Tuning the progressive springs.

[Freebird]

Progressive is the brand name. You can find them a lot of places.

[Flyinfool]

 

And as for the oil weight and amount to add, that is part of the tuning the front suspension to your preferences and riding style. That is what I am going thru now. Tweaking to get it to feel the way I want it to feel.

 

Since I never rode a new bike I do not know what it is "supposed" to feel like, Others ride much more aggressively than I do so they may want a slightly different setup, same as others that ride less aggressively than me will also want a different setup. It also matters what kind of roads you have. Wisconsin has the 2nd worst roads in the country. Connecticut is the worst. What I call smooth roads is what others call off roading. In fact there are dirt logging roads that are better than some of our highways.

 

So I do not think there is any one right answer as to how to set up the front end.

[CaseyJ955]

I've read everything on fluid levels from 5.5" to 6", I see the inlay that came with the springs says 5.5" so thats what I'm going with. Unless I'm way off here I dont think the amount of fluid will change fork behavior unless its full enough to blow through the seals or too low to offer damping through it's full travel range.

 

Since I had progressives in it before I started I'm guessing the horribly cupped/feathered tire and shot neck bearings were responsible for the crappy ride. I cant see how to post in classifieds but if anyone here has a parts bike or any bits/pieces laying around I really could use the fork air line that supplies the left air collar, it looks like a knuckle buster to replace with the bike together so I'm sort of waiting until I can find one to complete reassembly.

Edited September 21, 2016 by CaseyJ955

[syscrusher]

It also matters what kind of roads you have. Wisconsin has the 2nd worst roads in the country. Connecticut is the worst. What I call smooth roads is what others call off roading. In fact there are dirt logging roads that are better than some of our highways.

 

You make it sound like such fun! I'd never read about Wisconsin on any of the adventure touring forums I've visited. Actually, I've traveled around Spring Green, Prarie du Chien to La Crosse on Hwy 35, Madison, East Troy, and all over Door County. I never did find this mean, nasty, road of which you complain. Not that I'm doubting you, but all of the WI roads are not so bad. Although maybe I'm just used to worse. Nebraska has some cruddy roads, that's for sure. You've gotta love the ones that include a mini speed bump about every 50 feet to 100 yards that just keep jarring you as you go down that road.

[bongobobny]

Most of us use "Progressive" brand progressive springs...

[CaseyJ955]

Go here to progressive sight and start with "Select Your Bike" and run through until you get your part number.

http://www.progressivesuspension.com/product/1465/fork-spring-kit

 

We recently had quite a thread discussing fork oils and viscosity that might be a good read if your going to go and do this.

 

I cant recall the part number for mine right off the top of my head or if they are different for gen 1 and gen 1.2. Once you have the part number hop over to Ebay and find the cheapest reputable seller. I think I got mine for $82 shipped.

[BlueSky]

Makes sense to me that the oil level has to be lower (from the top) with the forks extended than the distance the lower forks will travel to be bottomed out to keep from "hydrolocking". Addtitionally, the higher the level is without "hydrolock" when the forks compress the quicker and higher the air pressure will increase above the oil level. If there is very little room for air, I would think you need to be careful how much air pressure you put in the forks because the pressure doubles when the volume decreases by half.

[Flyinfool]

Makes sense to me that the oil level has to be lower (from the top) with the forks extended than the distance the lower forks will travel to be bottomed out to keep from "hydrolocking". Addtitionally, the higher the level is without "hydrolock" when the forks compress the quicker and higher the air pressure will increase above the oil level. If there is very little room for air, I would think you need to be careful how much air pressure you put in the forks because the pressure doubles when the volume decreases by half.

 

The oil level is measured with the springs out and the fork tube fully compressed. You are correct that the more oil you put in effectively increases the spring rate because of the air being compressed. That is why oil level is part of the tuning process. The oil level is adjusting the strength of the front springs.

 

Hydro locking the front forks would not be fun......................

[OutKast]

The oil level is measured with the springs out and the fork tube fully compressed. You are correct that the more oil you put in effectively increases the spring rate because of the air being compressed. That is why oil level is part of the tuning process. The oil level is adjusting the strength of the front springs.

 

Hydro locking the front forks would not be fun......................

 

Kind Sir, please define "fully compressed". We had the bike on center stand, springs out, and just lowered the jack so the weight of the bike was on it. Set it at 5.75" on the high side. Instructions said 5.5" from top was MAX. Then jacked the front up and dropped the springs in with 3/4" spacers. 12.5w was not available, so used 15w based on my 230 pounds of lard, hot Texas heat, and plans to remove Class and antidives in their entirety. It has a "fork brace" sourced from a parts bike.

 

Rides and handles great now, but I get a "thunk" through the bars on a significant bump. Should I have weighted the front of the bike when measuring the fluid height?

 

How do you tag people? @yamagrl @van avery @Squidley

[Flyinfool]

Lowering the front end until there is weight on the front wheel while the springs are removed will "fully compress" the front forks. It just means to compress the forks to the stop. you do not need pressure on the fork. Little by little I am shortening my spacer.

The next step is no plastic spacer, just the factory aluminum one with the O-ring on it. I am still looking forward to the day that I get DOWN to only 230lbs of lard................. I am expecting the slow speed handling to get even better with no plastic spacer, it has improved with every shortening so far and the high speed handling has not changed with the spacer getting shorter. I know that at some point you cross a line and the low speed keeps getting better but at the expense of the high speed handling getting worse.

 

Factory recommends 10W oil some people recommend 15W oil and some like me that can not decide, mix the 2 together to get 12.5W oil. Is it better or worse, I am to lazy to do the testing to find out.

[OutKast]

I am pretty sure now that I have messed up. I believe we actually set it with the forks extended (it was a long day!). I now remember lowering the jack to "work it in" and it came all the way to the top when "compressed". I used over a pint, probably 18 ounces, in each leg, but have now found the stock volume is only 13-14 ounces and it should be a little less with the progressives.

 

Oh well, to the store for the 17mm hex and two more pints of oil. Based on the oil that came out, could probably use a second change anyway.

 

Lowering the front end until there is weight on the front wheel while the springs are removed will "fully compress" the front forks. It just means to compress the forks to the stop. you do not need pressure on the fork. Little by little I am shortening my spacer.

The next step is no plastic spacer, just the factory aluminum one with the O-ring on it. I am still looking forward to the day that I get DOWN to only 230lbs of lard................. I am expecting the slow speed handling to get even better with no plastic spacer, it has improved with every shortening so far and the high speed handling has not changed with the spacer getting shorter. I know that at some point you cross a line and the low speed keeps getting better but at the expense of the high speed handling getting worse.

 

Factory recommends 10W oil some people recommend 15W oil and some like me that can not decide, mix the 2 together to get 12.5W oil. Is it better or worse, I am to lazy to do the testing to find out.

[camos]

Lowering the front end until there is weight on the front wheel while the springs are removed will "fully compress" the front forks. It just means to compress the forks to the stop. you do not need pressure on the fork.

 

Rides and handles great now, but I get a "thunk" through the bars on a significant bump. Should I have weighted the front of the bike when measuring the fluid height?

What Flyinfool said about compressing the forks to the stop and 5.5" with springs out is right on. When I did my forks I put half of a 946ml container in each fork and got 5.5" from the top. One US quart equals 946 ml. The only fly in the ointment with this is I did not drain the forks from the bottom just loosened off the anti dives and let it run into a bucket so perhaps there was a little left in the fork.

 

If you end up with 5.75" from the top it probably won't matter much. I think the Progressive springs are larger than the OEM springs that I have. What is important is that there needs to be exactly the same amount of oil in each fork.

 

Regarding the "thunk", have you adjusted the steering head bearings? I was getting a thunk when I crossed my driveway curb and re-packing the steering bearings fixed it.