They are pretty good on the street. In fact, they were better for me on the street than Koni Sports. And many solo national championships have been won on Koni RACE. They're a good shock... but it doesn't mean they can't be better.

Don't worry, you don't. It's a pet peeve of mine when threads get cluttered up with repeat or irrelevant information (like this post :)).

Bernie, discuss montube gas pressure. I think Bilstein uses about 350# pressure. What do you use and why?

And you'll see people who went from stock suspension to anything not blown out that they'll be better on track and the road. A better designed system can do multiple things better.

Doesn't mean that a good shock is good in general though.

Read the thread around post #26. This talks about the gas pressure. If you still have a question about it after that, please pm me.

Do you have an ultimate point? I must be missing it. At the same time, what's comfortable to me may be uncomfortable to you. Both my cars have coil-overs with high spring rates and both cars have fixed back bucket seats, and both cars have stiff engine mounts (poly filled on one, and the miata is getting a hybrid setup eventually)-- if that's any indication on what is tolerable and "comfortable" to me.

It seems you're trying to shoot down ANY discussion at all of a shock that works on the track and can be driven home on. I don't think that is the case and I'm here to learn what the deficiencies are of what I have to avoid with my future setups.

Yes. My point was that a good race shock does not equate directly to a good street shock. I've said that many times.

Comfort is one factor, and as I've said before, it's always dependent upon setup of car and preferences of driver.

Okay, and I concur, it just seems you directed towards me solely as if to correct a statement I made. (I'm here to learn, so correct me directly if so).

To me, I'm comfortable if the car can handle bumps and maintain grip. In that regard, whether you're WOT through a bumpy sweeper at 90+, or doing 70+ on a bumpy freeway on the way back home, a shock should be able to keep the tire planted. I think a "good" shock should have no problem doing one AND the other.

Maybe we just have to wait until Bernie is ready to lead the discussion towards shock tuning...

I'm talking to Bernie about a set of shocks tuned for me, and when he asked if I mind if a firm ride for the street.

I pretty much said the same thing. Firm is good, just not crashing or jarring.

Here's some Bilstein videos:

http://www.youtube.com/watch?v=W4ZZY...eature=related

http://www.youtube.com/watch?v=IKPZ8...eature=related

http://www.youtube.com/watch?v=QpQNzzy_o_k

I have my own synthetic. I have it made by a company out of the Midwest. The oil I use was a blend that Petty Enterprises developed.

It comes the way light viscosity oil should in that it is rated by centistokes. I have a #5 that is equal to a standard 2.5 wt., and I have a #9 that is equal to a standard 5 wt.

The standard oil I use, however, is the Bilstein. I have to use it for the spec miata shocks, and it's actually a pretty good oil. I use it in all of my street/dual purpose shocks.

The synthetic is reserved for the race shocks. Nobody wants to pay the difference for street use.

Why not just dump some Mobil 1 5W20 in a shock?

I know there are a lot of things to consider with oil such as expansion rates, viscosity break down and anti-foaming among others.

However, I am not an oil expert so I leave that to the guys I know can do a better job.

That's smart business-admitting that you don't know all the answers but you can find someone who does.

The requirements for a high performance damper fluid are quite a bit different than virtually any other part of a passenger car. Like Bernie, I'm not an expert in this but basically, no you don't want to just dump lightweight motor oil in there. I'm sure the damper would function more or less but definitely not at optimum. No more than dumping 20w damper fluid in your engine would be a good idea.

All oils are specially produced with different additives and levels of additives for the specific purpose. With shock oils, one of the big design concerns is cavitation. For supercharger oils it is atomization....and so on. Bottom line, use the oil specified for the purpose.

I'm with you in that I like to have my cake and eat it too. Here's a response to a thread on Miata.net from some other fellow which might shed some light on your questions:

"When I spoke with Bernie, I told him I would be primarily driving the car on the street with a half dozen or so autox events a year also a consideration. I installed them in April and have 6 months on them with about 2.5K miles and 7 autox events. Current setup is 13F/13.5R ride ht, 1 1/8th tubular front bar, 11mm rear bar, 36mm/46mm FCM bumps, and NB tophats. Car rides very well considering the spring rates being used. The only time the spring rates start to get irritating is on broken pavement/frost heaves. The autox events I travel to are between 100 and 210 miles away so a decent ride was very important as well as the best car/wheel control.

Overall I am very happy and have no regrets. My car handles very well and is very tolerable on the street. My wife also enjoys driving the car and doesn't complain about the ride. Friends that have driven the car typically say the ride is pretty stiff without being harsh. Autox performance has been very good allowing me to win about half the events I was in this year with a FTD as well."

Here's the link if you want to dig a bit deeper:

http://forum.miata.net/vb/showpost.p...6&postcount=97

+1 imo.

Fwiw.

I don't believe it is asking too much for a shock to handle those two situations, if that's what you are implying-- I think a better shock will handle bumps more comfortably than a shock that is not as good.

I thought we were "over" the fact that shocks are always a compromise. On the tracks I can go to, they have their share of bumps. I've read Emilio name them (SOW, BW) as one of the best tracks to test your shocks because of it. So because of this, a "good" (to me) shock should be able to handle bumps and road irregularities as I would find similar bumps on the street and on the track.
I read in a link someone else provided that as spring rate increases, less bump valving is needed. I can't find it now, and you don't have to believe me anyway, but it said something along the lines that on the bump stroke, the shock is working WITH the spring and on the rebound stroke, the shock is working AGAINST the spring, therefore needing a higher ratio towards rebound.

We'll find out soonish. Going to be ordering a custom revalve from SD with 700/400 springs, seeing how they compare. :)

Don't be so defensive, greeentreee, and re-read my post. Have you been so beat down on this thread that you can't even tell when someone's supporting your position?;)

Perhaps. I'll tell you all right now, i have first-hand experience with TEIN SS (valved exactly the same as the FLEX for the same application), JIC FLT-A2, and finally Buddy Club Racing Spec Dampers on my other car. An Acura RSX, McPherson struts up front w/ trailing arms in the rear, horrible (I think it was 1.5 to 2:1) rear motion ratios, which explains the 16k rear spring rates. Track tested all of them aside from the TEIN SS at Streets of Willow, CA and the car has seen all sorts of revisions to the track. The wide section after the back straight going CW? It used to be a chicane back in 06-07. Now it is wide open.

On the Miata I am on Megan Racing shocks, that I find have too much compression and too little rebound on the same settings, so regardless at what setting they are at, there is a compromise. This is when I started appreciating that my Buddy Club RSDs were rebound only adjustable. My RSX with RSDs 10/16k vs my coworker's RSX on Megans with 10/14k rides like two different cars. Especially when he has fatty 205/55-16" tires compared to my 255/40-17", the ride difference is astounding. I think I can safely assume one brand is better, at least for this application. In that same respect, I know more RSXs using Buddy Club RSDs on the track than TEIN FLEX users-- for a reason. Then if you look at the Miata, the TEIN FLEX is more respected and seen more often at the track.

To many of you, these brands are on the low-budget side of things, and I can't argue with you. They are a compromise... but they still are shocks.

i think the shock compromise (dual duty) situation has to be looked at in extreme situations to become clear.

The perfect shock would be tuned for a specific situation. i.e. Those that race would ideally have a set of shocks specific to the track that they are racing. For most, this is cost prohibitive. Already, in this situation they are compromising. This is one extreme. The other extreme is for supreme comfort. Even for comfort there is a compromise because it is not going to be perfect on all road conditions( large pot holes, etc), but it can probably be dialed in for 95% of them.

Now we have our two extremes. I'm going to put them together.

I'm going to use a nascar. At Lowes motor speedway I have witnessed cars going 180 mph. Imagine how stiff the shock and spring setup must be to compensate for the down force being applied and remain stable at 180mph in turns.

Now, how comfortable do you think this car is going to be driving around town??? The suspension probably won't budge over any of the mild bumps that are experienced on a dd commute.

As our use of the vehicle moves closer to the center of these two extremes; The closer the appearence of a "dual duty" shock becomes a reality.

Just because someone can tolerate a harsh/plush ride, doesn't mean the shock is "dual duty". It just means they are able to deal with the compromise.

"Dual duty" shocks are created in the individuals head, not the shock.

I'm stopping now. I don't know if I'm making sense anymore.

greeeenteeee, I explained why elsewhere in this thread. It's up to you which explanation to believe.

But can't you add bigger sway bars to reduce the roll? How does less rebound damping affect handling on an autocross track?

I have a 2000 LS with the original Showas, 125,000 miles. I just bought the car for my son to drive and to attend the occasional autocross. We are autocrossing for fun, but winning is fun too! For a car mostly street driven, would I be better off with stock springs and big sway bars? Are used NB Bilsteins a good choice for stock springs?

I spent the last several hours reading this thread (and watching football). I learned a lot from this thread, and I appreciate everyone's input.

Before anything else you said matters, you need to decide how serious you are about winning, and what class you want to win. Also, seeing what you're up against locally would be wise.

After that, then ask for advice. Figure out where your focus is, how much you want to spend, then decide where to go from there... otherwise we and you would just be shooting in the dark.

Street comfort is more important than winning. I'm not going to spend $$$$ to go fast. I've been there and done that. Just trying to get by without spending much money. From what I've read, used Bilsteins are better than new GR2's. And they could be re-valved if I get the itch. But right now I'm trying to keep costs down.

In that case, are you planning to keep the rest of your suspension stock? Just want to change shocks?

Sounds more like you're doing maitenence... and that you would be best served by making your own thread instead of turning "Shock Tech 101" into "What shock should I buy for my car." It's rather hijacking.

The cheap combo would be to find used Bilstein R's. HD's lack low speed rebound which isn't ideal for AX.

For street comfort, the rpackage shocks want a spring in the 450ish rate, not stock. I'd recommend Illuminias, from what I've heard, but still... this is a hijack. Let's stop posting on this.

What should be discussed next?

Are we ready to move on and take a shock apart to describe each part?

YES! Pictures and exploded views with lables and discriptions would be perfect. :bigtu:

Sure! Maybe you could explain how the bleed orifice is changed during a rebuild. And different ways a shim stack can be set up for different characteristics.

Hell yes, we are...

Maybe we should start with how not to kill yourself disassembling a Bilstein without a hyperbaric compression chamber.

Bernie, I used Penskes on a Panoz GTRA that I owned up until recently and was very happy with them. They were valved by a guy named Brian Finney on Merritt Island, FL. Circle track guy. I set them up in the middle of their adjustment and was very happy with the car. Particularly at Sebring, which is where we normally run.

Prior to going to the Penskes, I was running the "stock" Konis that come on the GTRA cars. Toward the end of a 30 minute session you could really feel the car going away, almost like the tires were overheating. But that wasn't the case, the shocks were going away as we found the Konis fell off pretty rapidly on the dyno. Once the Penskes were on, the car was consistent throughout the session.

Is the design of the Bilsteins such that I could expect a similar level of performance to what I experienced from the Penskes, ie. not going away? I can't help but feel I got a little lucky with what Brian did to the Penskes given that he knows Sebring.

Another note, we found the cars ran better without a rear bar (ran front bar). Taking the rear bar off and doing it with the spring helped the car hook up much better. I'm thinking of trying something similar on the Miata. The car is new to me so we'll see.

Thanks,
Jim

http://jmimac351.smugmug.com/photos/...09_HtnhA-S.jpg

Oh, and yes, I would like to see what the inside of the Bilstein looks like. I've seen the shim stack used in the Penskes. Wondering how they are similar or different.

Can a Bilstein be bottomed out and damaged internally?

From what I've heard, the shaft on a Bilstein doesn't go far enough down to bottom out, it'll hit the top of the shock body first.

I'd like to see some pictures of high quality race parts vs standard bilstein vs cheapo chinese crap.

Here is a layout for a standard Bilstein build. Everything is in the order that it will go on the shaft.

Attachment 19119

Looking at the picture above, you will notice a notched shim. This is typical of how Bilstein achieves the bleed in their shocks.

The picture below shows how the notched shim sits on the piston. By changing the thickness of this shim you are able to change the amount of bleed.

So, to update everyone. I have purchased a Bilstein shock that will be dedicated to this thread. I will use this to show you the internals of the shock, and also how to create different curves on the graph.

Here is the shock on the dyno being set up for the initial runs. At this point, I am setting the preload and about to adjust the IR temp sensor.

So if I'm seeing this correctly based on the size of the shims, as the shock changes from compression to rebound and visa versa it's using different ports on the valve.

I'm a bit of a dummy, Bernie; could you retake that photo but with everything in a single line? Alternatively, could you tell me if the order is top to bottom and left to right, or something else if that's not right.

If you look at the picture in post #278 it will make more sense.

Ok, I think I get it.

When we're looking at your photo it actually looks like there are two notched shims.

1) Is that how the thickness is adjusted for the bleed shims - by adding or subtracting shims?

2) Are there bleed shims on both sides of the piston, or is bleed for both damping and bump adjusted from just one side of the piston?

3) Is bleed also controlled by other means; say differences in the bleed holes between different pistons, or different shim shapes?

4) Are the internals we're looking at the same as, or only similar to those within the yellow Bilstein's we're more familiar with for our Miatas?

Maybe I'm missing something. Where do you see two notched shims?

The bleed is adjusted by the thickness of the notched shim, along with the number of notches. This one in the picture has 8 notches, but they also have them in 4 and 2 notch.

The other way I adjust bleed is by drilling the piston. I've included a picture below of a piston with a .060" bleed hole.

Attachment 19128

Do you use a variety of shims from different manufacturers to fine tune?

Ok, Bernie explained the shim stack and I'll explain it to you.

Let's start with the second photo, the one with the completed piston assembly.

The red thing on the bottom - that's the droop bumper and it keeps the piston assembly from banging up against the top of the shock when the suspension goes into full droop mode.

Now let's move over to the photo of the various components. Imagine you have the shock shaft between your knees with the part of the shaft that's inside the shock body pointing up.

The first thing that goes on - at least for the sake of this discussion - is that red bumper. We're then going to take those various other shims and washers and put them on next - starting at the bottom row of the photograph.

On the bottom row there are two shims; one big and the other small. The big one, let's call it the "bottom plate", goes on first. It's job is to be the contact surface for that rubber bumper.

The smaller shim on the bottom row, let's call it the "top off shim", goes on next. I'll leave it to Bernie to explain what it does, but the "top off shim" comes in different diameters.

Moving to the next row from the bottom, the next shim to go on is the larger shim; let's call it the "main compression damping shim". Next is the smaller shim next to it, which we'll call the "pre-load shim". Again, Bernie will explain the function, but the "pre-load shim" comes in different thicknesses.

Ok, next the piston is slid onto the shaft, and then we move up to the row of shims above the piston.

The first to go on after the piston is another pre-load shim, but this one is for rebound damping; again, it comes in different thicknesses.

The slotted shim, which we've already introduced as the "bleed shim" is next. As Bernie mentioned this comes with different size and different numbers of slots. Interestingly, it's designed so that no matter how it's clocked on the shaft the same amount of bleed opening is exposed.

After the bleed shim comes the next large diameter shim in the row, which we'll call the "main rebound damping shim".

We're finally at the top row, and we'll begin on the right. The right most small shim is another "top off shim". Next to it, and next on the shaft, is the "top plate", and to the left of it, and the last on the shaft, is the washer against which the Nyloc nut that holds the assemble on the shaft rests against.

So, in summary, in order of assembly, we have:


Got it? Good.

Fluid always passes both ways through the outmost ports of the piston?

Hang on, let me put down my Martini. Honey, where are my reading glasses? Damn, I can hardly see through this cigar smoke.

There it is, see those multiple lines....

Negative.

The inside circle of slots on one side of the piston is common (connected) with the outside circle slots on the other side of the piston.

Flow through the piston is from the outside circle of slots to the inside circle of slots and then past the shims.

At the 6 o'clock position in the outer ring of slots, it looks like there is a hole. Is this used to allow a certain amount of fluid bypass for low speed comfort? Does this hole get adjusted?

Yes, you are correct. This controls the low speed on the graph.

I drill the pistons with a selection of bits ranging from .010" - .060".

Saw this thread and thought that perhaps I could rebuild my own bilsteins.

I am not thinking that any more. :)

The parts are relatively simple, but knowing what sizes etc is way beyond the diy'er without years of experience and a shock dyno. I'm happy that Bernie has the knowledge to do this.

Do bilsteins break in?

Besides knowing what parts to install, there are two other issues.

First, there's a highly pressurized chamber at the base of the shock. This probably isn't as big a problem as it first seems because you can probably just drill a hole at the base to evacuate the chamber and drill and tap the hole for a Schrader valve. That's what Shaikh does.

The other issue is Bilstein stakes the end of the damper rod so the plain nut they use doesn't fall off. Removing the nut buggers up the threads and they need to be recut; again more an issue of having the proper thread chaser/die rather than a major problem.

But yeah, the bigger issues are what do you put on there and how to you test it. In the long run, even if it's just R&R seals without changing damping, it's probably easier and cheaper to just send it to Bernie.

Bilsteins can be bought for under $400 shipped (NB HDsport).
Wouldn't it be cool if Bilstein would do a SD spec'd edition and give Bernie a royalty. It would make life easier and cheaper for everyone and give SD more time to do custom spec.

Bilstein has files on hand and can revalve to questionable specs such as the R and FastMike versions. It's only $35 more to get Bernie to do the revalving.

Also, after speaking with Bernie, I'm pretty sure Bilstein isn't interested in being nearly as meticulous as Bernie is; it would take too much time and money. In Bernie's case his reputation is on the line in a way Bilstein's isn't; his customers expect a superior product and Bernie's got to deliver.

Bernie preps parts in a way Bilstein doesn't, and has some custom assemblies Bilstein doesn't use. Think of it as blue-printing your shock vs a factory job.

+35 bucks per shock to get revalve? Do I buy my shocks and send to him or buy from him and add $35?
Dang that's good. I'm gonna wet myself.
I have an NA. I have NB hats, do I get NB HDsports? Or should I do NA HD and drill the hats (diy FMC hats)?
Forgot I was on mt.net. Give me a second to get my flamesuit on before replying to my dumb questions. Thanks in advance.