monoshock internal repair - not hard anodized 1983 YZ

[alexbrown64]

Hi,
After sending my monoshock from a YZ125K to Shock Treatment for the full Race Tech rebuild, they are saying that it is knackered.  The problem was they were not hard anodized at the factory so the internal shock body wears out and  they reckon it will leak when they put it all back together with new components.  They have said that they have heard of a place in Melbourne that can repair the shock body internally but dont know who they are.  Anyone heard of this?  The wear would eventually occur on all the early YZ's.
I have purchased a few cheap working monoshocks in the US in the hope that i get one that isn't worn and can be rebuilt.  Shock Treatment says that if they can rebuild one, they will hard anodize it to stop the problem reoccurring.
Thanks,
Alex

[Viper79]

I wonder if Electrosil would be able to do it?

http://www.electrosil.com.au/

[evo550]

YSS

[Nathan S]

They don't leak with a worn body. What happens is that the oil can bypass the valve piston, and the shock action will be inconsistent.
Most blokes won't feel it. The valving is horribly primitive, and plenty of VMXers are used to riding with three-quarters rooted shocks - a rebuilt shock with minor/moderate wear in the body, is going to work better than an unworn shock with 30+ year old oil in it...

None of this is to say that the wear is a good thing: it isn't.

There's enough decent shocks out there, they you should be able to track down an unworn body.

It seems that good maintenance of the shock (keep fresh oil in it, not black sludgey grinding paste), not riding the bike with a worn out seal head bush (easily identified by the shock leaking), not riding the bike once the oil has leaked out, seems to make the difference.

I've seen some high mileage ITs with good shock bodies, and some low hour YZs with buggered bodies.

[alexbrown64]

Thanks for all the good advice so far....I have emailed electrosil with the details... http://www.electrosil.com.au/ may be after xmas now but i think they could get the shock body back into spec as they specialize in aluminum.  I will gather all my options... send the 2 working shocks to Shock Treatment and also find out more about the electroplating and boring process for shock bodies.  How would the original internal measurement be worked out.  Is there sections of the internal bore that remain unworn and measurements can be taken from?  Or would Shock Treatment send them a shock body with a new valve piston or whatever goes in there to get the correct bore?
Cheers,
Alex

[smed]

Another option is to have works performance make you a new shock all set up with spring & valving to suit you, Maybe cheaper & better in the long run    


http://www.worksperformance.com/  They have a price list but it says no info on the K but does have for the L, If I am reading the list correctly the prices seem pretty good,They may be worth contacting

[Rossvickicampbell]

not trying to take business away from Mr WASP - however did find the Works Performance route to be the best for my YZ - at the time (when currency was somewhat different) $500ish delivered to the door, set up to suit me with a followup call from them to see how I was going.

[alexbrown64]

Thanks, Roscoe, Wasp, Smed etc on input into this.  I guess all the old YZ and IT shocks are slowly coming to the end of their shelf life.  I had a look at pricing for the Works Performance ultra shock which they make for the N.  Its about $1200 US and that comes with a remote res and rebound/comp adjustability.  But that would be $1500 AU after conversion and post.  Race Tech says they can also build me one they have been developing for $1600. 
A honed steel body replacement by Wasp may be the go... also thanks for the specs and info there Wasp.  But also, i have two good used shocks coming that may be of use and also the electrosil process to repair worn ones.  So there are a few great options there.
Wasp, can you explain a little more on the steel bodied replacements.. Not just for me but also for others searching for replacements now and into the future.
Cheers,
Alex

[OverTheHill]

remember a guy back in the day making a piston ring out of [something black plastic or nylon--teflon i dunno] but made it super tight to get in past the unworn bit with the theory she'd be all good in the 'very worn' part, worked good too. Think it was a TT600 just thinking back.  Years since i've seen inside one [& i own a 490k--now i'm worried lol] but thought the piston had a couple of small diameter rubber o rings to keep outward tension on the ring & bore so should get away with some wear even with a new std piston ring. My 2 cents worth anyway. Cheers.

[Nathan S]

Alex , the principle of my body replacement is to use as many parts as possible from your existing unit and combine it with my systems .We offer  ID 30 , 36 , 40 ,44 46 or 50 mm . I guess yours is 46 mm ? More elaborations on that , you will have to call . If you have been around a while , you will understand why . 

46mm.

-------

If you said "I'm going to VMXdN and I want to win", then that's totally different to "I ride two events a year and I'm happy of if don't come last".
Similarly, there's a big difference between "there's a slight groove in the body around right height" and "it's been run for several hundred kilometres with no oil at all" or "the valve piston ring destroyed itself in 1986 and it's done 29,729km with the steel valve piston wearing against the alloy shock body since then".

If you're serious, then you will need to spend some money.
If you're casual, there are many cheaper/simpler options.

[rocketfrog]

I may have a lead on a NOS unit, It would be the sub assy including the res and shock body piston and rod. You would need to use your lower mount, spring and retainers.

[alexbrown64]

There are some great suggestions and leads there fellas.
Rocketfrog, if the lead comes through, perhaps you could PM with details.
Cheers,
Alex

[Momus]

It shouldn't be too hard to make a new shock body. From the CMNSL website the key part looks to be an aluminium bore tube welded to a cast or forged bottom section valve body/mounting head. 

http://www.cmsnl.com/yz125k-off-road-19831984_model8976/24x-22210-00-6w_24x2240100/#.VJUhIsB8g

With the design to copy, any jobbing engineer could machine the tube and it's features and TIG weld it to the old head.  The bore would be turned slightly undersize and a small cylinder hone and kero post welding will bring it to tolerance.
6061 grade material is the usual choice for this. It is readily available locally, fully weldable and can be hard anodised. Material cost would be negligible- perhaps $25.00 for 55mm diameter- and probably around 2 hours machining and welding.

[Nathan S]

I think Alex wasmore  after professional advice , Nathan . Your method would suit more a shonky wheeler dealer . 

My point was that some wear does not automatically mean that it has to go in the bin.
A shop like Teknik won't want to risk their reputation by doing a less than perfect job. I was pointing out that Teknik's idea of "knackered" may be overkill for his needs.

I used to know a bloke who rebuilt Mazda rotary engines for about a third of the cost of most other shops. His engines were just as reliable, and made just as much power.
The difference is that he understood what was a good used part and what was junk, whereas most other shops lacked that understanding and they would simply replace everything to cover their own arses... Didn't give the customer a better outcome, it just cost more.

[Tomas]

It shouldn't be too hard to make a new shock body. From the CMNSL website the key part looks to be an aluminium bore tube welded to a cast or forged bottom section valve body/mounting head. 

http://www.cmsnl.com/yz125k-off-road-19831984_model8976/24x-22210-00-6w_24x2240100/#.VJUhIsB8g

With the design to copy, any jobbing engineer could machine the tube and it's features and TIG weld it to the old head.  The bore would be turned slightly undersize and a small cylinder hone and kero post welding will bring it to tolerance.
6061 grade material is the usual choice for this. It is readily available locally, fully weldable and can be hard anodised. Material cost would be negligible- perhaps $25.00 for 55mm diameter- and probably around 2 hours machining and welding.

Not sure about machining and welding cost Momus. Some shops charge an arm and a leg for jobs like this. I would go with Wasps idea. He can suplly 46 mm shock body plus Alex may have to find suitable shock end. I agree with you Momus. Itwould not be hard to make but it is hard to find a place that would be happy to help and price it reasonably. Had crankcase machined - 52mm diameter 15mm deep to 56mm diameter 15mm deep and the guy asked $150 for it. I dont think that he spend more than an hour working on it.