shock tuning for enduros

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Have you considered air for your own initial charges?
Some tyre shops have found that they can charge extra for filling car tyres with nitrogen(!) and those tyre shops may be talked into cranking up the pressure to 10 bar and recharge your shock at a token fee, as long as you have a shrader valve that they can connect their valve chuck to. Then enjoy at the public room your money saving .
 
my shock bleed gear is now on the way.

i hear ya smorgy but if i'm getting a 200lb pressure gausge i'll get some nitrogen to go with it mate if i can.
as it is i don't ruun a moisture filter on the compressor and it won't even go to 250 i don't think so....

regards

Taffy
 
smorgy? per?

et al?

what is the starter price (SP) on using air then?

i believe nitrogen runs cooler, that air has moisture and oxygen aids oxidisation etc. i would have imagined that in my cooler climate the temp would still be ok?

drehwurms kit came last night....looks good, all new gear. need to set it all up and see what the hell he has been on about.....!

regards

Taffy
 
You get air at the petrol station; BP, Safeway or whatever place that have decent pressure. Would you get 7 bar on a good day?, Its free in most cases. 10 bar is the nominal WP pressure though.
Considering that you will disassemble to drill new and larger holes in your pistons every second week to come, and refilling with fresh oil, you would not be worried by the oxidation. Moist the same thing, let the air tank stand cool if possible to condense the moist before the fill, or just pick a frosty day when the air is dry. Most of it is nitrogen anyway.
Does Nitrogen run cooler? How much cooler, do you have a figure?
You should service your shock often but most shocks do not get serviced for years and years, this is where you really want nitrogen. If you have argon then just use it, it is more expensive than nitrogen but if you already have it for your welder just use it. That is what I would do if I was into shocks, use argon. But I'm not so all of this may just as well be bs anyway. :computer:
Then get the nitrogen when you feel like doing it by the book. Regards.
 
True, air is almost 80% nitrogen, as much as nearly 80% of the expansion of air would be the same as nitrogen (since it actually is nitrogen) and whatever difference there might be in the rest of it would only be able to influence it up to a minor degree.

Good point.
 
For those that want to use air as temporary fill for the reservoir and dont have access to a 150 PSI capable compressor, a good option could be a high pressure hand mountain bike shock pump - cheap & capable of pressure reqd.
 
Cheap 12v car compressors often have high-pressure capability 200psi or more. Generally the cheaper the better up to a point- smaller piston.

Have used "Truck air" compressor made is the USA it’s a piece of crap for 4wd trips but works good on shocks. Goes up to 220psi claims 275 but can't.

In my limited experience (with one KYB shock and one Showa over the last 10 years) it is almost impossible to tell the difference between dryish air ( 5-15% rel humidity @ 35deg C) and nitrogen with regards to expansion and temp. the change in oil viscosity with increasing temp seems more significant making the VI of the oil more important than the choice between nitrogen/air.

As Smorgasboard pointed out if you happen to be pulling the shock apart often to drill a great many holes and change a great many things at one time possibly requiring even more pull downs to get where you want to go then air is ok but really it's probably best to use nitrogen in WP shocks because of the possibility of water condensing on the sides of the res and then small amounts getting past the piston.

May or may not occur but seems much safer corrosion wise in a bladder shock.

Regards
 
Gentlemen
it is dangerous to use air in shock, why you ask you are mixing oxygen with oil
given the right circumstance it could exploded, you atomize oil in oxygen with heat
and it will explode, thats how a diesel engine works, so use nitrogen

happy shock tuning VIKING
 
Fit a glow plug, a high pressure atomizer and you will be able to beat the KTM hop every time...
 
Shrader valving your shock.

Tube_shraders.thumb.jpg

A shrader valve from an inner tube. Pick the least rusty in your inventory of punctured tubes.


IMGA0892.thumb.jpg

Shrader valve inserts come in different lenghts, the short ones do not need an inner shoulder in the valve body so if you want a really short Shrader valve just cut the valve body off and use a short insert.


Cap_shrader_screw.sized.jpg

Here is the cap, the Shrader valve that won the beauty contest and the stupid WP N2 screw. (And a z shaped allen key.)


Drill_7_7mm.thumb.jpg

Just drill out the stupid threads. I used a 7.7 mm drill for the hole to suit the shrader valve.


Stickingout.sized.jpg

Shrader not sticking out much. Adjust the protrusion to suit your air chuck.
Loctite and let it settle.
 
RE: Shrader valving your shock.

smorggy

does it take air wirhout leaking? it's very short and i wondered how short it is before the air line can't grip it?

regards

Taffy
 
The side claw air chuck doesn't go inside the recess and the shrader valve have to stick out more than in the picture for it to grab properly.
There will be changes. I'm getting a thread on air chuck. The nut that you can see in the recess will be replaced with a lower one. Hopefully the original rubber plug will still be usable and nothing to stick out for the chain to ruin.

Regards
 
That Shrader chuck seems like a very good one. I won't spend that money though. A simple one that you press against the shrader manually will probably do, provided that it opens the valve insert while sealing only. At 10 bar of gas pressure the force to overcome is just 3 kg and then some to compress the seal. I do not really see the need of a gripper for the N2 hose for anyone with normal stregth. The Shrader valve can then be so short that you can put the rubber plug back without any problem. And nothing sticking out.

Anyway, here is what was inside.
PDS Shock OEM shimming. Year 2000.
nut
21 x .3
30 x .2
32 x .2
34 x .2
36 x .2
Piston without the 1 mm hole.
44 x .25
42 x .25
40 x .3
38 x .3
36 x .3
34 x .3
32 x .3
26 Holed Spacer Heigth 14 mm. The holes look small to me...
21 x .3
32 x .2
34 x .2
36 x .25
36 x .3 Preload ring with a 32 x .2 Centering shim
36 x .2
36 x .2
Piston with the 1 mm hole in one port wall.
44 x .2
44 x .2
44 x .2
44 x .2
32 x .15 split shim
38 x .25
38 x .25
28 x .1 split shim
34 x .25
34 x .25
34 x .25
21 x .3
43 x 4.0 mm disk
rod

If anyone have any ideas on how to improve this old shock then please let us know. Post or PM are equally appreciated.

Regards.
 
now i thought i had bought a shock from a 2001 but when i got it it was from an earlier bike (the *******s!!!). the compression screw is a domed black plastic cap and i think (sdat in the house) it faces the back of the bike and not outwards like the later models?

if you have the above i would just weep, sob and then cry. get a later shock spo we can both speak the same language!

if it is the same as later models i have some settings for you.

regards

Taffy
 
Smorgasbord said:
That Shrader chuck seems like a very good one. I won't spend that money though. A simple one that you press against the shrader manually will probably do, provided that it opens the valve insert while sealing only. At 10 bar of gas pressure the force to overcome is just 3 kg and then some to compress the seal. I do not really see the need of a gripper for the N2 hose for anyone with normal stregth. The Shrader valve can then be so short that you can put the rubber plug back without any problem. And nothing sticking out.
Click to expand...

If you hear any "spssssst" when you remove the chuck you've probably lost 70lbs of nitrogen pressure from the reservior...THAT is the reason for the sealed chuck. If you insist on doing it the cheap way, then you better jack the initial setting up to compensate for any loss...doing so you will have no way of comparing one shock build to another cause you can't really know what pressure you had in them?
 
Good point, actually.

ktmlew said:
If you hear any "spssssst"
Click to expand...
It wasn't me....

I said:
provided that it opens the valve insert while sealing only.
Click to expand...
Of course that order of function will have to be verified. The "spssssst" thing would have to apply to any hose chuck, cheap or expensive. A hose chuck with a manual Shrader insert activator, however it is activated, would be the best and safest.

Regards
 

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