It's not if there's a bladder that's makes them smooth or not it's the seals. You should know that. And they don't offer more faction or not. It's your set up. Where do you get your BS from?

the only thing i didn't read here is that on emulsion shocks the more they work the more the foaming that starts happening and compensates for more roughness in my opinion, versus the bladders that do not have that ability to change with the roughness changes i.e. the track getting tore up and more line ruts to deal with vs. the first heat when the track is smoother. the bladders work great and are the most consistent but sometimes you need the shock to change with the track conditions and that is where emulsion shocks will show their difference just my opinion. please feel free to correct me if anyone has had different results.

I really got to add that I find this kind of ironic. Who knew, all those years I raced pre-dating bladder shocks, I was actually running emulsion shocks.

There is no scenario where I will personally run emulsion. Opinions vary of course.

Interesting read,
For what it's worth,
1/10 has an almost exclusively emulsion shock design, since, well forever.
1/8th has use a bladder design almost exclusively for most of its age (in the last 5-6 years, some Mfg.'s have played with the vented cap styles here and there)

For whatever reason, the engineers/designers have traditionally stuck with those two designs for those two scales

More recently it seems that a number of Mfg.'s on the 1/8th side are playing with the emulsion cap designs and only Tekno offers all three shock/shock cap designs in their kits (emulsion, bladder, and vented). As for which is better and older what conditions, I have no clue, but I'm pretty sure there's reasons by those whom are probably far smarter than most of us as to why they would want to use one design over another or, why they would be offering parts to switch designs.

That is the easiest way to ensure there is no air mixed with oil. I found out the hard way that you have to be careful not to over tighten the shock caps with some shocks as you can disturb the bladder and let air in.

Have you tried venting your shock caps? If you drill a tiny hole in the cap, it relieves the pressure behind the bladder.

Hiya folks,

There is another type of shaft volume compensation which was evident in vintage rc cars of the 70s to early 90s.

Foam compensation!

a blob of foam was placed under the piston and as the shock shaft extended into the damper body, the foam compressed.

This prolly didn't work as well for large or long shocks as the amount of foam will have to be quite extensive...

I believe yokomo, ayk and some other companies had this kind of shocks in their old vintage cars.

-Alexander

Wow Alexander I forgot about those. I sort of remember placing a block of foam in the cap head of the shock also. With the bleeder screw on 1/10 scale shocks I would really think your getting allot of the air out. It really used to be messy without the bleeder system.

I've seen Adam Drake, back in his TLR days, in an instructional on YouTube about how to do the foam compensation in the 8ight shocks. I've also heard of Tessman using a bladder with the vented cap: that makes the most sense to me as far as bladder shocks goes.

I know this thread is resurrected from the dead, but today it appears nearly every major team driver is running emulsion almost every race. That's in 1/10 and 1/8 scale! I only got into racing a few years ago, but I've only run emulsion. The kit setup for my 8ight-E 4.0 is bladder, but all the posted setups are emulsion so I went with emulsion too.

the TLR 8ight 2.0 EU had foam compensators that where sandwiched between the bladder and the cap.

With a bladder build, a molded, rubber bladder will want to return to it's natural shape, if not affected by either the air pressure or vacuum found behind the bladder.

Some manufacturers are now providing shock caps that allow you to build your shock under multiple configurations:

-Bladder with a Vented Cap
-Bladder with a Non-Vented Cap
-No Bladder - Emulsion with a Bleeder Screw in the Cap

Bladder with Vented Cap (openly drilled hole in cap, no screw)
With the bladder builds, if you remove the closed in cap from the equation, the elasticity of the rubber bladder and how far it needs to stretch (based on the volume compensation as the shaft is pushed in) will determine how much it (the bladder) will want to recede back to its original shape, after releasing the shock shaft. As the bladder tries to recede back to its original shape, it will pressurize the oil chamber, forcing the shock shaft to come back out. Therefore, having a shock cap with a vented hole in it, above the bladder, will simply use the spring of the rubber bladder to affect rebound.

Bladder with a Non-Vented Cap
Now consider what happens when you place a bladder in between the oil and the space inside a non-vented cap. This space will contain air; which is compressible. As you push the shock shaft in, displacing the oil, the bladder will push into the air chamber behind it, compressing the air as it moves inward. Now when you release the shock shaft, the compressed air behind the cap will assist in pushing the bladder back out. The air now acts as a small spring behind the cap. Higher rebound is easily achieved when building with bladders and non-vented caps.

Bladder with a Vented, Sealable Cap (bleeder screw provided)
Here's where things can get interesting. The volume behind the shock cap has air in it. With the shock shaft fully extended and no pressure in the shock body from the oil, the bladder is at rest. The air behind the bladder is neither pressurized nor has a vacuum on it. Leave the bleeder screw out of the cap, and again, you get no help from the air pressure as the air escapes from the bleeder hole in the cap. Put the bleeder screw in the cap, closing the cap, and you now get added air pressure behind the cap as you compress the shock shaft.

But, what if you push the shock shaft in halfway with the bleeder screw out? The bladder will deform slightly, due to the displacement of the shock shaft in the oil. It will also NOT be pressurized because the air can escape through the bleeder hole. What happens now if while holding the shock shaft at this position (half stroke), we then insert the bleeder screw, closing off the air chamber in the cap? As we let go of the shock shaft, will it push out or stay still (no rebound)? If we were able to create enough vacuum behind the cap to equalize the elasticity of the rubber bladder, in theory, the shock shaft would have no rebound from this point. It won't move. Push the shaft in slightly and we begin to pressurize the air behind the cap. Pull the shaft out slightly and we begin to create a vacuum behind the cap.

Now go to extremes. With the bleeder screw removed, push the shock shaft all the way in, deflecting the bladder completely, then install the bleeder screw. In this configuration, in theory, you begin to create a vacuum behind the cap the instant you start to pull the shaft out. This vacuum might then want to pull the shaft inward, creating the opposite effect of rebound.

Watch Gord Tessman in this video as he discusses this when building the new HB shocks.

http://www.dailymotion.com/video/x3015ls

Hybrid - Vented Cap, Bladder with Foam Spring
Another hybrid form of achieving consistent rebound, as mentioned in a few other posts, is the use of a vented cap, with a small piece of foam rubber behind the bladder (in the air chamber). The theory behind this was to maintain consistent rebound throughout the course of a race (when facing 30 to 45 minute nitro mains). The theory is aimed at a shock's temperature changing due to the friction of the parts (making the shock warmer) or cooler ambient air (making the shock cooler). Either way, air temperature affects air pressure. Therefore, a shock with a bladder and a closed cap (no vent hole) might have different pressure behind the cap, should the shock temperatures changes during a race.

So, pick your poison. Personally, I build bladder shocks with vented caps. I drill an additional 1.5mm hole in the cap to ensure the hole is large enough to let the air volume breathe in and out, with no restrictions. I am able to build a fairly neutral shock (very little rebound or pull back), relying on the bladder to be the only push/pull spring, not the air pressure or vacuum. My shocks are fairly consistent even when I neglect them longer than I should. The only drawback to the bigger hole in the cap is that it sucks a little more dirt in behind the bladder. Does not appear to affect performance as this dirt never gets in the oil nor is enough to fill the cap.

Another cool benefit to running a bladder shock and using the bleed screw to adjust the rebound, based on how far you push the shock shaft in, is that you can easily adjust your rebound without having to add or remove oil. You could effectively build a set of shocks, set to full rebound. Mount them on your car such that you can easily reach the bleeder screws without removing the shocks. Run the car at full rebound first. Get a feel. Come into the pits. Have a buddy remove the bleed screw, push the shock all the way in, replacing the bleed screw. Repeat for all four shocks.

Now you can quickly compare full rebound to full pull back on one tank of fuel or single battery.

For really bumpy tracks, or tracks with a lot of woopties(sp?), moguls if you will.

How are folks approaching tuning shocks in these situations. Is bladder preferred over emulsion?

Emulsion seems to be the trend among some of the top manufacturers, but not all.

As mentioned by others, emulsion adds air to the oil, to allow for the volume compensation that the shock shaft displaces when pushed in. Also suggested is that the added air slightly dilutes the oil, reducing its effective viscosity.

It is possible to build zero rebound or "dead" shocks with either build method. Whether one is better than the other on a specific track, for a specific driver simply needs to be tested.

The easiest thing to do is to find another set of shocks. Build them identically, aside from bladder or emulsion. Or, just have the O-rings, bladders and/or shock caps available to easily switch between the build types on a single set of shocks.

Run some laps with each. Swap them out. Play with the oil weights and spring choices. As much as I love racing, a good test and tune day is quite rewarding. Remove the guess work. Become your own "pro" at tuning and making educated changes to your car on race day.