Fork Oil Questions

T_C

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I'm trying out the Bel Ray 7 wt. in my next fork oil change. Also will be switching to flat rate springs as a suspension upgrade, so I won't be able to compare the SS-8 that's in there now with the Bel Ray 7 wt.
When I dropped in Sponic Springs the 7wt was what was recommended by them. Works good so far and if I want to go a little lighter or heavier I can do that with the Belray easy enough. No mixing SS7/SS-8. Just buy the weight I want.
 

dduelin

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I don't see how that works given there's a limited space the spring occupies within the fork. If the spacer takes up more space there's less space for the spring. Doesn't adding preload close the distance between the coils in the spring? Take this to the extreme and the spring is totally compressed by the spacer and the fork travel is zero. In our real world with a fork spring that's close to the right rate for the application, preload would have little effect on the distance between the coils, but even adding a small amount of preload should reduce the space between the coils and therefore the distance the fork can compress.
Consult any suspension tuning guide and take it a piece at a time. Additional preload does not reduce travel if the spring rate is within the range acceptable for rider weight. Try this image: yes, adding to stock preload compresses the coils more but the top of the spring is now pressing up against the bottom of the fork cap which is now that much further from the end of the spring so the top of the fork is further from the ground. All that changed is ride height.

Whether you understand my attempts to explain it's true and if you choose the 1.0 and have too little sag you'll have to reduce preload to hit target sag. Within limits it's easier to add preload than shortening the spring.
 

MajorTom

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I don't really think dwalby, you and I are really disagreeing here, just talking about different cases, i.e. real-world application in your case versus theoretical, but not realistic limitations on my part. Thanks to both of you for your patience and careful explanations.

Anyway it's now irrelevant to my situation as I've managed to track down and order the 0.95 kg/mm Race Tech springs on the fortnine.ca website. As I have the Bel Ray 7 wt. oil on hand I'll start with that.
 

rogo

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Tried to procure fork oil today at cycle gear. Alas no 8 weight. They had 7 and 10. I like my suspension and don't want any surprises with handling. Any recommendations? The Honda shop where I got my bike is no longer in business. I miss my old parts counter.
 

T_C

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Tried to procure fork oil today at cycle gear. Alas no 8 weight. They had 7 and 10. I like my suspension and don't want any surprises with handling. Any recommendations? The Honda shop where I got my bike is no longer in business. I miss my old parts counter.
If you are looking for 8wt because you saw Hons a oil is SS-8, it isn't.

I'm using 7wt (Bel-Ray) but I also dropped in stiffer springs.

PS if you really want 8wt, buy the 7 and 10 and mix. You'll have 8.5 with mixing 1:1.
 
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rogo

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If you are looking for 8wt because you saw Hons a oil is SS-8, it isn't.

I'm using 7wt (Bel-Ray) but I also dropped in stiffer springs.
PS if you really want 8wt, buy the 7 and 10 and mix. You'll have 8.5 with mixing 1:1.
What is Honda SS-8? That is the only spec' I can find in the OEM service manual. Counter guy at formentioned "parts" counter couldn't help. I am staying with the factory setup.
 

rogo

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What is Honda SS-8? That is the only spec' I can find in the OEM service manual. Counter guy at formentioned "parts" counter couldn't help. I am staying with the factory setup.[/I was going to order on line and found it to be 10w. Going to pick up Delray 10w
 
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SS-8 is broadly equivalent to 10W oil. The reference I have states a viscosity of 39.7 cSt at 40C which is at the upper end of a typical 10W oil.
 
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Tom,
I'm tipping the scale at 230 these days, geared up prolly north of 245. I think Sonic is over springing the deal a good bit. $.02
 
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I tried the 2.1 sonic with 7 wt oil and found it way too harsh. I switch them out for the sonic 1.1 springs, 140 mm spacer, one washer, and 7 wt oil at 125 mm from the top. Perfect for my weight and riding style.
 
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I weigh about 190 dressed with gear and carry around about 20 lbs. of stuff in the bags. I change the fork oil about every 20k miles, fill to the level in the shop manual and run the stock springs. SS-8 or Belray 10w is what I always use. Can not tell any difference in the two. Belray is much less expensive.
 
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