Progressive spring oil...

[jasonm.]

Hey folks, My '83 I installed Progressive fork springs. These spring have more coils, taking up more space. I know you are suppose to put in less oil. I have 8oz. in now. Bike rides about 3/4" higher with 1.75" of static sag previously it was ~2.3". I had lost that quick turning. SO I have pulled the forks UP 10mm(.4"). Now the quick turning has returned. But does anyone know the exact amount of oil to now be used.? Stock is 9oz. Did I put in too much oil?

[Extent]

Don't measure by volume (you'll never be right) but instead by distance to the top of the fork leg completely compressed and with no spring.  I forget the measurement for stock oil level, but I'm pretty sure it's in the helms, if no one else posts up I'll find it sometime tomorrow.

[h2olawyer]

Fork oil specs - Chapter 1 in Haynes:

RJ - 8.7 oz. per side
       6.0 in. (152mm) from top of tube, forks completely compressed, no springs

RK - 9.0 oz. per side
        5.0 in. (127mm) from top of tube, forks completely compressed, no springs

H2O

[jasonm.]

Okay guys, I'll try again. I have the factory manual. So I know what you are saying BUT...YOU don't put the factory amount in with Progressive springs. Because they consume more of the forks volume(many more spring turns). Otherwise you will have too much of a rising rate. This is what I was told by Progressive when putting Pro-springs on my Venture. At that time they knew the proper amount for the old Venture. I have 8oz. in the Vision now. As is the front end will never bottom out. But I need some feedback of a good range without guessing by adding and draining again and again. So has anyone figured out how much less than stock to put in a Vision w/prog. springs? Please, anyone have a first hand answer with positive results?

[h2olawyer]

Jason -

Should have re-read your initial post.  I understood it at the time, but after reading Extent's post, decided that I could post the info he wanted to post later - since I have the Haynes at my desk for now.

The only thing I can come up with is to find out what the oil level is with the stock springs in the forks.  Could be done with tubes extended or compressed.  Get the measurement from the top of the tube to the oil.  Remove the stock springs.  Install the Progressives & see how much higher the level is.  Use a syringe & tubing to suck out the excess or drain some out the screw.

A piece of wire could be slid down the tube between the wall & the spring.  Mark the wire@ the top of the tube & slide it back out.  Measure the distance between the mark & the oil line.

Just a quick thought but it should get you real close to the correct level.

H2O

[Extent]

I should have read more carefully.  My understanding is that the air at the top of the fork (space not taken up by the oil) mostly provides a buffer against bottoming, since air compresses progressively, or something like that.  If your sag is too tall in the front you need less preload (shorter spacers) to get you back into the right spot in your suspention travel.

H2o's way for comparing oil levels sounds good.

[h2olawyer]

As I recall, Progressives eliminate the spacers.  Not positive om that but remember reading something about it on their website.

h2O

[jasonm.]

H2O has the right idea. I feel stupid now. The springs do not need spacers. Lucky for me I have an extra set of forks with the proper amount of oil. The trick is making an accurate dipstick. But I think I have some stiff guide wire that will work. Since I will not remove the forks from the bike. I'll have to figure the rake a bit when using the "dipstick".  I'll try it, Thanks...

[h2olawyer]

After rebuilding my forks twice in the last two years -- once for the seals - once for the 83 fork lowers -- I found that using a large syringe from a vet supply store works very well for many things.  I have three I use on the V.  One for pulling brake fluid through the system, one for engine & diff oils, and one for the fork oil.  For the fork oil, I added a piece of tubing about a foot long to the end of the syringe.  I put a small hose clamp on the tubing to mark the top of the fork.  Originially I had it 6" from the end so I could slightly overfill the fork & suck out the excess.  When I installed the 83 fork lowers & springs, I changed it to 5" to compensate for the difference in the specs.

Get the large horse syringes.  The ones I bought hold 60cc (2oz.).  They have a plastic case to clearly mark what they're for.  Only a couple bucks each & are very handy!

H2O

[Riche]

Jasonm

Try a wood dowel as a dip stick. Easy to see the oil on and can be marked with magic marker for reference. There should be plenty of those small flags around after Memorial Day.

Back in the early 80s we used to set the fork oil level on our dirt bikes through a little trial and error. Starting with what was less than enough. Measure the heigth with the forks compressed, air blead out and springs out. Ride it hard and see if it bottomed. The first ride was expected to bottom. Add a little oil at a time untill the bottoming stopped, check the level and record for the next change. Always checking to be sure they were even while adding oil. Those forks were the same basic design as the Vision's

[jasonm.]

Lucky for me I found a measring tape thin enough to go inside of the spring. With the stock springs in place on the original forks. The level is ~12.5" from the top. I measured the new forks with the Pro-springs w/8oz in. Measured 13.5" from the top. BUT even with the brakes on hard going to a steep downhill stop. Only 4.5" of travel is used. The max travel available on these forks is 5.5". The static height of the forks is 1.75" - 2" from fully extended. With my brake bleeder taped to the measuring tape, I lowered the level to 14" from the top. Travel and static measurements stayed the same.? The handling and ride are great. Partly because the new forks had such low miles. And the "no bottoming" effect keeps the fork brace from hitting the wiring harness. I still have the forks pulled up in the trees 10mm which gives quicker turning than the stock position. I changed it to 5mm for a while. But put it back up to 10mm.