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XR4 Shock Rebuild

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Team,

I am getting ready to rebuild my rear shock. Well, I am aiming to just change the fluid. I was looking in my manual and it looks pretty straight forward. However, it also talks about taking the valve out of the reservoir and filling it with fluid. Then that gets presurized to 142 PSI. Is there really fluid inside of the bladder? How much fluid do you put in? It seems like they want you to top it off. Does that leave enough room for the nitrogen? Any info. or tips would be greatly appreciated.

Thank you in advance,

J :excuseme:ustin

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There is no fluid in the bladder just nitrogen.

A simple oil change isnt too expensive, I'd just have a shop do it rather than hassle with the bleeding procedure. Getting all the air out can be a PIA.

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The service manual talks about filling the bladder with oil so that it will be non-compressible as part of their bladder disassembly technique (i.e. they don't want the bladder and cap to shoot across the room).

If you are aiming to just do a fluid change and have no interest in inspection or valving changes, then there is no point in dismantling it. Suspension shops take things apart and then refill at the seal head, drilling a bleed hole below the o-ring if not equipped, but as you can see in your manual, you can also refill and bleed via the compression adj. port. The showa seal head o-ring drops into the clip groove much worse than a similar KYB, making seal head removal and reinstall a bit of a pain - so you will avoid this.

Remove shock, spring from shock, open both adjusters fully, cycle the damper several times to try and get as much particulate suspended in the oil, release the nitrogen, remove the compression adjuster, pump out 99% of the used oil, clamp the shock in a soft vice at an angle and refill.

Because the showa has such a small hole into the body below the comp adj. it can be tedious to refill. Sometimes using a small straw from e.g. a WD-40 can allow the air out as the oil goes in. Otherwise you can "suck" it in a bit at a time by extending the damper as it is poured in.

The key is the bleeding of all the air. Since you aren't a shop working on the clock for $$ you can take your time and run the damper back and forth until you haven't seen even a tiny bubble in the last 10 minutes. Tilt appropriately so that the comp. adj. port is the highest point. You can also temporarily screw in the adj. so that you can cycle the damper a few times and make sure there is no air in the piston and shims and then let stand for a while so the air won't be suspended in the oil. Also tilt so any air in the bladder chamber can get out. Sometimes holding your thumb 95% over teh compression adj. port will let you get a more appropriate tilt while keeping the oil above the openings.

The small precharge in the bladder ensures it holds its shape when filling the shock and when screwing in the comp. adj. that any excess will just flow over the sides. All said and done, it will use less than 1/2 a litre. There are also some tips on the N2 recharge in the "Normal after rebuild" thread on the suspension forum (also regarding an xr400 shock).

Disclaimer: I am not an expert, this is just "works for me" type info gathered from personal experience etc. Use at own risk, blah blah blah...

:cry:

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I came across the same section a couple of weeks ago, but it turns out that is the bladder disassembly section. I doesn't sound like you need to disturb the bladder, so I believe the section you want is somewhere after that section of the book. If I can remember to find it when I get home, I'll post.

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Finally got around to looking at the manual. The sections you probably want in Chapter 14 are in the Shock Absorber section (beginning on page 14-10 in my book):

Damper Disassembly (page 14-15)

Piston Ring Replacement (page 14-16, if necessary)

Damper Rod Disassembly (page 14-16, if you're revalving)

Assembly (page 14-19)

In all these sections, the bladder stays installed.

If you only want to change the oil, you can be done in less than an hour once you have the shock in hand. Just be sure that you follow the manual and spend some time getting the bubbles out. Good luck :cry:.

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