Progressive Front Fork Springs - Spacer and Oil Volume


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XJSRider
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Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »



Subject says it all. My progressive forks springs did not come with instructions and I can't find them on Progressive's site.

I have heard that they call for 15 wt oil, but a lot of guys here seem to like 10 wt.

There is a note on the website that no spacers are required. I guess I'll find out this afternoon if that means they just don't ship with any or...
are there spacers inside the forks that I will not need to use?

Final part since the forks are coming apart for a total rebuild, what volume of fork oil do I add? On other bikes I know that when switching fork springs (especially if there is a spacer that is being removed) volume of oil changes. I think stock volume is also different right vs left fork on this bike.

Can someone give me some quick info here? Getting ready to pick up the motorcycle lift and go to town.

My garage looks like a bomb went off in a honda parts factory.



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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Also for guys with schrader valves in their forks, I believe I read somewhere that they should run at 0 psi set with wheel off ground and forks fully extended, hopefully someone can confirm. Thanks.

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1goldwingnut
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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by 1goldwingnut »

Here is a link on the subject part way down are levels depending on the springs. viewtopic.php?f=14&t=43387&sid=fb76fe44 ... 323d4c262c

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thebruce
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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by thebruce »

There is a measurement from the top of fork tube to oil with no springs installed and fork completely compressed. 1goldwingnut provided a link for this. Since you are completely rebuilding the forks you should use this method.

I have progressives in mine, I didn't use spacers, and I don't think I need them.

I am also using 15w or maybe a bit heavier as I just poured 10w on top of the 20w that was in the forks since rebuilding them last year. The stock dual springs occupy a fair bit more volume than the single wound progressives.

The ride is a little harsh at certain speeds on bad roads, but I prefer a firm front fork compared to the sloppy thing that it was when I bought it.

You will not be unhappy with the results with 10w, but if you like a firmer fork, try 15w.
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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Thanks guys. I was hoping someone had a volume measure so I could just pour it in without having to make the tube to suck back out to correct level. Guess I need to get a vacuum pump

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by CrystalPistol »

GL-1500 bike, Progressive # 11-1152 springs, NO spacers, they only say to start with 15wt (but you can experiment).
No air added, just treat the Schrader valves as "plugs", I ran OEM volumes of oil, always had sufficient air space for compression.

Below is info I saved for some reason or other many years ago. I think it was a compilation?
This method is works only if there is a schrader/air valve in the top fork bolt.

I have started doing the fork oil change as annual maintenance. There is a method to do it where you can do it very simply and get the level right every time.

The confusing thing is that level and volume keeps getting interchanged but in essence, they are basically one and the same. If you can figure out the level (distance from the top of the fork tube), then you will already know the volume (amount of cc's) that need to be added. These forks need the level to be equal in both forks even though different amounts of oil go in each. This is because there are different components in the left as opposed to the right and this changes the amounts of oil each one holds. (Although this doesn't apply to Interstate models, they use equal volume in both forks.) But the one constant is that the level will end up being identical. This is because of the level of air needs to be the same in both sides. Even though Progressive says to add no air which technically is correct, there is still air in the forks and this plays into the damping. When the forks are compressed, as in driving down the street, going over bumps, cornering, etc... This amount of air will also play into the mechanics of how the fork works. Because of this, the amount of air needs to be identical in each or there will be different amounts of pressures at work on the left and right forks which could cause a serious handling issue.

An example of volume and level.... Let say you need 1-1/2 cup of milk. You pull out a glass measuring cup and carefully measure it out using the markings. Now you pour that into another glass cup that you plan on using all the time that has no markings. So after you pour the milk into this separate glass, you make a mark at the level where the milk is. The next time you need 1-1/2 cups of milk, you will no longer need to measure it, you just pour the milk into this glass up to the mark and if it goes over, you pour out the excess. If it's too low, just add some more. This will work for every time you need 1-1/2 cups of milk. Technically you are still measuring out 1-1/2 cups each time but you already know in advance that putting the milk to the mark will get you the amount you need. So no need to think about it.

Satan on this board took the time to do some extensive measuring of the 88-94 and 95-00 forks and simplified the levels. Most times the service manual only gives the levels and volume with springs out and the forks fully collapsed. That is the hard way. Changing the fork oil with the forks fully extended with the springs still in wasn't known and most folks took their best guess at what it should be. But this information is what was wanted. He was in the middle of a fork rebuild so was able to take both measurements and this is what he came up with:

Oil fill with forks collapsed and springs out (from the shop manuals):
239mm / 9.4" for 88-94
194mm / 7.6" for 95-up

Of course that kinda sucks if you've got springs in your bike and you're refilling through the air valve...
... so measuring from the TOP OF THE FORK NUT (schrader valve removed) looks more like this --

Oil fill with forks fully extended and springs installed (measured from the top-plane of the fork nut with the air valve removed):
400mm / 15.75" for 88-94 (Progressive springs installed tight end down)
406mm / ~16" for 88-94 (Progressive springs installed loose end down)
408mm / ~16.1" for 88-94 (OEM springs installed)
* 355mm / ~14" for '95+ (Progressive springs installed tight end down)
* 361mm / ~14.2" for '95+ (Progressive springs installed loose end down)
* 363mm / ~14.3" for '95+ (OEM springs installed)


With that said, the method is foolproof and actually pretty easy way to do it quickly and get the same results each time. All you need is a way to jack up the front of the bike while on center stand so the forks are fully extended, a bottle of your favorite fork oil, a length of aquarium air hose and a syringe like
this one




(Satan used a length IIRC of 3/8" copper tubing straightened and a fender washer to set his level. I use the aquarium tubing because I already had it.) Cut 2 lengths of aquarium tubing. The first one make long enough to reach the bottom of the bottle of fork oil and attach this one first. Second, based on above mentioned levels, figure out which measurement fits your particular application and cut the aquarium tubing to the proper length. If the tubing is too tight, you can use a larger phillips head screwdriver to expand the tubing. It usually has quite a bit of flex before it tears. Obviously drain the old fluid during which removing the schrader/air valve makes it drain quicker. I will sometimes usea nozzle on my compressor set at low and stick it in the top hole and help blow some of the remaining fluid out. Don't use too high a pressure or fluid will spray everywhere out the drain hole and make a mess. After it finishes draining, put the drain plug back in and start pulling fork fluid from the bottle through the first aquarium tubing filling the syringe. Now take the end of the aquarium tubing and start putting it through the hole left by the removed schrader valve. Squeeze out the new fluid. Do this about 5 times in each side (based on using a 60cc syringe).

Lower the jack and take the bike off the center stand. While sitting on the bike, grab a handful of the front brake and vigorously get the forks pumping up and down maybe 10-15 times. This will allow the fork oil to work down into the lower part of the forks. Now get it back on the center stand and jack up the front end again. Now attach the longer tube and fill up the syringe one more time about halfway. Same thing as above, if it gets caught up, twist the syringe and tubing so all the tubing goes down in. Squirt that in but this time after the syringe is empty, while the tube is still inside, start drawing the plunger out. If fluid starts filling the syringe, you know that it was overfilled and you are now drawing out the excess. empty the excess, put the tube back in and repeat until no more fluid enters the syringe. If nothing comes out then you know you have to add more fluid to that side. Repeat on other side. Pull the tube back out, put the schrader valve back in and you are done. You now have the proper amount of fluid in there. The beauty of this is that it doesn't matter if a little fluid was left behind from draining, the level will never change. If some fluid was left, using the level method, you end up putting in less new fluid automatically anyway. If you were to completely ensure that you drained all the fluid now in the forks, the volume otherwise known as cc's would match the cc's called for in the factory manual.

As a side note, you will now have the proper amount of air in there for Progressive springs. If you check it, even though there is air, it will measure 0 psi. Now when you lower the jacked up front end and take the bike off the center stand, there will be small measurable psi but it actually never changed. The reason this is important is that if you let the air out while the forks are slightly compressed, (normal riding position) it will limit the forks ability to extend all the way if they need to such as rebounding over bumps because you will end up in a negative psi condition with the forks fully extended. Kind of like a vacuum chamber....

Edited to correct the wrong info on the 95+. Thanks again Stan...
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thebruce
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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by thebruce »

XJSRider wrote:
Sun Aug 16, 2020 11:45 am
Guess I need to get a vacuum pump
Nope.

Find a straight, somewhat rigid piece of something that you can mark the appropriate measurement on. I like to use a long zap strap. Preferably a couple inches longer than the measurement.

Pour fork oil slowly into the fork, you can probably see the level of the oil as it rises in the tube.

Before you reach full, expand and compress the fork a few times to get oil inside all the bits, then continue to pour slowly.

As the oil level nears the appropriate level, use your measurement "stick" to slowly bring the oil up to the appropriate level.

I'm sure there will be those who disagree, but 1/4" over full isn't gonna make a lick of difference.
It doesn't matter what you ride, as long as you have your knees to the breeze.

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by WingAdmin »

I started with 15 weight fork oil with my Progressive springs, with 0 psi (with front wheel in the air). The pressure was good, but the stiffer springs were too much for 15 weight oil, and the front end was harsh over bumps. I switched to 10 weight oil, which made a big difference.

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Yesterday I got the forks off the bike and broke in my new bike lift. She looks so helpless sitting up there, no forks, no fairings, no rear wheel or driveline, naked and vulnerable...

Anyway in the past to uncap the forks I've used a piece of square stock tube with a hole in it that I can get an extension through but not big enough for the socket (sized for forktube cap) to pass through. This allows one person to push down on the square stock, keeping pressure on the socket while a second person can tighten or remove the fork cap using a ratchet connected to the extension. So essentially, from bottom up, fork cap, socket on it, square stock pushing down on socket, extension in socket passing through square stock, to ratchet. 2 person job, one guy is the muscle the other the finesse. Fork tube will be in a bench vise with soft jaws. Disaster waiting to happen, or...….

Unless someone talks me out of it I'll post some pics of the operation.

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by thebruce »

*anything short of using the appropriate tool can be dangerous, and even when you have that tool, used incorrectly, it can be dangerous. "Serious death or injury may occur" or some such.

I have, many times, set the assembly on the ground, pushed the fork cap down into the fork tube with socket and ratchet to save my hand and just spun the fork tube.

Rather than trying to turn the ratchet, the fork tube has a lot more stability, so why not turn that, I figure.

I did this last year, by myself, with the stock dual springs, and again 2 months ago with the progressives.

Bear in mind I am a relatively young, 200-ish pound man who has worked with his hands for the past 20 years.

2 people could easily accomplish this; one to force the spring/cap down, and another to pull the fork tube up into the cap and spin the tube.

Pretty much the same process you describe but forget the vise and spin the tube, not the ratchet. Far less chance of cross threading this way.

If for some reason you try this and it feels unsafe; for God's sake, stop. Your intuition beats my experience every time.
It doesn't matter what you ride, as long as you have your knees to the breeze.

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by CrystalPistol »

thebruce wrote:
Mon Aug 17, 2020 7:48 pm
"Serious death or injury may occur"
Sounds like bad juju to me. :P


Hard to resist, so I let it out. :D
Make Courtesy your "Code of the Road" …

… & Have a Safe Trip!
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XJSRider
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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Bruce- LOL at legal disclaimer. I'll roll the dice :). Yesterday after work we hit the range at fish and game club, will try to disassemble the forks tonight.

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

I got the fork caps off yesterday.

I ended up going with my square stock / ratchet on top method.

Getting the fork caps started was very difficult. I ended up having to use an impact which is nuts because I think the torque spec is only like 17 ftlbs. The flats on the nut on top of one of the caps is not looking so pretty right now, the impact actually spun a bit. But it seems like I will have enough engagement to reinstall and tighten. I would replace but 50 bucks!? Man.

I popped the forks into the bench vise and pulled down on the square stock while my lovely ass-istant worked the ratchet. She actually let me know that there was no more resistance and I slowly let the spring up; I was able to keep it completely compressed without any thread engagement with very little difficulty. When time to reinstall I will most likely have a friend work the square stock so I can tighten the caps and avoid cross threading (not sure if Kate is up to that task).

Overall though, in terms of cap removal, it was mostly a "nothing burger". (insert Bruce's legal disclaimer here)

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Today I started rebuilding the forks. All was going well until I grabbed my trusty 1.5" sched 40 length of pvc to drive the seals, which I have used on other bikes. It would not fit over the fork. I cut a section and then cut a groove lengthwise so I could open it up a bit to get over the forks. The oil seal has openings on both the top and the bottom, and it felt like I was hammering on the part of the oil seal tight against the fork; afraid of causing a leak I stopped.

Really don't want to spend 50 bucks on the motion pro tool (not sure what size I would need to order anyway).

I went to lowes and looked at some ABS but dimensions and wall thickness matched my sched 40 which I thought was really strange.

What do you guys do to drive the seals?

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

OK so I got them in. I used old dust cover over old seal and just pushed them down, carefully extracted old items, and snap ring clicked right in. made sure the two guide bushings were flush with each other before pushing the seals in with my bare hands. Whats the over under on percent chance it leaks when I put it back together? :?

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by 4given »

If you left any marks at all on the tubes, they will leak. I’m sure you already know that. Ask me how I know. ;)

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by CrystalPistol »

4given wrote:
Thu Aug 20, 2020 7:26 am
If you left any marks at all on the tubes, they will leak. I’m sure you already know that. Ask me how I know. ;)
Any mark or knick will do it.


I like to take a sheet of 1200 grit wet or dry paper and polish around the tubes looking for any defects or even any dried old bugs, etc. Hope you padded those vice jaws with leather or heavy rubber or wood blocks.
Make Courtesy your "Code of the Road" …

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XJSRider
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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Yes... I had vice jaws padded with "soft jaws" and only attached far enough up on the forks where they will never slide into the seal. Nothing visible on the forks in terms of scratches or anything. I was more worried about damaging the seals with my pvc.

After work today I'll try to get the springs back in if my buddy is available. Just picked up some fork oil during lunch.

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Re: Progressive Front Fork Springs - Spacer and Oil Volume

Post by XJSRider »

Getting the springs back into the forks using the piece of square stock was an absolute breeze. My buddy pushed down on the square stock while I lined up the cap and turned the ratchet it took 5 minutes to do and was a piece of cake. If you have a friend to help you this was absolutely painless.

-soft jaws in vice.
-don't clamp to part of fork that will drop below the seals (just in case).
-without spring in the fork try to set the cap to find the spot where the threads start to catch. I made a little mark on the cap and tube so I knew where the engagement spot was, this made it very simple.
-Tell your buddy pushing down if it is not going down straight to prevent cross threading.



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