What size rear springs for an LS1?, worried that the 100 lb-ers may be too soft. Options

[dadaDaveed]

Before I decided to convert to an LS1, I was planning to use:

stock 914 torsion bars
100 lb. rear springs
stock sway bars
Bilsteins all around.

The car is steel flared and will have a proper 5-bolt conversion running 16x8 up front and either 16x8 or 16x9 in the back.

This will be a street-only car. Should I put stiffer springs in the back? If so, how much stiffer?

[shoguneagle]

When I had my 914-V8, I was running a stock 911 front end with 180-200# springs, adjustable perches, and Koni Adjustable reds. It was fine for the supension on the street. Did not run a rear sway bar since I was not running a limited slip differential. I also had mininum stress kitting in the key areas. Handled like an old type Corvette - wanting to throw you to the opposite front corner as you were making a left or right turn.

These characteristics were not the problem of the suspension I used but because the engine gave a higher center of gravity that the stock -4 or -6 engines.

I built this cay back when the only kits were very crude from Rod Simpson and the first owners of Renegade Hybrid. Very little information was available at that time.

Subsequently, building a 914-Sixer (Porsche 3.2 Carrera engine with a rebuilt 901 transaxle. Stress kitted the body to the max with Racer Chris' products (I mean everything), seam welded in critical areas, 22mm torsion bars, 21mm sway bar (thru body type), 180-200# springs with the red Koni adjustables and adjustable perches, rebuilt rack and pinion steering, inner and outer long stress kit, etc. Do not run a rear sway bar since it is not limited slip differential.

How does the 914-Sixer handle? Very quick and nervous car. What I have done is eliminate the flex in the car body which is probably needed along with too heavy of suspension. I will have to soften the suspension either through the shock adjustments, sway bar adjustments, or replacing the torsion bars in front.

For the street and based on my experience on the two cars I have built, I would go with a stock 911 front suspension with a 21mm sway bar and 180# springs in the rear. Do some stress strengthening but watch out the type you do so you do not make it a rigid body. You need some flex in both the suspension and the body for the street. The trick is to find out the right amount for both.

I actually like my Sixer and its suspension but it is very nervous and "darty" which a problem I am currently working to solve. Slight move of the steering wheel and it moves very quickly laterally.

I only got long winded since I believe you should take your build in stages for setting the suspension and reinforcement. For now set the rear with 180-200# springs since starting at 140# was a little too light for my tastes. The 140# can be used but they were not for me. Also, I would use the stock 911 front suspension (19mm torsion bars) and an aftermarket through body front sway bar. Brakes should be considered at this time and there are a lot of opinions on this subject. I used 911 (3.5in type) brakes on the front and the 914 brake setup on the rear with 19mm master cylinder.

Believe me you can go all over the ballpark, just set the basis as you see it from receiving all the information; then, start planning the next moves to make the best car possible for your needs. It will become the car you want if you just take your time and evaluate each stage.

I do not like the idea of doubling the rear spring rate without changes to the original stock front end. This does bother me since I really believe you will have a totally unbalanced car even for the street. The 914 front suspension is strong enough including the brakes for a starting point except I would consider increasing the torsion bars from 17mm to 19-21mm. Then again you have to eventually consider shocks and brakes.

Hope this helps.

Steve Hurt

This car essentially a race car built for the street