2001ex500 said:
Yes, definitely. I'm going to go the thrifty route again(for now) and cut the front springs and make some metal spacers. I've got the formula for calculating the spring rate and may do it twice to learn about the feel. I'll also be going to 10W synthetic fluid in the forks. I'm still debating as far as raising the front, because I won't need the clearance for cornering anytime soon. And then I'll be saving toward emulators. After the tires that's the next priority on the list.
Thanks
PS. Thanks for the spring preload measurements; that will save me a lot of time!
I've not cut springs on this model so I don't have any specific recommendations that I know work but it IS a viable alternative. I'll give you some generic guidelines for this as considerations. While not all may apply in this instance they are good considerations to treat as generic knowledge for this type of work. Forgive me if they are things you already know but even if you don't need them, maybe they'll be helpful to a lurker following this.
I'm 90% sure those front springs are progressive wound. I don't remember for sure. If they are, which end you cut will make a big difference in the end result and over the range of travel. Make your cut at the soft end, the tighter spaced coils, to get the rate higher but also more linear. Put the cut end up against your spacer.
If they are progressive wound that end would normally be installed at the bottom. If so, flip the spring with the cut end up. Make sure the bearing area of the original top end is OK where it will settle well against the lower shoulder. It might be good to use the washer that's normally at the top against the spacer and move it to the bottom if you're not sure. If you do, you will need to find a washer to use at the cut end (top) so that the cut end will register well against the spacer. Never put the hard spring against a soft spacer,
especially if you use PVC pipe to make the new spacer. Always use a washer between those faces.
If you have to flip the spring, take an extra minute to inspect the ground flat end for sharp burrs that may project out past the diameter of the spring. If they are there, they can gouge the inside of the tube and screw up the shock piston ring as it travels over that spot. If there are any such burrs are sharp edges they need to be ground back to assure they can't rub the inside of the tube. That end would normally have been installed at the top where it doesn't move and also where a score mark will not effect a sealing face. Therefore they are sometimes not dressed to make sure they can't rub. This may not be required as you may not have to flip them if they're not progressive and you didn't cut that end.
Even if they're NOT progressive, still check both ends before to cut because
sometimes they'll wind that very last coil slightly smaller diameter to assure it clears, can't rub on the ground flat edge. If that's the case, smaller diameter at the last coil and NOT progressive wound, don't cut that end and none of this will matter. Good generic stuff to consider although it may not apply to these. Check it all to be sure, though.
You can rig up a bathroom scale to prove out your work, your new spring rates. Take the spring cap out but leave the spring in the tube to guide it. Get a broom stick or some equivelent tool to push the spring down with. This way you're getting direct spring readings without any error from fork stiction. Get someone to help stabilize the thing and to help with the readings, standing it up on the scale as you press down on the spring. Make sure to subtract the dead weight of the fork out of your readings.
The ratings can be taken in pounds of force per inch of compression. Pre-load about 1/2" to settle the spring and call that number zero. Then check over a couple of inches to prove the readings and your arithmetic. To do this, put a mark on your broom stick to align with the fork tube top at about 1/2" compressed, then make a couple of more marks at even inch increments. Compress the spring to each of those marks and get your readings.
The number .455 is used to convert kilograms pounds. If you know the kg, divide it by .455 to get lbs. If you know the pounds, multiply it by .455 to get the kg. Then to convert those numbers from kg
per millimeter to pounds
per inch, use 25.4 multiplier. Per millimeter
times 25.4 will give give per inch. Per inch
divided by 25.4 will give per millimeter.
Example: Convert standard .
90kg per mm rating to
lbs. per inch rating.
.9 /.455 = 1.978
1.978 x 25.4 = 50.24
So we would look for a 50# reading per inch compressed on our bathroom scale. 2" compressed would be 100# and so on. Convert your actual readings back to kg per mm to see how they fit the recommendation charts. I would think .90 is what you're after.
Then reconsider the fork oil level as that is your new progressivity adjustment. With these as soft as they are they run a relatively high fork oil level as stock. The stock is recommended at 4 5/8" but with the right spring that will be too progressive. The .90's that you should be striving for will only require about a 5 1/2" oil level and possibly as little as 5 7/8". 4 5/8" with the right spring will be too progressive and will show up as too much unused suspension travel on hard braking. BTW, that very high fork oil level is a patch to the very soft springs. Light springs for a light rider yet very progressive for bottoming with a heavier rider. A compromise that tries to address all situations but still a very big compromise.
Remember, lower level is more air, therefore less air spring, therefore less progressive. I'd start low, maybe around 5 7/8". Wrap a wire tie on one of the fork legs to use as a travel indicator. Check it after some hard braking and after your first few rides. If you've never bottomed, done some real hard braking and/or hit some pretty good bumps, yet still have about 1/2" of travel left, that's probably pretty good. If you've bottomed, add oil, maybe 1/4" at a time until it leaves you at least 1/2" reserve travel. And if you've not used full travel (less 1/2" to 3/4" for reserve) consider removing 1/4" at a time until you have the right full travel range. Monitor it over time to be sure it's good.
Another trick to make it easy to read the fork bottoming travel once it's together, is to trace a line with a Sharpie permanent marker at the fully compressed position while the springs are out and you can fully collapse the front easily. Clean the tube with something like carb cleaner where you'll be tracing it so the mark won't wipe right off, collapse the front, and then trace around the tube at the fork seal. Do both legs. Then, leave a wire tie around the leg while riding. It will get pushed up to the max travel position while riding and with the traced bottom mark, you'll be able to tell at a glance how close you've come to bottoming. Makes life easy.
To cut your front spacers, if you get in the range of .90 springs, your pre-load on the front springs will be in the range of 3/4" to 7/8". Drop the spring in, extend the tube and measure from the top of the tube down to the top of the spring. You can figure out the measurement by measuring the top plug/cap height, snap ring groove location down in the tube, and figure out what spacer length you will need to pre-load at about 7/8". Expect that dimension to be about 1/4" less than the very top of the tube, again, tube fully extended, not compressed as you would do for the fork oil level.
BTW, it's better to work out your spring spacer
before to put in the fork oil so that you're not dealing with the oil dripping all over as you put the parts and tools in and out of the tubes. Put the oil in last. Make sure the front static sag is at least 1 3/16", not more than 1 3/8". You can even fully assemble the front end to the bike and get your sag readings without the fork oil in. That way, if you need to trim the spacer, you can remove it without dealing with the mess of the oil. Just don't test ride without fork oil.
Refer to that suspension guideline post I made if any of this isn't perfectly clear. What's neat is here's a real world exercise using that information. If you take the time to understand those posts and then complete this job, you'll have a real good grasp of the principles and they don't change one bike to another.
Good luck.
