I had Progressive 1" lower springs installed with stock oil/weight. The forks hold air and I run 5lbs. I would have installed the new Progressive 1" lower cartridge if they had been available at the time. The springs are fine, but considering install labor, I would just go all the way the first time if funds allowed.

 

To Hackd; Would you check out my post "1991 FLHS Fork springs" and see if you can help me? Thanx bro.

 

As others have said here, it's not a front fork "air suspension" system - but only an "anti-dive" system. The one on Bertha, my 1995 FLHTP, still works and I run about 8 lbs of air pressure in it. It's only active when you apply either the front or rear brake.

The air reservoir is in the engine guard on older Evos, or in the handlebars in newer Evos. Mine is in the handlebars, with the air fill Schrader valve on the end of the left handlebar under the left grip. Harley got rid of the anti-dive system in the twinkie touring bikes starting in 1999. The last of the Evo touring bikes may not have had it either, but I don't know exactly which year the MoCo got rid of it.

When you apply the brakes, the anti-dive solenoid energizes, trapping a small volume of the pressurized air inside the forks. When the solenoid closes, the much smaller volume of air actually in the forks cannot compress as much as the larger volume of air in the whole system. This helps the forks resist diving as the bike slows down and more weight is transferred to the front forks.

The anti-dive on Bertha appears to work as advertised, and I have never had the forks "bottom out" as many others in this forum have reported. I have thought about putting progressive springs in the forks, but since I don't have the bottoming-out issue, it doesn't seem to be necessary on Bertha.

Hope this helps.

 

The air does make a BIG difference in the ride. The "Book" gives different pressure limits than the original decals on the bike. I'm 215 and 12-15 front, 0-5 rear works very well for me and has for over 120,000 miles. Anything heavier than HD type "E" or ATF will not give good results if you use the factory air suspension. Unless you develop an air or oil leak, they are trouble free. And if you're thinking about converting one to air suspension, be very careful with the parts - the springs are different from non-air systems.

 

I run 16 front and 6-10 rear depending on the load ( Old Lady,Leather jackets etc.) I have a pump I bought when I got the bike.

 

i have a 90 fxrs-sp, the springs are longer than a standard fxrs, likes been said it's mainly an anti-dive feature. Mine still works and I love it. Replaced bars and fabbed up a bottle to take the place of the bars. When that goes south I'll be ditching the air forks. But think it's a good idea, I run only about 5 lbs. Always use a hand pump on the fork pressures or you'll have problems, don't ask me how I know, or you'll be relacing fork seals.

 

Ken,

The front air system is both suspension and anti-dive. The handlebars and forks together form an air reservoir that supplements the springs and provide a degree of adjustment for different loads. I use around 10psi solo and 15psi 2-up.

On applying the front brake the handlebars are isolated so only the air in the forks compresses as the forks dive, effectively stiffening the fork springing temporarily.

 

I dont know how old this quote is but i like it i just pulled all that off a 93 flhs that had been wrecked for two reasons it leaked and the road king nacelle would not fit over tha square block worked fine and i didnt even change the springs

 

I rebuilt my forks and replaced all the seals for the antidive system when I restored the old ultra I bought last year, J P cycles carries a seal kit for the antidive.

The more air you have in the front, the more affective the antidive is.

I run 15 in the front and 5-10 depending on the load.

 

Wow, just noticed how old this thread is, anyway, it still works.