Hi All,

A friend has a very nice, complete early 911 front-end that he is planning to install in his 914 project car.

The suspension has a 23mm, low-mounted swaybar and I'm concerned that it will be so stiff that the car will end up with hopeless UNDERSTEER.

So I'm asking if anyone on the site is running such a setup and what you found with the chassis setup.

Thanks,
Terry

As the underneath style sway bar has longer arm length, I'd try it and see if it's not too bad. Stiffen up the rear springs and it should work.

Hey George,

Thanks for the response.

The issue here is trying to understand just how stiff the front end will be with the sum of torsion bar and swaybar delivering the wheel rate (different from spring rate).

My bud would like a softer ride for comfort and thus, it is not desired to just stiffen the rear until chassis balance is achieved. Thus, I'm trying to "qualify" the front bar before going to the rear rates. If the 911 bar is as stiff as my formula indicates, then the only answer is to DUMP it and go to "the usual" 914 front bar.

My track car is running about 570lbs/in rear Wheel Rate and the balance is great, but my back is good, so not problem!

I was told that the dimensions of the 911 bar are a twisting length of 28.5" X 23mm thick w/ the twisting arm length at 6.25". Can anyone verify these are the right measurements for that bar?

Thanks,
Terry

I'm running with a stock 911 sway bar but think it is 16mm. My ride was already stiff before installed but cornering is tighter after. Not a huge change but definitely noticeable. I'd be in the market for the 22mm which should be the largest size, if he's interested.

Frank

Terry,

Thanks again for your expertise . I seem to remember that the 87 Carrera front end stock sway bar was only 18.8 mm. I think mine mea sured .91 in. What is the conversion rate for . 91 in mm? Is mine stock?

Mike

hopeless snow plow. buy tire chains

.91" = 23.11 mm
Divide .91 x .03937 =23.11mm
Multiply 23.11mm x .03937 =.9099 "

Jack

Not a fan of that arrangement at all.

Depending upon driving styles, and which type of bar, a stock 911 bar can be a dream or a nightmare. A stock 23mm would be a nightmare in my opinion.

Street/occasional autocross - Stock 15mm through body bar.
Serious about autocross but still driving on the street - 19mm bar and 140lbs springs in the back.
Beyond that - check with the pros who are here and actually driving on an open road course (Brandt and Sean above come to mind) and gather your information wisely.

For anyone adding a bar, I think I would recommend a 19mm bar with longer arms so, it could behave as stock if needed/wanted or be tightened up if needed/wanted. Through body only. It's more work but I feel it's a much better design.

Eric......when you say longer arms .....do you mean adjustable drop links?

It depends entirely on what your friend is gonna do with it and in any case, it's a matter of coordinating the front and back components.

If this is to be a street car my automatic answer is to build it like a road-race car and as stiff as you wish depending on your comfort level. I wouldn't want that particular bar on the car in any case on an otherwise stock suspension unless it's adjustable and the stock 911 bar isn't. It'll understeer like crazy until you beef up the rear spring/shock combo, which you would have to do.

I run 23mm torsion bars and a adjustable 22mm anti-sway bar. But I also have very stiff rear end and an LSD. I want the car to handle like a road course car because street driving is just that, and DE's handling is excellent.

It's a terrible AX car in this form.

Bah ....

An anti-roll bar does not affect the ride of a vehicle until you load it ... as in a corner or possibly hitting a chuckhole.

The Brown Turd had an SC front end under it with a 2.4L six ... handled beautifully .. flat thru turns and wasn't tail happy any more than a stocker.

It is not often you see a hanging curve ball like this one.... I so badly want to knock it out of the park.




My take on the whole sway bar thing is different.

Get the car balanced without any sway bar. It will roll and corner slower, but make sure it will go through a corner without understeer or oversteer.

Then add front AND REAR bars to keep it neutral while making it roll less. The ride will be nicer, and you will get the same effect as adding a buttload of back breaking spring rate to the rear.

And for those who preach the conventional wisdom of "Front bar, rear springs", take a look at all the 914-6 GT pictures you see. ALL of them had rear bars.

My car actually needs a stiffer rear bar to cure the understeer I have due to the tire size differential. Or I could just put 16x8 rims on the front and match the tires front and rear.

No, I mean longer arms... The lever thingies

Hey Sean,

That's EXACTLY the kind of feed back I was looking for! ...and also my fear with the 18.8 (19mm) front bar.

Lord know understeer is enough of a problem with V8 conversions and I just don't want to set up a friend's car with that problem.

It took me a long time to stiffen the rear, add a rear swaybar and balance out the TERMINAL understeer my car had on the track! Did I mention I HATE understeer?

Best,
Terry

Hey Mike,

With your front swaybar measuring .910" thick...and 25.4 mm = 1.0", then 25.4/.91 = 23.114 mm. It appears you have a much stiffer than stock 19mm front 911 bar.

The difference between 19 and 23 mm is HUGE since in the formula for computing torsional rate, the value for Diameter is to the 4th power! Thus the 23mm bar would be 2.14 times stiffer than the 19 mm bar.

Here's the formula: K = (1,178,000)(D4/LA2)

Best,
Terry

Ron,

While you are correct about a swaybar only effecting spring rate in cornering and not going straight down the road, you have missed my point.

I have an application where I'm trying to balance out a chassis with a very stiff front and a goal of a ride and good handling.

So if I keep the stiff front end, then I have to go stiff in the rear which will be a summation of coilover and swaybar rates. Since I'm trying to limit the ride stiffness, I have to go with a HUGE rear bar to achieve balance.

However, before committing to a plan, I'm trying to understand if the 23mm front bar is TOO STIFF and the best answer would be to JUNK it and go to a softer front bar.

In my initial calculations, to balance the front with the 23mm bar, I would need a total roll wheel rate that would be much stiffer than my V8 track car. This would NOT be an acceptable answer.

Best,
Terry

Just say no to underbody, non-adjustable sway bars!

I have a 18mm 911 sway bar.

There;s a thing about a hanging curve. An inept pitcher will throw one & sometimes they don't break. That will put a bump on your head if you hang in there too long waitin' for it.

Rear sway bars ain't for shit unless you have an LSD. They vast majority of 914 owners don't. Maybe you've never gone fast enough to get a 914 to lift the inside rear wheel.....too bad. I have and in this case CW is right.

To the OPs thread. I'd never install a non-adjustable anti-sway bar on any car.

By chance, I went to the Pellican catalog and found that there are 3 different sway bar diameters for the 911 that are the under-car type: 16mm (74-77), 20mm (74-85), and 22mm (86-89). Doesn't say if they're interchangeable, but the illustrations look the same. As such, you at least have an option to go softer; not optimal to tune as with an adjustable bar, but at least there's a choice.

Andys

Correction - it's a 20mm underbody