OK, so I'm rebuilding my shock...

[t3mp0r4ry nzr]

...actually, its just in bits at the mo, assessing the damage while waiting on seals to arrive.

question: the nitrogen bladder, when out of the shock body and pumped up a little with a bike pump, leaks out air where the bladder slips over/mates with the air valve cap. does this mean its gonna leak when inserted back into the body (ie, will the pressure of insertion make bladder air tight)? I cant see how air tight it could possibley be, as it slips over the vlave cap easy enough.

question: to fill the shock Im planning on filling from the compression adjustor plug, shock unit on its side, plug at top, in order to get most of the air out of systemt as poss. Are there other, more efficient ways of filling and bleeding that I have overlooked? (total submersion looks impractical).

shock is off 96' CR125

[James Deuce]

It's broken. Throw it away. They were never built with fanatics like you in mind. All race bikes are disposable, especially Hondas. CRs are designed to last one single season of being beaten to death with rocks.

That's the good news.

I hope you have some cash lying around to buy a suitable replacement.

May be bad news.

[notch]

Danger should be able to help you out with some new parts and a nitro refill too...

[cheese]

It's broken. Throw it away. They were never built with fanatics like you in mind. All race bikes are disposable, especially Hondas. CRs are designed to last one single season of being beaten to death with rocks.

That's the good news.

I hope you have some cash lying around to buy a suitable replacement.

May be bad news.

Wow, great advice.......

Talk to Greg (Danger) he is the expert. Mind you he may not be keen on giving out his trade secrets.

[theblacksmith]

Workshop manuals are handy.BOOOM might be able to help ya too. Personally Ive never been inside a Honda shock - or I'd be happy to help.

[Danger]

question:does this mean its gonna leak when inserted back into the body (ie, will the pressure of insertion make bladder air tight)?

Provided its not damaged it will seal. But if the shock had no nitrogen and the seal head was leaking I would suspect it has damage.


question: to fill the shock Im planning on filling from the compression adjustor plug, shock unit on its side, plug at top, in order to get most of the air out of systemt as poss. Are there other, more efficient ways of filling and bleeding that I have overlooked? (total submersion looks impractical).


That way will work if you have an Ohlins vacuum bleed pump (about $10,000). Otherwise I don't know anyone that uses that method to finish of a shock rebuild. These can be dangerous if not serviced correctly and I would suggest that it is not an area that you should be trying to take short cuts with.

[CookMySock]

if you have an Ohlins vacuum bleed pump (about $10,000)Can you not make up a valve manifold and gauges, and connect a surplus fridge motor as vacuum pump?

Steve

[Danger]

There are certainly people that can do that. However you want the vacuum to be pulled and then on reverse cycle the shock to be filled with oil. There is one guy making them in NZ with all the fittings for most applications and his also removes water from the oil. His is a little more expensive though at about $13,000 and I don't think its quite ready to go, but its close.

[CookMySock]

fark, I'm in the wrong business. I'll build ya one of those. Why bother recovering oil with water in it? Why not just refill with clean oil?

Steve

[2_SL0]

I successfully rebuilt my rear shock, thanks to some advice from Danger. However I have access to equipment the average person does not have.

Can it be done? Yes, if you have a reasonable mechanical understanding and ability. Would I recommend it for the average person? No, give it to Danger and let him fix it.

[t3mp0r4ry nzr]

Provided its not damaged it will seal. But if the shock had no nitrogen and the seal head was leaking I would suspect it has damage.



That way will work if you have an Ohlins vacuum bleed pump (about $10,000). Otherwise I don't know anyone that uses that method to finish of a shock rebuild. These can be dangerous if not serviced correctly and I would suggest that it is not an area that you should be trying to take short cuts with.

thanks for you concern danger.
I read about the method I described above from another site, but subsequently I found the more traditional method of filling and bleeding, that is, filling the shock as you assemble the components (with shock vertical) and bleeding by cycling the piston to remove air.

as for the bladder, will install and pressurize and check for leakage/pressure holding.

[Danger]

fark, I'm in the wrong business. I'll build ya one of those. Why bother recovering oil with water in it? Why not just refill with clean oil?

Steve

The shock oil should always be replaced off course. Oil exposed to air absorbs the air. Same as water absorbs air (thats how fish breath right?)
Air contains water. The vacuum bleed pump removes air but water can still be present in the oil.
This new pump also removes the water from the oil. Is this necessary for most rebuilds? No. Neither is removing all the air totally necessary all though it is desirable. Air under pressure is absorbed by the oil. Oil under vacuum removes the air. Less air and water in the oil provides a more consistent shock absorber.

Steve what is your back ground or expertise in building vacuum systems capable of removing air and filling the shock with fresh clean vacuumed oil? Also fittings for various applications would be needed but if your qualified and capable we should talk.

[CookMySock]

Air contains water. The vacuum bleed pump removes air but water can still be present in the oil. This new pump also removes the water from the oil. Is this necessary for most rebuilds? No. Neither is removing all the air totally necessary all though it is desirable. Air under pressure is absorbed by the oil. Oil under vacuum removes the air. Less air and water in the oil provides a more consistent shock absorber.

Steve what is your back ground or expertise in building vacuum systems capable of removing air and filling the shock with fresh clean vacuumed oil? Also fittings for various applications would be needed but if your qualified and capable we should talk.Ok I am one of these people qualified at nothing, but knows enough about everything to get myself into trouble, and probably out again.

Yeah I have done enough refrigeration work to know what you mean about removing almost every grain of water from a system, and I see why you want a dry system for shock servicing - removed water is money in the bank 12 months down the track when water will have started eating everything nearby.

If I lived just down the road from you, I'd turn up with pencil and paper and set to work, probably for no charge as I find it interesting, but I'm four hours away.

Really, its just some stainless pipework, swagelok fittings and valves, vacuum gauge, fridge motor, and a nice steel bench, and maybe some graduated-scale clear glass vessels for oil charging. Not dissimilar to conventional refrigeration gear.

My bottom line is, I could hack something up (and so could you), and it would work, but for how long.. Its not rocket science though - maybe some others on KB would collaborate and come up with a design and even a product.

Steve

[Danger]

The beauty of the Ohlins unit is it vacuums the oil all contained in a 300x300x400 case, controlled by solenoids and automatically. Its a time saver and easy to use but an expense that needs to be recovered.
The WP unit is a bit more clunky and requires more user input, has less fittings for various applications and is about $2,000 cheaper.

[B0000M]

Workshop manuals are handy.BOOOM might be able to help ya too. Personally Ive never been inside a Honda shock - or I'd be happy to help.

the only help i could be would be a suggestion of send it to greg.

the insides of suspension are an area i wont touch

[t3mp0r4ry nzr]

after testing the bladder I am happy that it will hold pressure.

have just repainted the spring and polished up the swingarm. She will look beautiful again!:woohoo:

My reckoning is that I should be able to do as good a job of the rebuild as the average bike shop. Sure the quality is gonna be less than the standard of discerning suspention professionals (and Im sure I rank high on the cringe factor for them) but I reckon the money I save by doing the labour is worth 4-5 trail ride entry fees. That is a reasonable saving for a student with an expensive sport. As for safety, the shock had half the oil it should have, no gas, no bump stop and heaps of air in the system. Surely a shock rebuilt by myself with sufficient oil quantity, new seals, new bumpstop and a fresh charge of nitro (with an unavoidable minute quanity of trapped air) is gonna be 10 times more "safe" than how it was.

[t3mp0r4ry nzr]

For those interested, I have finished the shock. End cost, $80 in total, for genuine honda part seal head and bump stop and good quality Rock Oil 5w shock oil (all at retail). But note, this isnt counting a nitrogen recharge (still shopping around, thought $20 was a bit steep).

Im not thumbing my nose, but it was REALLY straight forward. The most time consuming and frustrating bit was compressing the spring to get it off and back on, honestly. As for special tools, the spring compressors were used but other than that I got away with not using a vise and I dont even have a work bench!

It took about an hour to swap over seal heads, insert bump stop, reassemble, fill with oil and bleed And I didnt know a thing about shocks before I took it apart.

Savings? between $150-200. learnt heaps and the satisfaction of knowing a job well done, priceless!! the savings will go towards repairing me dented expansion chamber

thanks all for the advice

over and out

[NordieBoy]

The learning and satisfaction bit are great arn't they :niceone:

[2_SL0]

Excellent news dude.