mcnulty Posted February 7, 2009 Report Share Posted February 7, 2009 (edited) Need help with my friends 05 sherco 2.9. The front forks do not have a plush cushion feel to them. There is zero sag when mounting the bike, acts as if its (forks)locked up. With body weight force we can get the forks to compress and rebound but just does not feel anywheres near as nice as my 06 sherco. I will list the things we have tried and if you know of anything else please let me know. 1. loosened up all pitch bolts and axle and checked for twist in the legs. This also includes the fork fender brace. 2. compressed the forks and cracked the top cap to see if air comes out .. which there was. The forks seals/dust covers on the slide tubes look brand new..not cracked at all. Should our next step be change the shock oil? Do a full blown fork rebuild? My friend just purchased the bike and it looks as if the previous never did any type of maintinance. Edited February 7, 2009 by McNulty Quote Link to comment Share on other sites More sharing options...
feetupfun Posted February 7, 2009 Report Share Posted February 7, 2009 (edited) A bent tube or bent tubes can cause this effect. You should be able to check for this by loosening off the tube clamps for one tube and the axle clamp and rotating the fork tube within its clamp. Another way to find out where the stickiness is coming from is to put the bike on a stand and take off the fork caps. Move the wheel up and down through the stroke. That way you take the spring force and air pressure out of the equation. Edited February 7, 2009 by feetupfun Quote Link to comment Share on other sites More sharing options...
jse Posted February 7, 2009 Report Share Posted February 7, 2009 Need help with my friends 05 sherco 2.9. The front forks do not have a plush cushion feel to them. There is zero sag when mounting the bike, acts as if its (forks)locked up. With body weight force we can get the forks to compress and rebound but just does not feel anywheres near as nice as my 06 sherco. I will list the things we have tried and if you know of anything else please let me know.1. loosened up all pitch bolts and axle and checked for twist in the legs. This also includes the fork fender brace. 2. compressed the forks and cracked the top cap to see if air comes out .. which there was. Should our next step be change the shock oil? Do a full blown shock rebuild? My friend just purchased the bike and it looks as if the previous never did any type of maintinance. (I'm assuming the last sentence refers to the forks, not the shock) It sounds like the forks need to be dis-assembled and inspected, provided you tightened the fasteners in a way that kept the forks aligned correctly and the problem persists. Generally, the two things that contribute to fork stiction at this level are (1) worn bushings and (2) bent fork upper tubes. I have seen lower legs hit hard enough to dent them and cause internal binding but this is, luckily, rare and a problem with the cartridge internals could also cause stiction, but is also unusual. After the forks are completely apart, look carefully at the bushings (these are the internal "bearings" that allow the tubes to smoothly interact). There are two in each fork, one at the end of the upper tube and one inside the top of the lower leg. They usually are steel, with a copper coating the a coating of grey Teflon (the Teflon is on the outer part of the upper bushing and on the inside of the lower leg bushing). If the grey coating is worn through anywhere at all, they will need to be replaced. The upper tubes are checked with v-blocks at each end and a dial indicator probe at the center area. The tolerance is usually .003", which does not sound like much of a "tolerance", but a small deviation at the top end of a fork equates a large deviation at the other end and it does not take much to cause binding. I wouldn't try straightening them yourself without special tools, like a diameter specific pressure plate (it fits the exact diameter of the tube) and diameter specific support blocks that prevent distortion and flat spots. A good suspension or machine shop should be able to do the job relatively inexpensively. Jon Quote Link to comment Share on other sites More sharing options...
lineaway Posted February 7, 2009 Report Share Posted February 7, 2009 Forks will also act this way when over filled. The problem lies in adding the recommended capacity, but not taking the correct measurement of level afterward. Or another way to look at it was not completely dry when the new fluid was added. Try calling RYP for a correct measure ment with the forks collapsed. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 7, 2009 Report Share Posted February 7, 2009 On the '05, the quantity is 330ml per leg. Good cleaning and fresh oil of 5wt may go a long way here, although they are different than the later models to some extent. Quote Link to comment Share on other sites More sharing options...
b40rt Posted February 7, 2009 Report Share Posted February 7, 2009 On the '05, the quantity is 330ml per leg.Good cleaning and fresh oil of 5wt may go a long way here, although they are different than the later models to some extent. I would try this first, was the previous owner 20 stone ? He might have put in heavy weight oil. Quote Link to comment Share on other sites More sharing options...
mcnulty Posted February 7, 2009 Author Report Share Posted February 7, 2009 Thanks for the responses....We drained the oil and are finding metal shavings in the drain oil..also finding metal shavings in the and around the top caps. Any body got clues for the metal shavings. Also looks as if the right fork leg was low on oil..maybe filled with about 250cc. Also with the caps, oil and spings out the the action of the tube still seems to catch near the bottom of the stroke.. any ideas guys? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted February 7, 2009 Report Share Posted February 7, 2009 Metal shavings = pull that fork leg apart to investigate. Many possibilities for cause. Not worth speculating. Quote Link to comment Share on other sites More sharing options...
jse Posted February 8, 2009 Report Share Posted February 8, 2009 Thanks for the responses....We drained the oil and are finding metal shavings in the drain oil..also finding metal shavings in the and around the top caps.Any body got clues for the metal shavings. Also looks as if the right fork leg was low on oil..maybe filled with about 250cc. Also with the caps, oil and spings out the the action of the tube still seems to catch near the bottom of the stroke.. any ideas guys? Are they actual "shavings" or dark metallic powder-like particles? Either way it would be a good idea to pull them apart for a good inspection. The dark powdery particles (they usually collect in the bottom of the lower leg) are normal as they are deposits from the outsides of the springs that rub on the inside of the upper tube (a lot of riders mistake them for dirt, but a quick check with a magnet tells otherwise). If you look closely at the springs, you'll see how the outside of the coils, mainly in the center of the spring, take on a polished look. The stiction at the bottom of the stroke sounds like a bent upper tube and you'll also probably need to replace the bushings as a bent tube will damage the bushings if the forks have been used for a time with a misaligned tube. Jon Quote Link to comment Share on other sites More sharing options...
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