Fork tube dimensions

Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models

Created: 2015 March 24

Updated: 2016 April 11

I extracted this information from Jason Telford off of the old Yahoo! Loopframe_Guzzi news group (which has now moved to Groups.io). In Jason's own words...

There are some differences between the original and the European replacements.

	Original disc brake fork tube	Replacement drum brake fork tube
Taper length	18 mm	16 mm
OD at top of taper	32.2 mm	32.5 mm
OD of tube	34.7 mm	34.7 mm

Overall length on replacement is about 4.5 mm shorter than the original.

Just by a hand-fit, the original tubes fit in the steering head yoke with about 3.3 mm between the top of the tube and the top of the upper steering head clamp. The replacements have just under 7 mm.

The replacement tube has the oil hole (valve?) at 47 mm from the bottom and there is a waist all the way around the tube. On the original tubes, there is no waist, the hole is either 47 mm or 105 mm (I have two different tubes) but there is a small chamfer on the original tube with the 47 mm hole.

On the replacement tubes, they are threaded (29 mm × 1 mm by the look of it) on both ends. No threads on the bottom of the original tubes.

The machining of the taper and the waist are acceptable, but not super quality. It looks like they were cut, but not finish cut (I can feel the tool marks). The tubes themselves are smooth, the chrome looks good and they are a nice fit in the shock sliders.

Thanks to Charlie Mullendore of Antietam Classic Cycle for sending me this additional information. In Charlie's own words:

Jason must have bought the economy drum-brake fork tubes, like I did for customer's 850 GT. The seem to be slightly thinner wall and weigh about 4 oz less than the originals. I didn't like the waisted area for the oil hole and the taper was a bit unevenly machined.

The better quality Italian fork tubes from MG Cycle are more like the originals regarding the taper, though it seems to be approximately 2 mm shorter. Plus, the original tubes when inserted into the top plate by hand are flush, these are approximately 5 mm down from flush. There's no waisted section at the oil hole, it too is more like the originals. Chrome quality appears excellent. These are also thinner wall by approximately 1 mm and weigh 4 oz less as well.