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Coil suspension for my SC?

I’m new to the torsion bar suspension world. I’ve previously owned a 964 and 993. So I’m curious as to what kind of suspension upgrades you guys have done on your older aircooled 911 suspensions?

Old 12-01-2020, 08:58 PM
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Lots of suspension threads here...

What seems to be the most popular:

- Increasing torsion bar sizing

- Using digressively-valved shocks matched to the torsion bars

- Raising front spindles to lower ride height while maintaining suspension travel

- Playing with bushing material (various rubber durometers, rigid bronze, everything in between)

- Adjustable sway bars

- There are coil-over conversions - generally requires reinforcement of the tub

Porsche did a great job providing a platform that is infinitely adjustable - depending on what you want to do. It's easy to go overboard and make the ride harsh.

Elephant Racing has a great overview of many options...

The stock setup is sometimes hard to beat for a reasonably-driving street car.
Old 12-01-2020, 09:21 PM
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I’m mostly looking for a suspension that will feel like my old 964 and take the harshness out of the torsion bars. Is that even possible without having to “reinforce the tub” as you say?
Old 12-01-2020, 09:31 PM
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Quote:
Originally Posted by Kansas View Post
I’m mostly looking for a suspension that will feel like my old 964 and take the harshness out of the torsion bars. Is that even possible without having to “reinforce the tub” as you say?
The structure of the car is designed to support the car from the T-bars, not the shocks. If you want to change where the car is supported you should expect to need to reinforce the new structure.

Changing from t-bars to coil springs isn't going to "take the harshness out of the torsion bars" because there is nothing innately harsh about a torsion bar. In fact a coil spring is a torsion bar that has been wrapped into a helix. (Think about a single coil. When you compress it it is easy to see that the deflection is twisting it in the middle.)
The advantages of a coil spring is how it is packaged where you need to have a shock anyway, the fact you don't have to support the car through a bending load in an A-arm, the ease of making springs of different spring rates, and the ability to make progressive spring rates.

There are some very large differences in the suspension of the 964 from the earlier cars. In the rear the obviously biggest change is that instead of having an outer link (the spring plate) that is horizontally flexible, the later car has an inner arm that is horizontally flexible. They say they did this to change the toe characteristics of the rear. (Apparently to take advantage of what they learned from the 928's "Weissach" axle.)
Plus the 964 added power steering which is going to make a major change in the feel of the car.
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Old 12-02-2020, 03:02 AM
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Originally Posted by Kansas View Post
I’m mostly looking for a suspension that will feel like my old 964 and take the harshness out of the torsion bars. Is that even possible without having to “reinforce the tub” as you say?
As mentioned above, coil springs are just cleverly shaped torsion bars. There's nothing inherently harsher about using a straight one as a spring instead of one bent into a cylinder.

What we do have is a lot of cars that are lowered way below stock. We also have old school hard rubber bumpstops. So a lot of cars are just crashing off of those due to the lack of travel caused by lowering.

Basically what it's going to come down to, is not too low, not too big of torsion bar, not too big/heavy of a wheel, and a decent shock.

There's a million threads about 911 ride quality on this board. There hasn't been too many huge breakthroughs or products recently, so most of the info should be up to date. The newest item is probably the KW shocks, and they also did bring out a coil conversion. Search those terms to get info on them.
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Old 12-02-2020, 04:56 AM
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And the shock valving can make either spring design feel harsh. Prepare to spend $6K+/- on making this car handle like your 964.
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Old 12-02-2020, 06:40 AM
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Quote:
Originally Posted by Kansas View Post
I’m mostly looking for a suspension that will feel like my old 964 and take the harshness out of the torsion bars. Is that even possible without having to “reinforce the tub” as you say?
There’s nothing harsh about torsion bars. They are just a spring. Maybe you’ve got Bilstein sports on the car? Looking into some of the threads about revolving the struts. I suspect you’re looking at the wrong source for your complaint.
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Old 12-02-2020, 06:57 AM
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Thanks for all the info. Sounds like a bad idea all around. And I’d never want to go back to the power steering feel of my 964. That’s one of the big reasons I wanted an earlier car.
Old 12-02-2020, 07:14 AM
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If you are new to the car you first need to ID what is currently on the car. Do some investigating (if you are mechanically inclined), read through any records you have or find a good shop that knows how to setup a 911 correctly.

What year car? That really helps. The details of suspension setup will vary by year (weight) of the car.

Is the suspension original? - Old bushings are likely completely worn out. This can give metal on metal contact, noises and harshness. Additionally, the stock rubber bushings are designed as part of the suspension such that they stretch in a rotational way adding to the spring rate. If they are hard as a rock and aged out the car will definitely feel harsh.

What shocks (dampers) are on the car? - Koni, Boge and Bilstein all have different ride characteristics. What is on the car?

Has the suspension been modified? - Lowered cars can sit on bumpstops. Larger torsion bar sizes can feel harsh when the compression damping is too high for the increased spring rate. Combined with original bushings this can become a handling disaster.

What wheel and tire package? Are tires in date? Rubber on the tires adds to suspension compliance. smaller aspect ratios and incorrect tire pressure will ride harsh.

There are lots of threads on refreshing and updating suspension. First, baseline what is in the car and then we can provide more detailed answers to give you suspension compliance and cornering confidence.

A well setup 911 suspension is where its at.
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Old 12-02-2020, 07:38 AM
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I appreciate that. I actually don’t take possession of the car for another 2 weeks. It’s a ‘78 SC club sport with original suspension, 16” wheels, rebuilt engine and tranny last year.
Old 12-02-2020, 08:05 AM
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It will be your can and you can do what you want to it.

HOWEVER,

Please drive it for a while and get to know the car before you start modifying it. Read the hundreds of threads on suspension. There are pretty much infinite opinions and ways to modify the suspension.

I have a 1985 Carrera and the suspension was tired. I replaces all the rubber suspension parts with new Elephant racing rubber parts and the standard turbo tie rods, and new ball joints. I went up one size to 21mm front and 27mm rear t-bars. And went to Bilstiens HD shocks. For me, it is perfect. My wife will still ride on long road trips, and I think it handles great.

Your SC will never handle like a much heavier 964 with power steering, and way more power without a lot of expensive work. Tweak the suspension to fit your needs, but don't expect it to be something it is not.

There are countless threads of people spending lots of money un-doing some suspension modifications. Best advice, drive your new SC a year or more and several thousand miles and get to know it and how it handles. Then think about mods.
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Old 12-02-2020, 08:38 AM
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i thought the SC you ultimately got was pretty original and in great shape? i don't follow why you would want to molest it so significantly out of the box when you really have not driven it much by your own admission. a lot of good info for you to digest in the 1st reply to this thread after you've lived with it for a few thousand miles. if the suspension is truly original there is a great deal of improvement that can be obtained with the suggestions given..

if you are concerned about the suspension just wait until you find the lack of power afforded by a CIS system as compared to your 964 and 993. it being much lighter will offset that to some extent, but you may ultimately find greater disappointment there. i could not get the CIS off my 75 quickly enough when i got it after having experienced carbs on my previous spec911.

im curious to hear your impressions after truly experiencing what the car has to offer after some time with it as it sits.
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Old 12-02-2020, 08:53 AM
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This may have been mentioned, but what are your tires and how old are they. Any number of brands that will work well with your car, but the biggest ride and handling improvement you can make is a better tire. Michelin is I have found to be the best. Bob
Old 12-02-2020, 12:17 PM
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I appreciate that. I actually don’t take possession of the car for another 2 weeks. It’s a ‘78 SC club sport with original suspension, 16” wheels, rebuilt engine and tranny last year.
Club Sport eh? Tell us more about this super rare model...
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Old 12-02-2020, 12:21 PM
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Quote:
Originally Posted by Matt Monson View Post
Club Sport eh? Tell us more about this super rare model...

Maybe he meant 87 not 78...


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Old 12-02-2020, 12:33 PM
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Club Sport eh? Tell us more about this super rare model...
Me too!
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Old 12-02-2020, 12:38 PM
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These Guys get grumpy when you pick on old 911 tech.
You can see ...I don't post much

Have fun with your New (to you) toy!

Try the T-Bars then do what you want. A lot of people on here change to a coil over after the first time changing height or tuning for the Track.

Watch a Vid or read the how to.
You can see the time invested changing ride height with T-Bars.
With Coil over you turn and lock a collar and add a few bolts to change springs out.
Old 12-02-2020, 01:50 PM
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Quote:
Originally Posted by JeffShoots View Post
Kansas,
These Guys get grumpy when you pick on old 911 tech.
You can see ...I don't post much

Have fun with your New (to you) toy!

Try the T-Bars then do what you want. A lot of people on here change to a coil over after the first time changing height or tuning for the Track.

Watch a Vid or read the how to.
You can see the time invested changing ride height with T-Bars.
With Coil over you turn and lock a collar and add a few bolts to change springs out.
I honestly can't care less what someone does to their car with their money. I see lots of people that can't wait to backdate, remove the heat exchangers and the AC and make it their vision of perfect. That is not my vision, but it ain't my car.

Do whatever you want to your car. It is your car, and it is just a car. There are lots more.

But I will suggest the owner drives the car for a while before making any changes. Just a suggestion, and I only hope they like their 911 as much as I love mine.
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Old 12-02-2020, 02:29 PM
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Quote:
Originally Posted by JeffShoots View Post
Kansas,
These Guys get grumpy when you pick on old 911 tech.
You can see ...I don't post much
your 1st statement makes no sense

the second we can all be grateful for.
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Old 12-02-2020, 03:57 PM
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Originally Posted by juanbenae View Post
your 1st statement makes no sense

the second we can all be grateful for.
Haha ...Too easy

Old 12-02-2020, 07:27 PM
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