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Suspension Setup/Toubleshooting

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SUSPENSION TROUBLESHOOTING
 
 
 
This information contains a list of concerns, and solutions to the most common problems riders have with their suspension.
 
Damping Extreme's
 
1. Too much rebound damping (also known as packing)
The suspension is held down in the stroke because it cannot rebound fast enough and each bump created additional compression.  The ride becomes harsh due to too much force being needed to initiate movement.  This also creates a loss of traction due to tire deflection.
 
2. Too little rebound damping (Pogo)
When there is too little rebound, there is not enough control of the spring energy.  This causes a pogo like action.  This can cause vertical movement that can lift the wheel off the ground, and cause a loss of traction.
 
3. Too much compression damping (harshness)
When you have too much compression damping, this will cause the front wheel to deflect off the rock, log, stump, root, or rut on impact because there is too much resistance to movement.  This will equal are harsh ride.
 
4.  Too little compression damping (bottoming)
The wheel moved past the crest of the crest of the whoop, rut, log, rut during compression and is not able to follow the backside of the bump causing a loss of traction.  This will feel mushy an can bottom easily.
 
 
There are a number of conditions that contribute to your everyday suspension action.  There are so many variables that go into suspension set-up that are completely unnoticed. Something as simple as changing the brand, and type of tire can affect your suspension positively or negatively.  The section below will go into troubleshooting your suspension action.
 
 
Forks
 
 
Bottoming
 
1. Oil level is too low.
2. Not enough low speed compression damping
3. Not enough high speed compression damping
4. Spring rates are too soft
5. Not enough pre-load
6. Valving shims are distorted.
 
Too stiff-Deflects, Harsh, Nervous, Twitchy
 
1. Too much compression damping adjustment, high speed, and or low speed
2. Too much compression damping internally
3. Spring rates are too stiff
4. Too much low speed rebound damping= packing
5. Oil level is too high
6. Stiction
 
Poor traction
 
1. Poor tire/compound
2. Too much tire pressure
3. Tire pressure too low
4. Too much low speed rebound damping
5. Too much low speed compression damping
6. Too little low speed rebound damping
7. Not enough low speed compression damping
 
Not enough weight of the front end:
1. Axle placement is too short
2. Swing-arm is too short
3. Sitting too far back
4. Bars to high, or sweep too much
 
Doesn't turn
This happens to be the most misunderstood and misdiagnosed fork symptom.  It typical is more of a geometry issue, than a suspension issue, though these do overlap. 
Do the bars turn easily, or is hard to turn the bars?
 
If it is easy to turn start with section 3 (poor traction) then 5 (pushes)
If it is hard to turn (requires excessive force) go to section 6.
 
A. Tire profile is too flat or wide
B. Riding position- not enough weight on the front end
1. Seat too low
2. Bars too high
C. Riding style (not everything is the bike)
1. Riding style
2. Rider doesn't understand the concept of counter steering
3. Not weighting the front end
4. Elbow down riding style
5. Sitting too far back
6. Rider centerline to outside of bike centerline
7. Not looking through turns
 
Pushes
(Easy to turn the bars, but the bike doesn't turn, low traction)
 
1. Front end rides too low in comparison to the rear (check sag)
2. Raise the forks (slide forks down in triple clamps
3. Lower the rear end
4. Fork springs too soft
5. Not enough fork pre-load
6. Low speed rebound too high, causing packing
7. Not enough low speed compression damping
8. Increase low speed compression damping
9. Anything that makes the rear higher than the front (Sag)
 
Takes excessive force to turn the bars
(Plenty of traction, doesn't complete the turn.  This is more of a geometry issue that suspension action.)
 
1. Front end is riding too high
2. Lower the front end
3. Too much spring pre-load
4. Spring rates too stiff
5. Rear ride height too low (Sag)
6. Forks have too much air (bleed forks)
7. Lower the rear end (Sag)
8. Too much low speed compression damping
9. Too narrow of a bar
10. Sticky forks (Stiction)
 
Dives under braking
 
1. Modern forks should, linkage (BMW) front ends may even rise
2. When braking the dive is controlled by spring forces only (rate, pre-load, and air gap) valving has nothing to do with this.
3. Fork angle is too flat, choppered out, too much rake
4. Fork springs too soft
 
 
Feels loose
 
1. Not enough low speed rebound damping
2. Not enough high speed rebound damping only on big bumps
3. Not enough compression damping
4. Spring rate too soft
5. Steering bearings loose or worn out
6. Swing arm bearings, or linkage bearings worn out
7. Tire pressure to low or high
8. Fork flex, chassis flex, swing arm flex
9. Suspension needs servicing (oil broken down, bushings worn)
10. Worn out rebound piston bushing (rare)
 
Sticky forks
 
1. Misaligned forks
2. Triple clamps bent
3. Bent fork tube
4. Bent axle
5. Bushings worn
6. Poor bushing design
7. Upper tube anodizing worn
8. Air pump (seals worn)
9.  Poor quality seals
10. Poor oil quality
11. Triple clamps too tight
12. Misaligned fork tube height
13. Forks not broken in (twin chamber)
14. Metal imbedded in bushings (Pre-load washers not located properly, aluminum washers, steel springs directly on aluminum caps, fork caps improperly installed)
 
 
Headshake
(Fast side to side movement of the bars)
 
1. Chassis not straight- twisted or offset
2. Misalignment of wheels, axle marks off
3. Fork flex, chassis flex, swing arm flex
4. Not enough trail-not enough self centering effect
5.  Worn out or loose steering bearings, binding, dragging
6.  Too much trail- returns past center than re-corrects the other way quickly
7. Oil level too high
8. Not enough low speed rebound damping
9. Too much high speed compression damping-deflects on bumps
10.  Tire pressure too high or too low
11. Poor tires
12.  Tire not properly mounted
13. Wheel out of balance-bent rim
14.  Brake rotor is bent
15. Sticky forks
 
Chatters
(This can be a vibration/harmonic problem when the input frequency matched the natural frequency of the suspended system,  This is often confused with and can cause headshake)
 
1. Not enough pre-load damping
2. Not enough compression damping
3. Spring rates to stiff
4. Too much compression damping
5. Too much rebound damping
6. Too much or too little tire pressure
7. Poor tire design
8. Chassis flex
9. Sticky forks
 
 
 
Bounces off the ground on jump landings
 
1. Bottoms heavily (see #1)
2. Not enough high seed rebound damping
3. Not enough low speed rebound damping
 
Deflection
 
1. Too much high speed compression damping
2. Spring rates too stiff
3. Too much pre-load
4. Too much low speed compression damping
5. Too much low speed rebound damping
6. Sticky forks
 
Leaky seals
 
1. Old seals
2. Nicks in tubes
3. Worn bushings
4. Bent tubes
5. Improper installation
6. Fork tube too smooth (Extremely rare Solva suspension)
 
 
Shocks
 
Kicks
This is commonly misdiagnosed.  This symptom is usually diagnosed as not enough rebound damping however, it is usually caused by one of two things, It's too stiff, or way too soft.
 
1. Too much high speed compression damping
2. Spring rates too stiff
3. Way too much low speed compression damping
4. Too much rebound damping
5. Linkage bearings bad
6. Too high of tire pressure
7. Way too much pre0load
8. Sticky shock
 
Bottoms
 
1. Not enough low speed compression damping
2. Not enough high speed compression damping
3. Spring rate too soft
4.  Too much static sag
5. Suspension fluid worn, or poor quality
6. Not enough nitrogen pressure
7. Blow bladder
8. Distorted valving shims
 
Swaps
 
1. Too much high speed compression damping, deflecting, not bottoming
2. Not enough low speed rebound damping-loose
3. Not enough high speed rebound damping
4. Spring rate too stiff
5. Spring rate too soft
6. Sticky shock
 
Feels loose/shock pump
 
1. Not enough low speed rebound damping
2. Not enough high speed rebound damping
3. Not enough low speed compression damping
4. Spring rate too soft
5. Too little pre-load
 
Poor Traction
 
1.  Too much low speed rebound damping
2. Too much low speed compression damping
3.  Not enough low speed rebound damping
4. Too much tire pressure
5.  Tire worn
6. Shock heim bearing worn
7. Linkage bearings worn
8. Spring rate too stiff
9.  Too much pre-load
10. Sticky shock
 
Not tracking
 
1. Too much low speed rebound damping
2. Too much high speed compression damping
3. Too much low speed compression damping
4. Sticky forks, or sticky shock
 
 
Sticky Shock
1.  Linkage not maintained
2. Swing arm bearings worn
3. Shock eyelet bearing not lubed
4. Bent shock shaft
5. Worn/ poor quality seals, fluid, bushings
 
 
Suspension Set-Up
 
Front Forks and Wheel Installation
Installing the front wheel incorrectly can cause the forks to bind, this will create a harsh stiff feeling as the forks go through the stroke. Most lower triple clamp lower bolts should be torqued to 12 to 15 ft. lbs., with the uppers being torqued 17 to 18 ft. lbs. Consult your service manual for the correct torque setting.
Installing the front wheel correctly will ensure you do not bind the front forks.
1. Install front wheel.
2. Slide axle through forks, and tighten the nut (O.E.M torque spec) leaving the axle pinch bolts loose.
3. Remove the bike from the stand, lock the front brake and compress the suspension 4 times to center the axle in the fork lugs.
4. Tighten the axle pinch bolts to manufactures torque specification.
Shock Installation
When installing the shock onto the bike, always torque the bolts to manufactures torque specification. We always install the shock, take the bike off of the stand a put it under a load, then torque them to specification. This will insure there is not any binding in the linkage, or on KTM's in the heim joints.
 
Tire Pressure
A high amount of tire pressure can cause harshness and deflection which will create a feeling of unbalance on tough rocky, root infested trails. Depending on the weight of the rider, we typically suggest for 2 strokes 10 to 12+PSI, and for four strokes 10 to 14+ PSI. Of course this is dependent on where and what type of terrain you are riding
 

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