Andy Hollis
Andy Hollis
9/28/20 8:38 a.m.

When it comes to suspension modifications, most people take their cues from fellow enthusiasts—buddies or message board gurus who own a similar car. The plan of attack? Parts sourcing? Those ideas usually come from peers. Of course, you can always count on websites and magazine ads to offer t…

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BA5
BA5 GRM+ Memberand Reader
9/28/20 9:50 a.m.

Strut top bars can be effective on a-arm cars as well as McStrut cars.  Many a-arm cars have the upper suspension member bolted somewhere near the strut.  Loads from cornering are transferred into that structure and bracing can limit the movement of that structure, therefore limiting deflection of your upper suspension member under loading.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/28/20 9:59 a.m.

But if they don't have struts, are they still strut bars? wink

wspohn
wspohn Dork
9/28/20 10:21 a.m.

Good list.

I had to laugh at one idiot that lowered his car way too much because 'it looks cool', induced unacceptable levels of bump steer and then despite accurate advice to raise the ride height, went out and spent hundreds of dollars on supposedly cool suspension components that had absolutely no effect on the problem he had caused himself. He ended up selling the car, having come to the wrong conclusion - he figured the car was useless instead of the obvious explanation, that he was an idiot.

 

BA5
BA5 GRM+ Memberand Reader
9/28/20 12:37 p.m.
Keith Tanner said:

But if they don't have struts, are they still strut bars? wink

I always assumed that the 'strut' referred to the cool way one walks after installing the bar. laugh

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/28/20 12:43 p.m.
wspohn said:

Good list.

I had to laugh at one idiot that lowered his car way too much because 'it looks cool', induced unacceptable levels of bump steer and then despite accurate advice to raise the ride height, went out and spent hundreds of dollars on supposedly cool suspension components that had absolutely no effect on the problem he had caused himself. He ended up selling the car, having come to the wrong conclusion - he figured the car was useless instead of the obvious explanation, that he was an idiot.

One thing I found in Donohue's book as well as Horseman (aka Gulf Racing GT40/917s, maybe it was Wyer) and Yunick - all three of them found themselves chasing handling problems that turned out to be a gradual erosion of available suspension travel as the cars evolved. Larger tires, lower ride height, whatever. 

This is a pretty good list.

Tom1200
Tom1200 Dork
9/28/20 1:58 p.m.

It's good list indeed.................I've lost count of the number of cars I've climbed into where they have the damping cranked to eleven cuz it "feels" good to the uninitiated.

Also +1 on the bump stops.

fidelity101 (Forum Supporter)
fidelity101 (Forum Supporter) UltraDork
9/28/20 2:29 p.m.

"Just think how bad it would be to drive a car with a rear suspension that toes out as it rolls into a turn."

like the Mazda OEM DTSS system on the FC rx7? thats exactly whats it designed to do and everyone deletes this. 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/28/20 2:57 p.m.

And the NC Miata rear suspension as well. 

Then on the ND "sporty" suspension, Mazda jacked up the damping and the car felt fast but jitterbugged all over the place. I'm convinced this nervousness is why people love Bilstein so much, they figure it's sporty. Meanwhile, people seem disappointed that our stuff feels like the spring rates are softer than they are. That's because we're letting it move and we're giving it room to move!

Ben Jolly
Ben Jolly New Reader
9/28/20 9:31 p.m.

These aren't just problems on low and fast cars. I have been studying suspensions on off-road vehicles, since I want to add one of the those to my fleet eventually.

When you lift a vehicle just by raising the static ride height like so many 'lift kits' do, you often lose a ton of the down travel, and consequently end up with handling and ride problems, and poor articulation. The 'engineering', if you want to call it that,  which goes into a great deal (possibly a majority) of the suspension kits I've seen on the market is focused on making sure it looks cool and delivers exactly the amount of lift the box promises. 

This issue is especially bad with independent suspensions, turns out you have to spend a lot of $$ to retain the factory range of travel or increase it.

What Keith is saying is the reason I am just refreshing my NC's suspension with new stock components, and saving my $$ for down the road to do a properly balanced setup like one of the ones he sells. I am quite thankful my NC didn't come with the so-called 'sport' suspension.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/28/20 10:01 p.m.

The early NC (2006-08) sport suspension went the other way - it was badly underdamped. By 2013, it was pretty competent. You know, Mazda got their special suspensions wrong a lot more than they got them right on the Miata...

Interestingly, down travel (aka droop) is more important in rock crawling than up travel (bump) is. 

Hi Ben!

TXratti
TXratti Reader
9/30/20 7:08 a.m.
Keith Tanner said:

And the NC Miata rear suspension as well. 

Then on the ND "sporty" suspension, Mazda jacked up the damping and the car felt fast but jitterbugged all over the place. I'm convinced this nervousness is why people love Bilstein so much, they figure it's sporty. Meanwhile, people seem disappointed that our stuff feels like the spring rates are softer than they are. That's because we're letting it move and we're giving it room to move!

Square left in 50 caution ocean! - Author of How To Build a High Performance Mazda Miata

I've always felt this way about Koni's but on the high speed damping side. Compression cracks on the highway (for example) and ALL the jitteriness that wasn't there before. I have had them on more than one car, and it has been mentioned by more than one person w/o leading them to it.

thashane
thashane GRM+ Memberand Reader
6/22/21 6:25 p.m.

Zombie bump-

 The MINI favored oversteer at the limit, and was slowing down the car to the point I was considering down-sizing back to stock from the 22mm rear bar. Had I not rear this article, while searching for something else, I would've never tested the bars bushing resistance. Needless to say I could move it with two-hands with some effort.

So after some grinding, adding washers (+ a zerk that works really good on one side, and good enough on the other), I can now move the bar with two fingers. Thanks GRM!

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
6/22/21 7:24 p.m.
fidelity101 (Forum Supporter) said:

"Just think how bad it would be to drive a car with a rear suspension that toes out as it rolls into a turn."

like the Mazda OEM DTSS system on the FC rx7? thats exactly whats it designed to do and everyone deletes this. 

That's... complicated.  Swingarm suspensions naturally will toe out under cornering because of bushing flex.  That's part of why 911s were such handfuls.  Mazda tried to combat this by installing toe links to keep the arm from toeing out, and then that weird swing link on the trailing arm to keep everything from binding.

But then they decided that a small amount of toe out under LIGHT lateral loads was beneficial for snappy turn-in, so they mounted the wheel bearing in a separate knuckle on the swingarm with soft bushings in a certain place so the wheel would toe out under LIGHT loads.

But that was unacceptable for HEAVY cornering, so they had another bushing that was stiffer, that would compress the other way once cornering loads got heavier.

When everything was new, and you were on OE spec tires, it was fairly seamless.  On grippier tires, it was a little wonky because the extra grip would overpower the bushings differently.  And after a few dozen thousand miles, when the bushings aged, it could get downright scary.

 

So in 1986, DTSS was good.  In 1996, it was not quite so good anymore.  This is the downside of bushing kinematics.

 

Beam axle suspensions have a similar problem, the beam flexes under cornering loads, causing toe-out.  This was traditionally battled by lots of static camber and toe-in in the rear.  VW basically invented kinematics (sorry Mazda) with the Rabbit by putting the beam bushings on little ramps, so side loads would push the outside forward, toeing in the wheel to compensate.  They went more extreme on the A2 chassis cars with the ramp design.   BUT.  Some VW A1/A2 autocrossers have discovered that mounting those ramped bushings backwards will make for some wicked turn-in.  It's sketchy at high speed, but, autocross.

AnthonyGS (Forum Supporter)
AnthonyGS (Forum Supporter) SuperDork
6/22/21 8:06 p.m.

My 4th gen has too much rear roll stiffness.  I have Konis, a new sway bar and new brakes and fluid to do all in the rear soon.  The new smaller sway bar will help a lot too.  I may do all this in one day if I'm productive and lucky,

Appleseed
Appleseed MegaDork
6/22/21 10:58 p.m.
BA5 said:
Keith Tanner said:

But if they don't have struts, are they still strut bars? wink

I always assumed that the 'strut' referred to the cool way one walks after installing the bar. laugh

No. It's the things that keep your Cessna from becoming a lawn dart.

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