Are you also running anti squat?

[QUOTE=fredswain;10738482]I use exponential. It's another tuning aid. Use it! You can actually have a more aggressive car that is controllable if you take advantage of all the electronic features.

Love this! and I know I'm late to the game here but I've been using a bit of expo on throttle and steering for years. It's especially useful when your heat is up and the temperature just changed 10 degrees outside and suddenly your car feels a little frisky. Or just helpful to get an almost perfect car dialed in.

WERD :)

There are some people that claim that no expo helps them sharpen their skills and reflexes. They need to swallow their pride. If you don't want to take advantage of electronic features that help you, you may as well tune the car as terrible as possible for the same reason.

[QUOTE=13Maschine;13011250
Anyone have access to a shock Dyno? Also I wonder who has a spring testing machine or used a commercial one? It'd be nice to test older springs to see how they have worn versus new and also to do comparative testing between brands and such.[/QUOTE]

I've tested old springs with a digital scale (force per distance compressed). That's rather straightforward. Damping would be more difficult to measure.

The air in the shocks (especially emulsion shocks) probably does play a big role in the equation, but I certainly wouldn't know how to come up with a factor for it. That sort of goes back to Fred's comments about temperature. It just gets very hard to come up with a model for it. Of course, that doens't mean we won't try.....:sneaky:

+1 on the expo. Just used some more of it today with the old gold pan. Once you start using it, you will wonder why you ever didn't.

I no longer run emulsion shocks. I hate them. Bladder shocks all the way. They are so much more consistent. There is no truth to them not landing as well. I will never go back.

+1 on the shocks. I think that air mixed in with the oil would make the shocks way less consistent. That's probably the bike suspension tech in me though. I'm still suprised that someone with the resources hasent come up with a shim stack piston. Then u count tune compression and rebound separately. We use this in the bike world to custom tune customers suspension. Probably a little harder in the rc world though.

There has been quite a bit of talk and development in terms of dual stage pistons on this thread. A lot of development has been done here. MIP has their Bypass 1 setup (I'm currently experimenting with this), RC Shox has their dual piston setup….Perhaps try searching through the thread? I think Mantisworx is the guy you wanna talk too….Fredswain as well.

I'm not super famialiar with a shim stack pistons but I think the MIP Bypass system may be like this…

http://realshocks.com/MIP_Bypass1_Re...uspension.html

Yeah I've looked at both of those and they do seem like they work well. With a shim stack u can control both rebound and compression. I suppose the two stage pistons would be the closest thing to a shim stack.

Basically a shim stack is a series of thin washers. The main shim flexes to allow fluid to pass over or under it. U control this flex with other shims that are smaller in circumference and thickness. It's a similar concept that mip uses but u could adjust both rebound and compression instead of one or the other.

Again this might not work in the rc realm but it would add another level of tuning options.

How would a shim stack on both sides work? I would think that you could only run it on one side of the piston or your closing the shims on one side or the other no matter which way the shaft is traveling.
Unless maybe you had an inner set of holes for rebound with small circumference shims and an outer set of holes for compression with large circumference shims on the other side drilled out to let oil pass through the inner holes?

What suspension company do you work for? Just curious, raced DH for years. May be getting the intense out of retirement now that the local ski resort opened up for DH again.

Well the idea would be that there are no holes. Instead the shim would flex thus allowing oil to pass around it. For a visual take a dime put a quater on top of it then put another dime on top of the quarter. Now amagine the shock shaft runs through the middle of them. The coins would be very thin so thin that they flex. The dimes control the amount the quarter will flex. If u wanted more compression or pack u would use a nickel instead of the dime.

U could also take it one step further by adding multiple shims. Now instead of having a shock hydro lock a series of shims could be used. Dime, nickel, quarter, dime. This would allow the shim to flex in stages for lack of a better term. On a big hit the shim will flex both the dime and nickel but on smaller hits just the nickel would flex. U could tune the rebound in a similar way.

The problem with all this is that our rc pistons act as a guide for the shock shaft. The lower part of the shock body would have to be redesigned to support the shaft without the aid of the piston. For what they are the current shocks work very well and with mip and rcshocks pushing development I think it's only a matter of time till we get something like this. I mean if u think about it all the advancements in our hobby are pretty remarkable. Batteries, esc, servos, kit materials and design have come a long way over the years but we still have very similar shocks as the vintage kits.

Oh and I'm just a wrench at the lbs who does all the suspension work at the shop. Fox rock shock marzochi ect I can tune it. We don't do a lot of custom stuff but when somebody in the area wants it done they come to me.

a few weeks ago i saw a new tc shock that had the shock shaft go all through the shock and exit it again at the top to prevent rebound. It wouldn't need the piston to guide the shock shaft

T-Shox. Very cool design, however they work well for touring cars because of their small size and relatively low piston speed and overall piston travel. For that design to be adapted to offroad applications it would be a much more serious package in order to maintain the same amount of travel. It's also cheaper for touring cars since shock lengths are equal front to rear.

Ya and the top of the shock is protected on a touring car. Imagine a shock shaft sticking out of the top of an offroad shock, it would get ripped off in no time.

Not trying to hijack Fred's thread here, just answering some questions based on full-size shock / hydraulic suspension experience.

It is a linear value which you can measure with a viscometer. However this doesnt mean twice the pressure drop (damping) in an orifice, as a significant part of pressure drop is the inertia effect of accelerating fluid through the small hole (which is a function of fluid density, hole size and piston bore).

That's true - although there have been some measurements with temperature, and typically oils of a similar type (eg silicone) behave similarly with temp unless there are some modifying additives. This site here has some great info:
http://www.twf8.ws/new/tech/shocks/shock.htm It would be cool to see the viscosity vs temp for a range of fluids. Pretty much any university with an engineering lab will have access to a viscometer and test equipment to get this data if there are any students out there...


The effect of air in oil is difficult to quantify for sure. It adds compressibility (which makes many assumptions in hydraulic flow invalid) but it also changes viscosity. The viscosity change depends on the fluid properties - the surface tension of each bubble has an influence on the final viscosity, so some oils actually become more viscous when there are many tiny bubbles (which is counter-intuitive).

I would love to have access to a shock dyno... I know MIP and CSI have them. One of my mates built up a spring tester and it was really useful to compare rates, especially when the BB springs started to come out. They were generally more progressive than the smaller springs.

With a piston with shims each side, generally you will have holes drilled at an angle and the shims smaller than the piston. That way the oil flows into the piston around the shim, then comes out the other side of the piston closer to the shaft and has to bend the shim out of the way.
http://www.kingshocks.com/wp-content...5/tech_m_2.jpg

Pretty much any shock uses the piston to support side loading of the rod (unless you are talking full-size rally struts which use a large diameter outer shaft bearing). Im not sure if there are different designs in mountain bike shocks?

Its great to see the work MIP are doing, although if it becomes mainstream will add another complication to RC so Im not sure it would be in the best interest of the sport... but would be very cool for sure. The main issue seems to be getting repeatability in such small mechanical devices, and also preventing hysteresis from friction within the valves. Moving to 12mm shocks instead of 10mm shocks has probably helped in both regards. But having a dyno will become critical at the top end of the sport if these become more popular.

Some interesting discussion in this thread for sure.

Ray