JackOlsen

I don't want to disclose any shops' proprietary numbers. But I'm about to send my rear shocks in for rebuilding by Bilstein, and I'm looking for suggestions on what valving would work well for me.

It's a 911 with 500# rear coil springs. It weighs 2400 pounds with fluids but no driver. It's a dual purpose car, but I'm revalving for lap times more than comfort.

Anyone out there familiar with Bilsteins who's willing to contribute to some 'open source' tuning?

TheOtherEric

Looking forward to hearing responses. Seems to me it requires very specific advice, based on your weight and spring rates and level of damping that you personally like. I'd be glad to suggest a damping curve that I personally would want, but I'm also interested to see what process others are using.

I've done the calcs for a simple system that takes all the inputs and graphs out your critical damping % across shock speeds. I have some general goals for critical damping (low and high speed, reb and bump), so I use that as a starting point when setting my shocks. Works for me, but most people would think I'm insane for doing it this way. I honestly can't imagine any other way, except perhaps to have your current shocks dyno'd then ask for x% more reb/bump at low/hi speeds.

p.s. I'll just add that I'm a firm believer that all shocks must be dyno'd if speed is your goal. No ifs, ands, or buts.

Van

On my 944, I told Jose at Bilstein Motorsports what springs I was going to run, and the car weight, and he said they'd "valve them correctly for that". YMMV.

Dave 86 930 Fl

Have you talked with Chuck Moreland @ Elephant Racing? Great guy.

himself

In my experience, you really don't select valving when dealing with Bilstein - and in particular if you are using single adjustable (er, non-adjustable). You just select spring rates and they valve for you. Just call them up and they'll be happy to help, their tech support is actually pretty good. Cost is (well was) $65 for revalve per corner, and $35 for expedited per corner. So $100 and you get them back in just over a week.

What you really need is someone to tell you their spring rates for a similar setup. I would guess #700/#900 would be pretty a pretty good/aggressive combo.

Larry probably knows.

-td

TheOtherEric

That doesn't surprise me, but I think that's totally inappropriate. 3 reasons:
(a) You'd want different valving for a 3000 lb car versus a 2400 lb car. Do they consider that?
(b) Who says their damping scheme is ideal for your style and setup? Maybe you like soft rebound... is that how they set it up?
(c) Do they consider whether you're running coilovers or not? An inboard/torsional spring could demand totally different valving since the spring rate suddenly makes no sense without knowledge of the motion ratio.

And here's the proof in the pudding: I just yanked our Bilstein "custom valved" non-adjustable shocks from my E36 race car, installed Motons, set them based solely on my theoretical calcs about how I'd probably want it, and was immediately 1.5 to 2 seconds faster. So if I were re-valving my old Bilsteins, I'd want to recreate the damping curves that I knew would work for my car and setup.

Jack, if it's useful i'd be glad to run some numbers for you, but it sounds like you can't just give a damping curve to Bilstein and say "I want this."

himself

Perhaps I miss the point, but if you don't revalve, you can't use updated springs as your valve rates will be too far off. That is, you HAVE TO revalve if you are going to reuse the OEM dampers. So, even assuming your points are correct and you can't get custom valving schemes, you still get an improvement although on a macro level. And, IMO, you will still benefit from the updated suspension bits, even if they are not perfectly tuned from Bilstein or custom mapped. But, isn't that the nature of the non-adjustable suspensions? No ability to tune.

On this point, what would you suggest the OP do if he wants to use his OEM Bilsteins? He clearly can't use them with the new springs, and you suggest he could never get them right from Bilstein...

Did the E36 have custom damping from Bilstein? Or just a "normal" revalve? Did you put them on a shock dyno before/after? Just wondering.

Personally, I'm not sure MOTONS vs OEM is apples to oranges or proof in any pudding. The car might be faster because it now has MOTONS. That's the whole point of getting them. Many would be disappointed if they went from OEM to MOTON$ and ended up slower. Also, the car might be faster due to more adjustability (tuning) not bad valving of the OEM stuff - which may have been done perfectly. Again, that's the whole point in getting MOTONS, to benefit from superior parts/technology. And, the car might be setup much better with MOTONS, new tires, better conditions, etc. Too many variables to account for.

But, assuming everything is equal, 2 seconds faster after a MOTON upgrade tells me that stock/revalved Bilsteins are doing pretty damn good.

MOTONS are a benchmark, so saying OEM stuff is not as fast is pretty apparent - but that really doesn't prove that OEM is done wrong, even when revalved.

Just my $0.02.

-td

tomburdge

Not sure the Bilstein folks are your best source for revalving a Porsche 911.
I think they pretty much take a cookie cutter approach.
You'd be better off going folks like Steve @ Rennsport systems, Jerry Woods, Peter Dawe, Mike Bavaro or Elephant racing.
These folks have been in the 911 scene an awfull long time and after asking you a battery of questions , they would have a damn good idea on what kind of valving would suit your car, and your driving style .
They would ultimately get the parts from Bilstein to re-valve the shocks but thats about it.
And yes this has become very proprietary info which they will not share with you.
FWIW.
Tom B.

himself

^ Good points.

-td

James Achard

Dan Jacobs did mine for my 964 and they are fantastic. I'm running 600lb F800lb R springs with Bilstein RSR shocks and the car is perfect.

Cheers, James

cstreit

Jack,

Don't have numbers for you. Rather than experiment I paid for some experience. I'm really very happy with the setup that Jae at Mirage did for me. So much so that I used him again when I needed them refreshed after a few seasons. Had him tweak them just a tad.

Chris Streit

Minoclan

I used Stimola (SRP Engineering) in Long Island. Joe passed away but I believe that the shop goes on. They really know what they are doing. In talking to Joe for hours one Saturday I found out that a lot of the independents send the work to his shop and don't tell anyone that he did them. The work was perfect and fast.

JackOlsen

Thanks, guys.

My Bilsteins are not OEM -- they were put in when I converted the car to coil-overs. They were custom-valved at the time, but I've switched to softer springs since then.

In a perfect world, I'd get some of Evo's custom Ohlins back there. But in a perfect world, there would be no college tuition to consider.

I'm going to see what Eric comes up with. Although I might not be able to get all the data he needs.

Matt Romanowski

I'm not sure if SRP continues, but I know that Angelo was taking a lot of the work over. Great guy, learned from Joe. http://www.anzesuspension.com/

Todsimpson

I sent mine to Rennsport Systems, and then he sends them to Bilstein.

A few bucks extra for Steve's experience made sense to me.