Forks.
They were the one big ticket item I had absolutely no solution for.
So, like a farmer praying for rain in times of drought, I just kept my head down, went about my business, and tried not to think about what I needed to fall from the sky.
It's all a balancing act isn't it? What is appropriate for the bike vs what you can afford. I mean, for a marque where many folks prize originality, the bike is a complete mongrel/bitsa: a 999RS engine in a bastardised 749R frame, with some good bits hanging off the back end....and it's still based around 15 year old mechanicals that won't set the world alight today. It has value to me, I'm not building it to sell it, but you don't really want to spend a shit ton of time and money on something that is ultimately worth bugger all. So as much as I'm an idjit, the idea of spending huge dollars on forks just made no sense....
....unfortunately Ducati's association with Ohlins over the years makes them the logical choice. But not even poverty-spec OEM Ohlins are cheap and anything of decent race spec is priced to have you contemplating if the ubiquitous gold tubes are solid not anodized. Some of the better (spec, not price, lol) options would also involve machining the 749R triples, which I would rather avoid.
Then, manna from heaven: I came across a set of brand new - never fitted, Gen 5 ZX10R Showa BFF forks for (super) cheap from an online surplus store. I instinctively start joining the dots:
- identical: axle size as 749/999/1*98, to suit a spare front wheel/brake rotors I already had
- identical: caliper spacing, to suit my spare 749R 100mm 4 pad calipers
- smaller: fork tubes 50/55mm vs 53/56mm 749R Ohlins triples, so the 749R triples could stay intact with no machining,
But would people lose their shit over Japanese Showa on a half decent Italian bike with R/RS DNA? Did I care?
Ultimately "comparison is the thief of joy" and so it was here: why was I comparing it to other bikes? I just wanted a great front end, and if I could do it without spending a small fortune all the better.
So for half the price of a set of Ohlins cartridges, let alone full forks, these absolutely brand spanking new 2019 ZX10R Showa BFF rocked up:
The BFF at 50/55mm vs 53/56 749R triples meant machining up some alloy bushes for the top and fitting some alloy 0.5mm shim for the bottom yokes (can barely see it)
And here we have it, not something you see every day:
The green caps are a lil' confronting, especially alongside the 749R plaque, but I'm telling myself the Italian flag is 1/3 green and used on the Tricolore bikes.....how else am I gonna sleep at night?!
The axle is just a smidge long, which wasn't too hard to sort, just extended threading and shortened appropriately:
The other issue is the rotor offset being too narrow for where the calipers sit, not quite clearing the internal guide pegs. No biggie, it looks like the typical 10mm vs 15mm offset issue that occurs with a few wheel/rotor swaps amongst Ducati's.
The cast ally rim below was originally going to be pressed into service but I've since magpied something a lil' more appropriate; just mocking things up here with the Brembo "T-drive" rotors that will stay:
This is about where things stalled for a bit, while I investigated rotor spacers, waited for the actual wheel to be used to rock up, and fiddle-farted around with other stuff.
I also had a lead on an affordable milling machine which would make things a lot easier. Now, I could continue the actual timeline of events and confuse the hell out of you, but I think (?) it's better to just show how I (eventually) progressed things.....so a few parts/beers/swear words flowed under the bridge between the above and the following a couple of months later.
I had a rear wheel sorted for this thing, so I'd been on the look out for a lonely lightweight front wheel to match and found it in the form of a Marchesini forged alloy 1198SP unit. It wasn't perfect aesthetically, which made it absolutely perfect for what is never going to be a show bike...and it's 1kg less in rotating unsprung mass vs the cast wheel above.
But I'd had no joy chasing up acceptable 5mm rotor spacers. Most come without the inner rotor locating spigot, basically just a flat plate, relying on the bolts alone for centring and support. Given this was a track bike with a bit of force going through the front end I wasn't really comfortable with that, so decided to have a crack at machining my own.....gulp! Brace yourself lil' lathe, your and my limits are about to be tested!
Luckily 6061 aluminium is cheap, so I was really only wasting time if I turned up nothing but swarf. From my admittedly beer addled memory we started with a 130mm OD cut-off:
So this is the rim/rotor hub profile I needed to replicate, in positive and negative forms (hope that makes sense) 5mm apart:
Mocking up a roughed out spacer against the wheel/hub:
And the rotor on that:
Getting closer! I just clamped the rotor/spacer combo together to use the rotor as a simple drill guide:
But they're pretty agricultural lookin' things aren't they?
The milling machine lead had eventually panned out; funnily enough it was near new but had sat wrapped up for the best part of 10 years in the corner of a workshop because it stopped powering up. The kind gent allowed me to do some quick fault finding, enough for me to realise nothing too major was wrong with it, and we arrived at a price where we were both glad to see it loaded onto my trailer.
I managed to repair it (yup, nothing major) but of course you can't just sit the thing on the floor so then you've another project on your hands making a stand to suit....sigh. She's nothing flash, completely manual, but perfect for my needs:
My tooling is next to nothing but eventually I get to take a bit of weight/ugliness out of the spacers (if you are a professional machinist look away now!):
After turning up some axle spacers I thought I was about done, 25mm Ti rotor bolts to replace the OEM 20mm bolts, fit up the calipers and grab a self-congratulatory beer....when I realised the calipers actually sit 5mm further out radially so the pads slightly overlap the rotor....poos!
The 749R has 8mm caliper spacers as standard fitment on these 320mm rotors but to use the calipers/rotors with these forks I was left with no option but machine 5mm from the caliper "feet" themselves, a difference of 13mm in the fork mounts. I could machine the forks, but that seemed like a one way street there was no going back down where realistically these calipers were the easiest/cheapest thing to replace if it all turned to custard.
It's not a decision taken lightly and I sat on it for a while but I figured if I maintain the original "footprint" of the mounting face, keep everything square, and I haven't compromised the stiffness of the caliper or gone anywhere near the pistons/fluid orifices there should be no issue (sound of running footsteps as I head off to check my life insurance...):
Postscript: it turns out Kwikasfuki made many changes to the ZX10R front end between the Gen 4 and Gen 5 models, most suited my project perfectly but one not so much:
- 2011-2015 Gen 4 ZX10R has Showa BPF (Big Piston) forks = usual Japanese 108mm caliper spacing and 310mm rotors.
- 2016-2020 Gen 5 ZX10R has Showa BFF (Balance Free) forks = Euro-spec 100mm caliper spacing and 330mm rotors.
- Both have a 25mm axle, same as 749/999/848/1*98
And therein lies the problem: I had a front wheel I knew would fit the axle, I had rotors to suit that wheel and I had calipers to suit the forks, the job's a good 'un and I'd just machine spacers to suit.....but it just never occured to me that OEM rotors had blown out to larger than 320mm diameter.
Every day is a school day.....
