SS front end conversion to 53mm SBK

[DesmoDerek944]

Has anyone done this conversion lately? I am beginning my project this spring and have a few questions? Will be using a brand new replacement frame (one was cracked) and need to source new steering head bearings. Anyone know what the bearing(s) mfg #'s are? (not the Ducati part #)

[TassieDave]

The spare pair I have here are both marked 639174 (inner and outer) and they measure 26X52X15. I had another pair I bought a while ago but any half decent bearing supplier should have them on the shelf.

If you search "bearing 639174" you will get quite a few results. SKF 639174 26X52X15

Tapered roller bearing SKF 639174 26 x 52 x 15.30 mm-Grene Webshop

Can't help with the other question - I replaced my fork internals (AK-20 kit)for probably the same money but seemed to be the easy option.

[Pablo Pirate]

Howdo!!

Used a set of 1098 forks on my Superlight - however the top yoke doesn't have enough meat on it so I had a set of adjustable yokes made by Pro-Mach. Very good upgrade, especially with the radial brakes.

Cheers Pablo

[amehl]

I JUST did this. Finished it about 2 weeks ago. Also if you are using **8/**9 forks you dont need different steering bearings. I got mine from All Balls, they seem ok.

I started my SBK fork upgrade...

[countcoupe]

Yep, done it myself!
916 Front Fork Conversion Completed

Had the top yoke milled out to fit and shimmed out the forks for the bottom yoke.

Got a 916 front wheel and spindle and mudguard to go with the 916 forks!

Played around with the internals of the speedo drive!

Lowered the clocks in the front subframe so I could use 916 clipons.

Hey presto.

Charlie

[countcoupe]

More recent picture.

[dhumphrys]

Hi, did this on my old 900SS and just done it again on my 851 (same front end as the SS/SL)

Get your top yoke machined out to 53mm, shim the bottom down with 1/2mm plate.

Wheel, axle and nut, mudguard, speedo drive, calipers and discs, bars from a 748, 916, 996, 998, SSie, any ST, any Monster of the S2/S4 era.

Get early 916 forks with 40mm caliper mounts and you can use your SS calipers.

The new front wheel won't match your existing rear as the spoke pattern is different. The only direct fit wheel that matches is from the 900SSie, these are very rare. The 600 and 750 were only 4.5".

You could probably fit a Monster ie or ST rear wheel but these run a 25mm axle so you'd have to modify your swingarm and adjusters or (probably easier) make a spacer to run a 17mm axle in the 25mm bearings.

Good luck!