Project Ducati Superbike 998 Part 2: Suspension and Chassis Geometry

The importance of setting a budget and timeline can’t be stressed enough. Otherwise, projects are guaranteed to take longer and cost more than you intended. Because I can’t heed my own advice and spend too much time on eBay, I stumbled upon some take off Ohlins FGRT813 forks from a low mile modified Ducati 848. No sense in not buying these.

Because these were intended for 848s, the tubes are 53mm diameter at the top and bottom clamp positions which means they sit in stock triple clamps without modification. Not that I ended up keeping those either. These new to me fancy forks meant I would also need brake calipers. Want great brakes? Ride a bike with great brakes, buy those, install them onto your motorcycle. Ducati’s 1199s have the best braking I’ve ever felt on a stock machine. Brembo M50 calipers that come on them are still in high demand as they are the production caliper. The previous generation 1098s were equipped with Brembo M4 calipers and were also great. Even ten year old M4s are $350-$450. Ducati, like other European makers, insist on 100mm caliper bolt spacing on their radial mounts, while Asia, whose used parts are always cheapest, use 108mm spacing. So nothing from japan-land works. BMW’s amazing S1000RR comes with Brembo calipers. They are not the latest and greatest, but they are 4 pad, 4 piston radial calipers with the correct 100mm bolt spacing. And the set I found even comes with the mounting bolts, booyah.

The gorgeous machined bottom and nitride coated tube of the Ohlins FGRT813 fork

Calipers all cleaned up, bolt them on, almost. BMW bolts are M10 x 1.5mm, not M10 x 1.25mm thread pitch. Pro-bolt sells great looking titanium fasteners for about $85. I’m cheap, so $40 in stainless Pro-bolts later, the calipers bolted to their brackets.

The stainless Pro-Bolt hardware also comes drilled for lock wire. Compared to the stock BMW bolt the difference in thread pitch is the main difference.

 

Brembo calipers from a 2013 S1000RR secured by stainless Pro-Bolt fasteners.

6 comments

  1. Be careful substituting in stainless steel bolts in the place of carbon steel bolts. Austenitic stainless steels like 18-8/304 are typically very low strength with the amount of work hardening that goes into making a bolt. Additionally, the different methods of making a bolt, and how much the threads are rolled drastically affect the final tensile strength of the bolt, to the point that they typically aren’t even rated for tensile strength or hardness.

    Most low carbon bolts are going to have a tensile strength in the 115-145 ksi range, while most commercial CRES bolts will be in the ~70-85 ksi range.

  2. Great comment Def. McMasterCarr sells multiple types of stainless fasteners. For clarification, I used the ‘High Strength Stainless Steel Socket Head Screws’ specifically because they have a higher tensile strength of 110 ksi vs the regular stainless’s 70 ksi.

    I think either would work though; titanium bolts are readily available as replacements and have less tensile strength than either type of steel.

  3. A good point to make Rob, it might be good to note this in the article because I was thinking the same thing as Def.

      1. Had the exact same thought regarding 300 series stainless fasteners. Nice find with the high strength options. That being said, there are many titanium fasteners that are 110+ ksi. The ones on mcmaster that quote 50 ksi are probably grade 2 titanium for corrosion resistance. Grade 5 is much stronger and that’s what is more typical for performance oriented fasteners (pro-bolt, allied titanium, etc.)

        1. You’re right. Pro bolt lists grade 5 for their titanium fasteners with a ‘greater than 120ksi’ tensile strength. They also list shear modulus, ductility, Rockwell hardens etc. Really quite impressive that they have all of this information for the customer.

          They also DLC coat the fasteners for corrosion resistance. Shame their too expensive typically for a cheap ass like myself.

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