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post #1 of 39 (permalink) Old 04-21-2010, 02:54 PM Thread Starter
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Fork Oil

Fork oils are as follows:

Harley Type E is 5 wt
Harley Type B is 10 wt
Screaming Eagle is 15 wt
Screaming Eagle Heavy (racing) is 20 wt

By adding the spacers in the fork tubes, you increased preload, causing less dive.

Adding thicker oil slows compression damping, however, if it gets cold in your area, 20wt can be a little too heavy and start making a "knocking" noise in the front, on fast movement, or while going over bumps. As can 15wt....

Your results will vary.

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post #2 of 39 (permalink) Old 02-21-2014, 08:13 AM
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Mobil 1 Dexron ATF is equivalent to a 7.5w fork oil.

Shovelhead service manuals used to call for ATF in the forks.

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post #3 of 39 (permalink) Old 02-21-2014, 10:51 AM
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Originally Posted by Kainam View Post
Mobil 1 Dexron ATF is equivalent to a 7.5w fork oil.

Shovelhead service manuals used to call for ATF in the forks.
Is it safe to run ATF in modern forks???

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post #4 of 39 (permalink) Old 02-21-2014, 10:59 AM Thread Starter
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Originally Posted by XL1200R View Post
Is it safe to run ATF in modern forks???
Yes. Its light hydraulic oil. The red is so you know what it is.

In the 70s.....Suzuki used brake fluid as a replacement oil.

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post #5 of 39 (permalink) Old 02-21-2014, 11:08 AM
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Originally Posted by Dave63 View Post
Yes. Its light hydraulic oil. The red is so you know what it is.

In the 70s.....Suzuki used brake fluid as a replacement oil.

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I may use that when I put my new springs in...I kinda don't want 10 that is in there now nor do I want the stock 5wt...

Link to my Youtube channel. All riding videos. Enjoy.
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post #6 of 39 (permalink) Old 02-21-2014, 11:15 AM Thread Starter
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Originally Posted by XL1200R View Post
I may use that when I put my new springs in...I kinda don't want 10 that is in there now nor do I want the stock 5wt...
My advice is just avoid type-F as it lacks lubrication qualities over other atf types. I've never used it myself and although fork oil is overpriced for what it is, I'd rather hear from someone that has firsthand knowledge using it.......

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post #7 of 39 (permalink) Old 02-21-2014, 11:17 AM
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Originally Posted by XL1200R View Post
Is it safe to run ATF in modern forks???
HD Front telescopic suspension design hasn't change since ...... well, ever.
So yep, still safe to use in current front forks.


I'm getting ready to head over to a friends house to change up my front suspension.
FLST upper tubes (1.5" shorter than stock),
Progressive Monotube internals (lowered 2", for a total of -3.5" from stock).
I'll be using ATF for the fluid on reassembly.


Dave is right on not using Type-F, use Dexron.

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post #8 of 39 (permalink) Old 02-21-2014, 11:28 AM
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Quote:
Originally Posted by Kainam View Post
HD Front telescopic suspension design hasn't change since ...... well, ever.
So yep, still safe to use in current front forks.


I'm getting ready to head over to a friends house to change up my front suspension.
FLST upper tubes (1.5" shorter than stock),
Progressive Monotube internals (lowered 2", for a total of -3.5" from stock).
I'll be using ATF for the fluid on reassembly.


Dave is right on not using Type-F, use Dexron.
I should have figured that lol.

Just wasn't sure in regards to seals and stuff..

Link to my Youtube channel. All riding videos. Enjoy.
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post #9 of 39 (permalink) Old 02-21-2014, 11:53 AM Thread Starter
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Originally Posted by XL1200R View Post
I should have figured that lol.

Just wasn't sure in regards to seals and stuff..
ATF is seal friendly. No issues there. Very benign fluid.

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post #10 of 39 (permalink) Old 08-11-2014, 09:17 AM
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I have been running off the shelf Lucas hydraulic fluid this year. Put it in because it's very inexpensive and has good seal conditioner and anti-foaming additives. Cost me about $18 for a gallon jug of the stuff and I can use it in my floor jacks too. My gut feeling was it would be too slow. But, I've been pleasantly surprised, on the slower end of the damping scale but it performs well. I've ridden in temps down to the mid 50's and no issues with knocking.

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