6 Over Fork Tubes + PVC Pipe?

[lexlax]

Hello everyone,

I recently bought 6 over fork tubes and new progressive fork spring from mikesxs.
I have been doing research about how to put all this together.

So my question is do I put in 6 inches or 6.75 inches of PVC pipe on top of the springs and then the fork cap?

Also read that the progressive springs are a little longer than normal so maybe I dont need to add that much PVC pipe?

How much fork oil and what weight should I use since im using longer tubes?

Thanks for the help and any input would be great!

 

[jd750ace]

Um, how exactly is it someone gets that far into what you are doing and know so little about how to do it correctly? I'm not trying to be a dick, but just can't understand how you have so many parts already in hand and little information. This is the information age, and you did not research your setup before you laid your cash down?
In an attempt to be helpful, if the tube is six inches over length, add 6 inches to the recommended spacer length for starters. Same thing with the oil height. The distance from the top of the fully compressed tube down to the oil should be the same. Go with 10W fork oil. Not ATF, or mazola or 10W40, but real fork oil, sometimes referred to as suspension fluid to make it sound more technical. That will be enough to ride it and see how it works for you.
If you want to get technical about spacer length, put in the spring, 2 washers, and the pvc in the tube with it fully extended. Free hanging holding the slider is good. Mark the pvc at the top of the tube. If you cut it off there, the preload value is the distance from the cap flange to the lower face. If you want more preload than that, add it above the line on the pvc. If you want less, cut it downhill from the line the amount you want to add. Tocalculate a useful amount of preload, figure your full travel of the forks, and 35 percent of that travel is how far the fork should compress with you on the bike sitting upright.

 

[lexlax]

I did my research I'm just trying to clarify on certain things that I have been reading up on. Better to be safe than sorry, ask questions than no questions at all, and to do it right once than having to take it apart and do it again.

 

[jd750ace]

Well, you are experimenting with suspension and steering geometry, so I would not count on not having to take it back apart a time or two for it to get happy.

The added length won't influence anything but how it handles and how much the front flexes. As far as the internal workings of the fork, the same spring as a standard fork with the same preload and same oil weight and height will perform just about the same as well. The weight of oil affects how well it flows through the metering, and the spring effectively just supports the weight. The height of the oil in the tube will influence how plush or firm the front feels. Slightly higher oil level (less air space in the fork) will make it a little more firm over smaller bumps, and also decrease braking dive. Less oil (more air space in the fork) will make it more plush, but that can make for heavy brake dive, and wallowing of the front under braking. Nothing feels worse to me than a fork that wallows around and feels like it wants to be anywhere but directly in front of the stem when you are on the brakes.