Bringing it back:, Improved Original for 4742910780 Options

[Van B]

Ok, so I’m working on adapting my stock 996 front sway bar to the 914. My reasons are varied, some rational, some sentimental, but mostly for the fun of it.

That said, I’d like some critical feedback from those of you who check in on this thread before I start welding.

To start off, here is how I have it mounted to the cross member supports:



Many things to annotate here. First, I chose to use the support bolt location because it will give the greatest strength against any twisting on the support bar vs welding on an extension to get the original bracket position. On the 996, the mounts are on the outside of the collar, I also thought moving them inboard a bit might soften the bar up a little bit. But on the other hand, I’m not sure it won’t induce bowing on the sway bar and thus, binding.

Next, here’s a preview on the link mount arrangement:


These are volvo sway bar links, but fit great and will make for an easy mount tab on the far end of the control arm for maximum leverage.

While checking clearances, the one limit I’ve found is that when airborne, I will only get one full wheel turn left or right before the tie rod end hits the sway bar shoulder. So, as long as I have one of the front wheels on the ground, I should be good. And, I think it looks like the turbo tie rod ends are a little slimmer… not sure I’ll get full lock at full travel. But, alternatively, I can always avoid jumps!

@Superhawk996 @StarBear @wonkipop @emerygt350

[wonkipop]

well well well.
thats quite a different approach.

i just have the schtandhardt faktory svay bar that goes through the fuel tank area.
with its absurdly long and small diam drop links!



i see yours will work quite a bit differently.
very short drop link.
i think i can understand the benefits of that but am not a suspension expert.
you would well outqualify me on that front.

i can see how the set up i have keeps me and the steering wheel out of trouble on that front, if the impossible ever happened and the 1.8 got enough suds up to lift off.
i can also fore see a situation where you would get airborne. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/biggrin.gif)

[Van B]

I could swap the link to the inside of the sway bar end and be about the same place as the OE bar, but I want more leverage on this stiffer bar. I’m pretty sure sway bar links are mostly strained under tension which is why a 10mm rod is plenty.

[wonkipop]

I could swap the link to the inside of the sway bar end and be about the same place as the OE bar, but I want more leverage on this stiffer bar. I’m pretty sure sway bar links are mostly strained under tension which is why a 10mm rod is plenty.

yes its always tricky trying to get my head around the physics of how the forces are working. (in relation to drop links). separating cause and effect in my brain. i always feel that compression must somehow be involved. but i guess it isn't. or the forces are axial and the rod is sufficient. i have been known to do very thin steel columns in some of my buildings and am always amazed at what my engineer will have the nerve to get down to, so long as the loads are purely axial (in either direction). the back links make a lot more sense to me. however your observation regarding air force short combat take offs and climb outs related to sway bar interference possibly highlights the porsche design a little better?


i understand if you go too far on stiffness of sway bar you can end up lifting the inside wheel. i'll leave that for the experts like @Superhawk996 !
(IMG:style_emoticons/default/biggrin.gif) i know my RS Clio (fwd) happily lifts its rear wheel all the time if you give it a bit of good cornering action.
its got one hell of a sway bar across the rear (as well as the front). but its designed to lift that wheel and transfer all the weight to the outer wheel to stop lurid oversteer.

but i see that what you are after is a particular sort of feel and performance handling enhancement that is beyond the old showroom set up which was actually really an excuse to soften the spring rates for comfort and then dial back some anti-lean characteristics - at least when it came to the rear bar. (IMG:style_emoticons/default/smile.gif) thats probably downselling it a bit but......, its not particularly aggressive as a set up - the stock sway bars.

[Superhawk996]

Personally, I’d never accept the tie rod hitting the anti roll bar under any circumstance. Having a tie rod get hung up even momentarily could become catastrophic.


There will be dynamic deflections that haven’t been accounted for.

1) the bar walking side to side even with stopper collars in place at the bushings.

2) Deflection of the bar as it winds up with the outside wheel moving into compression and the inside wheel moving toward rebound.

3) Deflections imparted on the suspension from lateral load.

If a sanctioning body like SCCA were to find something like that interference during a tech inspection, I don’t think it would pass tech.

[wonkipop]

Personally, I’d never accept the tie rod hitting the anti roll bar under any circumstance. Having a tie rod get hung up even momentarily could become catastrophic.


There will be dynamic deflections that haven’t been accounted for.

1) the bar walking side to side even with stopper collars in place at the bushings.

2) Deflection of the bar as it winds up with the outside wheel moving into compression and the inside wheel moving toward rebound.

3) Deflections imparted on the suspension from lateral load.

If a sanctioning body like SCCA were to find something like that interference during a tech inspection, I don’t think it would pass tech.

(IMG:style_emoticons/default/pray.gif)

[Van B]

Superhawk, thanks.

1.) Forgot to mention that collars are on order

2.) Compression doesn’t have a clearance issue, but I agree on full rebound.
- I’m lowering the bar mount and measuring the installed size of the turbo tie rod to see if that get me full clearance.

3.) The drop link joints will absorb those with no binding and no interference short of failure.

Basically, copy all on the need for full clearance even at the limit of movement. I’ll see what adjustments I can make.

[wonkipop]

yeah, get rid of the steering interference.
i enjoy your posts and inquiring mind.
it would be a shame to have it fall victim to an ejector seat malfunction. (IMG:style_emoticons/default/biggrin.gif)

i don't know enough about suspension.
nor the theory. perhaps i should since i benefit from driving some good equipment.

however my RS Clio has a rock solid front end.
admittedly its front wheel drive.
but its all incredibly solid.
sub frame. sway bar with no drop links. and in the super duper versions it had a giant front strut external reservoir shock that was like a solid pole.
so impressive that harry of harry's garage and OCTANE fame was driving one as a camera car chasing ferraris and lambos up the alps and was surprised that he could glue himself to their arses. they got away from him on the straights but he was right there again in the corners. drivers of lambos etc were equally surprised they couldn't shake him.

he immediately bought the car. the camera car. and still has it.
so.....i'm not sure about what that means for mid engine cars.
but there might be something to what you are doing.
i'd have to process it.

[StarBear]

Yep; way beyond my wheelhouse (pun intended).
I have the original setup on mine, but I never go over 60 and most often more around 35 touring around town.
Best wishes! (IMG:style_emoticons/default/beer3.gif)

[Superhawk996]

I know reading books has gone out of vogue but I’m always going to recommend the Fred Puhn “how to make your car handle” book.



In keeping with the times - this is a pretty good website:
https://suspensionsecrets.co.uk/

[wonkipop]

here are stock sway bar dimensions i think (?) you were after @Van B
or best as i can measure here in the garage.
sway bar is under fuel tank so i can't do that one but its easy for you to get off your own car if the tank is out.

you can see in photos how the end of the sway bar is forged (or however its done) into a squared section of bar that the lever bar bolts to.

[Van B]

@wonkipop thanks. I’m actually looking for the arm length eye to eye from the drop link to where it attaches to the sway bar itself. And the overall sway bar length as near as you can approximate. I know that might be tough to measure when installed. I’m trying to use the calculator superhawk provided to see torsion differences between what I’m attempting and the OE bar configuration.

Thanks for the help!

[wonkipop]

the lever arm off the sway bar is 120mm eye to eye.
the eye at one end being the roll bar centre and the other end being the drop link centre.

i can only give you those dimensions above for the sway bar length itself.
it protrudes those dimensions either side of the wheel well. you need to be able to measure deeper down in the wheel well to get the interior length.
no can do with fuel tank installed. but you can and then add the 75mm each end.
i would call the square ends part of the sway bar. allow a small amount for inner wheel well thickness and you have the length of the sway bar.

i hope my photo above in post before makes sense. i am measuring the distance out from the wheel well to the cl of the lever arm. all in all the sway bar is 85mm long from the wheel well out. same other side. add interior dimension across the hole that swallows the fuel tank. but lower down than top. you can see where to make the measurement from my photo. can't access roll bar from below car even if i could get myself under it, which i can't. head is too big. (IMG:style_emoticons/default/beer.gif) bottom panel is in the way.
its fully interiorized man. (IMG:style_emoticons/default/beer3.gif)

[wonkipop]

realising maybe you are doing some calcs off site.
so here is a very approx dimension on interior dimension of roll bar length measure from top of fuel tank looking at edge of the cavity.

860mm.
maybe add 10mm to account for wheel well walls.
then 2 x75mm each end.
= 1020mm overall length.

good as 1000mm long give or take. the good old metre.

[Van B]

@wonkipop thank you kind sir. I think I can use your outside the wheel well numbers to reconfirm your length estimate. And your lever arm numbers are exactly what I need.

[Van B]

@wonkipop @Superhawk996
Thank you both for your help, looks like I’m definitely in the window for stiffness! First screenshot is the OE 914 setup, second is the 996 bar.



I think it’s likely the 914 is stiffer than predicted here. As Superhawk pointed out to me, the arms won’t flex like a single piece bar and are a clean 90 deg transition (no diff between x and z). For the 914 length, I measured the space under the tank, measured metal thickness at the pinch welds, and used wonkipop’s wheel well measurements.

[Van B]

Now I’ll continue working clearances and post up for further face shots from the tribe here lol! (IMG:style_emoticons/default/ar15.gif)

[Superhawk996]

I like it! Good attempt at a baseline understanding of what the new proposed bar is in comparison to the stock bar.

In the on-line calculator change the z dimension to something small like 0.1 and it bumps the stiffness to about 169 so not a huge change there.

Just as the online estimator will underestimate the stock bar, it will probably slightly overestimate your 996 bar which I think has a pretty substantial hump in the arm to clear the LCA.

Overall looks pretty reasonable as a starting point. Better than what my first gut instinct thought!

[Van B]

I may be at a dead end because of control arm clearance…
The pics here show a 20mm offset. But to clear the tie rod end at full droop and full lock requires 50mm! Which means the sway bar is the lowest thing on the car and couldn’t possibly be covered by a modified pan.

I’m trying to be pragmatic about this, but I’m also really bummed that it doesn’t seem like a reasonable mod at this point.

[Superhawk996]

Raise spindles to move the tie rod end up in Z? Raised spindles are generally a good thing to help with bump steer and the lowered front ride height stance that so many like.

Just a thought (IMG:style_emoticons/default/confused24.gif)

Alternatively there are the Elephant Racing bump steer spacer thing-a-Mabob - let me find the link.

Nope I’m a dope - that is moving the tie rod end down instead of the spindle going up which effectively brings the rack and tie rod down. Doh! Both are in wrong direction to improve clearance you need.


Wait what’s wrong with me trying to get you to keep that 996 bar over the elegant stock bar package. (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/av-943.gif)