Front Springs- Taper Up or Down?

[Andrew Shadow]

My brother-in-law has a 2007 ST 1300. He is changing the fork oil. Whil he was at it he decided to remove the springs to check and measure them. He has an old 2003 shop manual which states that the springs are installed with the tapered end facing up. When he removed the springs they came out with the tapered end facing down. He bought the bike used so he does not know if anyone has played with the forks before. He wants to know if the springs are supposed to be installed with the tapered end facing up as the 2003 shop manual states or has there been a change between 2003 and 2007 and they are supposed to be installed with the tapered end facing down as they were. He is also planning to use # 10 weight fork oil which seems to be a popular choice here.

Thanks in advance for any input.

 

[Scooter]

I only have the 2003 manual only so I'm no help with that aspect. I shouldn't matter which way they go in as long as both are oriented in the same direction and even that might not really matter. The forces are going to be acting on both ends of the spring simultaneously. For more reading material see this thread...

 

[kevh]

I've literally just finished installing Hagon fork springs in my 2009 Pan. The original Honda springs were installed with the tighter coils at the bottom. Thats what my Haynes manual states as well, it covers years 2002 to 2011.
Regarding fork oil, 10wt is what Honda recommend.

 

[dduelin]

Fork oil is very light and light oils do not measure well at all using the description of "weight". There are many 10wt fork oils on the shelf that are much thinner or thicker than the Showa SS8 "10 wt" oil that Honda both installed at the factory and recommends in the service manual. The only 10wt oil that you can sure of that acts the same as the OEM oil is replacing it with an oil that has the same centistoke numbers as Honda SS8 fork fluid. I replaced mine the first time with Bel Ray 10wt and the forks were much harsher. I almost immediately replaced it with Honda SS8 to get it right again. Later on when I learned about the problems using weight to describe light oils I came across a table comparing common fork oils by centistoke and it showed Bel Ray 10wt with significantly higher centistoke values meaning the oil acted "thicker" at normal ambient temperatures. There are 5 wt oils that are thicker than 10 wt oils and 10 wt oils that act like other brand 5 wt oils. Stick with Honda SS8 if you want the same "10 weight" action.

I think the spring taper has more to do with noise the spring may make inside the fork than anything else. In a very light bike the taper might make a difference in unsprung weight because the tighter coils become coilbound first and contribute sprung weight if the taper is upper and unsprung weight if the taper is lowermost. The ST is so heavy this is of minute consequence.

 

[CBR 46]

manual says tapered end up

 

[RaYzerman]

Usually you go with what the manual or the instructions say.... the taper has to do mostly with what it seats/rests on, so it doesn't slip over the washer/cartridge/damping rod/whatever you have. On mine, tapered end is subtle, but must be down because it seats on a washer affair, the bigger end would slip over. It does not matter up or down for spring rate/compression.

 

[LetErBuck]

It really makes no difference. Racers will install with the taper up as it is less unsprung weight down low where you don't want it.