Dissasembly of forks on 68 mark 3

[john jupiter]

Hi everyone,
I am trying to get some help on how to get the lower steering cone off of the lower yolk and stem. Does anyone know if this is pressed on or threaded on?
Any best ideas to get it out? The manual just says "fit it"...

Thanks

[Jordan]

It's pressed.
Been a while since I last did it. I think I used a chisel with a narrow taper to coax it off.
These days, it might be more appropriate to use a bearing seperator, as it's almost a sin to dent bevel Ducati parts if it's avoidable!


Jordan

[StewartD]

reduced091.jpg

John,

Check the photo I have attached. This yoke is from a 1965 Mach 1. I think your model has the same components.

There is no thread, the bearing ring is a light press fit on the shaft. I removed my bearing ring by just tapping with a hammer and drift, at opposite sides alternately. I didn't use heat, but this would be an option if it doesn't budge with light blows.

Heating could be done in an oven, say to 200 degree Celsius, and then chill the shaft with a wet cloth. Hold shaft in vice (not on thread), and then tap it again.

The yoke is cast steel. The shaft is 26mm diameter above and below the yoke, so I think it either a very heavy shrink fit in the yoke, or is bronzed into it. Alternatively, there may be a shoulder on the shaft, the bottom of the yoke counterbored to accommodate it. I cannot see this shoulder, the paint is thick. I think this would be a more sensible design option. If they did this, there would only need to be a light press fit, which is cheaper than a heavy press fit or extra work of bronzing. Has any one got any further knowledge of this?

The reason I am asking is that my yoke/shaft is missing the travel stops. Someone had a yoke/shaft on e-bay with a cutoff shaft. If I was sure of the connection method, then I could marry the two good parts. Top thread of shaft is M26 x 1.0 pitch.

Cheers,

Stewart

[john jupiter]

Thanks guys. The cone is so nicely knurled i did not want to damage it. Ill try a drift and some heat and maybe a bearing seperator if i can find one

[double diamond]

Stewart, The steering stem is a press fit into the lower clamp (no brazing), but it's a pretty serious interference fit, often made more difficult to remove due to rust formation. There's a wire clip on the stem in a recess on the underside of the clamp that prevents the stem from pulling up through the clamp when the stem nut is tightened. Also, the stem is made of fairly soft material. I've successfully removed stems from some clamps by pressing them out from above. Others have ended up with a bent stem or mushroomed threads. If you're going to attempt to remove a stem from one clamp and press into another, I'd suggest cutting the clamp you're replacing to relieve the press fit. Then it should be possible to easily remove the stem with out damaging it. Thread the stem nut on to the stem to protect the threads before pressing the stem out. If the stem on the clamp you're going to use has been cut off, I'd say cut the stem off just above the clamp and split the stem by cutting a slot in the inside of the stem to relieve the press fit, then press the stem out. Clean the bore of the clamp and the stem of any rust, then grease or oil the stem and press in from above. You'll have to press the stem in a bit beyond it's correct final position so you can install the clip. then press the stem into position from below to seat the clip in the recess in the underside of the clamp. Be careful pressing the end of the stem where the steering damper is located; the stem is slotted and the two tabs will bend easily, though it isn't difficult to bend them back into position if they do bend a little. Matt

[StewartD]

DSCF3800.jpg

Matt,

Thanks very much for the comprehensive answer.

John,

Check the photo. The bottom surface of the bearing ring, which is slightly conical, can be hit upwards, either side of the yoke. The bearing ring will be of very hard steel and you will not damage it by hitting it with a steel drift. Make sure the end of the drift is in good condition and make sure it is held square on to the surface. If the bearing ring was of steel soft enough to be damaged by the drift, then it would not last long in service!

Stewart D