Risse shock rebuild ramblings

[Bnystrom]

Risse Racing has done a great job of designing shocks that can be easily maintained by their owners. I just finished rebuilding my Astro 5 after I damaged it in a mis-timed log jump.

Instructions for changing the oil are available on their site, so I won't go into it in-depth.

(http://risseracing.com/technical/pdf_files/Oil_change.pdf).

All it takes is:

- A bench vise (preferably) or at least a rod that fits the top eye in the shock body, that can be used for leverage to unscrew the seal housing.

- A wrench or padded Channel-lock pliers that fit the flats on the the seal housing.

- 5 weight shock oil, which you can get inexpensively at any motorcycle shop. Don't buy bike shop oil, it's horribly over-priced. You can get a quart/litre of motorcycle oil for the same price you'd pay for 8 oz. of bike oil.

- A shock pump.

Once you've done it, you'll be able to do it in less time than it would take to read the instructions again. Changing/filling the oil is critical to maintaining the shock's performance. If the oil level in the body gets low, the shock will not extend fully. You'll notice that if you lift the rear wheel, the shock will extend and when you drop it, it will compress slightly and stay that way.

So, how does the oil get low in the first place? Although external leakage is a sure-fire sign that you're oil level is dropping. it can happen even if there are no external signs of leakage. In fact, internal leakage seems to be more of a problem. With my own shock, the seals on the floating piston leaked, allowing oil into the air chamber. This has two negative effects:

[orange]

you've left us all hanging - we all want to know what the 2 negative effects are...!

[Simon]

 Rebuilt my astro5 well just an oil change,
the problem that arose was when stripping I found an O ring damaged,replaced the O ring and filled up the shock as per instructions,unfortunatly after many
refillings and bleeding the shock would compress but not return,obviously there was more of a problem than I first thought,the air chamber in my opinion need stripping but due to the fact it needed a special tool to undo it (which I could of made up) but also it is an expensive piece of kit and I hadn't had it that long so had CVI (now no longer in business) overhaul it,wasn't to expensive but now I would do a full overhaul myself should it ever be necessary.

Ps my best GUESS the oil was bleeding into the air chamber on shock extension and returning on compression,if you look at how a Risse works you will understand what I meen.It could be the other way around but because the air chamber is smaller I'd imagine there to be higher pressure in the air chamber than in the damper chamber under compression.

Simon

[Bnystrom]

Sorry about that. The original post was too long and I didn't realize that this much had posted, since the site was acting up when I tried to post it. I'll repost this is parts, so you have the full report in its final form.

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Risse Racing has done a great job of designing shocks that can be easily maintained by their owners. I just finished rebuilding my Astro 5 after I damaged it in a mistimed log jump.

Instructions for changing the oil are available on their site, so I won't go into it in-depth.

(http://risseracing.com/technical/pdf_files/Oil_change.pdf).

All it takes is:

- A bench vise (preferably) or at least a rod that fits the top eye in the shock body, which can be used for leverage to unscrew the seal housing.

- A wrench or padded Channel-lock pliers that fit the flats on the seal housing.

- 5 weight shock oil, which you can get inexpensively at any motorcycle shop. Don't buy bike shop oil, it's horribly over-priced. You can get a quart/litre of motorcycle oil for the same price you'd pay for 8 oz. of bike oil.

- A shock pump.

Once you've done it, you'll be able to do it in less time than it would take to read the instructions again.

[Bnystrom]

Changing/filling the oil is critical to maintaining the shock's performance. If the oil level in the body gets low, the shock will not extend fully. You'll notice that if you lift the rear wheel, the shock will extend and when you drop it, it will compress slightly and stay that way.

So, how does the oil get low in the first place? Although external leakage is a sure-fire sign that you're oil level is dropping. it can happen even if there are no external signs of leakage. In fact, INTERNAL leakage seems to be more of a problem. With my own shock, the seals on the floating piston leaked, allowing oil into the air chamber. This reduces the oil volume in the shock body and allows air into it, causing the symptom detailed above.

It's very easy to tell if the floating piston seals are shot, as you'll get oil bubbling/spraying out of the valve whenever you adjust the air pressure. If you see that, I recommend that you change the floating piston seals immediately, as the problem will only get worse. Besides, having oil spraying all over you and dripping all over your rear wheel is a major pain in the butt.

When it comes time to change the floating piston seals, you may as well replace the others that are likely to need it. A complete seal kit is available from Risse for $10, but all of the seals are commercially available parts and most of them are simple neoprene o-rings that you can get at a hardware store. Buying them from Risse can be more convenient than trying to match the sizes and their seals probably haven't been on the shelf for years. Age adversely affects neoprene seals, which is one reason that even lightly used shocks need to be rebuilt periodically.

If there is no evidence of oil leakage on the shaft. you don't need to replace the two seals in the seal housing. These are the only two that are hard to find. Reassembling the shock after changing them requires a $10 "bullet" tool from Risse, a tapered plastic cap that guides the open end of the shaft through the tightly fitted seals. You could make something similar if you have access to a lathe, but for the price, it's easier to buy it. If you don't need to replace these seals, you can do all the o-ring seals for ~$5.

Worst-case, you can replace all the seals for a total of $26, including the seal kit, bullet tool and 2-3 day shipping. Other parts are surprisingly cheap, too. I damaged the eyelet on my shock (the threads stripped off) and the replacement was $20. A replacement shaft is $20. So, unless you manage to damage the body of the shock, repairs are pretty inexpensive.

[Bnystrom]

The first step in the rebuild is to disassemble the shock as if you were changing the oil. At this point, you can change the seals (o-rings) on the damping piston and bearing housing.

Next:

- Let all of the air out of the shaft.

- Clean off the shaft with alcohol or another degreaser, so you can grip it.

- Hold the "eyelet" (the end with the valve) in a bench vise, large adjustable wrench or paddled Channel-lock pliers.

- Wrap a piece of old inner tube around the shaft for a better grip, then unscrew the eyelet from the shaft. DO NOT use any tools to grip the shaft; you'll damage it. At this point, you can change the seal on the eyelet, if need be.

- At the other end of the shaft, unscrew the nut on the damping piston, being careful to keep the nut and the other parts in their proper order. The thin washers and the plastic piece in between make up the damping valves and improper re-assembly will screw up the damping. It's not a bad idea to make note of the number and position of the valve washers and the orientation of the plastic valve body for future reference.

- Once the valve assembly is removed, you'll see four holes in the top of the piston and the top surface of the floating piston will probably be up against them. Use a narrow (~1/8") rod of some sort to push the floating piston down and out of the open end of the shaft. The floating piston has two o-ring seals that need to be replaced. They're the culprits that cause the internal leakage.

- If you do want to replace the seals in the seal housing, pull the shaft out of the housing and pick the seals out.

[Bnystrom]

While you have everything apart, it's a good idea to clean off any dirt or other gunk you see. In particular, make sure all the seal grooves are clean. I used denatured alcohol, as it cleans well, evaporates quickly and it won't damage any of the plastic parts in the shock. Carburetor cleaner would probably work fine, too. In particular, clean the threads on the eyelet and the inside of the shaft thoroughly, as you will be applying thread sealant to them.

After replacing all the seals, the shock is reassembled in reverse order. Here are a few re-assembly tips:

- When using the bullet tool to fit the shaft through the seal housing, it may take several tries before it pops through with only moderate pressure. DO NOT force it or pound on the shaft, you'll damage the seals. Also make sure you assemble it in the right direction; the shaft goes into the side with the threads.

- When you're ready to insert the floating piston into the shaft, take a Q-tip and swab some oil inside the shaft wall BELOW the threads. DO NOT lubricate the seals, as that will contaminate the threads when you insert the floating piston.

- Insert the floating piston with the cupped side facing inward. It will be snug at first, but once it hits the oiled section of the inner shaft wall it will slide right in.

- Apply a bead of thread sealant all the way around the threads on the eyelet, then screw it in carefully making sure not to cross-thread it. Tighten it as much as you can BY HAND ONLY. Wrapping inner tube around the shaft as before helps.

- When filling the shock with oil, fill it to within ~3/16 of the threads in the body. That will minimize the amount of oil that oozes out as you screw the shock together. If no oil comes out, unscrew it and add a little more until you do get some ooze. You don't want any air space in the shock body.

The bottom line here is that no one should be intimidated by the idea of maintaining a Risse shock. They've done a great job of designing it to be easy and inexpensive to do.

[Bnystrom]

If someone can combine the parts of this procedure and add it to the DIYs, I'd appreciate it. I emailed it to a couple of different site admins and never heard back from either one of them.

[Bnystrom]

Simon,

There are no special tools required to disassemble a Risse shock and just one to re-assemble the piston rod through the seal housing/nut, IF you pull it out. You're correct about internal leaking into the air chamber causing the shock to fail to extend completely. If any oil comes out when you let the pressure out of the shock, the seals on the floating piston are shot and should be replaced as I detailed in my other post.

[shovelon]

So, with 5 wt. oil being the standard, do you think 2 wt oil or lighter may get past the floating piston too easily? I have talked to Risse about using lite spindle oil for the fluid, and they said that the seals would not degrade, but nothing about leakage.

I really like the light weight and robustness of the genisis on the vector and crosslink, so I was just curious.

Terry

[Bnystrom]

What advantage do you think there would be to lighter oil? Unless your shock is valved too stiff, I don't see any reason to go that route, unless perhaps if you're riding in really cold conditions consistently. The same is true of going heavier; it doesn't make sense unless the shock is valved too light.

Come to think of it, with the ease and low cost of re-valving a Risse shock - order the parts for a few bucks and install them during an oil change - I'm not sure it makes sense to mess with varying oil weights at all.

As for leakage, it seems logical to assume that it would be more of a problem with lighter oil, but I can't say that with any authority. I'm running 5W Spectro motorcycle fork oil in my Astro 5.

[shovelon]

What advantage do you think there would be to lighter oil? Unless your shock is valved too stiff, I don't see any reason to go that route, unless perhaps if you're riding in really cold conditions consistently. The same is true of going heavier; it doesn't make sense unless the shock is valved too light.

Come to think of it, with the ease and low cost of re-valving a Risse shock - order the parts for a few bucks and install them during an oil change - I'm not sure it makes sense to mess with varying oil weights at all.

As for leakage, it seems logical to assume that it would be more of a problem with lighter oil, but I can't say that with any authority. I'm running 5W Spectro motorcycle fork oil in my Astro 5.

I thought that if I popped it open, I may as well as have my choice of viscosities to play with. Risse has said that they pretty well maxed out on the valving, so I thought I would try the oil.

Probably I am facing stiction right now, and should just ride it. It really is pretty good, and may free up some more with time.  But it can't hurt to play.:-)

Terry