Topic: Race Tech emulator/spring front suspension setup help

[akabek]

I am probably just losing my mind but it makes sense now.  I will assemble the front end tomorrow night and report back after a test ride.

The problem I am having is no fork travel while riding the bike.  Measuring with a zip tie the only time the fork moves is after applying the front brake.  Hopefully loosening the tripple tree top and bottom bolts and compressing the forks a few time will realign the front end to remove any binding before I tighten everything back up.

[scottly]

Check out my post on this thread:
http://forums.sohc4.net/index.php/topic,159271.0.html#lastPost

[akabek]

Some good info in that thread Scottly.  I will assemble the forks and try the alignment technique mentioned in the thread.  After a test ride I will report back.

[akabek]

Last night I reassembled the front end.  I added 20mm of preload onto the forks and 160mm of fork oil at 15wt.  This time around loosened all the bolts holding the forks in place except for the lower tripple.  I installed the front wheel hand tight.  Then I sat on the bike and pushed down on the front end 4-5 times.  The front wheel axle forks bolts were torqued down followed by the top tripple screws.  Last I tightened the headlight ears to the forks.  Now when I sit on the bike the front forks compress a little.  I was not getting any response in the past.  The plan is to go on a test ride later today but at this point I am optimistic the forks will work much better now.  I will let you know.

[NobleHops]

Great job.

[akabek]

I ended up speaking to Matt at Race Tech and he offered to ship me two springs so I could try some lighter weight combinations.  The spring rate I was using was 0.85KG.  I ended up dropping the spring rate down to 0.75KG.  I still find it a little stiff but much better than before.

[grcamna2]

akabek,
I want to ask about the ride height of your bike in general;is the rear down lower than the front ? I ask because I feel that the ride height should be equal(similar to stock)front and rear and the spring rates of front and rear should match closely so that the front and rear suspension should compress together.

[akabek]

The rear is slight higher...maybe 5 degrees more.

[grcamna2]

The rear is slight higher...maybe 5 degrees more.

That shouldn't hurt anything.

[scottly]

Have you tried changing the oil level from 160mm to a greater number (lower level) yet? When my forks were overfilled, I had maybe two inches of travel before the forks seemed to "lock up". Lowering the level to about 215mm eliminated the locked up feeling, but felt under-damped. I'm going to try about 185mm next.
This chart from my CR 480 manual shows the relationship between oil level and force required to compress the suspension. The actual numbers don't apply to our forks, but the principle is the same.   

[akabek]

I dropped the spring rate from 0.85KG to 0.75KG.  I also had the lighter 26lbs springs with 3.5 turns on the emulator.  I went back to the 40lbs springs with 3 tuns on the emulators.  Now I get some travel while riding and it softened up the front end a little.  I am not bottoming out so I don't think adding more fork oil will be a benefit.  I just wanted to get some travel while riding to soften up the front end.

[scottly]

No, I was suggesting removing some fork oil; when I experienced the stiffness it was with a level of about 150-155mm, as least as far as I can guess now.

[akabek]

My mistake Scottly.  I did try 170mm oil level and when I hit the lip on my driveway it was close to bottoming out so I went back to 160mm.  I need to take the bike out for a longer ride to see how it behaves but it is much better now. I would have liked to try a 0.70KG spring rate in the forks to compare but I don't want the front end to be too soft.

[scottly]

Have you tried different oil levels with the .85kg springs?

[scottly]

While we're on the subject of fork oil level, I had a nifty tool for setting it, until the rubber squeeze bulb rotted into oblivion. You inserted it into the fork leg to the desired level, squeezed and released the bulb, and the oil was sucked up into the "turkey baster" until it matched the desired level. A similar tool can be fashioned using a syringe and a piece of brass tubing, with a snug fitting piece of tubing to set the depth.

 

[akabek]

I did try different emulator settings and oil levels when I had the .85kg springs but the front end was too stiff.  I had to hit a good size bump to get any fork travel.  Now the front end soaks up some of the uneven road.