rear shock servicing

Wheels, shocks, forks, frame
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fred
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rear shock servicing

Post by fred » Tue Jan 12, 2010 9:22 pm

Just wonderd if anybody had any pointers in servicing rear shocks,i need to know if the damper rod can be removed out of the cylinder.the nut has 2 half rounds probaly for tightening.dont know if left or right thread.oil grade and quantity ,ive got a full nitrogen bottle for £15 for regassing .it cant be that much of a black art ,any help would be realy appreciated.ta fred

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Howie
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Post by Howie » Tue Jan 12, 2010 9:38 pm

Actually I would be interested in knowing if anyone has serviced a rear shock cos I have one I will need to sort out soon.

If no one knows Fred, I'll have a pop at it this weekend & let you know.

Mind you, its a Kr1 shock without a remote resevoir on it but should be the same pretty much (?)

Howie

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Post by pablo » Tue Jan 12, 2010 9:48 pm

It can be done but I gave mine to a retired chap who used to work for Ohlins he rebuilt it with new seals and made a new centre rod for it,regassed it the lot.
I hav'nt really been much help there have I :oops:

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Post by Howie » Tue Jan 12, 2010 11:38 pm

No :lol:

Howie

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Post by Howie » Tue Jan 12, 2010 11:56 pm

http://www.dirthammers.com/technical/ky ... ervice.pdf
Just seen this in a google search, could be of use?

The rear shock is a showa on the Kr1's isn't it?

Howie

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Post by JanBros » Wed Jan 13, 2010 12:19 am

Howie wrote: Mind you, its a Kr1 shock without a remote resevoir on it but should be the same pretty much (?)
If I were you, I'd buy a crap KR1-S shock for little to no money (I'm sure somebody will have one up for grabs. I had some, but I putted 2 off them in pitbikes) and have that rebuild, unless you desperatly want to keep the bike "all original" :wink:
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Post by dave32 » Tue Nov 16, 2010 1:10 am

Bit late but maybe of help to some who wanna delve into there shocks..
The b2 and s shocks are nigh on identical same expect for the external reservior(gas bottle).
You need a soft jaw vice to do this,a assistant,and some basic tools.
First release the gas(if theres any in it still) on the scrader valve(looks like a tyre valve) (above spring on b2/on gas bottle on s models),remove the hose and bottle from shock body and drain the oil out,back off preload(spring) completely and you can then remove the 2 halves that are for seating the spring at the base,you need to compress the spring a bit,so may need an assistant unless you'r Arnie!
You need to remove the cover at base of shock body by prising it out using the 2 small cut outs then zip tie it out of the way,then you have to compress the internal damper assembly to access the snap ring that holds it all together,and remove this little bugger,can be tricky as the damper wants to return and cover it back up so get a friend to hold it down while your faffing with the ring.
If your shock was leaking you need a new seal head assembly,these are availabal from 'Off Road Only' by mail order for about £25.
You just need the internal(shaft) and external I.d for a KYB,if memory serves me there 14 x 40mm.
To access the seal head your gonna have to disassemble the rod assembly,both shim stacks (rebound and compression) need to be kept in order,theres about 15 shims and there all different so lay them out as they were,mix them up and you will be revalving(leave alone unless you kno what's doing what!)
To get to the seal head you need to remove the lock nut on the shaft,the shafts are 'peened' over for safety so you need to grind this off,dont try to undo the nut until all burrs are removed(use a file to put a nice chamfer)your damage the shaft thread.Just be careful and take you time.
Your gonna need a nylock nut to replace it,take the shaft to a fastener shop and they should have one to match.
When fitting the new seal head put a piece of plasic bag on the shaft with some grease so you dont damage the lip{theres a proper tool but this does the same thing).
Clean everything in solvent and re assemble the shaft,oil wise use something liket 5/7.5w or 10w silkolene srg(available from off road only),dont use normal fork oil as it will deteriorate with the heat.
You need to purge all the air out of the damper rod/shock body/hose etc,also use a new snap ring if your's looks iffy(lost its tension/damaged by removal),'Off road only' again.
If your using a kr1 shock,you dont need a high pressure of nitrogen as theres no bladder,so just add around 30psi of air through the schrader valve,once its filled with oil(just below thread),and purged of air.
You'r know if its purged as the action of shock during its full travel will be smooth,if its not theres still air in it.
Dont proceed until you'r 100pc happy its working ok.

The kr1s needs around 120 psi of nitrogen to work as it should.
If it leaks oil out of the gas bottle around the base you need a new bladder,also it wont hold pressure,the base is held in by a snap ring aswell so just compress to expose it,using a large socket.
Most of it is self explanatory when you start dismantling,and tbh theres not much in them,take pics and lay everything out in order.
Just make sure you purge all the air out and dont be afraid to get oil everywhere!
If your only changing the oil,you dont really need to strip it completely,you can flush it out through the part where the hose joins on the s model/schrader valve on b2 model,then fill with new.
Hopes this helps anyone who thinks its all a black art and we should leave well alone,(im assuming that anyone who's gonna do this is fairly competent and has a degree of common sense)
Any questions feel free to ask.
Dave
Last edited by dave32 on Wed Nov 24, 2010 6:25 pm, edited 2 times in total.

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Post by alimorg » Tue Nov 16, 2010 10:45 am

Excellent writup dave, going to make this a sticky
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Post by fred » Tue Apr 12, 2011 9:51 pm

will be doing this job in next few days ,and if i get the gist of it i can`t use 10w fork oil ,ive read or heard it will get to hot ? any pointers please gentlmen,if the rebound bladder fails i take it just loses pressure ,ile use the shock and resevour off bertie ,mine leaks ,i take it bleed to top of shock then attach hose and bleed again ,

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shock parts

Post by Professor » Wed Apr 13, 2011 12:36 am

If anyone's shock needs a new piston ring I have a few new ones that I had made, thay are no longer available from kyb.

I also rebuild shocks if anyone wants them doing
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Re: shock parts

Post by alimorg » Wed Apr 13, 2011 2:14 pm

Professor wrote:I also rebuild shocks if anyone wants them doing
Hi Prof,
How much for a KR-1S shock re-build
Cheers
AL
"A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. " - Douglas Adams

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Post by dave32 » Wed Apr 13, 2011 3:01 pm

Hi Fred,
Nope dont use shock only oil as your right it will break down fairly quickly.
Silkolene Pro RSF is what you want,7.5wt suits me at 12 stone for track use,use 10 if your a bit heavier.
The bladder in the reservior,if it wont hold any pressure yes its failed,its not specific to rebound it effects compression too.
You can remove the snap ring after releasing any pressure first,you need a bout 20psi though to help it out otherwise it just keeps dropping back down,once this is removed you can inspect the bladder ther fairly robust and generally last but any probs will be evident.
Bleed the main body of air first and leave it to stand for half hr or so then connect the pipe and fill this with oil using a syringe,then fill the resrvior til it overflows and connect.
If theres any stiction or its not smooth through its full travel theres air still,dont get it pressurised til its all gone!
A messy way but guarantees no air is to submerge the parts when you assemble them together(you need a fair bit of oil and a nice clean large container though and all external parts must be spotless else you contaminate the oil).
HTH a bit
Let us know how you get on
Dave

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shock cost

Post by Professor » Thu Apr 21, 2011 10:09 pm

Shock rebuild cost £69 + parts no VAT

a pattern seal head is normally £28

it might also need a bump stop, shaft or bladder
piston ring £16.

You should service your shock and forks every so often (5k miles or 1 to 2 years) just to clean internals and replace oil. If you don't some internals can be worn beond repair :cry:
Last edited by Professor on Sun Feb 07, 2016 8:19 pm, edited 1 time in total.
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Post by SP_BOTT » Tue Nov 22, 2011 9:52 am

Hi, anyone had their shock rebuilt yet? good S/H ones are few and far between, and mine could do with being spruced up a bit, as it's looking a bit tired and shabby.

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Post by 375 » Tue Nov 22, 2011 5:56 pm

Sp-bott,
Just had mine done by professor, (the post above) about 3 weeks ago, new shaft the lot its fitted but not on the road yet,

Took about 2weeks. Good communication, sent old parts back and receipt
for my records :)

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