Classic Motorcycle Build

Front Forks Overhaul Norton Commando

After disassembly and inspection, with all parts clean and accounted for, it's time to re-assemble the forks on the 1974 Commando Roadster.

fork assembly sequence Norton Commando

Click Here for Commando Fork Tube Removal

Click Here for Front Fork Disassembly

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Fork Damper Assembly

Below, left to right - damper rod with roll pin, fork damper valve, valve seat, and 3/8" UNF nut. If any of these show signs of wear, replace them.

fork damper rod valve and seat assembly sequence

With the damper rod mounted in soft jaw pads, re-install roll pin, damper valve, valve seat, and nut to bottom end of damper rod.

Norton Commando fork assembly sequence

Wrench size on damper rod nut is 9/16".

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With a Phillips screwdriver in workbench vice holding the damper tube, insert rod into tube.

Norton Commando front fork overhaul

The damper tube cap can now be installed and tightened with a 1/2" wrench.

Norton Commando damper tube cap

Damper Tube Cap

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Install Springs Now or Later?

At this point, there are two ways to proceed. The factory manual specifies installing the spring over the damper rod, then installing into the slider. Trouble is, when it comes time to add fork oil, the process will be long and slow due to the fork spring being in the way.

The alternative method is leave the springs out until later. Once the fork assemblies are back on the bike, oil will pour easily into the tubes.

DIY fork spring tool

To install the spring, the damper rod can be retrieved with a T-handled threaded rod with 3/8 UNF female coupler on the end.

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Upper Bushing Fit

The Commando restorer has a choice of upper fork bushings; original style Oilite or new technology low-friction plastic. For this 1974 Roadster, we're staying with original style Oilte bushings.

best fork bushings for Norton Commando

The upper bushings need to slide freely up and down on the stanchions, but due to variances in manufacturing, they don't always fit right.

Too tight a fit will cause binding when the forks are rebounding. Some techs refer to this as 'stiction'.

Here's an easy test for bushing fitment:

'Drop-Down' Test

Norton Roadholder front forks overhaul

While holding the stanchion upright, the bronze bearing should slide down from top to bottom with no friction.

replacement fork tubes Commando

One of the new bushings was a little too tight.

1974 Norton Commando restoration

Using a Digital Caliper, the measured difference in I.D. between these two bushings was .013". That little bit was enough to cause problems in fitment.

measure bushing inside diameter with digital micrometer

The solution was to hand-sand the ID of the new bushing with a piece of medium Emory cloth until correct fitment was obtained.

NOTE: Oilite bushings are a bronze material that retains oil within it's surface. Caution should be exercised here, as grinding may cause bushings to lose their self-lubricating properties. However, by hand-sanding, there isn't enough heat generated for this to realistically happen.

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Install Lower Bushing on Stanchion

The lower bushing is made from steel. Install it onto stanchion, making sure it rotates freely.

Norton Commando fork overhaul

It's held on by a clip, which can be installed with help from a flat-blade screwdriver.

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On this Commando fork overhaul, we'll be installing the springs later. So the next step was installing the damper rod assembly into the slider.

replace fork tubes Commando

Place damper rod assembly into slider. Install 5/16" bolt with washer into bottom of slider.

medium strength thread sealer on bolt threads

I added a few drops of blue (medium strength) Loctite to the bolt threads. Not only does this help lock it in place, it will help prevent leakage as well.

Install oil drain screw with fibre washer on bottom of slider.

Norton Commando Roadholder fork overhaul

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Lower Fork Bushing

Place fork leg upright and install new stanchion, with lower bushing attached, into slider.

Norton Commando fork assembly sequence

The lower bushing should fit smoothly into it's recess. If it doesn't, find out why.

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Upper Fork Bushing

Slide upper bushing onto stanchion.

install fork bushings Norton Commando

Tap with a drift and hammer until completely into recess.

Norton Commando fork assembly sequence

TIP: When tapping in the bushing, listen to sound of the hammer hitting the bushing. When completely in, the tone will change from a "clink" to a "clunk".

replace fork bushings Norton Commando

Drift and Lightweight hammer.

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Fork Seals and Washers

Before installing the new fork seal, the thin paper washer goes in first. It sits on top of the upper bushing.

Norton Commando replace fork seals

Fork seals are installed with the open part facing downward.

The new seal was lightly coated with fork oil before sliding over stanchion. If you don't have a seal driver, they can be tapped in lightly with drift and light hammer.

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Fork Seal Collar

Before threading in the top collar, apply some light grease to the threads.

Commando fork collar removal

Cannon plug pliers were used to install collars. A strap wrench can also be used.

fork assembly sequence Norton Commando

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Short vs Long Gaiters

The purpose of 'accordion' rubber fork gaiters is to protect the bare stanchions from dirt, dust, rocks, and other harmful debris.

Norton Commando front fork rebuild

Most U.S. bound bikes were factory-fitted with short gaiters that offer no protection.

Norton Commando build

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Re-Install Fork Assemblies on Bike

Fork assemblies install from the bottom triple tree. The tops of the tubes are tapered, as are the inside of the brackets they slide into.

replace headlamp brackets Commando

Don't forget the headlamp brackets and O-rings!

Loosening and tightening the pinch bolts is made easy with a 5/16" T-handle Allen wrench.

Norton Commando fork overhaul

Fork Oil Weight

Most motorcycle manufacturers recommend 20 weight fork oil for average conditions. For extreme conditions, use 10 weight (cold weather) or 30 weight (warm weather).

best motorcycle fork oil

All Commando models require 150cc (5 fluid ounces) of fork oil per leg.

Add Fork Oil

Norton Commando add fork oil

With fork springs not yet installed, oil can be poured easily into the tubes.

Norton Commando build

Next, place fork spring into tubes, then thread the T-handle rod onto top of damper rod and pull up.

Install gauge cups, washers, nuts, thick washers, and top nuts.

install front wheel Norton Commando

Once the fork tube assemblies are back on, you'll need to adjust them to get them square with each other. Re-check fit and alignment before tightening everything up.

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Parts Diagram

If you get confused about what parts go where, Andover Norton has a large exploded diagram of Commando front forks on their website. To see it click here.

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Related Articles:

Remove Fork Tubes
Front Fork Disassembly
Commando Brake Caliper Overhaul
DIY Motorcycle Tools
Norton Commando Project - Homepage
Norton Commando Upgrades
measure bushing inside diameter with digital micrometer

Read: Digital Caliper Review