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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
I expect that you are at least half Candian. They like to up catsup on every thing. Kinda like your 20W. Without talking about the for type, it's pretty much the same. Many stock HD forks work OK with 20w but not all.
Multi viscosity might be good but it's harder to define it for hydraulic oils. It's good to find an oil that changes viscosity the least but even multi viscosity oils for motors change viscosity. The thing is you don't notice it in a motor.
Multi viscosity oils work over a 200 degree range, where fork oils are typically less 80 degrees (F).
While Cavitation can be an issue, aeration what make the oil foam up. Cavitation is more like detonation in a motor..
As Ed says don't use motor oil in the forks. If anything use ATF.
I expect that you are at least half Candian. They like to up catsup on every thing. Kinda like your 20W. Without talking about the for type, it's pretty much the same. Many stock HD forks work OK with 20w but not all.
Multi viscosity might be good but it's harder to define it for hydraulic oils. It's good to find an oil that changes viscosity the least but even multi viscosity oils for motors change viscosity. The thing is you don't notice it in a motor.
Multi viscosity oils work over a 200 degree range, where fork oils are typically less 80 degrees (F).
While Cavitation can be an issue, aeration what make the oil foam up. Cavitation is more like detonation in a motor..
As Ed says don't use motor oil in the forks. If anything use ATF.
Not Canadian but do love catsup.. lol... especially on scrambled eggs.. Any ways Never really though about fork oil as Hydraulic oil.. But yes that's exactly what it is.. Did a little research and am finding that Spectro makes for Harley and BelRay makes for Drag Specialties and Amsoil well is Amsoil. What I did find is that the viscosity ratings of one brand of 10 weight is not the same as other brands of 10 weight. So maybe one should know the viscosity rating and not just go by brand.. For example an Amsoil 10 weight is 7.3@100* where as the Spectro/Harley 10 weight is 5.51@100* but the Amsoil 10 weight is very close to the Spectro/Harley @ 7.95@100*. Still looking for the BelRay/Drag specialties data sheets.
The last forks I changed out were on a 2018 FLTRX, I used the the HD Type E oil and was happy with the results. In the past I used ATF on other bikes, and was happy with that too. Having used the SE Heavy Duty on earlier touring bikes, I thought the front felt too harsh in the winter. It seemed like I felt every minor bump in the road.
Servicing the front forks on late model HD touring bikes is different than previous models. On the earlier models, HD included fork drain screws and the ability to refill from the top without actually disassembling the forks. On the later touring bikes, 2017 ^ there are no drain screws, and the top fork cap must be removed to refill, which releases the fork springs. So in my experience, a quick oil change isn't an option if you end up not liking the oil viscosity. Hopefully someone out there has figured out a nice way to accomplish without disassembling the forks, but I haven't.
Not Canadian but do love catsup.. lol... especially on scrambled eggs.. Any ways Never really though about fork oil as Hydraulic oil.. But yes that's exactly what it is.. Did a little research and am finding that Spectro makes for Harley and BelRay makes for Drag Specialties and Amsoil well is Amsoil. What I did find is that the viscosity ratings of one brand of 10 weight is not the same as other brands of 10 weight. So maybe one should know the viscosity rating and not just go by brand.. For example an Amsoil 10 weight is 7.3@100* where as the Spectro/Harley 10 weight is 5.51@100* but the Amsoil 10 weight is very close to the Spectro/Harley @ 7.95@100*. Still looking for the BelRay/Drag specialties data sheets.
I was going to post this link but missed it.. FWIW I would use the 40 degree C centistokes for reference instead of the 100 degree C. Oil temps in the forks don't get that hot. 40C is 104F Notice that it's sorted by the 40 degree column.
I believe for the Touring models they stopped putting drain plugs on in 2014. I know the 2017 on do not have them. And while some people have suggested just drilling a hole, the top cap nut does not have a hole to refill through like the 2013 and earlier models. taking the top cap nut our releases the spring, with some force. Not sure on Softail and others.
Before you take the forks apart, look at the instructions in the manual, they require a special clamp to compress the spring when reassembling. And I can tell you from experience I was not able to just push the top cap nut in place and start the threads, there was simply too much spring pressure. But in a pinch, I was able to clamp the tube in the lower tree and use a piece of all thread, a large washer against the top tree and an all thread nut to push the fork tube cap nut into the tube and start the threads. It's not elegant but simpler than it sounds, cheap and worked for me in a pinch.
The allthread nut goes in the fork cap nut to both keep the allthread in place, and allow you to turn the cap nut to start the threads once it's in the tube. See the pictures below and a little imagination and hopefully that makes sense.
Seeing that I don't have drains on my fork lowers and all time doing is changing out the Springs, going to Progressives, I'm just gonna suck it out with a mighty vac get all I can and measure what I take out and go from there... I really didn't feel like taking the whole thing apart Just to do new Springs in oil change. Anyone know how many ounces in a 49 mm 2013 FXDB? Thanks..
It's no wonder these front suspension sucks so bad...... I never seen such a short Spring in all my life and look at the size of that plug holy ****.... Like I was asking before about fluid levels not sure how much these 49 mm tube take... I don't have a manual but the fork oil is at a level that is only 9" from the top of the tube... Is this normal.?? I'l measure what I take out but it seems like a lot... I am used to anything from 10.5 to 12 oz a leg but that's the older 41 mm suspensions.. check out the pics.. Holy ****... Anything would be an improvement...
Oh and one more Thing I forgot to mention was the fork oil that's in this is like ****ing water... Now I see why these ride like ****....
Last edited by 98hotrodfatboy; Mar 19, 2021 at 05:06 PM.
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