Do It Yourself: Front Suspension Repair - Replacing Progressive Spring


Since the last time we spoke I have managed to get a few miles on the Bandit 1200 and I’m really pleased so far with how it’s coming along. It’s fair to say the new rear shock and tyres have transformed the bike and it’s a lot more composed down my favourite bumpy lanes – although the front-end was very soft and dives heavily under braking. I did experiment with winding the pre-load in to its maximum adjustment which made a slight improvement but it was still too soft and warranted more work. So I have purchased a new pair of progressive springs from Hagon. So here’s a step-by-step guide to refreshing your suspension !



Before removing the forks from the bike you need to measure how much the fork leg protrudes through the top yoke then release the top yoke clamp and release the fork cap by half a turn as once the forks are out it will be very difficult to undo the cap.


So with the bike on its centrestand on the work bench it’s time to undo the pinch bolts for the wheel spindle, release the wheel spindle slightly, remove the front brake calipers and speedo cable.


The bike was then raised with a scissor jack so the front wheel could be removed. Remove the front wheel and mudguard including the fork brace.


With the wheel and mudguard out of the way you can now release the bolts on the bottom yoke and remove a fork leg.


Now the fork leg is out you can now remove the fork cap and wind this up the pre-load adjuster to gain access to the flats on the adjuster. From there you locate a spanner and release the locking nut on the damper rod so you can remove this from the damper rod to allow the removal of the spring. All very fiddly!


Make a note of the position of the locking nut ready for reassembly time.


With the cap now removed you can remove the spacers and spring (noting the order of the spacer, washer and retainer) tip the forks over an oil tray letting the spring down gently then allow all the oil to drain from the fork.


Once all the oil has drained out, give the fork stanchion a wipe, check your required air-gap which for the these forks with the Hagon springs is 160mm now you need to measure 160mm on the oil level gauge and lock it off.


Compress the forks and add fork oil (10w) until it registers on the gauge.


Now attach the tube from a brake bleeder or oil removal syphon to the oil level gauge. This will remove any excess oil and you know the air gap will be spot on in both legs.


The new spring can now be fitted (put the tighter wound coils at the top) add the washer, spacer and then the retainer over the spring. Now you can refit the preload adjuster/cap to the damper rod noting its previous position.


Loosely fit the fork cap back into the fork stanchion, then refit the fork leg to the bike, check how much the leg protrudes through the top yoke set to the required height before doing up the pinch bolts in the bottom yoke. You can now tighten up the fork cap before tightening the pinch bolt in the top yoke. Carry out this again to the other fork leg.


With both fork legs rebuilt and refitted you can now refit the mudguard, wheel, brake calipers and speedo cable, it’s also advisable to treat the wheel spindle and caliper bolts to a little copper grease as they are out. Make sure you have checked everything is tight and don’t forget to give the brakes a pump before you use the bike!



Just looking at the springs side by side (pic below) you can see the difference! With the bike off the ramp the front end felt instantly firmer, next day we had a bit of a ride out planned so I decided to use the Bandit and see how the bike felt. We used a variety of roads from bumpy B-roads to dual carriageways, around 30 miles in total.




We stopped and I reduced the preload on the forks as they felt a bit too harsh. After this adjustment the bike now feels about as good as you could get it without taking it to a suspension specialist. To date the upgrades have cost a little short of £400 which in my eyes is pretty good value as the bike handles well now for a big old bus and it’s all stuff you can do at home with the correct tools and spare time.

Next time we will be on the dyno getting power runs with the standard exhaust, a Micron race can, a full Akrapovic race system and then with a Dyno Jet kit and free-flow air filter fitted so we can see how much power you get for your hard-earned.