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Posted by: perrin1097 May 15 2009, 05:33 PM

I would like to know the stock rear spring rate for a 74 914 2.0 w/ perforomance package.. the black springs with the green paint....

Posted by: RobW May 15 2009, 05:39 PM

I think stock is 100lbs. After 34 years?

Posted by: Larry Hubby May 15 2009, 05:39 PM

I believe all the 4 cylinder cars had 88 lb/in rear springs as stock items.

Posted by: bandjoey May 15 2009, 07:32 PM

what do the colored strips mean on the springs? Green? yellow?

Posted by: Dave_Darling May 16 2009, 09:33 AM

According to an old Up-Fixin Der Porsche article, the stock springs could be as stiff as 65 lb/in. I think most were less.

--DD

Posted by: 74914LE May 21 2009, 10:20 PM

This brings up a great question. How do you tell what the rating is on the springs mounted in a particular car? I recently baught a car that I know has much stiffer
than stock springs, but other than the fact that the fillings in my teeth are loose,
how can it be determined? Number of coils/OD of the spring/Un-mounted length?

The 100lb springs always seemed about right when matched with Koni or Bilstein, but what I have now, must be way north of that rating

Posted by: SirAndy May 21 2009, 10:39 PM

Your shocks don't happen to be white, are they?
Andy

Posted by: 74914LE May 22 2009, 09:02 PM

The set on the car are Black, with White KYB shocks.....

Posted by: SirAndy May 22 2009, 09:45 PM

That's why the fillings in your teeth are loose ...
Andy

Posted by: SLITS May 22 2009, 10:27 PM

KYB = Kill Your Back

Posted by: orcadigital May 22 2009, 10:50 PM

Weren't there 3 spring rates from the factory, with 1, 2, or 3 green dots? They ranged from 65 to 96lbs i "thought".

Posted by: BMXerror May 22 2009, 11:18 PM

Agreed! I had KYBs with floppy silly putty springs of some sort on them when I bought the car. Then this year I went to Konis and 200 pound rear springs, and my ride got smoother! Hijack over.
Mark D.

Posted by: Dave_Darling May 23 2009, 10:53 AM

Step 1: Remove them from the car.
Step 2: Put them on a spring tester.
Step 3: Read the results.

You can change out steps 2 & 3 for putting weights on the springs and measuring their deflection, but it's a whole lot easier to take them to a shop with a tester.

--DD

Posted by: ArtechnikA May 23 2009, 01:54 PM

/4's were "a little more than 50"
/6's were "about 60"
GT's were 70/80/90 soft/medium/hard

There are formulas for determining theoretical rates for steel coil springs - Carroll Smiths' and Paul Van Valkenburg's books have them. An old spring will probably have settled but that doesn't change its rate, just its free length.

The table of data with 'what the dots mean' can be found here: http://members.rennlist.com/chuxter/914CoilSprings.htm

Posted by: johnhora Nov 25 2019, 11:34 AM

Posted by: sixnotfour Nov 25 2019, 11:51 AM

Attached image(s)

Posted by: mepstein Nov 25 2019, 11:57 AM

Stock front torsion bars, 100lb rear springs, Bilstein HD shocks and oem size sway bars make for great handling that is still very comfortable.

It's very common to see people up the spring rates because they think more is better but you don't get grip when the car is so stiff it bounces off the ground on every bump. It happens a lot in the 911 world because guys don't realize how increasing the torsion bar size ramps up the spring rate. So both ends get increased by 50-100% with just a couple mm change. Big sway bars also affect the ride as well as stiff bushings.

I've also lowered my tire pressure over the years since most psi suggestions are for heavier cars.

Posted by: Mikey914 Nov 25 2019, 12:05 PM

I'd agree the 100 for the stock 4 is perfect.
However there are those that have heavier motors. I know Eric used some 200s at one point, but the 140/160 I think is a good complement to the additional weight.

Posted by: mepstein Nov 25 2019, 12:10 PM

I think Ben is using 140 on his 2.7 car and I have 160 on my 3.2 car and trying 180 on my Suby six. It's all subjective but I think guys are too quick to go to 21mm torsion bars on the front for a road car.

Posted by: jmitro Nov 25 2019, 05:25 PM

EDIT nevermind; looks like someone bumped it as a search

Posted by: porschetub Nov 25 2019, 07:40 PM

Mine are blue with no paint marks or writing PO said they are 100lb but he has told me other "stories" before ,seem great what ever they are with my Bilsteins and a "6".

Posted by: Mikey914 Nov 26 2019, 12:08 AM

If they are factory I can guarantee they are not 100#.

Posted by: Matty900 Nov 26 2019, 03:34 AM

I started to put some spring information together when our 100# springscame out https://914rubber.com/eibach-914-rubber-springs

Posted by: dr914@autoatlanta.com Nov 26 2019, 10:28 AM

here is a bit of a study our spring guy did

Posted by: tomeric914 Nov 27 2019, 09:46 AM

Ghetto spring tester for springs with a rate less than 300lbs/inch:

1. Place bathroom scale on bottom plate of press

2. Place spring on bathroom scale

3. Place scrap 2x4 on top of spring under press

4. Zero bathroom scale

5. Compress spring 1"

6. Read bathroom scale

Posted by: johnhora Nov 27 2019, 11:47 AM

For reference...
a pair of early springs off the same car...you can see the 2 green paint spots.
the top one is 4mm shorter....maybe from the driver side

Posted by: bbrock Nov 27 2019, 11:54 AM

Don't know how much difference it makes, but I read it is best to compress 1" to preload the sprig first, take a reading, then compress another inch and subtract the two measurements. Here's my ghetto spring tester i action. Would have been better to use a cheaper scale. These fancy electronic scales are only good for telling you how fat you are.

Posted by: maf914 Nov 27 2019, 05:07 PM

Brent B, bbrock,

Interesting. Nice test rig. Did it bind up where the horizontal upper board slides on the vertical members? It seems that might give a false reading.

How did your spring rate?

Posted by: bbrock Nov 27 2019, 08:55 PM

No issues with binding. The mortises the uprights fit through were cut really loose (almost a half inch oversize). The uprights just held the top board in place enough to let me snug the nuts on the all-thread without flopping all over the place. The biggest problem was that stupid scale. It only reads for a few seconds so in the end, I wound up have to just heft the top board down with my own weight and quickly read the damn scale when I got down to the 1 or 2 inch mark. Springs tested at 50 lbs. give or take. I decided that was close enough to stock rates to clean them up and use them. Engine isn't in the car yet so we'll see. Based on the test result, I gave them one green dot.

Posted by: maf914 Nov 28 2019, 07:31 AM

Brent, Thanks for the response. That is funny about the scale shutting down, especially after going to the trouble of building the test rig. Good work though.

BTW, Some time ago in the 90's I replaced the original sagging springs on my 76 with 100 lb Weltmeister springs (from Auto Atlanta) with red Koni shocks. They raised the ride height an inch or two. I should have measured before and after. But as for ride stiffness I couldn't really tell much difference.

Posted by: tomeric914 Nov 28 2019, 09:46 AM

Yes, a good ol' mechanical scale is what I used. Stock springs aren't progressive so measuring just the first inch should yield the same rate per inch as the following 4". I recall taking measurements as far as the scale and jig would safely read just for giggles.

Posted by: DickSteinkamp Nov 28 2019, 10:11 AM

When I did the V8 conversion on my 76 I was hopeful the extra weight of the V8 would bring the ride height down to where it should be. It actually took it down too far (I know...if it's too low, I'm too old ).

The Weltmeister 100 lb springs put it right where I wanted it...

Posted by: bbrock Nov 28 2019, 10:22 AM

I had to check my notes to refresh my memory, but my springs measured lighter in the first inch. One spring measured 42 lbs. at 1 inch and 92 at 2 inches. (92 is minimum) It was really hard to get an accurate measurement at 3 inches with that stupid scale, but it appeared to be adding an additional 50ish pounds. No way could I squeeze those springs to 4" and get a reading.