USD forks

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Old Scratcher

Old Scratcher

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Has anyone ever fitted them to a classic Commando? If so, how did they go, & which forks fitted? I bought my Cafe bike as a bit of an ongoing project, that I can modify to my tastes over the years. I'm probably going to start with a Corbin Smuggler seat & an electric starter, which will take care of the next few years disposable income for such follies. But eventually I'd like to change back to wire wheels, while retaining a modern triple disc braking system. So I'm looking at something aftermarket anyway, & probably custom built. & I'm thinking if I'm going to do that I should see if it's possible (& hopefully affordable) to mount up a nice pair of anodised gold USDs. Matched with a gold pair of Ohlins piggy-backs on the rear, it'd look the business while delivering the goods! Unfortunately finances dictate that these plans lie far in our future together. But I like to go over the logistics & cost these things out. So I know what my savings target is, & it gives me something to dream about while I'm saving. So whadayareckon? Is it doable? & more importantly, is it affordable?
 
Been a few sets of usd forks on Commandos here, over the recent past even.
Search, and ye shall find.

The ones with wire wheels look more in keeping,
although mag wheels and tubeless tires are the performance norm these days...
 
USD forks
 
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
 
Matchless said:
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
Click to expand...

I can't see how you could use stock triples with inverted forks unless you machine them out or find a fork with 35mm upper legs, and you would still have to bore the taper out of the top yoke and somehow convert it to a pinch setup. And please explain how inverted forks would increase trail, all other things being equal?

I would think anyone wanting to convert would use the yokes particular to the fork and just have a new stem machined to match the Norton steering head.
 
Danno said:
Matchless said:
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
Click to expand...

I can't see how you could use stock triples with inverted forks unless you machine them out or find a fork with 35mm upper legs, and you would still have to bore the taper out of the top yoke and somehow convert it to a pinch setup. And please explain how inverted forks would increase trail, all other things being equal?

I would think anyone wanting to convert would use the yokes particular to the fork and just have a new stem machined to match the Norton steering head.
Click to expand...

I think Matchless means 'standard yokes' as in those that are standard to the USD forks, not standard to Norton. Most modern yokes have very little offset. Carefull measuring and calculating must be undertaken before bolting on anything so different, in order to ensure no adverse effects on handling.
 
Old Scratcher said:
They look great! What are they off?
Click to expand...

The tubes are from a ZX9.
The hub is from a KZ750 with Bucannon spokes and an Excel rim.
The calipers are from a Honda.
The rotors are from a GSXR
The triple clamps, caliper adapters, rotor adapters and axle are whittled out by me.
It was basically what I had laying around at the time. Jim
 
Matchless said:
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
Click to expand...

The triple clamps have the same offset and angle as stock MK3 clamps. The trail is 3.9 in. The rear of the bike has been raised a few inches.
 
comnoz said:
Matchless said:
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
Click to expand...

The triple clamps have the same offset and angle as stock MK3 clamps. The trail is 3.9 in. The rear of the bike has been raised a few inches.
Click to expand...

did those few inches have anything to do with the front end mods? did those inches come just by going longer shocks?

while i'm at it, is the brake hdw (details pls) adapted to a stock swingarm?
 
84ok said:
comnoz said:
Matchless said:
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
Click to expand...

The triple clamps have the same offset and angle as stock MK3 clamps. The trail is 3.9 in. The rear of the bike has been raised a few inches.
Click to expand...

did those few inches have anything to do with the front end mods? did those inches come just by going longer shocks?

while i'm at it, is the brake hdw (details pls) adapted to a stock swingarm?
Click to expand...

I raised the rear end to reduce the trail and make it steer quicker. That plus I don't like dragging hard parts and prefer a tall motorcycle.
Generally speaking -I have always found a Norton handled better if it was raised.

The rear swingarm is stock MK3. The shocks are 14 inch and I run a tall tire.
The rear brake is a CNW rotor with a spot caliper bracket whittled out by me. Jim
 
Matchless said:
The one main problem I can see, is if you intend using the standard yokes. (triple trees) All these seem to have very little offset which if used with a 27 or 28 degree head angle would give a trail of well over 5" even if using a smaller front wheel. This would tend to make the steering rather leaden & floppy at slow speeds. I think Mr Comstock has made his own yokes with greater offset.
Click to expand...

i'd like to know how the usd few dealt with this?
 
ZX9, ZX6 & TL1000

All work quite nicely, I don't know the geometry numbers...

USD forks


USD forks


USD forks


ZX6 & ZX9 required very little modification to the yoke stem, TL required a new stem (from a pile I already had, no clue it's origin); used standard Norton steering bearings.

All required modified steering stops due to the tanks.

All used Dreer VR880 hubs; the TL had no more than 1/6" clearance between the caliper bodies and the spokes.
 
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