Understanding your RSV Rear Shock

[Rick Butler]

Understanding your RSV Rear Shock

 

Many of you have seen my old RSV shock that I had cut open to expose what the inside of the shock looks like. Well I have gone to the next step.

 

I just had my Works shock rebuilt and this is when I realized these shocks don’t last forever and rebuildable shocks need to have the oil changed out every 35,000 miles or so because the oil wears out and get contaminated with the nitrogen. Once I understood this, I felt that the oil in the RSV should probably be changed out as well.

 

So when I went to pick it up I took this cut-up and exposed shock to let my professional shock rebuilder look at this shock and give me his evaluation of what makes this shock work and what is the purpose each section of the shock. And I was a bit surprised but after he looked at it and we talked it over, everything made perfect sense.

 

So here it goes….where you can refer to the diagram in the attached file:

 

You can see that I have identified four basic parts of the shock:

 

• Outer Body
  
• Inner Sealed Shock Valving
  
• The Outer Shock Seal
  
• Polished Ram

Item 1. is the upper black part of the shock just above the rubber boot. This is nothing more than an air chamber, where in conjunction with (4.) the polished ram and (3.) the seal, allows air to be pumped in via the hose and Schrader valve to control shock preload and bike ride height.

 

Item 2. Is where the real shock valving resides and is completely press sealed like what you would see on one of your Monroe shocks. I assume this contains oil and maybe a nitrogen charge, but the latter is only a wild guess.

 

Item 3. is the outer body seal that keeps air in the upper chamber. There is a metal bushing just above it to keep the upper body in alignment with Item 4. the polished ram.

 

Item 4. Is the polished ram that resides under the rubber boot. Even though this piece is polished, it is not hardened and is susceptible to scratches, mostly from a dry bushing. Another purpose of this piece is to act as a reservoir for 7.5 oz of oil that stays inside the shock to lubricate the outer shock seal and ram. The reason I know the amount of oil, is that I took out the Schrader valve, hung the shock upside down and let it drain for 5 days until it stopped.

 

With the shock upright, the oil will stay in this cup pretty much undisturbed, with the exception there is a 1/8” hole about ¾” down from the top of the ram. I can only assume that as the bike moves from side to side some oil will come out this hole, run down the ram and help lube the bushing and seal. Now this also means that if the bike is laid on its side, most of the oil will run out and down the outside of the ram. I can only suspect when this happens, a shock will start leaking (seeping) oil out the bottom if there are scratches in the ram. But if the ram is not scratched and the seal is holding this will not present a problem with the shock action. This will only help lube the bushing and seal.

 

In fact in those cases where the shock is making that squeaking or groaning noise, it is doing this because the seal is dry and really needs to be lubricated. At this point, I would suggest that you could lay the bike down on it’s side and let some of the oil run down the side and I’ll bet your groaning shock will quiet down. Also, I would have no problem taking the schrader valve out and squirting in a couple ounces of 20 weight fork oil down the hose to help lube the ram.

 

You will also note that this shock has a full-length spring but with a spring rate of only 839 lbs/in and the shock travel is 1.77 inches.

 

Now my conclusion on this shock is that you could cut the upper body and the polished ram completely off and you would still have a fully functional shock……but without any preload or ride height adjustability. And it’s not a bad design for what it does for the average rider. But if we are taxing the load limit of the shock beyond 839 lbs. or the maximum load limit of the bike of 419 lbs., we should be looking for a heavier shock. The spring rate on my Works shock is 1,200 lbs.

 

Finally, if the shock is leaking oil, the ram is scratched and maybe the seal torn so it won’t hold air much longer anyway so it should be replaced under warranty. If it’s groaning it just needs some internal lubrication, where I have given you a couple of options to satisfy this.

 

There you have it,

 

Rick

Shock Diagram.PDF

[Snarley Bill]

Understanding your RSV Rear Shock

 

Many of you have seen my old RSV shock that I had cut open to expose what the inside of the shock looks like. Well I have gone to the next step.

 

I just had my Works shock rebuilt and this is when I realized these shocks don’t last forever and rebuildable shocks need to have the oil changed out every 35,000 miles or so because the oil wears out and get contaminated with the nitrogen. Once I understood this, I felt that the oil in the RSV should probably be changed out as well.

 

So when I went to pick it up I took this cut-up and exposed shock to let my professional shock rebuilder look at this shock and give me his evaluation of what makes this shock work and what is the purpose each section of the shock. And I was a bit surprised but after he looked at it and we talked it over, everything made perfect sense.

 

So here it goes….where you can refer to the diagram in the attached file:

 

You can see that I have identified four basic parts of the shock:

• Outer Body
  
• Inner Sealed Shock Valving
  
• The Outer Shock Seal
  
• Polished Ram

Item 1. is the upper black part of the shock just above the rubber boot. This is nothing more than an air chamber, where in conjunction with (4.) the polished ram and (3.) the seal, allows air to be pumped in via the hose and Schrader valve to control shock preload and bike ride height.

 

Item 2. Is where the real shock valving resides and is completely press sealed like what you would see on one of your Monroe shocks. I assume this contains oil and maybe a nitrogen charge, but the latter is only a wild guess.

 

Item 3. is the outer body seal that keeps air in the upper chamber. There is a metal bushing just above it to keep the upper body in alignment with Item 4. the polished ram.

 

Item 4. Is the polished ram that resides under the rubber boot. Even though this piece is polished, it is not hardened and is susceptible to scratches, mostly from a dry bushing. Another purpose of this piece is to act as a reservoir for 7.5 oz of oil that stays inside the shock to lubricate the outer shock seal and ram. The reason I know the amount of oil, is that I took out the Schrader valve, hung the shock upside down and let it drain for 5 days until it stopped.

 

With the shock upright, the oil will stay in this cup pretty much undisturbed, with the exception there is a 1/8” hole about ¾” down from the top of the ram. I can only assume that as the bike moves from side to side some oil will come out this hole, run down the ram and help lube the bushing and seal. Now this also means that if the bike is laid on its side, most of the oil will run out and down the outside of the ram. I can only suspect when this happens, a shock will start leaking (seeping) oil out the bottom if there are scratches in the ram. But if the ram is not scratched and the seal is holding this will not present a problem with the shock action. This will only help lube the bushing and seal.

 

In fact in those cases where the shock is making that squeaking or groaning noise, it is doing this because the seal is dry and really needs to be lubricated. At this point, I would suggest that you could lay the bike down on it’s side and let some of the oil run down the side and I’ll bet your groaning shock will quiet down. Also, I would have no problem taking the schrader valve out and squirting in a couple ounces of 20 weight fork oil down the hose to help lube the ram.

 

You will also note that this shock has a full-length spring but with a spring rate of only 839 lbs/in and the shock travel is 1.77 inches.

 

Now my conclusion on this shock is that you could cut the upper body and the polished ram completely off and you would still have a fully functional shock……but without any preload or ride height adjustability. And it’s not a bad design for what it does for the average rider. But if we are taxing the load limit of the shock beyond 839 lbs. or the maximum load limit of the bike of 419 lbs., we should be looking for a heavier shock. The spring rate on my Works shock is 1,200 lbs.

 

Finally, if the shock is leaking oil, the ram is scratched and maybe the seal torn so it won’t hold air much longer anyway so it should be replaced under warranty. If it’s groaning it just needs some internal lubrication, where I have given you a couple of options to satisfy this.

 

There you have it,

 

Rick

rick thats great info .got a question my bike has 12,000 mi. on it and the shock started groaning all of a sudden.could the outer seal be that dry with that few of miles? mine is consistant and very loud,when i bounce on it.bill

[Rick Butler]

Bill,

 

The answer to your question is Yes and it needs some oil on the ram to lube the seal. Why don't you lay your scoot over and see if you can let some oil in the ram seep over the top and down the ram. It's my opinion that your groaning shock will quiet down.

 

Let us knw,

 

Rick

[gibvel]

Rick,

I have the same problem with a groaning shock. I was considering taking the schader valve out and putting the oil into that passage as you suggest. Do you still suggest this or do you thing laying the bike over would be a better solution. Which do you think would, in the longrun, be the best solution?

Maybe I'll wait and see what wpredock finds out.

[Bvinson]

I have a 99 with the original shock and it has groaned off and on. The last time it started groaning (about a year ago) I pulled the core from the schrader valve and gave it an injection of 1/2 ounce of transmission fluid and 1/2 ounce of synth 20wt. It has not groaned since. With that said it will probably start again today. FYI, I use an old syringe with point ground off for shooting it down the tube.

[gibvel]

I have a 99 with the original shock and it has groaned off and on. The last time it started groaning (about a year ago) I pulled the core from the schrader valve and gave it an injection of 1/2 ounce of transmission fluid and 1/2 ounce of synth 20wt. It has not groaned since. With that said it will probably start again today. FYI, I use an old syringe with point ground off for shooting it down the tube.

 

Hmmmm I just happen to have 2 of the three of those. By synth 20wt do you mean regular motorcycle oil or fork oil? If motorcycle oil then I've got all 3.

Thanks for the real world experience.......please let us know if you jinxed yourself by telling us.

[1BigDog]

I have a 99 with the original shock and it has groaned off and on. The last time it started groaning (about a year ago) I pulled the core from the schrader valve and gave it an injection of 1/2 ounce of transmission fluid and 1/2 ounce of synth 20wt. It has not groaned since. With that said it will probably start again today. FYI, I use an old syringe with point ground off for shooting it down the tube.

 

Yes, what type of oil was used? Fork oil or engine oil? Also what type of trans fluid? Delco? Ford?

 

Thanks for the great info on the shocks.

[gibvel]

Oh, and just out of curiosity, why put transmission fluid with the 20 wt. oil?

[Bvinson]

It was 20wt syn fork oil. The reason for the DELCO trans fluid is because it swells seals and helps stop leakage. My thoughts were with the age and miles on my bike it could not hurt. I saw the shock Rick Butler cut apart and decided that if mine was anything like that one internally it would help by swelling it some.

[gibvel]

Okay, so now I'm back to having only 2 of the things.

Thanks for the info Bill!!

[Rick Butler]

Guys,

 

I support Bill's idea of using a heavy fork oil mixed with Delco to swell the seal and think it will work.

 

Rick