How much does suspension type really matter?

[Goingnowherefast]

Originally Posted by ZDan

It's not a big deal.

From a normal HPDE standpoint I agree. From a competition standpoint I disagree. The more negative camber you have the worse straight line performance you have. Double wishbone cars have a huge advantage in this area since they don't have to run ridiculous amounts of camber like we do. Again, there's a reason why bespoke performance cars aren't MacPherson strut.

[ZDan]

Originally Posted by Goingnowherefast

From a normal HPDE standpoint I agree. From a competition standpoint I disagree. The more negative camber you have the worse straight line performance you have. Double wishbone cars have a huge advantage in this area since they don't have to run ridiculous amounts of camber like we do. Again, there's a reason why bespoke performance cars aren't MacPherson strut.

I don't consider 3.5 or 4 degrees ridiculous, and a lot of wishbone cars run similar camber. Not an expert on pure race-only versions of FT86 or S2k, but my impression is FT86 generally run about 0.5 degrees more front. Also, as noted, a wishbone car will gain a lot more front camber under braking, so actual contact patch at max braking isn't going to be that different.

Most competition classes will classify cars based on their inherent performance, so any difference between wishbone and strut is often built-into the classification.

Ultimately, yeah, wishbones or multiink are "better", but for 90% of us who track these cars, not really...

Ultimitely, I still think the crap weight distribution holds these cars back much more than front struts instead of wishbones.

[marco_mc22]

I agree with Zdan, Mx5 and S2k are better cars primarily for their weight balance (if you’re skilled enough to exploit it of course, more nose weight means less performance maybe but it’s way easier to handle for a non pro driver), I’ve only driven the s2k which is heavier so I guess the lighter ND2 Miata is even better…the DW probably helps but it’s not the whole story, a well built strut car with a good setup and a decent balance plus not a crazy weight like our twins performs better than a crappy DW car with too much weight and a bad steering feedback like an Audi A5 for example.

Car which has given me the best steering feeling so far was a strut equipped 991 Porsche, tons of caster and not a standard strut yes but still a strut.

[DarkSunrise]

Originally Posted by ZDan

It's not a big deal. You do have to run a bit more static camber, not really a major prob. When I studied geometry of my 240Z vs my S2000, IIRC the Z's struts gained about 0.5 deg. camber per inch of travel vs. S2000 at about 1 degree per inch. So run a bit more static camber. Note that this doesnt really hurt braking as you don't gain as much camber as the front suspension is compressed as wishbones do.

I think the FT86's 55/45 weight distribution is a bigger hindrance to performance than front struts...

FWIW the s2000 has a similar camber curve, around 1* negative camber per 2” compression. It’s not enough, even with factory adjustment.

I was instructing a friend in his ap2 yesterday and drove his car for one session at around 9/10ths pace. The wear on the tire shoulder was pretty extensive after just one session, and that was with the factory camber adjustment maxed out to -1.9*.

[kevaughan]

Then we have guys that are custom fabricating cantilever suspension setups.


https://www.instagram.com/p/CTa5hZcHvj9/

[SCFD]

I would argue that the type of suspension a car has, either stock or modified, does not matter as much as how well the car is tuned/optimized.

[Ohio Enthusiast]

Originally Posted by DarkSunrise

FWIW the s2000 has a similar camber curve, around 1* negative camber per 2” compression. It’s not enough, even with factory adjustment.

I won't reply to all posts, but this is a really good point - both on the MX-5 and on the Lotus Elise (just examples I've read about) the consensus about track camber alignment is "as much as you can get". On top of that the aftermarket offers improved A-arms that allow greater camber range for the DW.

[Ohio Enthusiast]

Originally Posted by marco_mc22

Car which has given me the best steering feeling so far was a strut equipped 991 Porsche, tons of caster and not a standard strut yes but still a strut.

Try a Lotus Elise - manual steering, DW and very low caster angle that gives one of the best (if not the best) steering feel of any car at any price. I would agree with "many ways to skin a cat" and "suspension tuning trump suspension type".

[NoHaveMSG]

Originally Posted by ZDan

It's not a big deal. You do have to run a bit more static camber, not really a major prob. When I studied geometry of my 240Z vs my S2000, IIRC the Z's struts gained about 0.5 deg. camber per inch of travel vs. S2000 at about 1 degree per inch. So run a bit more static camber. Note that this doesnt really hurt braking as you don't gain as much camber as the front suspension is compressed as wishbones do.

I think the FT86's 55/45 weight distribution is a bigger hindrance to performance than front struts...

I think it is a combination of both issues overloading the fronts more easily. I have watched video from the same track of an S2K with similar mods to me and my car will not turn in the way that car does. Not even close.

[SCFD]

Originally Posted by NoHaveMSG

I think it is a combination of both issues overloading the fronts more easily. I have watched video from the same track of an S2K with similar mods to me and my car will not turn in the way that car does. Not even close.

But is that really because of the geometry and weight distribution? If you want your car to have sharper turn-in just add some toe-out in the front.

[EAGLE5]

A lot can be done to change and move grip around. Spring rates. Tires. Unsprung weight. Total weight. Height. Damping. Alignment. Roll bars. Weight distribution. Aero.

My understanding is that double wishbones have some advantages in the alignment department. That's a pretty important department, but it's not like other suspensions are shit, and it's just one department among many.

If I wanted sharper turn in, I could stiffen up the rear springs or damping or roll bars, add toe out in front, add camber in front, trail brake, and probably some other things.

Of course all of this would affect the car on exit too, and in all kinds of fun and interesting ways.

Or am I wrong?

[NoHaveMSG]

Originally Posted by EAGLE5

A lot can be done to change and move grip around. Spring rates. Tires. Unsprung weight. Total weight. Height. Damping. Alignment. Roll bars. Weight distribution. Aero.

My understanding is that double wishbones have some advantages in the alignment department. That's a pretty important department, but it's not like other suspensions are shit, and it's just one department among many.

If I wanted sharper turn in, I could stiffen up the rear springs or damping or roll bars, add toe out in front, add camber in front, trail brake, and probably some other things.

Of course all of this would affect the car on exit too, and in all kinds of fun and interesting ways.

Or am I wrong?

Absolutely, and a lot of it is my trail braking has gone to shit since I only got to drive my car on track once in 2020 and it really regressed my footwork. I also miss-spoke, it is not turn in that I have a lot of issue with, but mid corner understeer, a lot of it I fixed late in the season but it is still present. I just think there is a an advantage to the S2K platform that allows them to have to deal with less compromise.

[EAGLE5]

I wouldn't argue that the S2K is not superior. It probably is in most ways on the track.

If you had mid corner understeer, maybe Bilstein would tell you to...
Increase rebound rate on front.
Increase compression rate on rear.

[ZDan]

Originally Posted by EAGLE5

If you had mid corner understeer, maybe Bilstein would tell you to...
Increase rebound rate on front.
Increase compression rate on rear.

That wouldn't do much for mid-corner understeer, I don't think?

For mid-corner understeer: Increase rear roll stiffness (more rear spring rate or rear bar). Or decrease front roll stiffness (less front spring rate less front bar). Or increase rear ride height (raise rear roll center).