Coilovers springs and rates?

speednme1 · 05-17-2013, 07:47 PM

Trying to figure out what springs and spring rates are on my car(930). Installed by previous owner. They have the green housing(Bilsteins?)..any help would be greatly appreciated.

IMR-Merlin · 05-18-2013, 02:09 AM

is there any writing on the springs? You can get the rate from them. If not, you will need to have a press and a spring rate gauge. Oh and cross post this in the autocross/racing thread, you might have better luck there.

speednme1 · 05-18-2013, 08:55 AM

Thank you I will try cross posting it.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Take the springs off and measure them. It's the only way to be sure. Many shops will have spring testers, but you can approximate yourself.

Remember, springs are rated in lbs/in. That's pounds of force per inch of displacement. So a bunch of weights and a ruler can help you figure out the rate--how many pounds does it take to make the spring one inch shorter? Two inches shorter?

I can't really tell anything about the struts, but I don't have much experience with 911 struts--and none at all with coil-spring 911s. I will say that these don't look quite like the Weltmesiter threaded collars that I got for my 914 rear suspension, and they definitely don't look like the Ground Controls that I bought for my CRX back when.

--DD

speednme1 · 05-18-2013, 10:12 AM

Thanks Dave

IMR-Merlin · 05-18-2013, 11:38 AM

As Dave says... but you have to remember a 300# spring will take 300 lbs to compress 1 inch and 600 lbs to compress 2 inches. That's a lot of weight to have on a spring with no support. I am willing to bet there is a late model or pro-stock shop in your area that has a gauge. Call around if nobody on the auto cross forum can help.

speednme1 · 05-18-2013, 11:56 AM

Quote:

Originally Posted by IMR-Merlin

As Dave says... but you have to remember a 300# spring will take 300 lbs to compress 1 inch and 600 lbs to compress 2 inches. That's a lot of weight to have on a spring with no support. I am willing to bet there is a late model or pro-stock shop in your area that has a gauge. Call around if nobody on the auto cross forum can help.

Safety first! I'm going to check the other 3 for markings. Hopefully I will find something. Thank you again for looking out.....best part of this community..

MikeD930 · MikeD930's Garage

Quote:

Originally Posted by speednme1

Trying to figure out what springs and spring rates are on my car(930). Installed by previous owner. They have the green housing(Bilsteins?)..any help would be greatly appreciated.

I would not feel comfortable with this setup in regard to the spring being loose when the front end is unloaded. I don't think it's safe!

I suggest to install helper springs to take up any gap between the spring and perch (springs should always be preloaded). If there's still gap then install a cable to shorten the unloaded front strut. See my setup below.

speednme1 · 05-18-2013, 02:26 PM

Thanks Mike, I will further investigate this. I could hear my wallet crying already..

..lol

IMR-Merlin · 05-18-2013, 03:41 PM

Quote:

Originally Posted by speednme1

Thanks Mike, I will further investigate this. I could hear my wallet crying already..

..lol

cable is about $15 at Home Depot with ends. Helper springs are pretty cheap too. If this were a track car, I would just make short limiter cables. But for the street were the extra pound or so of 1/2 sprung weight is not that big of a deal, go with helper springs.

speednme1 · 05-18-2013, 04:15 PM

Quote:

Originally Posted by IMR-Merlin

cable is about $15 at Home Depot with ends. Helper springs are pretty cheap too. If this were a track car, I would just make short limiter cables. But for the street were the extra pound or so of 1/2 sprung weight is not that big of a deal, go with helper springs.

Cool! will need to do this soon...

fredmeister · fredmeister's Garage

Quote:

Originally Posted by speednme1

Trying to figure out what springs and spring rates are on my car(930). Installed by previous owner. They have the green housing(Bilsteins?)..any help would be greatly appreciated.

You can calculate the rate yourself with the following formula:

Rate = (Emodulus for steel x wire dia^^4)/(8 x no. of active coils x (OD of spring-wire dia)^^3)

It takes some measuring and some judgement to determine the no. of active coils but this should get you what you need.

Fred

speednme1 · 05-20-2013, 07:34 AM

Mystery is halfway solved. The coil overs are from the Racers Group. The spring rate will be determine soon. Thanks for all your help guys.

Kraftday · Kraftday's Garage

Quote:

Originally Posted by speednme1

Trying to figure out what springs and spring rates are on my car(930). Installed by previous owner. They have the green housing(Bilsteins?)..any help would be greatly appreciated.

I believe those are some older Hyperco springs. They should have the mean rate etched on the bottom flat of the coil. High end quality springs made in America. You may try emailing them the picture for some latest info / support.

Then also a great set of RSR type threaded body Bilstein struts that still look good. The billet machined spring hardware is decent too although I would suggest installing some spring seat bearings to prevent the coil binding. The main coil could be supplemented with a tender or helper spring to take up some slack.

Generally with a softer rate the tuning can be achieved by the anti-sway bar that you have. Great set up, hope this helps!

turbobrat930 · 05-22-2013, 07:42 AM

I have the same suspension setup on my car. They are in fact from TRG.... They were at the time, the highest quality stuff without going to a full race setup with remote reservoirs....

My car is currently on my lift. I can try to see if I have any numbers on my springs, if you want me to. IIRC, I think I have 300 in the front and 600 in the rear.... No torsion bars.. but its been awhile.. It is a great suspension setup... ( I think it was close to $1000 to $1500 per corner)

speednme1 · 05-22-2013, 01:36 PM

Sure guys any info is great. Thank you for your help and compliments.

turbobrat930 · 05-24-2013, 06:46 PM

I tried to find the spring rates that were once etched into the blue coating of the springs... Couldnt locate them.

Try calling Kevin Buckler of TRG... I bought mine directly from him. He should still be able to remember what Lbs the springs are.... IIRC, the colors stand for different rates...

speednme1 · 05-25-2013, 04:36 AM

Kraftday was correct, there is writing on the flat surface....but my flat surface(that the writing is on) is on the top(bottom flat surface is blank) of the spring so it's a little hard to see. So far the fronts look to be 350lb...I will have to double check. The rears will be checked in a couple of weeks when the engine gets pulled. My car will be mainly street so I'm trying to determine the best rates without being too soft or too hard. I've done the search and it seems the consensus is 300 front...400..rear. Is this close? Any suggestions will be greatly appreciated.

Oh and thank you Turbobrat930 for trying to find the rates on your coils.

IMR-Merlin · 05-25-2013, 09:15 AM

I did 300/450 in a friends 911 last year and he is very happy with that set up but with the higher HP and rear weight of the 930, people are going with a slightly higher rear spring rate.

I am going 400/800 on my build, but it will be a dual purpose car.

ONQRACIng · ONQRACIng's Garage

I too have the older TRG setup on my mid 80s IMSA 911.. 400/600 on mine. Same colors,and perches.. Bilstein RSRs.