R Yokes

The 749R was built specifically to compete in World Supersports (WSS). Many of the parts on the R were specific to the bike.


The yokes are very special for a 'road' bike and this post intends to describe them in some detail.
This is all about steering angle and the degree to which it can be changed. Some circuits have tight, slow bends, requiring a steep steering angle, others, like Monza have long fast straights, which require a more stable bike and a more relaxed steering angle. Generally a bike that excels at one type of circuit will not do so well at another. This is why Ducati have adjustable headstocks on certain models: to enable the rider to change the characteristics of their bike. This adjustment has it's limitations: it has two settings - road and 'race'.


The 749R and most of the RS models take the concept a little further: the steerer tube itself is adjustable.

This picture shows 999S and 749R bottom yokes and steerer tubes. The item on the left is the 999S. The steerer tube is a hollow tube with a correspondingly large top nut: the 749R has an eccentric (like a cam) outer tube that contains the steerer tube. From what I can read through the grime, the part numbers on the cast part of the yoke are identical.

The inner tube is loosened (the lower nut) and the hex socket in the top of the tube is turned to change the steering angle within the normal eccentric (some RS' run magnesium headstocks, others the normal aluminium ones). As you can see, the yokes on the left have no adjustment.
These yokes used in conduction with the adjustable headstock enable the steering angle to be set extremely accurately and extend the range of adjustability considerably, so much so that in order to use this adjustability, the lockstops need to be moved.

These pictures show the eccentric on the yokes set to maximum and the headstock set to road, then race.
It is clear that in race setting, the frame would foul the standard lock-stops, so these yokes have been modified to bring the lock-stop further forward.

The standard 999S yokes have cast lockstop mounts: These have been machined away on these R yokes so that an extended and replaceable lock-stop can be used.
The lock-stop shown in both these pictures is the extended RS part.

Top yokes

All the same, right? Well, I'm not so sure. A couple of months back, I bought a set from Targetmotorsports. These are the guys who regularly buy pretty much everything from Ducati Corse at the end of the season and sell the parts they don't want. Their collection rivals the Ducati museum. It must be amazing.


They usually only have WSB parts and a very small number of GP parts, but I've had some of Lanzis Breil fairings from them, so when some R yokes came up, I was interested enough to buy them. The picture here shows what was of interest on ebay: the markings at the front of the yokes. I'm sure I've seen these same markings on a Breil bike somewhere.  

On the bottom of the standard yokes are the normal production markings: the part numbers and the manufacturing date. On the (I'm presuming) WSS yokes, there are no such markings and the steering damper mounting is clearly prototype.

Less visible is the '01' marking on the front of the yokes and the machining marks, which are horizontal rather than vertical as on the production part. This is clearly an early race or prototype part made before the production parts were ready. Interesting.