Commando front forks left stock have lots of room for improvement. The front end has only 4 ½ inches travel in stock commando form. If you check each end of the travel you will find a mechanical clang at each end. My bikes toped out real bad, and my friends bottomed real bad. To make matters worst you use up an inch or one and one half of the 4 1/2 when you sit on the bike.
We started to fix this by buying and installing the aluminum fork dampener tubes from British spares in NZ and installing “the Coventry kit”. They come with the oil flow holes in a new higher position so as to address the top out problem with a fluid stop. But “the kit” also added loose fitting bushings 1 ½ long between the steel bush and the top high hat bush.
What is more important is the over all travel. The threaded rod that supports the valve in the dampener tube down in the oil is the mechanical limit of the downward movement of the sliders. The clang you hear on top outs is the dampener valve hitting the alum. Cap on the dampener tube and it is held by a two mm dowel. This rod screws into the fork cap and is held in place with a lock nut.
It’s not a bad idea to increase the length of this rod by two inches so you get 6 inches of travel. We have done this with the use a kit with new aluminum rods that are two inches longer than stock. And adding Ford valve springs 2- 9/ 16 long one spring on each set up. We replace the old stock thick washer with four grade eight thin washers, two for in-between the new progressive springs and two under the reused jam nuts in-between the extra springs and jam nuts. If you have already installed the Coventry kit, you will need to remove the extra aluminum bushings that you installed with the kit. They limit travel and are no longer needed for top out dampening because you have put the valve that goes up and down in the tube on the end of the rod deeper into the oil. Now your getting 1 ½ more travel and the rod is two inches longer to keep the valve away from the cap on top outs. It may be found that if you have the more modern dampener tubes with the holes in the tapers they may work as is. Your steel dampener tubes can be changed buy blocking the holes at the taper on the bottom of the tube and re-drilling them so that the new hole is just on top of the taper. So now the bottom of the new hole is even with the top of the taper.
The new aluminum dampener tubes already come this way. I moved them when using the old steel tubes on another bike because the new tubes have the holes moved up off the taper. You can add holes smaller and higher yet to tune the fluid stop but this must be done for the rider’s weight. The aluminum dampener tubes have to use 8mm fine tread bolts to hold them in the bottom of the sliders and are not provided with the new tubes. So you need to buy them. We use a longer bolt that stock because the thread is in aluminum.
The thing we are after here is a more compliant working front ends with fluid stops at each end. Depending on rider weight I like to see at least 1 ½ inches of settling when the bike is sat on by the rider. We have been using ATF for fluid and the ride is very good. I have two Commando’s one with stock springs and one with Progressive’s I like them both but they are quite different. The stock springs preload the set up much higher this makes using the center stand a little unstable as it’s not quite tall enough for flat ground now. But having two inches for potholes and four inches for bumps is real good. We now make kits for this mod and they are 55.00 us dollars plus shipping. You get two new alum dampener rods. Two new ford valve springs, two new 2mm dowels and four new grade eight washers in the kit. Fine tuning the kit to your needs is your project. Pre- loads, springs, fluid types can all be played with for best results. Norbsa
