GS850 79-80 model forks mod

[Guest]

Hi all,

I'm looking to upgrade my air forks on my GS850. Are there any other models that will fit, that are better or will I have to carry out a rebuild?

Pete

[Steve]

The best way to upgrade your air forks is to remove the stock springs and replace them with Sonic Springs.

Their rate calculator seems to be not in working order, so give us an idea of your gravitational attraction and riding style, we can help you make a choice. I have a frame-mounted fairing on my 850 and have a gravitational attraction of about 16 stone, so I chose the 1.1 rate. With a lighter rider and no fairing, the 1.0 will likely be good. Install the new springs, then add the appropriate quantity of 10w fork oil and enjoy the ride.

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[peterd123]

Thanks for this. Is it just a matter of draining old oil and tipping out old spring, then replace with this spring and new oil?
Or is there anything else that I will have to do to add these springs?

Pete

[Steve]

If your seals are in good shape, yes, you could get by with simply swapping springs and oil. However, the question is "how good are your seals?" Just because you don't see any leakage does not mean they are good. If you don't know the history of the bike, it's entirely possible that the seals are worn, all the oil is gone, and there is simply nothing left to leak out, giving you the impression that the seals are good. One clue would be to measure how much oil comes out the drain hole. If you get nearly what it specified, your seals are likely OK. If you don't get much, plan on replacing the seals. My philosophy has been to compare how much extra it costs vs. how much it will cost to do the job over and include the extra item. In this case, the seals are not that much, and replacing them involves removing the entire front end (again) to do the job.

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[Rob S.]

In this case, the seals are not that much, and replacing them involves removing the entire front end (again) to do the job.

That's what I've always heard, particularly if you're doing the work yourself. The seals are practically pennies, why not replace them every time you're in there?

Am I wrong/oversimplifying?

[Wingsconsin]

In my experience it is better to do the entire rebuild -
Oil - Springs - Seals & dust seals - Slider bushings -
While you are in there it is simple work - the tutorials you can find are really helpful
And you will learn a bunch about your bike -

Pay attention to the seals - there is an UP & DOWN -- it does make a difference --I know because I got to do mine twice -