I have gotten to the point where I need to consider the spring rate. The rear trailing arms are in with true 5 lug hubs, 911 brakes, and some reinforcement. The shocks are bilstein sport. It is a road car with 16 in wheels running no flares so the tire size will be 205.
I have the original springs from the 1972 four cylinder donor. So ladies and gentlemen, please help me with shopping, or not shopping. Thank you!

I bought a set of 165. But it's just a guess. If I don't like it, I'll change it. Rode in a stock body with 180 and it seemed a bit harsh on pa roads but I have no idea what shocks were on the car and if they were any good.

I just bought a set of 140 pound progressives for my Six, stock bodied with a 3.2, Bilstein Sports, Elephant Racing rubber bushings, 18mm raised spindles, deep sixes widened to 7" all the way around. I am hoping it all works well together and provides a nice ride w/o being harsh.

200 or more. If it's harsh, consider your bushings. Go Elephant or equivalent...

Mine are 200#. This was on recommendation of Brad Roberts and Ron Kain of IPB Autosport...

I run 225 on the rear with 21 mm upfront. Elephant bushings everywhere. Car is a 3.0 that weighs 2050 with half tank of gas. Timetrailer and autocrosser. Some street use. The car rides great. It is not too stiff om the street. Most people that ride with me comment on the nice ride.

I run 200's on KoniSports - it's a race car, it's harsh on lumpy backroads but great on hiway & track - rear tires are 245/45x16 so that's a factor

softer might be better for AX (and thus for street) according to what i've read on these forums by the dedicated AX guys such as DD

so on that note, i b'ot a set of 165 progressives from GPR long ago - still in package and probl'ly will go on ebay one day

. do a search on AX suspension recommendations for a lot more ideas

.

Guess I'm a softie.....I run 140's and love them.

I ran on my 3.0 conversion 180lbs springs with the Elephant Bushings. Great ride and good on the track. Had a Weltmeister Front sway bar 19mm if my memory is correct.

Can the numbers be explained...higher vs lower #'s? What's the pro/cons of higher vs. lower?

I think one has to consider the total car and since it is going to be for road, the possibility of stressing the rear suspension if heavy spring loads are going to be used.

I have a 74 914 which has been converted to 1987 3.2 Carrera, complete 911 Carrera front suspension, Doc Evil rebuilt transaxle with flipped H gear, 911 front engine mounts including Mr. Johnson's mount, solid rear transmission mounts, 911 Carrera brakes all four corners, red adjustable Koni's all four corners, 110CV joints and drive adaptors with Sway-A-Way axles, interior stress kit, Brad Mayeur Long stress kit, boxed rear suspension mounts, rear adjustable spring perches, 180# springs, front and rear suspensions mounted Elephant Racing brass/bronze insert bushings with zert fittings, front turbo tie-rod kit, 911 brakes including rotors all four corners, modified 911 E-brake, rear suspension ears reinforced, rear suspension mounting stressed to fire wall, and numerous other items I have forgotten about. Some of the other items involve rear stock sway bar, 21mm aftermarket sway bar, 21mm front torsion bars, 17 inch Cup II rims with 235/45 9 inch in rear; 205/17 7 inch in front, etc. In sum, the car DOES NOT HAVE ANY FLEX and it is really stiff (no roll cage).

I changed the car suspension from what has been listed above to: front torsion to 19mm, rear springs to 19mm, 21mm front sway bar set to lightest, stock rear sway bar installed, all four corner Koni's set on light setting.

What is the meaning of all the information above? First, you have to consider like you are doing the suspension type, mounting stressing, driving style, brakes, etc. All this will determine how you will build the car.

What I would I do differently? I would determine what I wanted the car for and stay with it. I originally built for both road and racing; it can be done but in my case I forgot to keep everything defined for the road and the race track. I got to building and ended up with a car better for the track than the road. In sum, I would stay with the road driving and use that setup for occasional race romps.
911 or modified 914 with 19mm front sway bar, 19mm torsion bars, Adjustable Koni Reds/Yellows or Bilsteins all four corners, original sway bar in rear, 120-140# springs in rear. I believe the 914 brakes are more than adequate in stopping the 3.2 when properly built and maintained (19mm brake master cylinder ???) and very good top end brake pads.

I would box in the rear suspension console for distribution and strength. I would be very careful in welding up the car body seams. We are now getting into an area which has to be understood and carefully defined because you are now affecting the roadability of the car and taking it into racing type driving.

I am just a "frustrated, long winded engineer" who enjoys his hobby of building a 914. They are truly great cars and thus making a very enjoyable hobby.

The are considerable threads on this site and people who can give you better advice. Do you research, listen, and understand to the level where you feel comfortable in building your car.

Hope the above helps.

Steve

Here is what I put on my 3.2 conversion: Bilstein Sport Shocks, Eibach 175lbs springs, and their adj. perch kit. I'm very happy with this setup.

Click to view attachment

Old number 2 is a track car and very stiff she has a Petty bar. It had 180 lb springs when I purchased her and they were soft. After a custom trans and axels she is sporting 300 lbs and rockets on corner exit. It is indeed all about the entire set up.

200 is a good start ...

I run a 2.8 with more horsepower then a stock 3.2. For the track I would suggest 350 in the front and 220 in the rear. Coil overs in the front if they are affordable to you. Good balance. 914 unlike 911s need more front spring. I have dabbled with all types racing for the last several years and this is what the imsa cars raced with back in the day. If it is for a street car I would soften it up a bunch, but for pure racing this is the combo that works.

F


140s on the /6 and the wide body.

Wow! Hopefully I am going to be very happy with my #140 springs Glad to hear the feedback of others who have gone that route.

If you use the adjustable spring perches and the smaller diameter springs, you can get springs in 25 lb increments, and they are a whole lot cheaper that the three springs you can buy at the stock diameter.

So, the smaller ones are cheaper, and loads more choices for you over time.

You didn't say what say what your sidewall ratio is, and it will play a role in spring rate as well. I have 205/55/16's with 225lb rear spring/Koni adj's with larger torsions up front.
Though comfort is very subjective, I find no problems with this set up for 90% of my highway, and touring through the Tail of the Dragon.

I'm running 450 front and 400 rear on track only car. I also have been running with both a front and rear sway bar. Approx 330 HP from 3.4 liter. Seems to work pretty well for me. Tires are 245/45/16 front and 275/45/16 rear. Shocks are custom valved Bilsteins.
Corner weights, spring rates, sway bar sizes and unsprung weight measures and type of race courses that I frequented were provided to Bilstein and they came up with some nice low, intermediate, and high oscillation shock settings for me in compression and rebound.

Dumb question is the spring rate the same on Weltmeister springs versus Eibach?
I was running 21mm front and Weltmeister 140's in the rear with a 901 gear box. I was quite happy with the setup. I also had a 22mm sway bar in front and the stock sway bar in the rear.
I just changed the trans to an 86 915 trans, so I upped the rear springs to 165. The car isn't running yet, so I can't comment yet.

Front
23mm torsions
22mm sway bar
Bilstein sports

Rear
200# on Coleman adjusters
Koni yellow adj.
No sway bar

Elephant bronze on both ends

Obviously I like a kart. But that 3.6 is heavy and the 200's are the minimum I want back there. The "featherweight" 2.7 was good with #180's but they weren't stiff enough for the 3.6. The LSD has changed things and either I'll go up to 250's or add a small rear sway bar to dial in a little bit more stiffness... just not at the same time.

Good Luck

I'm running 205/16's with 200 lb. small diameter springs, and Bilstein shocks, and adj. perch's. 19mm front bars.

Wow! Those are a lot of replies and all useful.
I am building a street car, that I hope to tour with. The hope is that it will look a lot like the original 1.7 car, with normal body work, bumpers and trim. I think the sail is going to be painted. Planning on adding some modern conveniences with a console so it will cruise always wit a quickness, but without attracting attention. I am now leaning towards the narrow springs with anodized adjustable perches.