I have the 14 in WP shocks. Finding seals is stupidly difficult and the shock is stupidly difficult to work on. Modern KYB and Showa seem simple in comparison. I have 2 of these bikes with these shocks and both are blown and sad shape.
Does anyone know of a direct bolt on alternative from Jap or otherwise bikes? Shocks that you don't have to change clevis's or any of that.
Looking around I came across a 355mm(14 in) YCF single shock with the correct eyelets for around $240. Adjustable somewhat. Apparently this goes on a bigger Chinese pit bike. Now, I don't know the shaft size and wondering what your thoughts are for putting this on an ATK 406?
My concern is snapping it in two. ATK's are lighter but not pit bike light. Although these pit bikes are designed to be ridden by adults.
It has been mentioned that WP KTM shocks of that era might fit......the later ATK shocks are 16 in.
Delays and other problems with ATK "suppliers" are legendary around the internet. "Out of stock" being common.
I am in the process of swapping modern Jap forks on my 406. Thus, I get modern brakes and wheel parts that are easily sourced. Heck, you can get whole Chinese knock-off brake components complete through caliper to master cylinder....bolt on.
Getting folks to reply and playing phone tag and email roulette just gets old. Buying parts from Europe makes me queasy.
I am a expert level vintage racing rider. Weigh about 230#. Pretty hard on a bike I'm told. Thanks.
What I have decided...
There are twin shock street bike replacements on Amazon. Ohlins "looking" knock offs.
This particular set is listed for a SR500 and several other heavy street bikes. My ATK weighs around 200#+. These street bikes weigh 2-3x's that. Can you see my reasoning?
I measured the shock shaft for my WP shock and the shaft on the Ohlins knock offs is bigger by about a mm. Concluding it's stout enough.
These replacement shocks are comp/rebound adjustable and nitrogen filled. And are length adjustable also with the correct eyelets.
I do realize the damping will be dicey. I do not know if they will be able to be re-valved. I also realize the springs/rate could be massively off.
I need two shocks for two bikes and this will at least solve that problem.
I'm guessing these shocks can't be any worse than what I have. Current shocks are just pogo sticks.
Thanks for listening.
There was a thread a few years ago about a rebuild:
https://www.vitalmx.com/forums/Bike-Builds,46/1989-ATK-406-Restoration,…
Side note, I'd be surprised if you can't find a more modern WP PDS shock that can't be made to work. I would think the spring would be easy enough to get right, and the valving could be in the ballpark already.
I'm sure almost anything can be made "to work".
Finding seals is the hard part as noted above. Dealing with the folks that may or may not have them.....
Finding machine work to modify things etc.
And a rebuilt oe shock in perfect condition isn't very good anyway.
I'll report on my aftermarket shocks.
My thinking is that there are a wide range of PDS shocks available over the last 20 years. Seals, modifications, damping settings, and more should be much easier for a later model PDS than fitting a shock from a totally different bike.
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Have you ever looked at a 1989 WP shock from an ATK? They are 14 in long. They don't have clevis's. Just because it's something WP doesn't make it remotely similar.
Just put in seals(internet) for that ATK shock and see what comes up. I find it interesting that no-one seems to have found a solution to this problem. I see pics of lots of rusty old WP shocks on ATK's. Finding parts for ATK's is like finding vintage Husky parts or SWM's and Penton's....you are at the mercy of the folks that have them. Few and hard to deal with.
Now, maybe I don't have the right resources or search criteria to draw on.
Most if not all don't have any relation to my shock. Overall length being the most critical. Later year ATK shocks are 16 in. They are similar looking but too long.
I just don't agree about a PDS should be easier......most folks don't have access to machine shops and the like. Nor do we have unlimited amounts of time to R&D such. My bikes are unusable until I get at least something more than the pogo stick props holding the frame off the tire. BTW, I also have a budget and realize I could have a shock made or such or buy an OHLINS.....but then that would be a grand down a rathole.
The ATK 406 is an oddball of a bike (part of the reason I'm interested in them). Expecting that anyone has a replacement in kind shock is unreasonable, IMO.
From the thread I linked, I did find some useful information for future rebuilders: (as said, I'm curious about these bikes):
Company mentioned for info (and parts?): https://csrsuspension.com/
Info on rebuilds found by searching "WP 4681": https://www.advrider.com/f/threads/servicing-the-wp-4681-bavp-shock-abs…
And here: https://www.advrider.com/f/threads/lc4-shock-rebuild-parts.645859/page-2
Shop manual from one of those threads: http://www.maxxracing.fr/ressources/WP_3612-4681_Shock.pdf
Doesn't seem that bad overall.
Good luck.
I find it strange the remarks about the difficulty in working on the WP Shocks.
They are nothing special with regards to servicing them. You should be able to find a competent repairer who can do them for you. Or, with just a bit of work, if you insist that you do the rebuild, you'll find parts. If it's simply the 'difficulty' in the WP charging port, well, a Valve can easily be fitted.
Check out Michadoggs thread that eric_94COBRA put up, and also the Absolute Wealth of references he put up in his later posting.
If the shaft(s) are damaged - something I've seen on ATKs with their unshielded proximity to the rear tyre, well, that can be a problem, and, if , say the inner surface of the body is damaged ( some early WPs had Steel bodies - it takes a Hell of a lot to damage their ID) well, that can be a problem.
But contemplating putting some cheap shocks, meant for ( I assume) Road Bike usage - well, I just don't see you having something that works remotely well, even with far more faffing about than rebuilding the WPs. Hell, they'll have damping and springs, set up for a leverage ratio of around 1:1 / 1.2:1 leverage ratio, or barely higher than that, with the 2 shocks being used at the same time. The ATK has a ratio in the vicinity of 3:1+, with just the one shock spring and damped for that. Those WPs / well, the whole ATK set up, worked very well, by the way.
Besides the valving, You'll have to sort out a spring - believe me, no matter the weight of the road bike, 2 shocks handling the rear, with 2 springs with a Far lower leverage ratio, will mean much much lighter springs on them, than what the ATKs need. So, you'll inevitably be trying to match the WP spring to one of those shocks.
Besides the eye to eye length, you have to have directly comparable shock travel. Less shaft travel, + less rear wheel travel. More shock travel for the same eye to eye - well, wheel into mudguard / frame unless you limit the travel.
It's a while since I went through the various PDS shock lengths - I did a Lot of research prior to my PDSing my CRE500. For that, I used the 417.5mm length Ohlins TTX shock of the 2015 - 2016 era. Early PDS shocks were shorter - I'll have these numbers wrong, but I think around 408 / 410 / 411 + length. They gradually got longer, until , I think, the 2017 models. Off course, then you've got the Clevis on all of them to contend with..
However, the Non Linkage Husabergs, of the integrated Case and Barrell engine, just prior to the 2009 70 degree Barrell Engined bikes, have 2 'normal' eyes. And, I think they were either 400 or 405mm. Though, they may be quite rare.
Another thing to consider - the Body eye / reservoir positioning. The original WP shocks on the ATKs have quite the 'drop' to the reservoir from the body eye center, and you may not be able to fit other shocks because of that. I'm not sure if they are also 'clocked' to fit inside the frame. Butchering a frame to fit shocks, that probably will be sub par, is not a good idea.
This may all read as my being nasty / a smartarse, but you need to do it properly. Far better to have the original shocks rebuilt, or, find a Shock designed for at least a similar application. To repeat , go read Michadoggs 406 rebuild thread, he's gone through much of what you will / may go through with your 406.
I really think you'll end up with a dreadful rear end on both bikes, if you go the way of the Cheap Road Bike Shocks.
Nothing special. I agree. A modern KYB or Showa so simple with their seal head. No matter.
What you seem to gloss over are the shock lengths. Mine are 14 in or 355 mm.Not 400 or 411 And you seem to dismiss the clevis...this could be insurmountable.
Again, I don't have a machine shop or endless amounts of time.
I took another look at the original shock positioning of the reservoir. It is a concern. We'll see.
The shock spring is bigger(wire diameter) than the new shocks. Yet, the shaft of the new shock is bigger. We'll see. Springs are plentiful and relatively cheap.
I considered the use of two shocks for a single shock. We'll see.
And valving? Well, who knows? Who's to say the valving was spot on for street bikes? Maybe it might just be clicked away. They are completely adjustable(claimed).
If these new shocks make the bikes somewhat rideable....well that's better than collecting dust like now.
Thursday...we'll know.
Respectfully, not much help at all.
Well, I got it wrong - thought I'd read 400mm.
But, the points I put up with regards to leverage ratios, and their effects on spring rates and and valving specs, plus the reservoir positioning, are still valid. Here in OZ, we've plenty of suspension specialists that could refurbish the WP shocks, and / or supply parts. Surely in the USA, you can get them sorted.
It seems you are determined to try those Road Bike shocks, and not take anyone's advice. Good luck with that. "One Click away"......... it would be a miracle.
Eric-94COBRA, really has provide Very useful information, if you deign to check it all out.
Be sure to keep us posted.
Race Tech has developed their own shocks so I'm thinking if they could get one and get it apart they could work something up for it. They offer services to replate the shock shaft and hard coat shock bodies. Hit them up, it sound now like you have nothing to lose.
Also try Worx Shocks, maybe they can come up with something for you.
I agree. I'm sure you realize what two scratch made shocks would cost.....
My bikes aren't worth much and in the end might be better off parted.
I like the idea of air-cooled motors and simplicity.
They need all plastic, brakes refurbished etc. Putting $600 shocks on them just won't happen.
It's the parts, man.
Stories of 6 month waits and such just won't cut it. Sending my shocks off to oblivion.....
I checked out the source's listed......nary a mention of those shock parts.
Say, could you list a few of these suppliers for a concrete lead? That would have 1989 ATK WP seals and parts? CSR suspension sure doesn't. At least according to their website. My feeling is I'm going to have to find someone that happens to have those parts. It's a big world. Thanks.
Hydraulic cylinder shops can repair worn out bodies and shafts for sure, they might be able to find seals too.
99%+ of the bearings and seals in the world are straight out of a catalog, the challenge is finding them. Make friends with a bearing and seal man, they speak that language.
I have been down this same road my self. I also planed on using a late model Shock but the 14" Length that is not going to happen. You pretty much have two choices. Talk to Keith at American Dirt Bike. He is probably the most knowledgeable person on earth when it comes to anything ATK. He can rebuild your shock and also re valve it. He is swamped with work do not exspect a fast turn a round. He can also sell you the parts to rebuild it either by you or your rebuilder. Then there is Race Tech. They can build you a new modern shock to replace the WP one. I know of nobody who has done it yet but maybe it has been done. Somebody might also be able to shorten the Rod on a Modern Shock but that's a different story.
Here are one or two shocks for you (not my listing):
https://orangecounty.craigslist.org/mpo/d/fullerton-atk/7594838065.html
Has the OP talked to Keith at ADB or Frank White? When I had my ATK 605, they were the 2 guys to go to.
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