Keith Tanner
Keith Tanner MegaDork
9/6/18 7:49 p.m.

We spent most of the day today at the local kart track testing 2019 suspension. 

One note: there are two versions of Club suspension for the ND. Version 1 was used on the 2016-17 soft top cars. Version 2 is on all RFs and 2018-19 soft tops. V2 introduced some changes in the rear bumpstops as well as revalved shocks and a reworked steering rack. This is an important distinction because the V1 Bilsteins are overdamped while the V2 ones are much better suited to the stock springs. The car is a 2019 GT-S, which means it has an LSD. The car was also fitted with a set of 245 Bridgestone RE-71Rs because, well, that's what it had on it.

We had two drivers. One (me) is used to our very high power/weight cars so it took a bit of adjustment to get used to the different lines required by the ND2. The other spends more time in momentum Miatas, so you get a couple of different viewpoints.

Here's what we tested and the reports. We're still crunching numbers, I don't know if the lap times will be useful due to some other variables. We do have some interesting vertical acceleration data that may illustrate what the drivers reported. We'll release some of that tomorrow once we've determined what's useful.

All stock: This is a really good stock suspension, we've been impressed. But pushed hard on track, it started to struggle a bit on transition speeds and the LSD was working hard to put the power down. This setup rewards smoothness, otherwise you can find yourself landing on the (improved v2) bumpstops pretty quickly. Lots of roll.

Stock springs, Koni shocks (full soft): This worked quite well. The car was very composed and easy to drive. Definitely an improvement over the Bilsteins. This was a fun setup even if it still had a fair bit of roll.

FM springs, Bilstein shocks: This is a tolerable combo on the v1 Bilsteins. Neither of the drivers liked it at all with the v2. "Frequently saving my own life" was one comment. The car was not settled over some of the bumpy areas and the tail was having trouble maintaining traction on some corner entries. You could also feel the weight of the big rubber more. Not recommended, even if it is a cheap way to make the car look better.

FM springs, Koni shocks (aka FM Stage 1). This was the easiest one drive consistently and the most reassuring. Very quick in transitions, very stable, very composed.

mazdeuce - Seth
mazdeuce - Seth Mod Squad
9/6/18 7:55 p.m.

How much stiffer are FM springs than stock?

Keith Tanner
Keith Tanner MegaDork
9/6/18 8:20 p.m.

Umm. I'll have to back to the records for that. Fairly significantly, and more so in the rear than the front. We believe in keeping the car off the bumpstops as much as possible so we run higher rates than most other aftermarket options. None of this goofy "drop it 1" and bump the rates by 15%" crap around here. They ride and perform better due to that decreased bumpstop interaction.

Justjim75
Justjim75 HalfDork
9/6/18 9:19 p.m.

In reply to Keith Tanner :

Forgive me, I'm a noob.  Does that combo translate to a harsh ride, and could I expect similar results from the FM NB offerings?

Keith Tanner
Keith Tanner MegaDork
9/6/18 9:21 p.m.

No, it’s a very good ride because the suspension stays active almost all the time. The NB FM springs have a really good reputation in the market. 

The results are roughly equivalent to what you’d experience on an NB. 

Justjim75
Justjim75 HalfDork
9/7/18 9:02 a.m.

Thanks, I plan to make some significant changes after the Challenge 

mazdeuce - Seth
mazdeuce - Seth Mod Squad
9/7/18 9:49 a.m.

Thanks to FM for real numbers. You guys are awesome. 

Keith Tanner
Keith Tanner MegaDork
9/7/18 10:31 a.m.

You wants numbers? I gots your numbers. Well, the spring rates anyhow.

2016 GT soft top springs are 155 front and 70 rear according to my calculations. The rears are comically scrawny when you hold them in your hands. FM springs are 300/175 for that car.

Keith Tanner
Keith Tanner MegaDork
9/7/18 10:52 a.m.

One thing I forgot to mention about redline:

The ND2 is definitely faster as the higher redline allows us to skip at least one shift on a short straight. There's one spot where we were holding 2nd up to just over 7400 before braking. On an unmodified ND1, we'd be into 3rd for a short period then downshifting again.

For interest's sake, I was also holding the car on the rev limiter on another short second gear straight instead of lifting. It was peaking at 7400-ish and then slightly tapering off. I want to spend a bit more time with this data to figure out exactly what it's doing and to make sure the channels are identified properly.

Every time we tried to get above 7200, we got above 7200.

nderwater
nderwater UltimaDork
9/7/18 3:00 p.m.

Keith -- Do you plan to continue your testing with the addition of aftermarket swaybars?

Keith Tanner
Keith Tanner MegaDork
9/7/18 3:32 p.m.

Probably not with the full mix of potential spring/shock combos. We were particularly interested in the v2 Bilstein setup. We already know how the car responds to sways, so I'm not sure if doing any more testing would be valuable.

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