HD Fork Oil Viscosity
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Seasoned HDF Member
Joined: Nov 2006
Posts: 5,889
Likes: 1,902
From: East Coast, USA
HD Fork Oil Viscosity
I've read through a number of different threads/posts on this forum and their seems to be conflicting information as to the viscosity of the HD fork oils. Some people claim: HD's fork oil
(E) is 5wt
(B) is 10wt
and other people have it the other way around:
(B) is 5wt
(E) is 10wt
Add to the fact, if you look at some of the information provided by various oil vendors, even they don't agree:
http://www.spectro-oils.com/wp-conte...Data-Chart.pdf
http://www.maximausa.com/wp-content/...4/06/vtwin.pdf
http://www.thunderpress.net/wp-conte...Chart_01-L.pdf
http://www.synthetic-lubricants.com/...20Fluid%20.pdf
Can anyone provide a clear and concise answer? At the very least, which is heavier, B or E?
(E) is 5wt
(B) is 10wt
and other people have it the other way around:
(B) is 5wt
(E) is 10wt
Add to the fact, if you look at some of the information provided by various oil vendors, even they don't agree:
http://www.spectro-oils.com/wp-conte...Data-Chart.pdf
http://www.maximausa.com/wp-content/...4/06/vtwin.pdf
http://www.thunderpress.net/wp-conte...Chart_01-L.pdf
http://www.synthetic-lubricants.com/...20Fluid%20.pdf
Can anyone provide a clear and concise answer? At the very least, which is heavier, B or E?
Extreme HDF Member
Joined: Jun 2011
Posts: 10,216
Likes: 224
From: Glendale AZ
Just like which oil to use in various 'holes', fork oil viscosity is also subjective. When it came time to do a flush on my RK, I put Bel-Ray 5w. it softened a very stiff front-end and I've been very happy.
Last edited by TUCCI; May 18, 2016 at 12:43 PM.
Intermediate
Joined: Apr 2006
Posts: 43
Likes: 1
From: Ontario, Can
I used SE heavy in my 13 ultra and found it to harsh at slow speed, so I changed it out to a 50/50 mixture of E and heavy and it's good now.
In my research I came up with these numbers,
E - 5wt
B - 10wt
SE heavy - 15wt
SE race - 20wt
In my research I came up with these numbers,
E - 5wt
B - 10wt
SE heavy - 15wt
SE race - 20wt
Road Warrior
Joined: Jul 2012
Posts: 1,566
Likes: 55
From: Londonderry, NH
I've read through a number of different threads/posts on this forum and their seems to be conflicting information as to the viscosity of the HD fork oils. Some people claim: HD's fork oil
(E) is 5wt
(B) is 10wt
and other people have it the other way around:
(B) is 5wt
(E) is 10wt
Add to the fact, if you look at some of the information provided by various oil vendors, even they don't agree:
http://www.spectro-oils.com/wp-conte...Data-Chart.pdf
http://www.maximausa.com/wp-content/...4/06/vtwin.pdf
http://www.thunderpress.net/wp-conte...Chart_01-L.pdf
http://www.synthetic-lubricants.com/...20Fluid%20.pdf
Can anyone provide a clear and concise answer? At the very least, which is heavier, B or E?
(E) is 5wt
(B) is 10wt
and other people have it the other way around:
(B) is 5wt
(E) is 10wt
Add to the fact, if you look at some of the information provided by various oil vendors, even they don't agree:
http://www.spectro-oils.com/wp-conte...Data-Chart.pdf
http://www.maximausa.com/wp-content/...4/06/vtwin.pdf
http://www.thunderpress.net/wp-conte...Chart_01-L.pdf
http://www.synthetic-lubricants.com/...20Fluid%20.pdf
Can anyone provide a clear and concise answer? At the very least, which is heavier, B or E?
I had the same problem...it's hard to define what HD fork oil actually is.
I recently changed the fork oil in my 2005 FLHSTN (Deluxe) and used Bel-Ray 15W. Ride quality is good and brake dive is improved, so I assume HD Type E is lighter. I'll be doing the same for my Road King Classic soon.
From my research Viscosity Index is a better measure for comparison...and that may be what Spectro, Belray and others are using for their comparisons. Fork Oil Weight varies wildly.
I prefer to use a supplier that rates their fork oil. If I don't like the characteristics, I can go up or down accordingly.
Extreme HDF Member
Joined: Jun 2011
Posts: 10,216
Likes: 224
From: Glendale AZ
I had the same problem...it's hard to define what HD fork oil actually is.
I recently changed the fork oil in my 2005 FLHSTN (Deluxe) and used Bel-Ray 15W. Ride quality is good and brake dive is improved, so I assume HD Type E is lighter. I'll be doing the same for my Road King Classic soon.
From my research Viscosity Index is a better measure for comparison...and that may be what Spectro, Belray and others are using for their comparisons. Fork Oil Weight varies wildly.
I prefer to use a supplier that rates their fork oil. If I don't like the characteristics, I can go up or down accordingly.
I recently changed the fork oil in my 2005 FLHSTN (Deluxe) and used Bel-Ray 15W. Ride quality is good and brake dive is improved, so I assume HD Type E is lighter. I'll be doing the same for my Road King Classic soon.
From my research Viscosity Index is a better measure for comparison...and that may be what Spectro, Belray and others are using for their comparisons. Fork Oil Weight varies wildly.
I prefer to use a supplier that rates their fork oil. If I don't like the characteristics, I can go up or down accordingly.
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Seasoned HDF Member
Joined: Jan 2013
Posts: 10,637
Likes: 1,246
From: Lake, Ms
A little over a year ago I changed mine to 15wt Spectro fork oil. The ride was stiff and harsh. I ran it for a while to see if it may break down and soften up but it never did. Changed it out to the Spectro 10wt and I'm completely satisfied with the feel now. Absorbs the bad bumps the way it should now.
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Ultimate HDF Member
Joined: Feb 2010
Posts: 8,039
Likes: 1,305
From: Jayhawk Country
That can be attributed to using too much front brake when coming to a stop. It took a little practice for me but I found if I use the rear brake to complete the top the nose dive is non existent.
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