It's all installed. Now what? (geometry and stiction)

Questions and comments about converting to beefier forks..
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turtle
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It's all installed. Now what? (geometry and stiction)

Post by turtle »

I've completed my conversion. I noticed the front and rear don't move up and down together unless I am standing on the bike, feet on pegs, and giving it a pretty good bounce. Just bouncing my rear on the seat results in rear suspension movement while the front mostly stays put. So I started researching on stiction. LOTS of info. Overwhelming amounts, actually :). The stiction search also led me to results on front end geometry, so I started reading there too. I have some concerns about my setup.

First, the tops of my forks are about 25mm (1") above the top triple. This allowed me to maintain the geometry I had with stock forks in terms of how high the front of the bike is off the ground. Basically, I had reference measurements before conversion that I matched after. Is that too much sticking above the top triple? I haven't ridden it fast yet, but I read posts about instability at speed and quickening (or making twitchy) the handling (turn in) with the forks that far above the top triple. Thoughts?

Stiction concerns me too. I want to minimize it. Here is my plan after reading and compiling info on this site. Does this look like a good comprehensive plan? Sorry in advance for the long post and thanks for the help!!
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CHECKS FOR STICTION:
1. Bounce test: With the bike off the stand, gently bounce the front end up and down by standing next to the bike, foot on peg and hands on bars, no front brake. Forks should easily go up and down without the bike wanting to roll forward or having to overcome some sort of initial resistance (stiction). If there is resistance, loosen axle nut and axle pinch bolts. Bounce again. Make sure the axle pinch bolts are loose. Take the bike off of the stand and push on the handlebars several times so the forks compress to mid-stroke. Place the bike back on stand and spin front tire and hit front brake several times. Tighten axle nut then pinch bolts.

2. Check if sag is different by pushing down on the forks and slowly releasing compared to pulling up on the forks and slowly releasing. The difference is stiction. In a perfect world, ride height would be same for both methods.

3. Check the fork free sag. It can be utilized as an indicator of stiction. If there is no stiction the free sag should be between 15-30 mm. Loosen all the lower clamps and check. This will eliminate any possibility of the clamps being too tight. If the sag is correct, re-tighten the lower clamps and check again. The forks should settle in at the same sag distance.

CORRECTIVE MEASURES:
If there is resistance, loosen axle nut and axle pinch bolts. Bounce again. Make sure the axle pinch bolts are loose. Take the bike off of the stand and push on the handlebars several times so the forks compress to mid-stroke. Place the bike back on stand and spin front tire and hit front brake several times. Tighten axle nut then pinch bolts. [DETAILED METHOD: Stand on the left side of the bike, holding the bars and put your right foot on the left peg. Bounce your left foot on that peg. The forks AND rear shock should go up and down at about the same time. If you have to use the front brake to get the forks to move, you are doing it wrong. The bouncing is so the forks can move on the front wheel axle and get straight. Many people crank down on the axle nut and it tweaks in the lower part of the forks, putting a bend in them so the lower part of the forks are closer together than the point where they enter the lower T-clamp. By bouncing, the forks will seek their natural point along the front wheel axle so there is no bind or bend to them. Now, while bouncing, hit the front brake. Do this several times. The purpose is to get the wheel to move along the axle so the rotor lines up with the caliper and the pads in the caliper. Your forks should now be in their natural straight position without any stress trying to force them in any direction and your wheel should now be floating exactly aligned with the caliper and the rotor not dragging. Tighten the pinch bolts on the front axle. Then try your bounce again. The forks should continue to move freely with the weight without using the front brake. Next, tighten the front axle nut. Then go and do the bounce again. If it starts sticking, you've over tightened the axle and it's bowing in the lower fork legs. Next tighten the upper T-clamp to torque spec. Bounce and make sure everything is still good and nothing sticking. Finally tighten the lower pinch bolts to 10 foot pounds. Bounce. There should be no or very little stiction If you have stiction after this, the problem is something unusual like maybe bent axle or your upper/lower T-Clamps are not aligned right. If it's the upper T-Clamp not lined up with the lower clamp, you'll have to start all over but this time loosen the stem nut at the start and get them in line.]  "Float" top triple clamp until forks are bolted up to keep top clamp in alignment with bottom clamp. Otherwise you will put a bind on the upper fork tubes that could result in stiction when the axle is torqued down. Keep the upper tree free to rotate until the fork is up into it and you torque down the pinch bolts. Then tighten the nut holding the upper tree. The order I do mine is: Front axle torqued down first, then lower tree pinch bolts, then upper pinch bolts then upper tree nut.

RECHECK WITH BOUNCE TEST. If still present,

* Put the left fork (caliper side) into the triples with the fork at the desired height. Torque the triple pinch bolts to "spec", spec being the 11-12 ft-lb torque suggested. It DOES make a difference.
* Place the right fork into the triples and lightly tighten one of the triple clamp pinch bolts (you may not even need to tighten anything - my triples, for example, held the fork in place on their own).
* Install the axle only - no spacers, nothing - with the nut very lightly tightened.
* Rotate the axle with your hand between the left and right fork. Continue to rotate but slide the right (loosely-held) fork in the triple clamps in small increments. You want the right fork located where the axle turns most freely.
* Torque the triple clamp pinch bolts for the right fork to "spec".
* Install wheel, brakes, axle/axle nut. Torque the left-fork axle pinch nuts to spec (leave the right-fork axle pinch nuts loose).
* Work the forks deep into their travel several times. Spin the wheel and use the brake several times.
* Torque the right-fork axle pinch nuts to spec.
* Assemble wheel with the axle to the forks making sure that torquing down the axle nut does not cause the fork legs to be drawn together. Clamp the axle down to each fork leg first, then tighten the axle nut.

RECHECK WITH BOUNCE TEST - hope like heck stiction is gone!
Bill
Central IL
2004 KDX220R
2011 Triumph Tiger 1050 SE
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rbates9
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It's all installed. Now what? (geometry and stiction)

Post by rbates9 »

Did you replace the seals and bushings? If so I would check as above with tightening this and that then go for a ride, put a little time on them and see if the stiction is better. If you had them apart then you may just be up against new seals being a little snug. But I'm no expert. At all. Especially with suspension.

I did have simular issues with mine when I did the fork swap and after many tightenings, loosenings, tightenings and adjustments and tightenings, and loosenings, and tightenings and beers I just said screw it went riding and then after 40 or 50 miles and one more adjustment sequence everything was right with the world. (Or at least the forks)

Good luck with it.
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turtle
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It's all installed. Now what? (geometry and stiction)

Post by turtle »

Wow. I looked at my post last night when I went to the garage, and several parts of it dont even make sense ... I was hoping to end up with a summary others could use but it might be best for a laugh and that's about it.

Thanks rbates. I do have new seals and bushings so I know that will make it worse till those break in. I messed with the axle and pinch bolts some and set my compression and rebound clickers. It's a little better. I'm going to ride it for a while and see what needs to change if anything.

It turned out nice. If I can get the time to set up a photobucket account I'll post pics.
Bill
Central IL
2004 KDX220R
2011 Triumph Tiger 1050 SE
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turtle
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It's all installed. Now what? (geometry and stiction)

Post by turtle »

Here's a lousy pic. There's a couple details to finish up, but hopefully you can see it turned out pretty good.

Image
Bill
Central IL
2004 KDX220R
2011 Triumph Tiger 1050 SE
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turtle
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It's all installed. Now what? (geometry and stiction)

Post by turtle »

Rode it today. What a muddy mess, but the forks worked awesome. They take big hits well and overall feel great!
Bill
Central IL
2004 KDX220R
2011 Triumph Tiger 1050 SE
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rbates9
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It's all installed. Now what? (geometry and stiction)

Post by rbates9 »

Good to hear! I think that after a fork swap many people (myself included) get a little too worried about everything working "perfectly". I would bet that the next time you have the forks off for something they will just get tossed back on and off you will go. :wink:
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turtle
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It's all installed. Now what? (geometry and stiction)

Post by turtle »

rbates9 wrote:Good to hear! I think that after a fork swap many people (myself included) get a little too worried about everything working "perfectly". I would bet that the next time you have the forks off for something they will just get tossed back on and off you will go. :wink:
I'm bettin' you're right, rbates. I do get caught up in that 'has to be perfect' thought process. Thanks for all your help through the conversion.
Bill
Central IL
2004 KDX220R
2011 Triumph Tiger 1050 SE
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