JG Pasterjak
JG Pasterjak Production/Art Director
1/13/21 10:56 a.m.
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Shoutout to the SCCA for adding a major national-level Solo event at our official test track, the Florida International Rally & Motorsport Park in Keystone Heights, Florida. Wait, what? It’s in three weeks? Man the wrenches!

Our original plan was to install and sort a new suspension in our 1991 Toyota MR2 Turbo before the mid-March event that usually kicks off the national Solo season, the annual Tire Rack Dixie Tour at South Georgia Motorsports Park. But just last week, the SCCA announced that Pro Solo 1 event—which brings the drag-race starts of Pro Solo to a single-course autocross format—at the FIRM for February 12-13. So our build schedule got compressed a bit. Hopefully we can have a somewhat sorted ride ready for XS-A competition in just a few weeks.

Any suspension upgrade should start with a basic look at what you're trying to accomplish and what problems you're trying to solve. With an SW20-chassis Toyota MR2, those problems are manifold, and the path to fixing them can be a little more complicated than just applying traditional methods.

We know we want to increase spring rate, adjust corner weights and control body motion. So a set of coil-over shocks is the easy solution there, right? Well, yes, but it’s only part of the equation.

Read the rest of the story

Matt B (fs)
Matt B (fs) UltraDork
1/13/21 11:33 a.m.

I'm going to go out on a limb here and guess that a following installment will involve the Wilhelm geometry kit.  It looks pretty nice. I wish someone made something as comprehensive for the Mk1, but all I can find are the T3 RCAs.

z31maniac
z31maniac MegaDork
1/13/21 11:46 a.m.

So part of the reason for the increased rates is to offset the increased leverage for the roll center change?

JG Pasterjak
JG Pasterjak Production/Art Director
1/13/21 1:08 p.m.
Matt B (fs) said:

I'm going to go out on a limb here and guess that a following installment will involve the Wilhelm geometry kit.  It looks pretty nice. I wish someone made something as comprehensive for the Mk1, but all I can find are the T3 RCAs.

Yeah, did we foreshadow that well enough?

JG Pasterjak
JG Pasterjak Production/Art Director
1/13/21 1:29 p.m.

In reply to z31maniac :

Yeah, if you;re just building a fun street car, you can get awa with lowering and just bumping spring rates a bit to compensate. For something you want to be able to properly tune, though, correcting the roll centers will be necessary. UPS guy is on the way with those solutions :)

Matt B (fs)
Matt B (fs) UltraDork
1/13/21 1:47 p.m.

In reply to JG Pasterjak :

As soon as I saw their name it was clear. smiley

I wasn't aware of that they did that level of modeling though. Cool stuff.  Looking forward to seeing the same graphs with their kit installed.

This kind of thing makes me think if I were a smarter man I'd switch to a Mk2, but I just can't seem to quit my doorstop.

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
1/13/21 7:58 p.m.

That looks a lot like SusProg3D!

Vajingo
Vajingo Reader
1/13/21 10:51 p.m.

Subbed. Keenly interested. 

Vigo (Forum Supporter)
Vigo (Forum Supporter) MegaDork
1/14/21 9:22 a.m.

These charts make me happy. I've been meaning to 'manually cycle' the rear suspension on one of my cars on the alignment rack to try and diagnose some weirdness. 

It's pretty funny that the net effect of the front and rear toe changes is the car doesn't want to go where you point it. How wonderful lol.

Typ85
Typ85 Reader
1/14/21 5:47 p.m.

Audi and VW's have the same issue with their strut suspension, the cure is installing "ball joint extenders" 

JG Pasterjak
JG Pasterjak Production/Art Director
1/15/21 9:31 p.m.
Typ85 said:

Audi and VW's have the same issue with their strut suspension, the cure is installing "ball joint extenders" 

Yep. We have a similar solution on teh way from Wilhelm. Hopefully his powder coater gets around to them soon so he can get them to us in time for the Pro Solo.

 

Alex_W
Alex_W New Reader
1/18/21 7:59 a.m.

In reply to Matt B (fs) :

At the risk of stealing some of the thunder from one of JG's future articles, the rest of my analysis is on my website: https://wilhelmraceworks.com/suspension-analysis

I can't comment on the toe curves without modeling it, but the camber curves are likely very similar on the MKI, and all of the same improvements will apply.

JG Pasterjak
JG Pasterjak Production/Art Director
1/18/21 12:51 p.m.

In reply to Alex_W :

At least go ahead and make the link work :)

https://wilhelmraceworks.com/suspension-analysis

But, yeah, we'll be leveraging a lot of the hard work Alex has already put in during our build and sharing a lot of his findings. I'm really excited to drive on the stuff soon. I'm hoping to get at least a quick test day in before the Pro Solo, but more likely than that I'll be experiencing everything for the first time at the February Pro. Which, honestly, is fine. I'm obviously really familiar with the FIRM and how the surface behaves, and every autocross there is basically a variation of the same theme, so of all the places to sample a new car that's probably the least risky for me. 

Ugh, now I have to go finish installing that rear swaybar, because I just realized like five minutes ago that the entire rear subframe has to come down a bit to get it in place. Y TOYOTA?!?!

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