steering and suspension Stock Spring Rates

[BerScott]

Hi! I'm new here but I come for a feeting visit to make only one question.

I'm working in a automotive software simulation (rFactor) and I'm trying to collect all info from the '73 2002 Turbo and I wonder which spring rates has the stock version. I've check out this web: http://www.bimmers.com/02/suspension.html Really good info, but seems that the spring rates are not expressed in N/mm or lb/in and it is the only info I've found.

So here are my questions:
1. Which spring rates has the stock 2002 Turbo?
2. Is it possible to calculate the N/mm (k) with the info the web I've linked has?
3. Are those: green, white and red the stock springs?

Regards.

[nbcbird]

Try this:

http://www.bmw2002faq.com/topic/130822-tii-oe-spring-differences-red-white-green/?hl=green+spring+rates#entry60358

[BerScott]

Thanks nbcbird, but the spring rates are not expressed in lbs/in or kg/mm what is that I need. That's why I ask for a formula to calculte it.

[Rustpile]

Well, its says kp. It can not be just 280 kp. Then it would not have any value, because it does not explain anything about the springs. It has to be kp by something. As kp is a metric unit, it is safe to assume that it is kp per square millimeter. 1 kilopond is equivalent to 1 kilogram. So the rates will be correct. 

[bnam]

(Kilo)pascal = (Kilo)Newton/m^2

Edited January 5, 2014 by bnam

[BerScott]

I found another link from this forum: http://www.bmw2002faq.com/topic/116349-stock-spring-rate-what-is-600lbf/
 

I have noticed the same thing and I think it means "total recommended force on the spring" (when installed in a 2002).
"Rate" is a measure of change and 600lbs/inch would be over the top even for a racecar.
Your measurement is pretty close. The stock rate is about 180 lbs/inch from what I remember. With that rate the spring would collapse 3.33" with a 600lb load.

 

Albim has mentioned an interesting numbers. As he said the coil spring will collapse 3.33". So I've divided the stock force specified in the link I've posted in first post: 585lb/3.33"=175.67lbs/in. This is a reasonable spring rate for the front spring.

But how I know how much the rear springs collapses?

I've tested in the simulator the spring rates based on LBS/3.33" and it works perfect, but I want to refine the rear suspension to leave it as it should be.

[Preyupy]

I will pull my stock springs out and run them on the spring rate checker,  I should have the numbers for you this weekend. 

[BerScott]

Thanks to you all for all the feedback.

@Preyupy, I will wait patiently for those numbers, really appreciated.

If you are interested on simulation software I really recommend to check it out. I'm actually using rFactor and it works with applied physics formulas, so the behaviour of a car is really matched out. The best way to use it is with a good forcefeedback steering wheel hardware, the best quality/price is the Logitech G25.
I've made some cars and some of them has been checked by real owners who give faith of the realistic them are. (I'm don't making this for money or marketing, really, this is a hobby which I enjoy a lot).
I want to mention too that soon I will port the cars to rFactor 2, which have a really top noch tire and chassis flexing physics model, which give the simulation a really good approach of what is expected from reality.

This is a pic attachment of the actual 2002 Turbo I'm working on. Hope you like it:

Edited January 7, 2014 by BerScott

[max210]

Hey thats pretty cool. Are you doing a single car series? Did you do the modeling and physics yourself or with a team? I used to be in iDT a while back, we did the Champ Car series on ISI's F1 Championship and also for rFactor.

[BerScott]

@May210. Thanks. I use a mod called Shift Street as a base, it have nice textures for the interior. I use to convert Forza Motorsports 4/Horizon models (them are pretty well done). I make all alone: texture placement, integration and physics. I only make street cars, but I add some upgradeable parts based on real data. This BMW has the Ireland Engineering and the Ground Control already integrated, also all sway bars I've found in the market. I also add some suspension alignment specs based on real setups (for track day, autocross, etc). I've added also the Group 2 engine and some another parts, always based on real data parts.

If you want to see some more of my work take a look here (facebook group): https://www.facebook.com/groups/309037485903081/photos/

 

[Preyupy]

BMW lists 3 different springs for the Turbo by color (Green, White, Red) but they do not give the spring rates for any of them.

My car had:

Red front springs:  12.5" free length 175 lb/in non progressive 350lb at 2" and 525lb at 3"

Green Rear springs:  13.5" free length 100lb/in non progressive  200lb at 2" and 300 at 3"

 

The listing for the rear springs describe them by color and Turbo (ie Green Turbo)  the fronts are just listed by color.  There may be a difference between the "Green" spring on a standard 2002 and a "Green Turbo" spring, I don't have any other stock springs laying around to check. 

[BerScott]

Thanks a lot Preyupy. That is also enought to measure the rest of spring specified in the link I've paste in the first post.

I've also tried to find the H&R abd Eibach lowering spring rates, but seems that isn't specified too. If there is the possibility to know them could be awesome too.

Much appreciated, thanks a lot for the support.

[Preyupy]

I think I have a set of HR's I'll look in the garage, if I do I'll check them for you

[BerScott]

Preyupy did you managed to measure the H&R springs?

I'm continuing the 2002 and I've found all the complete Gr. 5 specs for the DRM, what a rocket! I'm replicating and measuring the theorical 1.4 400hp turbo engine power curve (it reach 440bhp at 1.5bars), but seems that the engine lack of power below the 5000rpm. It needs a constantly and hard gas pedal management to make a proper start and deal with turns while taking care of the gear.

[Preyupy]

Turns out I don't have a set of H&R's laying around, sorry.