I am trying to get a pretty quick response from any of you running the Robispec springs in the MR Bilsteins, and figure out what custom valving you had done by Bilstein.

Essentially they don't have a boiler plate valving setup for those springs, but they did ask me if I knew other customers, that had custom valving, and they could look up those specs as a reference.

I think I gathered from other threads that the Robi spring rate is 240 lb/in F, and ~280 lb/in R.

Now I already had custom valving with the stock springs, and thought that was good I have decided to go to these springs based on comments from many of you. This leads me back to what in the heck I should ask them for. My setup is there waiting for me to give some feedback, or some names (of those of you comfortable PMing me your first and last names for reference in their dyno database.

Any help appreciated.

M

This is a thread I commented on, but its more about purchase than Bilstein setup for them.
https://www.evolutionm.net/forums/ev...c-springs.html

 

Nobody? There must be plenty of you with RobiSpecs.

What about those of you with custom valving on progressive springs in general. What settings did you get by Bilstein.

anyone?

 

Bueller?

 

I sent in my MR Bilsteins to be revalved for my GTWorx springs. I gave them the spring rates and told them what kind of driving I did (DD, auto-x). In retrospect, I should have asked for some extra low speed compression

 

What would the result of more low speed compression have been? And, are the GTWorx springs progressive?

 

The GTWorx springs are listed as linear in the sticky at the top of the forum.

As for the low speed compression comment, I believe that it helps smooth bumps out better. However, someone else can chime in and elaborate a bit more. Its been awhile since I actually looked it up lol

This thread also has some good information regarding Bilstein rebuilds - https://www.evolutionm.net/forums/ev...n-revalve.html

 

Thanks, the sticky doesn't have the robispecs in it so I forgot to check there.

That other thread is a doozy, but I couldn't completely follow the conclusions in what I could communicate to Bilstein.

1- request 65% critical damping and go as digress ice as they can.
2- 2/3 and 3/2 more rebound than compression 'rule'
3- increase rebound control by 30% (from robispecs)
4- stock valuing
5- give them the spring rates and let them do their magic

About the spring rates. In all the posts on this the stock rates are always noted differently. They all say smile said X, but then X is always different.

200/270 stock
Is what I calculated off of to give the form 240 F and 280 R.

 

Have youe tried getting in touch with Robi and asking him about valving the Bilsteins?

 

I sent an email that was not answered, but on a few other posts people who state that they got him via phone he essentially just noted what's on the website about the spring rates. Not anything that could provide the vaving details.

I have since gotten my struts back and installed them. The car doesn't run yet because of a couple other mechanical issues ( cam replacement &and diff bushings ) but as soon as its running I will provide some feedback and pics of the Dyno sheets from Bilstein.

 

I thought it might be very valuable and education for some of us if I share the graphs I received from Bilstein on my revalves.

The first set is for stock springs and custom revalve and the second set (my current setup) is RobiSpec springs and custom valving.

I gathered as much info as i could during this process, but the information I recent verbally was often not consistent and usually confusing. Maybe here on the forum we can get some input so that I can gain some knowledge from this stuff. I have now spent just over a grand total in custom valving and its all 'black box' to me. This was my third time and I would really like to learn something more concrete from these numbers.

First up is the graph I was given for what 'was' the custom valving I received last November, 11/29/11, for my stock MR springs. Can anyone identify what this actually means so the rest of us can gather some meaning from it?



Next is the data that goes with the above graph from 11/29/11. Again, any comments on what all these data elements actually mean or indicate of the shock performance.





The last of this set is a bunch of scribbles I noted over the phone, when I called Bilstein back and tried to extrapolate meaning from the data in forms I could try and understand. rebound, compression, rate, etc. You can tell by my notes I was lost and I felt the guy talking to me was just BSing me with nonsensical stuff that contradicted. He initially noted it was technically impossible to provide me this data except orally. This last go around I was able to get a print out of that data from someone else.





Finally the more relevant data is this, from what my current setup is. This is the data with the new custom valving and RobiSpec springs. I would like to know how I could read that for meaning.




Hopefully this data can peak some gurus' interest for a discussion.

 

Bilstein has a valving manual on their website that is worth looking at. It goes into the rebuild of some of their motorsports shocks, which internally are very similar to their production car stuff. As far as Bilsteins valve coding goes, unless you are using linear valving, it doesn't really tell you much.

The 368/190 code for example means the shock dyno measured 368 lbs of force on rebound and 190 lbs of force in compression when the shaft velocity was 0.5 in/second. If the valving was linear, then if you double the shaft velocity, the force would also double. Based on the chart though, it is digressive valving, doubling the shaft velocity doesn't double the force at that point. Where the curve "knee" is and what the different slopes are can vary greatly and yet the shock could have the same force at 0.5"/s.

Now I think you wrote down "2436" on one part which actually could be a stack code for the digressive valving. The digressive valve stack codes don't make much sense to me though so I have no idea what it means other then it may describe a specific valve stack.

As for what makes a good valving match, I can’t help you there. It is something I am currently learning about myself.

Here is your old and new charts based on your data.


Looks like you picked up some low-speed damping and dropped some high speed.

 

I have this setup on my front bilsteins only. My backs are still stock. If you would like any information pm me and i'll set you up with what i can. I will say that on rough streets these take a lot away from the evo but they are very solid and make the car handle amazingly well. Unfortunitely just after having them revalved i move to the worst street in town and it kinda sucks driving my car for a few blocks. Not nearly as bad as my customer cars with kw or bc coilovers.

 

I might have those curves labeled wrong actually? Are the rears the higher force dampers? I would think they would be due to the suspension motion ratios and relative spring rates.

 

Thanks for the input. I couldn't actually tell from the numbers, but more fundamentally I can say that I can compress by hand the front springs more easily than the rears, which might indicate the rears being or requiring higher force to compress. Its also somewhat logical that the tighter wound metal resists compression more strongly.

How did you create that graph? Xcel? If so, can you provide a copy here or PM it to me. I would like to recreate that, plugging in the numbers, and see if i come up with the same thing you did, and maybe be able to answer a question along the way.

Also, where did I write down "2439", I am missing that.

For the good stuff, and sorry if this is too rudimentary:

When you note that I picked up some low speed damping you are saying that because the key point on the graph at roughly 420lb by 2.5 in/sec has gotten much steeper. Meaning that at that lower speed shaft velocity the damper is resisting movement more strongly than it was for the dotted blue line which doesn't reach 420lb until about 8in/sec. Is that a correct understanding?
If so, does that imply a rougher ride over small imperfections? And that due to the damper and not the spring. or due to both because the damper is 'matched' to the spring?

Another interesting detail is that now when the car is at rest (suspension loaded) the progressive part of the Robi's are fully compressed and touching. That seemed very odd to me. They aren't doing anything when all the coils are touching already. Are they?

 

Low speed damping helps control body roll type movement. At least on the blue line, there is a significant amount more rebound damping and a decent amount more compression damping. The new valving should help reduce body roll on quick transitions. Long sweepers, the springs (and anti-roll bars) control the body roll and without a spring change, you won't really change the steady state handling characteristics of the car with valving changes.

The new valving is softer at higher shaft speeds. This will actually make the car ride smoother over bumps that get shock velocity over about 8 in/sec. Provided the shock doesn't bottom anyway. The new valving should reduce body roll on quick transition maneuvers and should be smoother over road irregularities. win win...

As for "2439" that's what it looks like on your paper to me but maybe it is something else. As for the graph, yes, it was done in excel. It is the exact data out of your tablulated data. Just type it in and then do a plot using shaft velocity on the horizontal axis and forces on the vertical. Change the negative shock velocities on the compression to positive numbers but leave the forces negative. I also converted to imperial units simply because that's what we are more use to seeing in the USA.