Flush and fill front forks


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Greenwinger
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Flush and fill front forks

Post by Greenwinger »



Hi all. Want to drain, flush and refill my front forks this spring. The seals are not leaking so it's just a flush and fill.
Was wondering what I can use to flush out the forks before refilling, and any recommendations as to what type fork oil. I realize I may start a new "Oil war" but hoping cooler minds will pervail :mrgreen: . Any suggestions would be greatly appreciated.

Thanks


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Re: Flush and fill front forks

Post by Rednaxs60 »

Good morning. Won't get into an oil war. You want to flush the front forks, take it you mean to do this to clean out all old oil and flush out any crud, and doing so without taking the fork apart.

Need a fluid, oil based, fill fork and put cap back on, shake the bejesus out of the fork tube, then drain, repeat a couple of times, then fill with the appropriate fork oil.

For my dollar, I'd take the fork apart, don't have to replace the bushings if these are in good shape - if not, still available from Honda. Clean the upper and lower fork components - only way to do a very good job. Buy a new oil seal and dust cap, put back together. Change the oil every 2 years max, and ride. $40.00 for an All Balls kit from FortNine - check Honda for pricing before going to FortNine.

While you have the fork springs out, check these. The OEM spring rate is approximately 0.98 kg/mm. The OEM springs are soft and really not up to the task. I'd replace these with a new fork spring, progressive or straight rate, of 1.1/1.2 kg/mm - preferably the 1.2 kg/mm. Sonic suspension straight rate spring - 1.2 kg/mm, $120.00 USD for a pair. Web site is: http://sonicsprings.com/catalog/product ... ucts_id=92

Just MHO.
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Re: Flush and fill front forks

Post by WingAdmin »

I used my old standby: brake cleaner to flush out my forks. It's an excellent solvent, dissolves even the nastiest gunk, and evaporates quickly leaving no residue.

I used probably one can for each fork until it flowed clean out the drain, then let them sit for a couple hours to make sure they were completely dry.

I then used Bel-Ray 10 weight fork oil for my 1500. I also tried 15 weight oil once, but the ride was far too firm. The 10 weight oil worked perfectly.
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Re: Flush and fill front forks

Post by DarthJ »

WingAdmin wrote: Wed Feb 23, 2022 11:14 am I used my old standby: brake cleaner to flush out my forks. It's an excellent solvent, dissolves even the nastiest gunk, and evaporates quickly leaving no residue.

I used probably one can for each fork until it flowed clean out the drain, then let them sit for a couple hours to make sure they were completely dry.

I then used Bel-Ray 10 weight fork oil for my 1500. I also tried 15 weight oil once, but the ride was far too firm. The 10 weight oil worked perfectly.
Did the same on mine, works the best and is easy to know when it's clean.
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Greenwinger
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Re: Flush and fill front forks

Post by Greenwinger »

Well thank you all for your response, even the big cheese himself. I guess the next questions is how much fluid in the forks. I replaced my front springs years ago with a pair of progressive springs from Progressive spring back when they were good quality. I will see if I can find the Bell Ray fork oil in my area.
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Re: Flush and fill front forks

Post by MikeB »

If you still have the installation instructions for the springs, you will see that they recommend 5.5 inches from the top of the tube.

If you do not have the instructions, look here: https://www.progressivesuspension.com/a ... Spring.pdf
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Re: Flush and fill front forks

Post by WingAdmin »

If you've never checked it out before, it's worthwhile going through our guide: How to change your fork oil which shows the entire process in detail.
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Re: Flush and fill front forks

Post by call-abe »

Can anyone tell me, after jacking the front of my 1990 Gold Wing GL1500A up to relieve the weight, whether I would STILL have a measure of pressure via the the springs to worry about as I unscrew the cap? Or is simply lifting the wheel and front fork up sufficient. (Not that I wouldn't be prepared for a potential bit of pressure as I unscrew things... I just want to know whether any special tools or precautions need to be taken...and whether this guy should really take it to a dealer in that case - or can do it himself).

Thanks for the insight that's not readily covered...
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Re: Flush and fill front forks

Post by WingAdmin »

call-abe wrote: Tue Mar 01, 2022 10:37 am Can anyone tell me, after jacking the front of my 1990 Gold Wing GL1500A up to relieve the weight, whether I would STILL have a measure of pressure via the the springs to worry about as I unscrew the cap? Or is simply lifting the wheel and front fork up sufficient. (Not that I wouldn't be prepared for a potential bit of pressure as I unscrew things... I just want to know whether any special tools or precautions need to be taken...and whether this guy should really take it to a dealer in that case - or can do it himself).

Thanks for the insight that's not readily covered...
YES!

There is enough spring pressure in there that when you remove the cap, once it gets to the last couple of threads, the spring can shove the cap out, shear off those remaining threads, and seriously injure you as the cap smacks you in the face.

Image

That's why the fork spring removal tool is used to remove and replace the cap.

Image

Some people make their own cap removal tools out of wood and threaded rods. Have a look through the How to rebuild your front forks article.
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