Quick tutorial #7: Bladders or emulsion shocks?

The big question, which is better? Diaphragm or emulsion shock absorbers?

It is quite difficult to answer this question simply because it will also depend a lot on the driver preference, the car and the geometry of the dampers.

But let's see here what are the advantages and drawbacks of each solution.

Shock absorbers with bladders

Without going into all the possibilities of different diaphragms on the market today... Let's stay on the case of the classic rubber bladder, which allows to separate the oil from the shock absorber and the air, and to compensate the volume of the shock shaft that goes in and out of the shock by its compression.

I find it really funny that some drivers come to me and ask me which diaphragm to use, the soft, medium or super hard?

When they don't even have the right oil in their shocks! 

At any level, I think that there are more important and primordial things to do before going into details about the hardness of the shock absorbers.

Yes, there can be a gain in some conditions and for some drivers, but often the more complicated you get the more time and versatility you lose.

The diaphragm is a simple system to compensate for the volume of the rod entering the shock.

It is the easiest, the most accessible and also the most economical system. Indeed, once your shock absorber is closed, you have less loss and less regular and less tedious maintenance than with an emulsion system.

We saw here how to build and close shock absorbers with bladders

The big advantage on the track is that it makes the car more responsive. We can summarize that the damping feeling in this situation will be harder, which can give the impression of more grip.

This can be a plus on flat tracks with little grip for example, as this solution tends to push the tire more on the ground.

Emulsion shocks

The principle is to mix micro air bubbles with the oil inside the shock absorber body. Unlike the diaphragm damper, there is nothing to compensate for the volume of the rod that goes in and out of the shock body.

The oil is incompressible, so it is the air inside the oil that will compress to allow the damper to function.

It is easy to understand that the air trapped in micro-bubbles in the oil will behave differently if the temperature is high or the atmospheric pressure is different.

This is why it is important to monitor emulsion dampers more regularly from one day to the next and even from morning to afternoon depending on the temperature.

It's going to be important to at least open and bleed the dampers on a regular basis during a day where the temperature varies and obviously from race to race.

If you don't do this, and the temperature rises for example: the air trapped in the oil inside the shock absorbers will rise in pressure, which can mechanically lock the shock absorber on track. On the other hand, if the temperature decreases, it will surely be necessary to add oil to avoid having too much air inside the damper.

The main gain on the track is a better damping of the suspension. On the big fast curves, the car will have more support and a better hold.

This is the choice for tracks with a high grip, fast tracks or on bumpy tracks. Also, there won't be as much bounce after a jump where the chassis always tends to snap and bounce.

As I write this in October 2022 I prefer the emulsion system which gives me a smoother but more precise car behavior with more mechanical grip at the wheel.

With Kyosho IFW469 shock caps, you can test both solutions and give us your feedback!

Don't hesitate to leave a comment bellow and share your experience with our readers!

Here is in video my technique to rebuild and close emulsion shocks

See you soon in a new episode!

The Shark 
Reno Savoya