Does anyone know the factory weight of the fork oil? I am going to change mine to help stiffen the front forks. I went to the local independent and the had 5w, 10w and 20w. I dont know what stock oil is so I dont know what to go with.

 

I believe factory uses type E or 5W.

 

Mine has 20wt, but at times it feels almost too rigid, unless I hit some real rough spots. I'd like a little more fork action. At times it feels like the tire is the only front suspension I have. I'm after more of a "Cadillac" ride. Not sure if it's the springs or the oil.

 

I went from stock (not sure what it is) to heavy at my 20K service. I'm a pretty big guy (275 lbs) and the heavy really improved the ride and drastically reduced how often I bottom out the front forks. I was really happy making the switch.

 

Unlike motor and gear oils the weight of suspension oils don't match up from one brand to another. With that in mind, Harley type 'E' comes in a roughly a 10w on a standard viscosity scale. Harley Screamin' Eagle Heavy is roughly 15w and the Screamin' Eagle Extra Heavy roughly 20w. Like Goldilocks said, "One is too soft, one is too hard and one is just right"

While you at it, look into Progressive HD fork springs. These springs plus the Harley Screamin' Eagle Heavy makes for a very nice bit guy ride.

 

The independents is silkolene. I dont think that I need 20w, that may be too much so maybe a 15w. I am 190 but the front end compresses way too much on the brakes.

 

I run SE Heavy which is about 15w on both my previous Fatboy and my RG. Remember that oil controls the dampening wont make much difference on the amount of dive you are experencing under braking that is related to preload and spring compression. Changing the oil will help a litle as it will slow down the action of the forks.

if your interested in a better spring i have a set of stock lenght Progressive springs for sale that werr used in a 05 Fatboy for about a 1000 miles and then changed when I lowered it 2". They are for sale for $ 40.00 plus 6 shipping

 

How big of a difference did they make? How hard are they to install?

 

Running the same. SE Heavy. It did cure my dive while braking and hitting bumps too.

 

I asked this question last year and never got a definitive answer, except that it varies from brand to brand. I ended up going with Bel-Ray 30wt.
https://www.hdforums.com/forum/frame...fferences.html