Hello guys.

Been wrenching yesterday and replaced front fork seals. Made a good amount of photos. I'll make a howto for the howto section.

But there's something that went bad: I dropped 382ml fork oil in each damper, as Clymer manual says. But I have ProgressiveSprings brand springs, and a lot of oil is displaced when I drop the spring in the tube.

I've been searching the forum and I found that with ProgressiveSprings I need to measure 5.5inches from the oil level in the fork tube, to the top of the tube, with fork tubes compressed and spring removed. Is this OK?

Anybody could tell the measure with spring installed and fork expanded? so that simply sucking the oil from the top I can arrange this?

Thanks.

Hi there,

This is a common Q here on the board.

Here's my advice to an earlier poster:

http://gstwins.com/gsboard/index.php?topic=51675.0

   
Re: adjust fork oil levels after spring upgrade!
« Reply #5 on: March 05, 2010, 02:04:28 PM »
   Reply with quote Modify message
Quote from: centuryghost on March 05, 2010, 12:51:44 PM
I'm trying to wrap my head around this; how do you keep your fork springs fully compressed and also be able to measure the level?

Hi Century,
That's easy.
He said it wrong -- he meant "FORKS fully compressed, without the springs."
That means you remove the springs, slide the inner fork tubes all the way into the fork lowers (that's the fully-compressed part) and then you measure the top of the fork tube down to the top of the fork oil inside the tubes.
I do it this way:
I have a set or Progressive Suspension fork springs in my 1991 GS500E.
I remove the springs, turn the fork legs upside down to drain the oil, clean it all out, then let them dry.
Then I push the tubes down in the lower legs, and pour in fresh oil. I have a piece of aluminum I pre-marked with the correct fork oil height per the Progressive instructions, and I fill to that point. When a bit of oil shows up on the bottom of the measuring stick, I'm there. It's essentially a dipstick. Smiley
When finished, extend the inner tubes out of the fork lower legs, then slowly slide the clean springs back into the fork assemblies. Go too fast and you'll squirt some of the oil out and you don't want to have to redo the measurements, do you?


So yes, you remove the Progressive springs, push the inner tubes all the way down into the outer legs, pour in fork oil until it measures 5.5" from the top of the inner tubes, and that's it.
Then extend the tubes back out, lower the springs slowly into the oil so it's not squirted out, and put it all back together.
If you want to know, that 5.5" equates to 11 ounces of fork oil in each leg.
I know, because I measured it one of the times I changed it and made it even easier to deal with.

So there you go.

The stock 382ml per leg of oil is used when you have the spindly stock springs and the stupid thin metal spacers.
They combined didn't displace much oil, so the legs needed more oil.
The Progressive springs are thicker so they displace more oil, therefore not needing as much inside the legs.

I hope this helps.
Best wishes,
Trwhouse

I have the Progressive springs and still have the sheet that came with them.  The 5.5" figure from the top of the fork tube to the top of the oil is the maximum oil level.  Safe operating range extends a considerable amount below that according to their sketch, just be sure you're not above the 5.5" mark.

I put in one new fork seal a while back and took the fork slider off with the tube still clamped in the triples and then removed the tube to reassemble it with the new seal and put it back on the bike.  I adjusted both fork oil levels with the front end all back on the bike.  I put blocks under the front of the exhaust pipes to hang the front wheel with the bike on the centerstand; shoved a piece of 2x4 under the rear wheel to keep the bike from tipping backwards; removed the fork caps, spacers, and springs; and lifted the front wheel and blocked it up to compress the forks and set the fork oil levels that way.  Had to suck some fluid out of one of them with a siphon tube.

Just make sure you have the blocks under the pipes when you pull the fork caps or you might dump the bike forward off the stand when the forks collapse, I came close when I first transferred the Progressives to the 02 GS from the old 97 GS.

I did it "the lazy way".

Placed a jack under the bike, removed fork caps, pulled springs and compressed the dampers with another jack. Then sucked oil till I got the propper clearance of 5.5" (I left 5,7", about 145mm) with a tube.



I had to suck not more than 1oz (30ml) to get correct height. That's 0.5oz from each damper.

Now the number that lots of people have been seeking: after installing the springs and releasing the dampers to full extended position, I could measure 23cm (9 inches) from the top of oil to the top of fork.

This is valid for people with ProgressiveSprings brand springs.

Quote from: Trwhouse on July 03, 2010, 10:19:02 AM
Hi there,

This is a common Q here on the board.

Here's my advice to an earlier poster:

http://gstwins.com/gsboard/index.php?topic=51675.0

   
Re: adjust fork oil levels after spring upgrade!
« Reply #5 on: March 05, 2010, 02:04:28 PM »
   Reply with quote Modify message
Quote from: centuryghost on March 05, 2010, 12:51:44 PM
I'm trying to wrap my head around this; how do you keep your fork springs fully compressed and also be able to measure the level?

Hi Century,
That's easy.
He said it wrong -- he meant "FORKS fully compressed, without the springs."
That means you remove the springs, slide the inner fork tubes all the way into the fork lowers (that's the fully-compressed part) and then you measure the top of the fork tube down to the top of the fork oil inside the tubes.
I do it this way:
I have a set or Progressive Suspension fork springs in my 1991 GS500E.
I remove the springs, turn the fork legs upside down to drain the oil, clean it all out, then let them dry.
Then I push the tubes down in the lower legs, and pour in fresh oil. I have a piece of aluminum I pre-marked with the correct fork oil height per the Progressive instructions, and I fill to that point. When a bit of oil shows up on the bottom of the measuring stick, I'm there. It's essentially a dipstick. Smiley
When finished, extend the inner tubes out of the fork lower legs, then slowly slide the clean springs back into the fork assemblies. Go too fast and you'll squirt some of the oil out and you don't want to have to redo the measurements, do you?


So yes, you remove the Progressive springs, push the inner tubes all the way down into the outer legs, pour in fork oil until it measures 5.5" from the top of the inner tubes, and that's it.
Then extend the tubes back out, lower the springs slowly into the oil so it's not squirted out, and put it all back together.
If you want to know, that 5.5" equates to 11 ounces of fork oil in each leg.
I know, because I measured it one of the times I changed it and made it even easier to deal with.

So there you go.

The stock 382ml per leg of oil is used when you have the spindly stock springs and the stupid thin metal spacers.
They combined didn't displace much oil, so the legs needed more oil.
The Progressive springs are thicker so they displace more oil, therefore not needing as much inside the legs.

I hope this helps.
Best wishes,
Trwhouse

So essentially, one could just suck out all the old oil from a leg, add 11 oz of new oil to the leg, insert the spring, etc. and repeat for the other leg, right?

http://gstwins.com/gsboard/index.php?topic=10357.msg85814#msg85814

Quote from: scratch on November 19, 2010, 10:30:34 AM
http://gstwins.com/gsboard/index.php?topic=10357.msg85814#msg85814

Thanks, Scratch. 350 ml works out to be approx. 11.83 oz. so I'll use 11 oz. as a starting point when I get around to actually switching the springs.

Quote from: crispy5 on November 19, 2010, 03:24:06 AM

So essentially, one could just suck out all the old oil from a leg, add 11 oz of new oil to the leg, insert the spring, etc. and repeat for the other leg, right?

Well, if you're replacing the fork seals, you have to take the forks off, anyway.  Also, I seriously doubt you'd be able to suck all the old oil out with the forks still on the bike.