Winter 2013/2014 Autocross Projects

Scott Johnson · **Posted:** Wed Dec 04, 2013 1:16 pm

I'll talk about adding a header and tune to the BRZ. I'll dream about getting fancy suspension, then in the spring time I'll autocross it with no changes and the same tires I was running in 2012.

Cash Davidson · **Posted:** Wed Dec 11, 2013 8:24 pm

More backyard engineering: Replacing sloopy rubber radius arm bushings with spherical joints. :sing:

Gotta love F-Prepared!

Ryan Holton · **Posted:** Thu Dec 12, 2013 9:16 am

In for finished product pics :thumbsup:

Jordan Normark · **Posted:** Thu Dec 12, 2013 2:36 pm

Scott Johnson wrote:

I'll talk about adding a header and tune to the BRZ. I'll dream about getting fancy suspension, then in the spring time I'll autocross it with no changes and the same tires I was running in 2012.

And you'll still be fast.

I think I'll change the oil in the Miata this winter and possibly drop the rear spring rate to the 350 lb range. Anyone have a spare pair of springs? Other than that If it ain't broke...

Les Davis · **Joined:** Fri Aug 29, 2003 2:04 pm **Posts:** 2059

Jordan Normark wrote:

Scott Johnson wrote:

I'll talk about adding a header and tune to the BRZ. I'll dream about getting fancy suspension, then in the spring time I'll autocross it with no changes and the same tires I was running in 2012.

And you'll still be fast.

I think I'll change the oil in the Miata this winter and possibly drop the rear spring rate to the 350 lb range. Anyone have a spare pair of springs? Other than that If it ain't broke...

I think I have some 60mm 6kg springs lying around, though that probably won't do you much good.

JamesMilko · **Posted:** Thu Dec 12, 2013 4:16 pm

Jordan Normark wrote:

Scott Johnson wrote:

I'll talk about adding a header and tune to the BRZ. I'll dream about getting fancy suspension, then in the spring time I'll autocross it with no changes and the same tires I was running in 2012.

And you'll still be fast.

I think I'll change the oil in the Miata this winter and possibly drop the rear spring rate to the 350 lb range. Anyone have a spare pair of springs? Other than that If it ain't broke...

I *may* end up with a set if I build the new Miata as an aero car. IIRC 600#/325#

Steven Carter · **Posted:** Thu Dec 12, 2013 7:50 pm

(1) clean all the debris out of the interior
(2) clean all the crud and conemarks off the outside
(3) change the oil
(4) new endlinks for the front a/r bar.
(5) mess with suspension
(6) like Scott, think about power mods

Cash Davidson · **Posted:** Fri Dec 13, 2013 7:57 am

Ryan Holton wrote:

In for finished product pics :thumbsup:

Rear suspension work continues . . .

The rear subframe is attached to the body with rubber bushings. To eliminate unwanted movement, I spent a couple hours on the lathe making solid aluminum mounting bushings to replace the rubber. Just like the stock bushings these are two-peice. One goes in the top and one into the bottom of the mounting hole.

I'm feeling more rigid already!
or
I don't know about you, but I'm bushed!
or
insert lame suspension pun. :lol:

Cash

JamesShort · **Posted:** Fri Dec 13, 2013 10:06 am

Cash Davidson wrote:

More backyard engineering: Replacing sloopy rubber radius arm bushings with spherical joints. :sing:

Gotta love F-Prepared!

Cash, is that 'receiver' to the rod end just going to be welded to the arm with 2 fillet welds on the top and bottom? What is the load on that arm relative to 'in and out' of the picture? For left and right loads, the welds will be in nearly pure shear which is fine, but in forward/backward load, part of the welds will be in compression and part in tensions and there isn't a lot of weld there. Unless there is some sort of supplementary mounting you are working on.

RodneyWright · **Posted:** Fri Dec 13, 2013 10:36 am

Cash can run some gorilla glue over the top of the weld and it will be just fine....

Cash Davidson · **Posted:** Fri Dec 13, 2013 11:09 am

JamesShort wrote:

Cash, is that 'receiver' to the rod end just going to be welded to the arm with 2 fillet welds on the top and bottom? What is the load on that arm relative to 'in and out' of the picture? For left and right loads, the welds will be in nearly pure shear which is fine, but in forward/backward load, part of the welds will be in compression and part in tensions and there isn't a lot of weld there. Unless there is some sort of supplementary mounting you are working on.

Yeah, I'm working on a plate that will box in the end of the radius arm and support the receiver at four points - allowing 4 fillet welds. There is very little lateral loading on the radius arm, almost all of it is longitudinal. BTW, the receiver is actually a bung that is designed to slide into a pipe and be welded all the way around.

You can imagine the "boxing" I'm talking about from this pic.

Stay tuned . . .

Cash

JamesShort · **Posted:** Fri Dec 13, 2013 11:30 am

I knew you had it covered Cash! :thumbsup:

Andrew Jonell · **Joined:** Mon Mar 23, 2009 6:43 pm **Posts:** 1350

Suspensions that aren't double wishbone look hard.

JamesMilko · **Posted:** Sat Dec 14, 2013 7:19 pm

The sunk cost fallacy will carry this project through.

2001 Miata LS, 171k miles. Currently residing in my driveway until I can get rid of my old one.

RodneyWright · **Posted:** Sat Dec 14, 2013 8:25 pm

JamesMilko wrote:

The sunk cost fallacy will carry this project through.

2001 Miata LS, 171k miles. Currently residing in my driveway until I can get rid of my old one.

That's a nice looking car. Wished I could fit into one of those beasts....

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