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Existentialism-- Just a bloody good excuse to go riding...

Monday, June 28, 2010

DIY Time Again: Thrust Bearing for the Coil

As usual, trust Dirty and his rancid mind to start another tinkering project or bring in another new component. Who else in his gang of dumpy old fart pals he got to be tester again this time!

Toyed with the idea before and read up some more here about the Obtainium adapters and removing the spring binding from the coil and thus eliminating another friction point on the shock.

Gotten the right size bearings for the shock with accompanying washers. Turns out to be 3gm lighter than claimed weight of 28gm

Grease up, slip into shock and adjusted preload as before. 1- 1 3/4 the point where it takes a bit of force to move the spring laterally.

About to swap a new Rubber Queen 2.4 on the rear but thought that might change things a bit and detract from noting what difference the bearing may make on my usual stairs+carpark-root -simulation.test. So no change and all settings on bike remains.

For now, it's lacking an adapter cup. However internal ID of bearing and washer leaves only ~1mm with the raised part of the lock ring when they are housed over it. Hence everything is sitting nicely with only the slightest bit of wiggle. Greased up and preloaded, lateral movement is further minimized.

[Note: when machining a cup will have to take into account the OD of spring and check thickness of material.

Can't fit a vernier caliper in the space to measure so to the best of my Eye-Ball-Caliper ability:

When pushed downwards, clearance of coil OD to piggy body is only ~4mm

When pushed upwards away from the piggy, clearance is max ~8 mm.

The Stair Test

...Straight out the lift and down the usual flight of 14 steps, slamming on the brakes just before the front wheel hits the last couple of step.

Expecting the same chattering rear like the last thousand time I did it... All I can say is things somehow seems to smooth out and those little kick from the rear is almost non-existent.

Strange, would have thought the effect of the bearings was to work more significantly in the last 1/3 stroke of the shock to ease the coil binding effect where it is most extreme.....

But I'm definitely not complaining....if this "smoothing out effect" or wadever u want to call it is not due to my imagination, I'll be smiling throughout the dense rooty downhill sections in some of our local trails come this weekend.

Carpark Root/Rock Simulation Test

Full throttle...just pedal on a higher gear. No significant difference from before putting on the bearing. Everything tracks just as well. Maybe the only absent thing is any knocking sound. Not sure if why or if the bearing somehow has got to do with it.

Stomped on the same place again in reverse direction but this time in granny. Nothing unusual again.

But this is the first time I see how slack a chain can get when ramming through a series of humps an ledges on a granny gear. Guess that explains the chain slaps I keep hearing on the trail. The previous chain guide was a love hate affair, decided to take it off last week for good.

Last thing I notice was doing tight turns around the carpark. Somehow the turning radius seems "smaller" and easier to manage out of the turn even when seated. Again cannot confirm if there is any change caused by the bearing but at max compression point when rounding a turn, I swear the sping rate felt lighter and making the rear track leech-like. Should be fun to test on berms this weekend.

Final Test...actually still trying to perfect my yet to be perfect J-hop from flat on the EG...
Ok I admit, this has absobloodylutely nuthin' to do with testing the bearing ...

Arrrghhh damn it, shifted my weight a split sec too early again. FARK $*@$*#Y#%$O*^O&$]


  1. good enough report to get me going. secretly i had to get you to do the raw thing. to make sure that there is some benefit before i start making housing, cages or use joint washers.

    just to keep RnD costs low. at the way things look, shld be awesome..

  2. Ha...that means i get to test the first cup too hor!

    Rotten mud from all these rain makes me not feel like the usual testing grounds

    Think will hit Ketam again on weekend. That "positive turning effect" should be testable on the nice berm at the end of "China Bowl"