Front Forks
Ducati stamped a date of manufacture on their forks, but hidden from view by the front brake.
June, 1965
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The war in Vietnam officially begins as the US State Department announces that American troops are engaged in combat. |
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Ed White steps out of Gemini 4 and becomes the first American to walk in space. |
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The Rolling Stones release "Satisfaction." |
The right-hand side fork tube had taken some kind of side impact. The upper shroud (5) was dented on its outward side, the dust cap (33) was severely abraded as were the threads on the lower sliding tube (29) on their outward side. Upon disassembly, an inward distortion of the lower sliding tube and it's sealing ring (directly behind the abrasion) was clearly visible. I put both fork columns (37) on a granite table and sure enough, the right side column wobbled as it rolled, indicating it was bent.
Fortunately, I had purchased a spare set of narrowcase forks at a swap meet a few months before I fully assessed this damage. I used a swap meet lower slider which had good threads and one of the swap meet dust caps into creating a good right-side fork assembly.
Another bit of good luck, the damaged lower sliding tube was on the right-hand side rather than the left side which displays the build date. The swap meet forks had come from a bike built in '68.
Unfortunately, some bad luck too. Both central columns from the swap meet purchase were bent. Although neither was as badly bent as my original, the outsides of the both spare columns were badly scored. These tubes are hard-chromed, so the swap meet tubes would need to be both straightened and hard-chromed again. For about $100, I could have a brand new hard-chromed column made by Frank's Maintenance and Engineering. For about $15 G.T. Enterprises would straighten my original one.
I opted for GT Enterprises, only so I wouldn't have to move the valve ball assembly housed in the base of the shock tube. Once back from GT, the tube rolled perfectly straight on the granite table.
With spares lined up for substitution for the damaged parts, the forks will just require freshening.
Here's a list of the items required to completely freshen the front forks:
Quantity 2, part # 0170.37.494, description: Gasket 8,1x13x1 (item 27)
Quantity 2, part # 0460.37.288, description: Ring Angus MIM 31,5/40/7 (item 31)
Quantity 2, part # 0460.37.295, description: Gasket 33,5x44,5x0,5 (item 32)
Quantity 2, part # 0270.37.260, description: Gasket 6,2x10x1 (item 21)
Quantity 2, part # 0460.37.478, description: Plug Sealing Ring 1=17,5 (o-ring on item 6)
If you must have new fork columns made, you'll need to extract the valve assembly in the bottom of the forks and move them over to the new columns..
Optional items required to refurbish the steering head:
Quantity 1, part # 0460.37.670, description: Friction Washer 26,5x45x2,5
Quantity 2, part # 0440.37.210, description: Lamp Holder Guide Rubber*
Quantity 48, part # 76835.0497, 3/16 ball bearing (4,76) RIV90152006
* = unobtainable! not being reproduced.
The forks are fairly straightforward. The two main components of each fork leg are the hard-chromed central column and the fork lower that the axle goes through. Inside the central column is a hydraulic valve assembly that works in conjunction with the large spring you see when you remove the fork assembly from the triple clamps.
The valve assembly is what holds the central column to the fork lower.
One of the biggest hurdles to taking the forks apart is to separate each central column from its fork lower.
To disassemble the forks the allen screw in the bottom of the fork lower must be removed. It's not the drain plug, the drain plugs are on the side of the fork lowers. The absolute bottom allen screw is holding onto a valve in the central column, and that's why the central column won't pull out of the fork lowers. The central column will only move up about 6 inches which is the distance to the top of the valve.
For about $1.29 get a length of threaded rod from a hardware store. Make a 90 degree bend for a handle on one end.
On the long end cut a slot with a hacksaw.
Drop the slotted end of the tool down into the center of the central column and rotate the tool to catch the pin in the valve stem that's bolted to the fork lower by the allen screw in the bottom. If you use a flashlight and look down into the central column you'll see the pin you're trying to keep from rotating. Once you've captured the pin in the valve you can keep the valve from rotating while you loosen and remove the allen screw in the bottom.
Once you've done this, you'll see just how simple the fork system is, and how easy it is to freshen the seals.
