I’m 175-185 lbs and 5’11”. I’ve been spending a lot of time suspension-tuning my Norton and I’ve finally started getting decent results.
I had opted for a Landsdowne fork damper cartridge system (inserts). This relatively expensive drop in option sells for around US $400 once you add shipping from the UK. It uses the standard Norton RoadHolder forks but changes the internal components to have some adjustability. Landsdowne utilizes the forks in an eccentric model; one has compression control, the other rebound. It also prefers linear wound springs, not more common progressive springs found on modified Nortons.
I experimented with the recommended setup using 150-160ml of 10W fork oil (Honda SS8 10W). However, regardless of adjustments, I found the 10W at maximum rebound control was very bouncy. I began to move my way up the viscosity densities. I change both fork’s oils to Motul 15W (EXP Med/Heavy 15W). Even at this viscosity and maximum setting, the fork rebound was still too bouncy.
From this point, I only changed oil on the rebound fork with a 20W (Maxima Heavy Weight “Harley”). Darn it, even if this too was not still not quite right. The bike continued with more bounce than needed even at maximum adjustment.
The compression characteristics were still ok in the left form with Motul 15W. I had the 50% of compression adjustability still available.
Essentially, this had become a chronic rebound problem. I started calling around to “guru’s” including RaceTech and TraxxionDynamics as well as others and doing a lot of my own oil viscosity research. I will not go into too much of that, suffice it to say weight density is not the only measure of the applicability when you are in this type of fine tuning and desperation.
Its all here:
http://mahonkin.com/~milktree/motorcycles/fork-oil.html
https://transmoto.com.au/comparative-oil-weights-table/
http://www.qemsc.com.au/documents/suspensionoils.pdf
I used the Viscosity Index (VI), where LOWER numbers are generally more suitable for control. Ironically, the VI information is nowhere to be found on any of the bottles just old school weights, which as we find are rather broad when you need to compare, etc. You have to do your research before you buy. So, this being my new measuring approach, here is what I had been using:
Honda (Showa) SS8 10W: 167-200 VI
Motul Med-Heavy Technosynthese 15W: 224-225 VI
Maxima Harley Davidson Heavy Weight 20W: 201-202 VI
So, to finally, make the bigger push I selected the BelRay High Performance 20W with 106-107 VI. And…. It worked just right! I now have my right fork’s compression setting at around 2 turns out from max using 20W (201VI) oil. My left compression fork left is filled with Motul’s 15W (224 VI) oil and 2.5 turns out from max. Maybe my ONLY point should be the BelRay works for me. Maybe my science is useless! However, through trail and error, I to this solution and thus far it is working the best - for me!
REAR (always impacts front and vice versa)
Since all suspension controls from front are related to the back, I’m using a pair of brand new Hagon 2810 shocks with slimline springs and rebound adjustability. The rebound on these are set with 8 turns out of maximum of 10, and do moderately well for the price. I wish they had compression adjustment but this option was more than twice the price. So, I think I’ve got best value for a street bike.
Pictures are here: https://1973nortoncommando850caferacer.shutterfly.com/
-->FJ
PS Let me add now, a fellow list member called me "The Dumbest Norton Owner On Earth". I agree with him. Point is dumb people exist on the planet, they buy things and experiment and now even share. PLEASE BE WARNED!
I had opted for a Landsdowne fork damper cartridge system (inserts). This relatively expensive drop in option sells for around US $400 once you add shipping from the UK. It uses the standard Norton RoadHolder forks but changes the internal components to have some adjustability. Landsdowne utilizes the forks in an eccentric model; one has compression control, the other rebound. It also prefers linear wound springs, not more common progressive springs found on modified Nortons.
I experimented with the recommended setup using 150-160ml of 10W fork oil (Honda SS8 10W). However, regardless of adjustments, I found the 10W at maximum rebound control was very bouncy. I began to move my way up the viscosity densities. I change both fork’s oils to Motul 15W (EXP Med/Heavy 15W). Even at this viscosity and maximum setting, the fork rebound was still too bouncy.
From this point, I only changed oil on the rebound fork with a 20W (Maxima Heavy Weight “Harley”). Darn it, even if this too was not still not quite right. The bike continued with more bounce than needed even at maximum adjustment.
The compression characteristics were still ok in the left form with Motul 15W. I had the 50% of compression adjustability still available.
Essentially, this had become a chronic rebound problem. I started calling around to “guru’s” including RaceTech and TraxxionDynamics as well as others and doing a lot of my own oil viscosity research. I will not go into too much of that, suffice it to say weight density is not the only measure of the applicability when you are in this type of fine tuning and desperation.
Its all here:
http://mahonkin.com/~milktree/motorcycles/fork-oil.html
https://transmoto.com.au/comparative-oil-weights-table/
http://www.qemsc.com.au/documents/suspensionoils.pdf
I used the Viscosity Index (VI), where LOWER numbers are generally more suitable for control. Ironically, the VI information is nowhere to be found on any of the bottles just old school weights, which as we find are rather broad when you need to compare, etc. You have to do your research before you buy. So, this being my new measuring approach, here is what I had been using:
Honda (Showa) SS8 10W: 167-200 VI
Motul Med-Heavy Technosynthese 15W: 224-225 VI
Maxima Harley Davidson Heavy Weight 20W: 201-202 VI
So, to finally, make the bigger push I selected the BelRay High Performance 20W with 106-107 VI. And…. It worked just right! I now have my right fork’s compression setting at around 2 turns out from max using 20W (201VI) oil. My left compression fork left is filled with Motul’s 15W (224 VI) oil and 2.5 turns out from max. Maybe my ONLY point should be the BelRay works for me. Maybe my science is useless! However, through trail and error, I to this solution and thus far it is working the best - for me!
REAR (always impacts front and vice versa)
Since all suspension controls from front are related to the back, I’m using a pair of brand new Hagon 2810 shocks with slimline springs and rebound adjustability. The rebound on these are set with 8 turns out of maximum of 10, and do moderately well for the price. I wish they had compression adjustment but this option was more than twice the price. So, I think I’ve got best value for a street bike.
Pictures are here: https://1973nortoncommando850caferacer.shutterfly.com/
-->FJ
PS Let me add now, a fellow list member called me "The Dumbest Norton Owner On Earth". I agree with him. Point is dumb people exist on the planet, they buy things and experiment and now even share. PLEASE BE WARNED!
