stick with what I know works.
 

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Discussion Starter #6
Today I learned that the thread pitch to mount the 40mm calipers is different than for the 65mm calipers.

My local Ace Hardware has a wide selection of metric fasteners. Can I use something stainless from them? Or should I find an OEM bolt from ebay or my dealer? Normally I wouldn't give it much thought, but brakes seem important enough to ask.

Thanks!

Brad
 

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I'd go for better grade steel as Stainless can be a bit hit and miss unless you know the source. 10.9 grade steel is a lot stronger than 304 stainless (and cheaper) If you are confident about the Stainless you are buying (from an fastener place rather than a hardware) Stainless would be strong enough.

These days there is some pretty poor quality crap out there in the fastener market. You might be fine but I've had some no name stainless fasteners that were supplied with a sub assembly that were just rubbish.
 

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In general I don't think stainless fasteners are appropriate for high load applications such as mounting brake calipers. I would use an appropriate size of the zinc coated steel bolts that were originally on the bike. Others may disagree
 

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in general i don't think stainless fasteners are appropriate for high load applications such as mounting brake calipers. I would use an appropriate size of the zinc coated steel bolts that were originally on the bike. Others may disagree
+1
 

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Discussion Starter #10 (Edited)
So close, but yet so far away.

I'm trying to use the OEM wheel with the new forks and 25mm axle. 25mm wheel bearings are installed, with the 748/996/998/ST2/etc bearing spacer.

The problem is that the speedometer drive is too narrow. The local shop had a 49810091A speedometer on hand, which is the 25mm axle superbike/etc speedometer drive. I swapped out the gears with no issue. Problem is that my original speedometer drive is spaced at 35mm wide, the Superbike speedo drive is 30mm wide and sinks too far into the wheel to work correctly.

What can I do about this? Or am I missing something hugely obvious? Have a custom spacer made?

Thank you guys! I can almost taste riding this beast again so soon!

(Edited for brevity and photos)
 

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More pictures needed:nerd:
 

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Discussion Starter #12 (Edited)
(edited my previous post for accuracy)
 

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Have you checked to see if the brake rotors and wheel are properly centered first? Different wheels have different hub sizes and if you used the 25mm ID bearings and did not space them the bearings may be sunk too far as the oem 25mmid bearings are thinner.

You might find it an easier conversion to bush the 25mm forks and run your solid axle that way everything fits and lines up as stock.
 

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Discussion Starter #14
Have you checked to see if the brake rotors and wheel are properly centered first? Different wheels have different hub sizes and if you used the 25mm ID bearings and did not space them the bearings may be sunk too far as the oem 25mmid bearings are thinner.

You might find it an easier conversion to bush the 25mm forks and run your solid axle that way everything fits and lines up as stock.
The tech who did the wheel bearings had done a SBK conversion on his SS many moons ago. He intentionally left the bearings a little wide and advised that I get them centered first. I'm not sure how I do that if I don't have the correct spacing on the speedometer drive side. That's unfortunately how I got to this conclusion.

I can throw the wheel in without the speedo drive, but then what am I looking for?
 

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With the front fender off mount the wheel and make the clearance between the fork tubes and the wheel equal. You also should have the rotors centered in the calipers as much as possible though it is not necessary as long as there is clearance from the caliper body and the rotors on both inside and out. Speedo side sets the wheel to center, opposite side is less important but will determine how much the axle sticks out or is recessed. If using a externally threaded axle and nut (25mm axle style) then make sure you have enough threads to take torque , also it cannot bottom or it will not tighten.
 

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Discussion Starter #16
With the front fender off mount the wheel and make the clearance between the fork tubes and the wheel equal. You also should have the rotors centered in the calipers as much as possible though it is not necessary as long as there is clearance from the caliper body and the rotors on both inside and out. Speedo side sets the wheel to center, opposite side is less important but will determine how much the axle sticks out or is recessed. If using a externally threaded axle and nut (25mm axle style) then make sure you have enough threads to take torque , also it cannot bottom or it will not tighten.
Excellent description, thank you!
 

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Discussion Starter #17 (Edited)
The good news is that the 5mm spacer behind the otherwise too narrow speedo drive worked a treat. Lined everything up from the speedo drive side and made the requisite bearing shifts to get the rotors mostly lined up in the calipers. With the LH rotor centered the RH rotor is a hair's width from the outer limit, giving the RH fork/axle a super light touch of spread and everything lines up - I'm not sure I like that as it sounds like a recipe for stiction. To note: I don't need to tighten down the axle to keep the spread once I spread it apart. Turns out this is from the LH axle shim being about 0.5mm wider than the fork bottom.

Is the shim supposed to be wider than the fork bottom?

The 25mm spacer/bearing/speedo combo is too wide for the axle, now I get the "custom bearing spacer" item on the checklist. Are there varying axle lengths? Or do I need to pull the bearings and spacer to have it machined down? Measuring everything up looks like I need to make up 4.5mm to engage all of the threads on the nut.

First photo - 6.75mm excess I have on the RH side of the axle.
Second photo - not enough thread to actually start threading.
Third photo - LH caliper/rotor alignment
Fourth photo - RH caliper alignment "unadjusted"
Fifth photo - RH caliper alignment with about 2lbs of tension applied to the fork.

Thank you all again for your input!
 

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