Hey all,

I've been digging around online for a while now and have read many an article on front suspensions but I'm not finding the answer I'm looking for, so I figured I'd try here.

I've got a 98 Wide Glide with +4 fork tubes and I'm curious what a good starting fork oil height might be.

From what I understand, as long as their is enough fork oil to cover the damper tube by a safe amount, additional oil does not directly affect the ride, but it does affect the volume of air in the fork which does affect the ride.

That said, it seems to me that I should add fork oil till I get the 4 to 5" measurement from the top of the tubes (forks compressed without spacers and springs). And not add 4" to the stock measurement to get 8-9" measurement from the top of the tubes.

Does that sound right?

 

Find the stock oil height prior to extending your forks. Add 4" to the empty space than measure ie: top of fork tube to oil level = (just say/example only) 110 mm. Add 4" to the 110 mm than suck out the rest.
Tool needed:

 

Thanks for the reply.

The problem is that I've never owned the bike with the stock length forks. They are however a stock diameter and use stock bushings, seals, etc. That said, it sounds like you're saying I should be able to use the recommended stock volume (height) of fork oil as a starting point in my +4" forks?

 

yes you can

 

Thanks again. I appreciate your advise. For some reason I was thinking you tune the forks by adjusting the volume of air over the oil. The more air, the more compressible the setup, in other words stock fluid height with extended tubes.

 

>>> That said, it sounds like you're saying I should be able to use the recommended stock volume (height) of fork oil as a starting point in my +4" forks?
<<< What I am saying is if you have 3" of air to your oil in a stock set up (you do not) and you add 4" to your forks, than you would have 3" + 4" of air.

Depending on what internals you have, back in the day when there were no aftermarket parts available (remember, this HD fork was first produced in 1948 and is just about the same product), we would weld up the holes and drill them out to a different size. Many times to see the changes. Drill ~ weld... you get the idea.

This was the only way to change the valving. Oil/air height plays no roll basically in valving. Now they have Race Tech cartridge emulators, Intimatiors, and a slew of products to change the characteristics of the forks.

 

...back in the day when there were no aftermarket parts available...we would weld up the holes and drill them out to a different size. Many times to see the changes. Drill ~ weld...[/quote]
Wow...sound like fun!

Thanks again for all your help...now and in the past. I wish I would have had the cash this past winter to just order an inverted / cartridge front end from you. I would have been much happier. Maybe I'll get to do that in a couple years.