Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Track Head Angle - Suspension Setup to Suit?

[chris.p]

Originally Posted by Shazaam!

No, raising rear ride height using the adjustment rod has no effect on sag values.

Sorry, it appears that the last part of my post went AWOL???
Meant to say-:


Quote:
Originally Posted by Shazaam!
If you've changed your sprockets and didn't record your initial height setting then you need to have Ducati use the factory ride height tool. With the rear fully extended, measure from the top edge of the tool to the dead center of the axle. This should be 237 mm. Lengthen or shorten the linkage rod to get this number.



Shazaam, are you saying that the rear of the bike must be "topped out" i.e. lifted so that there is no static sag???? when you measure from the centre of the wheel nut to the top edge of the tool???


Chris

[Shazaam!]

Originally Posted by chris.p

Shazaam, are you saying that the rear of the bike must be "topped out" i.e. lifted so that there is no static sag when you measure from the centre of the wheel nut to the top edge of the tool?

Correct, the measurement is taken with the swingarm fully extended.

Ride Height Adjustment

The rear ride height is set at the factory to assure the correct weight distribution and the proper fork angle. Ducati uses a fixture (ride height tool) that mounts to the frame at pick-up points that are fixed relative to the swingarm pivot point when the frame is welded. The distance to his fixture from the center of the rear axle (with the suspension fully extended i.e. no weight) is then adjusted by changing the length of the ride height adjustment tie-rod to increase or decrease the ride height.

With the swingarm fully extended, the distance from the tool (datum line) to the center of the axle should be 237 mm. The tie-rod is lengthened or shortened to get this number. The factory ride height specification is satisfied when the tie-rod measures 261 mm between pivot bolt hole centers.

First, measure the distance between the two ends of the tie-rod and record this length. Then when you change the tie-rod length, you have a record that allows you return to the factory setting or a previous setting. Length changes should be made in small 5-10 mm increments because the way the bike turns and holds a line is quite sensitive to the rear ride height. As a rule, the more rear ride height you add, the faster the bike will turn. The ride height is set to let the bike turn quickly without falling into corners, or requiring rider input to hold a line.

The tie-rod is adjusted using 17 mm and 19 mm wrenches. The bottom nut is a left hand thread and the top nut is standard. You turn both nuts the same way to loosen them. So, you only have to loosen the top nut, and then turn the rod in the reverse direction (i.e. unscrew the rod from the nut) to raise the ride height. The corsa rod has flats to make this easier. Finally, reseat the LH lower nut and tighten the upper nut.

When the bike sits on its suspension, the height that the rear bodywork sits relative to the rear axle is affected by manufacturing and installation tolerances of the rear subframe and the clock-position of the rear hub eccentric chain adjuster as well as rear spring preload and tire size/wear. This prevents you from establishing a different ride height reference value measured to a reference (datum) point on the bodywork itself.

If you haven’t made any changes yet to your rear spring preload, or adjusted your chain tension then you are still set-up to factory settings. So, following the first rule of making suspension adjustments, you should first measure your initial settings and record all changes.

This is the only time (without using the ride height tool) where you can establish a (factory) pseudo-datum at a different location on your particular bike’s bodywork to which you can measure the distance to the rear axle. Another same-model bike will have a different dimension to this datum even though both bikes have the correct ride height.

Once you have established a new bodywork location (unique to your bike) from which to measure ride height, then you can measure all future changes to ride height from this datum. So you won’t need to use the Ducati ride height tool as a reference datum. Again, this measurement is made with the suspension fully extended. You should also continue to record the changes to the tie-rod length to make it easier to return to your previous settings, if need be.

[chris.p]

Originally Posted by Shazaam!

Correct, the measurement is taken with the swingarm fully extended.

Ride Height Adjustment

The rear ride height is set at the factory to assure the correct weight distribution and the proper fork angle. Ducati uses a fixture (ride height tool) that mounts to the frame at pick-up points that are fixed relative to the swingarm pivot point when the frame is welded. The distance to his fixture from the center of the rear axle (with the suspension fully extended i.e. no weight) is then adjusted by changing the length of the ride height adjustment tie-rod to increase or decrease the ride height.

With the swingarm fully extended, the distance from the tool (datum line) to the center of the axle should be 237 mm. The tie-rod is lengthened or shortened to get this number. The factory ride height specification is satisfied when the tie-rod measures 261 mm between pivot bolt hole centers.

First, measure the distance between the two ends of the tie-rod and record this length. Then when you change the tie-rod length, you have a record that allows you return to the factory setting or a previous setting. Length changes should be made in small 5-10 mm increments because the way the bike turns and holds a line is quite sensitive to the rear ride height. As a rule, the more rear ride height you add, the faster the bike will turn. The ride height is set to let the bike turn quickly without falling into corners, or requiring rider input to hold a line.

The tie-rod is adjusted using 17 mm and 19 mm wrenches. The bottom nut is a left hand thread and the top nut is standard. You turn both nuts the same way to loosen them. So, you only have to loosen the top nut, and then turn the rod in the reverse direction (i.e. unscrew the rod from the nut) to raise the ride height. The corsa rod has flats to make this easier. Finally, reseat the LH lower nut and tighten the upper nut.

When the bike sits on its suspension, the height that the rear bodywork sits relative to the rear axle is affected by manufacturing and installation tolerances of the rear subframe and the clock-position of the rear hub eccentric chain adjuster as well as rear spring preload and tire size/wear. This prevents you from establishing a different ride height reference value measured to a reference (datum) point on the bodywork itself.

If you haven’t made any changes yet to your rear spring preload, or adjusted your chain tension then you are still set-up to factory settings. So, following the first rule of making suspension adjustments, you should first measure your initial settings and record all changes.

This is the only time (without using the ride height tool) where you can establish a (factory) pseudo-datum at a different location on your particular bike’s bodywork to which you can measure the distance to the rear axle. Another same-model bike will have a different dimension to this datum even though both bikes have the correct ride height.

Once you have established a new bodywork location (unique to your bike) from which to measure ride height, then you can measure all future changes to ride height from this datum. So you won’t need to use the Ducati ride height tool as a reference datum. Again, this measurement is made with the suspension fully extended. You should also continue to record the changes to the tie-rod length to make it easier to return to your previous settings, if need be.

Thanks for clearing that up for me

Chris

[skidlids]

Originally Posted by chris.p

Shazaam, are you saying that the rear of the bike must be "topped out" i.e. lifted so that there is no static sag???? when you measure from the centre of the wheel nut to the top edge of the tool???


Chris

The extended reading is ideally taken with the rear wheel lifted off the floor, not that easy to do with just one helper.
The figure I use is 242mm fully extended and 232mm with unloaded sag. I did try the 245mm extended with 10mm of sag that was recomended to me by a couple of SoT runners (one won the Superclub championship and the other was runner up in the Bemsee championship). but prefered it a bit lower, maybe my front rideheight is also a bit lower than theirs.

[chris.p]

Originally Posted by skidlids

The extended reading is ideally taken with the rear wheel lifted off the floor, not that easy to do with just one helper.
The figure I use is 242mm fully extended and 232mm with unloaded sag. I did try the 245mm extended with 10mm of sag that was recomended to me by a couple of SoT runners (one won the Superclub championship and the other was runner up in the Bemsee championship). but prefered it a bit lower, maybe my front rideheight is also a bit lower than theirs.

What height above the top yolk would you recomend the fork tops to be with showa forks Kev??? with Mag swinging arm & with standard swinging arm.



Chris

[skidlids]

Originally Posted by chris.p

What height above the top yolk would you recomend the fork tops to be with showa forks Kev??? with Mag swinging arm & with standard swinging arm.



Chris

Only my 996 has Showa forks and they are in adjustable offset Robby Moto Yokes so none of the figures tally up.
Setting a fork height through the top yoke is playing with the front ride height which is the same as adjusting the preload, so unless you are at one end or other of the preload adjustment try playing with that first, if you prefer it wound right in then have less fork coming through the top yoke back off the preload and start adjusting again.
if its backed right out let more fork (about an extra 10mm) through the yoke, add some preload and then start adjusting again