Bobby Tanner's new shocks?

[tiny]

I love how people talk about "tuning" air shocks when I've never even heard of anyone changing a shim stack in one.

I've changed lots, now you've heard about it.

 

[TacomaJD]

I've changed lots, now you've heard about it.

 

[patooyee]

I've changed lots, now you've heard about it.

Cool, got any general guidelines you want to share?

 

[tiny]

Sure, pootie. Most air shocks come 40/90. Neither the comp. or the rebound has enough restriction for the air shocks type of spring rate. High preload, very small rate gain, until the end of coarse. Especially when you get all foamy, as you pointed out.

However, I do call it tuning when I change the oil in them. Or even just add oil. Kind of like changing coils, on a coilover.

 

[patooyee]

Sure, pootie. Most air shocks come 40/90. Neither the comp. or the rebound has enough restriction for the air shocks type of spring rate. High preload, very small rate gain, until the end of coarse. Especially when you get all foamy, as you pointed out.

However, I do call it tuning when I change the oil in them. Or even just add oil. Kind of like changing coils, on a coilover.

My point about tuning was just that few have ever given air shocks a fair swing IMO and that people think they've exhausted their potential before they ever even touch the shims. I've literally started threads about shimming air shocks and either been ridiculed for asking or received close to zero input. (As everyone knows, I care nothing about being ridiculed.) How about flutter stacks, messed with them at all?

So you add a lot of compression and rebound? More compression I'm guessing? Have you played with the single bleed pistons at all? They're reputed to be more for crawling but everyone knows that crawling is boring.

You're literally maybe the second or third person I've ever talked to that has messed with air shock shimming.

 

[TacomaJD]

Sure, pootie. Most air shocks come 40/90. Neither the comp. or the rebound has enough restriction for the air shocks type of spring rate. High preload, very small rate gain, until the end of coarse. Especially when you get all foamy, as you pointed out.

However, I do call it tuning when I change the oil in them. Or even just add oil. Kind of like changing coils, on a coilover.

It sounds like you possess a good bit of intellect on air shocks, riddle me this. I've always read that when setting up your rig for air shocks, 4-6" of shaft showing is the sweet spot at static ride height for air shocks. Upon discussing this matter a good while ago, someone said "Well what about different length shocks, the sweet spot for a 18" shock won't be in the same vacinity as a 12" shock...."

I didn't know enough about them at the time to argue that point, but best I can gather, it has nothing to do with the travel of a shock, it directly references the 4-6" of air space between the piston and the top of the shock that creates the air spring, right? (This merely being a general rule of thumb, on your typical, average crawler.)

 

[xjpaddler]

I never messed with the shims, but i did mess with presure and limit straps! I found that on my old rig it performed a lot better with the limit strap pressed tight buy the air shocks. This was probly completely wrong in most people's eyes. But you could tell a huge difference in keeping the tires planted, And less body roll.

 

[patooyee]

I've always read that when setting up your rig for air shocks, 4-6" of shaft showing is the sweet spot at static ride height for air shocks.

I found that on my old rig it performed a lot better with the limit strap pressed tight buy the air shocks.

I hypothesize that both of these were band-aids for people who never messed with valving. I did both back in my 2.0 days and both worked. But having learned a little about valving and feeling the difference it made on my current c/o's I think that both of these things can be negated with proper valving now. That is part of why I have this sudden interest in air shocks again. I strongly feel I left a lot on the table by ditching them before I messed with valving.

What tiny is, I think, insinuating, is that air shocks come severely under-valved from the factory. So the valves are doing very little in terms of dampening motion in factory form. So people use taut limiting straps to preload them as well as little shaft showing to get them to ride right on the edge of the sharp up-swing in spring rate. This is also why they tend to beat the passengers to death when this is done.

I bet with the right valving you can get an air shock to ride right at 50/50 shaft height with little to no unloading and a nice soft ride and that the shims involved in doing this will be MUCH heavier than c/o shimming on the same rig. (Due to both small rate gains at that height and frothing fluid being thinner and going through the valves more easily.)

 

[TacomaJD]

My point about tuning was just that few have ever given air shocks a fair swing IMO and that people think they've exhausted their potential before they ever even touch the shims. I've literally started threads about shimming air shocks and either been ridiculed for asking or received close to zero input. (As everyone knows, I care nothing about being ridiculed.) How about flutter stacks, messed with them at all?

So you add a lot of compression and rebound? More compression I'm guessing? Have you played with the single bleed pistons at all? They're reputed to be more for crawling but everyone knows that crawling is boring.

You're literally maybe the second or third person I've ever talked to that has messed with air shock shimming.

There was actually a thread on Pirate that I read about a guy swapping the shim stacks, so it would be 90/40 instead of 40/90. You could do this by just swapping out the stacks already on the piston. One side, can't remember if it was compression or rebound, had an extra shim that had to stay (biggest shim on the "bottom" of the stack), but the rest of the shim stack would interchange between sides, virtually reversing the valving. His testimony was that it sounded crazy, but it made a huge (better) difference in his rig.

I've always thought it didn't make a lot of sense to valve air shocks like 40/90. My old Fox 2.0's were even 30/90. But then again, I'm just a web wheeler and don't have an education in shock engineering.

 

[TacomaJD]

I bet with the right valving you can get an air shock to ride right at 50/50 shaft height with little to no unloading and a nice soft ride and that the shims involved in doing this will be MUCH heavier than c/o shimming on the same rig. (Due to both small rate gains at that height and frothing fluid being thinner and going through the valves more easily.)

Since you set ride height with nitrogen, by the time you pumped the shocks up enough to support your rig and have half the shaft showing, would you not then encounter limited up travel because of the volume of nitrogen. Of course rig weight and a few other factors could play a part here, but the big thing I think is that the 4-6" of shaft showing is the 4-6" of compression space needed for the air spring. Once the nitrogen compresses so much to create the air spring to support the rig on a bump or when flexing, uptravel is no more. The nitrogen can only compress so much before uptravel stops and it begins to move the whole chassis instead. Now, if you have a 14" air shock, half the shaft would be 7".......50/50 shaft length would be more feasible maybe? But hell, then half of a 16" is only 8", maybe that would work by theory too? .....maybe I'm overthinking this entire thing or even completely thinking wrong?

I know I've only got about 6" of shaft showing on my 16" Fox 2.5's on the rear of my truck now and I have never bottomed the shocks out, and it rides plenty soft. Actually been thinking about lowering it about an inch on both the front c/o's and the rear air shocks to gain a little stability.

 

[patooyee]

Ride height set by No2 but rate gain is mostly set by oil level. So less oil maybe to prevent limiting up travel combined with heavier valving to control it all better?

I'm bound to secrecy as to what all happened with my current c/o's. But I was surprised by how much valving had to be added both in rebound and compression to make my current rig the way it is. And that was with a c/o where the oil isn't getting much thinner. But because of this I STRONGLY believe that an air shock needs WAY, WAY, WAY more valving than they come with.

 

[jojo]

The shocks were built in North Carolina at the digger shop. They are pretty much the same as what Ryan was running on his mud truck. They changed shims a few times on them last week trying to get it right but they didn't really have much time to work on it. Ryan is going to work on them some more. That's really about all I know about them.

 

[Blase]

I bet with the right valving you can get an air shock to ride right at 50/50 shaft height with little to no unloading and a nice soft ride and that the shims involved in doing this will be MUCH heavier than c/o shimming on the same rig. (Due to both small rate gains at that height and frothing fluid being thinner and going through the valves more easily.)

I'm building right now using 2.5" air shocks and the above statement caught my eye so I want to be sure I understand it. Part of your theory is that the shock will work better if at ride it is in the middle of its range of motion? So on a 14" shock 7" of shaft showing at ride height correct?

I was always told (I have never personally messed with air shocks before!) that since the charge was on the top the more shaft that you had showing the higher the charge needed to be. The higher the charge needed to be the more unloading would be present.

I have no clue when it comes to the shims but i'd love to see someone try adjusting the valve pack and report back on what works and what didn't!! :****:

Learn me something Patooyee

 

[patooyee]

Re: Re: Re: Bobby Tanner's new shocks?

I'm building right now using 2.5" air shocks and the above statement caught my eye so I want to be sure I understand it. Part of your theory is that the shock will work better if at ride it is in the middle of its range of motion? So on a 14" shock 7" of shaft showing at ride height correct?

I was always told (I have never personally messed with air shocks before!) that since the charge was on the top the more shaft that you had showing the higher the charge needed to be. The higher the charge needed to be the more unloading would be present.

I have no clue when it comes to the shims but i'd love to see someone try adjusting the valve pack and report back on what works and what didn't!! :****:

Learn me something Patooyee

Not really. I think the consensus with the high speed stuff these days is that you want something around 50/50 shock shaft just to give you more shaft to absorb hits with ANY shock. Most seem to have found this unobtainable with air shocks though because they loose control. My theory is that 50/50 may be obtainable if one were to actually bother tuning their shim stacks and not just air/oil levels.

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[Neal3000]

There used to be a few guys running air shocks at KOH in the early days, surely they tried everything in the book including shims to make them work?

 

[TacomaJD]

Re: Re: Bobby Tanner's new shocks?

I have read just about every article pertaining to setting up/tuning air shocks that I could search for on Pirate and other offroad forums also that came up in Google search results. I've never read anything that contradicted the 4-6" sweet spot rule of thumb. There's probably a reason for that. Now, ORI's are a different story since they possess an upper and lower N20 chamber. Most run ORI's with approx half shaft showing, as far as I've seen, since you can control the unloading with the lower chamber psi while still having plenty up travel. Youtube search for AZ Undertakers or Arizona Undertakers, and watch a few of their vids. There are several VERY capable rigs in their club that run air shocks, a lot are even running 2.0's and work excellent. All of their air shocks are set up with very little shaft showing.

Brandon's buggy before he swapped to C/O's for reference. 16" Fox 2.5's

Pic of my rear 2.5's, which came off of Brandon's buggy. They work well set with this much shaft showing. This was actually taken before my front end got linked and Angryfab recharged the air shocks in the rear before I picked it up. It's currently setting a little higher than in these pics and does good, but I plan on burping some N20 out and lowering the air shocks back down about an inch or two, to about what they are set at in this pic, then adjusting preload on c/o's to lower front end down to level.

 

[Skidkid]

My point about tuning was just that few have ever given air shocks a fair swing IMO and that people think they've exhausted their potential before they ever even touch the shims. I've literally started threads about shimming air shocks and either been ridiculed for asking or received close to zero input. (As everyone knows, I care nothing about being ridiculed.) How about flutter stacks, messed with them at all?

So you add a lot of compression and rebound? More compression I'm guessing? Have you played with the single bleed pistons at all? They're reputed to be more for crawling but everyone knows that crawling is boring.

You're literally maybe the second or third person I've ever talked to that has messed with air shock shimming.

I used to race harescrambles on dirt bikes years ago. I sent all my shocks out to be tuned except for the last set on my 2001 yz250. I did those myself. I installed gold valves and re shimmed them. They had an online calculator that helped you choose what shims to install. How much oil and it's weight also made an effect on their performance.

Shocks are sent out new dialed in to a generic and most common setting for overall fair performance. Go and modify them correctly and it will shock <- no pun intended, on how much better they can and will be.

 

[patooyee]

Re:

Did Brandon ever revalve? Have you?

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[TacomaJD]

Re: Re: Re:

Did Brandon ever revalve? Have you?

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I assume not, as when I asked what the valving was, he told me the numbers that were engraved on the shocks from the factory. However, I went to pick them up from him when he was at Pete Deck's (Dirty South Motorsports, who built the Ford buggy and done all the mods/tuning on it) and Pete mentioned that they played with the oil levels. He never said anything about valving.

When he was ready to sell, he had 2 bent ones and 2 straight ones. I said I wanted the two straight ones, because at the time I was not confident in my ability to tear the shock apart and replace the bent shaft. Turns out the straight ones were from different ends of the buggy. One was black top, and one was the previous blue top. One was valved 40/90, the other was valved 40/80. The one that was on the front had more N20 in it to support engine weight, but after burping it out enough to feel close to the other one and sit level side to side, they worked awesome and I could/can not tell a difference in the valving. HUGE improvement in body roll over the 18" 2.0's that were on it that were valved 30/90. Of course body roll was ridded completely when I got rid of the leafs and went to 4 link with c/o's in the front. Completely happy with how my suspension does now, although I still have some fine tuning to do.

 

[Technician]

Tires are really just an air spring that supports the entire vehicle. I'll not go into great detail about tire tuning here, but you should be aware that the tires, and the pressure in them, have a huge impact on vehicle ride and handling – regardless of the style of suspension used. This can be a complication in suspension tuning, but can also be used to advantage. For example, a stiff suspension set up for high-speed work can be made more comfortable and pliable in really rough terrain simply by adjusting the air pressure in the tires. The other reason I mention tires is because you often don't see them mentioned when people are swapping suspension advice and experience. That's a mistake. To properly understand and use the experience of another you need to be aware of, and account for, the type of tires they run and at what pressure.