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Progressive fork springs

W

wymple

Forum Sage
Past Site Supporter
1981 850G. The forks require air. If I bleed the air off the front sags a bunch, so much that the sidestand will tip the bike over to the right (I have lowered the rear 1-1/2 inches as well). The right side fork only holds air for a couple days and I see people recommending Progressive springs and using no air. If I buy the springs, do I need to add plugs to maintain the ride height with the air gone?
 
I don't know about adding plugs, some use PVC pipe and most here swear by Sonic brand springs (www.sonicsprings.com) and if using 20w you can go with no air. That's what I'll be doing.

Cartridge emulators are reccomended by some too, but I don't want to drill anything in my forks unless there's huge benefits personally.
 
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I have progressive springs in my forks. They are a little soft initially and firm up as they compress. I bought them about 12 or so years ago when they were "The Fix" for the leaky air assisted suspension. Most folks around here now recommend Sonic springs. The owner is a member here. I'll probably switch to Sonic in the near future.
 
wymple said:
1981 850G. The forks require air. If I bleed the air off the front sags a bunch, so much that the sidestand will tip the bike over to the right (I have lowered the rear 1-1/2 inches as well). The right side fork only holds air for a couple days and I see people recommending Progressive springs and using no air. If I buy the springs, do I need to add plugs to maintain the ride height with the air gone?
Click to expand...
Your springs obviously need some help or replacement. Progressive (brand) springs are definitely an improvement, but so are Sonic Springs. Many here feel that Sonic springs are better than Progressives because the air that is trapped in the fork tubes is also a progressive spring and the combination of the two increasing spring rates makes things a bit interesting. It is better to go with a straight-rate spring and let the air be the only progressive issue.

Removing 1 1/2 inches of height from the rear will definitely tend to make the bike stand up straighter on the side stand. My wife's bike just got new shocks on the rear that are 1 inch shorter, and we have lowered the front about 1 1/2 inches. No danger of tipping over (most of the time), but we do have to be more aware of which way the surface is tilted before parking the bike.

Why have you removed so much from the rear height? Is it for a "look" or just a "lack of inseam"? :-k
If it is for a "look", you might want to re-consider. The simple u-joint on the driveshaft is meant to run straight most of the time, with occasional deviations for suspension travel, of course. However, if you force it into a constant angle due to shorter shocks, it can accelerate wear in the u-joint and/or the splines in the wheel hub.



mikerophone said:
I don't know about adding plugs, some use PVC pipe and most here swear by Sonic brand springs (www.sonicsprings.com) and if using 20w you can go with no air.
Click to expand...
You can use "no air" regardless of your fork oil viscosity. There will always be air trapped inside the forks, the only difference is that you will not need to ADD any air.


mikerophone said:
Cartridge emulators are reccomended by some too, but I don't want to drill anything in my forks unless there's huge benefits personally.
Click to expand...
I have not (yet) installed emulators in my forks, but I have been told that the change is definitely worth it. The rather crude damping that is available in our forks is basically set up as a compromise between low-speed movement (dips in the road) and high-speed movement (potholes, etc.), and usually ends up not working well with either one. As I understand them, emulators have multiple damping passages, which allow different damping rates that are based on the speed of the impact. That makes for a more-consistent ride.
 
Any set of aftermarket springs will let you get rid of the air pressure, a good thing for a number of reasons.
Compared to a progressive wind, straight-rate springs do make a little better use of the available suspension travel and you can tailor the rate more closely to your weight and riding style. For lighter and/or slower riders there's not much real world difference, the bigger and faster you are the more you'll feel it.
 
I lowered the rear because I am only not quite 5'8 and the 850 gets top heavy real quick if I lean over a bit too far pushing it around. I also have a short inseam and like my feet on the ground when stopped. I will check out Sonic, maybe I can just plug what I have, the ride itself is OK and I'm certainly no corner carver.
 
mikerophone said:
I don't know about adding plugs, some use PVC pipe and most here swear by Sonic brand springs (www.sonicsprings.com) and if using 20w you can go with no air. That's what I'll be doing.

Cartridge emulators are reccomended by some too, but I don't want to drill anything in my forks unless there's huge benefits personally.
Click to expand...

Most use 10w not 20w and yes there are huge benefits with the emulators in my experience. :)
 
Todays finished fork spring upgrade...
Sonic springs , 10 weight fork oil , new seals ...
Excellent :cool:
 
I did have 30w it was new oil so just left it in when I installed the Sonics, way too stiff lol. The 30W as fine with the old stock springs but not the Sonics. Went with the 20W and so it has worked just fine for my application.
 
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