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Fork Oil

7956 Views 15 Replies 6 Participants Last post by  67Duce
So I am convinced that when the dealer did my Monotubes they put to much oil in the tubes, this is based on feedback I got from Progressive. I am wondering if I can open up the bottom 6mm bolt on the fork and just drain some oil and go for a test run to see if it is any better.
I would go to the dealer but really don't expect them to be honest with me and I have already decided I will never take the bike back to them. I had some other work done by them the same time I did the Monotubes and they did something just a little wrong on every project I had them do.

Anyway is it possible to drain so oil from the bottom of the fork?
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The answer is yes. But without knowing the amount of oil that's in the fork, you run the risk of removing too much. They should have put 5 ounces in. If you remove too much, you would have to remove the fairing to get to the cap which will be spring loaded to add more. The caps on the fork tubes are replaced with progressive caps which allowed filling without the spring release. This is much better understood if you google the installation on a you tube video. I just installed monotubes on my Ultra and realized that to change the oil I have to take the fork tubes completely off the bike.
Thanx Lambo

As I understand it you should not have to change that oil with the Monotubes, however the Monotubes have a service life anyway...

I plan to let a little out at a time and test ride the bike, it is going to be a pain but at least I will know without getting to deep into it and not having any cost. Cause if I am going to go theough the trouble of taking the front end apart, I am going to have a new set of Monotubes sitting next to me.

I was just a bit worried about things spinning around while trying to loosen that bolt or trying to tighten it.

Does the oil come out fast or do you think it would be dripping out?
The oil in the tubes is merely for lubricating the metal parts inside, nothing to do with the shock absorber function. I think it would be safe to drain an ounce or so out just to see if the forks feel different when riding.
Get the front wheel off the ground to extend the forks, there isn't any pressure in the fork tube so the oil should dribble out slowly. Do one side at a time.
Thanx, gonna try this and see what happens.
The oil in the tubes is merely for lubricating the metal parts inside, nothing to do with the shock absorber function. I think it would be safe to drain an ounce or so out just to see if the forks feel different when riding.
Get the front wheel off the ground to extend the forks, there isn't any pressure in the fork tube so the oil should dribble out slowly. Do one side at a time.
Schmidty, -- is that true for conventional (Road King) forks as well? I was under the impression that different weight oil changes the dampening characteristics. I'm not familiar with Monotubes, though. I really would like to know a little more about the differences, if you could explain a little bit. Thanks.

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The montubes are self contained shock absorbers that fit inside the forks replacing the stock parts. They are sealed units that are pre-oiled.
The stock Road King forks use dampers and oil that turns the whole fork into a shock absorber. Depending on what weight oil you put into the stock forks determines how fast the shock functions.
Schmidty, -- is that true for conventional (Road King) forks as well? I was under the impression that different weight oil changes the dampening characteristics. I'm not familiar with Monotubes, though. I really would like to know a little more about the differences, if you could explain a little bit. Thanks.

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Not Schmidty, but:

With suspension, the spring does the real work in terms of "suspending" the drive system. But, we all know how springs behave. They tend to return to rest VERY quickly when allowed to. So, you have to "dampen" their enertial energy in some way. Otherwise, think pogo stick.

There are a lot of ways to do this. The stock system uses a dampening rod system. This rod has a top with a rubber seal that fits in the fork tube almost like the inner plunger of a syringe fits in the outer barrel.

There are passages in the system that allow oil to pass from one side to the other. So, when the spring compresses, oil is forced out through those passages. This slows the compression of the spring. When the spring returns, the oil is "sucked" back, thus slowing the recoil of the spring and dampening the suspension.

The heavier the oil in the shock, the slower it will pass through those passages. Thus, the suspension stiffens up.

Monotubes are sealed, gas-charged shocks similar to an automotive shock or high-end rear shock. They work in similar way, but the oil is sealed inside the shock. The gas is in there just to keep the oil from foaming.
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Thanx Lambo

I was just a bit worried about things spinning around while trying to loosen that bolt or trying to tighten it.
Joe, don't take out the 6mm screw in the bottom, there are drain plugs on each side in the lower back of the shock. Nothing will spin around.
Yeah funny you mention that, I just watched a really good video on youtube.

But I need to see if I have those, because I have the Arlen Ness Hot Leg fork lowers. Bike is home, so this will probably drive me nuts till I get home to check....
Great explanations, Schmidty and Chas! Thanks

Which one is preferred? I'm a fairly conservative rider. More interested in a smoother ride.

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Great explanations, Schmidty and Chas! Thanks

Which one is preferred? I'm a fairly conservative rider. More interested in a smoother ride.

--


Sent from Motorcycle.com App
I replaced the front with monotubes and the rear with Progressive 430's.. Like riding an entirely different bike, handles to perfection and the ride is very smooth.
Draining the oil did nothing, I am doing the Ohlin's!
Though most associate shocks / dampers with good ride characteristics there main function is to keep the tires in contact with the road by controlling the springs as Chasarms explained.

If you have ever been rolling down the road and noticed a car with the rear tire bouncing like a basketball the shock / strut is gone and it's only in contact with the roadway some times.
Though most associate shocks / dampers with good ride characteristics there main function is to keep the tires in contact with the road by controlling the springs as Chasarms explained.

If you have ever been rolling down the road and noticed a car with the rear tire bouncing like a basketball the shock / strut is gone and it's only in contact with the roadway some times.
I think what you were trying say was try the Ohlin's and Rory back here to let us know what you think?
I think what you were trying say was try the Ohlin's and Rory back here to let us know what you think?
That too :)
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