Kosts Krazy Suspension Thread...
 

So my suspension build has been going completely unorthodox, and I figured I'd start a separate thread about it all...

A little backstory:

My first suspension mods were basic with my BRZ and were over 2 years ago. Swapped the FRS rear springs into the back, got some camber bolts for the front, and eventually went with a front Strano swaybar after some in-person input from C-stock Autox drivers. The car was FANTASTIC to drive with that basic setup, and I tried it with both stock tires and slightly beefier tires on 17x7's.

http://i15.photobucket.com/albums/a3...RZ/orange3.jpg

Of course not much longer after that I felt I needed to lower the car and go with bigger wheels like everyone else, but I still like my cars to handle and work for Auto-x too, so I went with RCE Yellows and staggered 18x8/9" wheels. The car was very under-steery to start with so I compensated with a larger rear sway bar, which wound up giving the car WAY too much snap oversteer (large rear bar = lifts the rear tire and causes the diff to not function and SNAP oversteer!). I ran the car like this for awhile, but it was just meh for driving...

http://i15.photobucket.com/albums/a3...0BRZ/bbs15.jpg
http://i15.photobucket.com/albums/a3...20BRZ/spin.gif

I then tried out some 16" wheels with that setup, and went with a smaller rear bar, but the handling was only OK

http://i15.photobucket.com/albums/a3...58010524_o.jpg

My previous (IE next to last) setup involved going to Bilstein B14's (I didn't want heavily adjustable coilovers, I've done that before and its not what I wanted in a "mostly" daily driver) with Group-N top hats. I also chose the B14's because I wanted quality Bilstein shocks, but couldn't justify going with the B8's and stock-style springs when the price of B14's were so close to the B8's and included springs. Plus, I knew that if I didnt like the spring rates I could go custom springs later. Again, I had to compensate with the change in Front/Rear spring rates by going back to the stock rear swaybar. I also changed endlinks with this setup (Whiteline adjustable fronts due to where the endlink mounts on the B14's) and Karboy rears.

Also, I went to 17x9 Wedsports with Bridgetone RE71R's... No more fooling around!!! Best tire/wheel combo for this car bar none:

http://i15.photobucket.com/albums/a3...0BRZ/Weds6.jpg

The big "issue" with the B14's is the bounciness, which as I discovered, is a direct result of the progressive spring rates that come with the B14's. The rates themselves are pretty good, and the car does handle pretty good with the B14's, but the intial turn-in with the B14 springs is horrible because of the initally soft spring rates that give in too much.

So, leading up to now, I decided to try LINEAR springs on the B14 stocks, starting with the fronts. Initial suggestions from the Bilstein Modification thread indicated 7" 65MM springs, so I went with some 7" Swift springs running on top spring perches from KW coilovers (Courtesy Racecomp, who are awesome BTW). They fit pretty well, minus one huge issue... Ride height!!! These springs combined with the stock perches and running the springs with a good amount of preload puts the car back to stock height! Thats no good...

http://i15.photobucket.com/albums/a3...212_112315.jpg

I spent some time searching around researching tophat options. Racecomp and HVT tophats do raise the top of the spring perch higher, but are unavailable. The KW tophats like this are also extremely expensive and apparently not sold seperatly. Raceeng was unable to design a completely new tophat for this (don't blame them). My only option was Ground Control...

Pic of everything assembled:

http://i.imgur.com/M9CQqfZ.jpg


Now, this brings me to where I'm at now and with my crazy ideas. The design of the Ground Control tophat is inverse of most camber plate designs, with the bulk of the tophat ABOVE the chassis. I wasn't sure if the Ground Control tophats would give me enough travel, so I came up with an idea... Add "spacers" under the ground control tophat, thus moving the shock mount location even higher! This would allow for even MORE shock travel with a lower ride height.

But hold your horses, cause my idea got even crazier... What if I could mount a STRUT BAR between the camber plate and the chassis!?!?! This would allow the mounting point to be raised directly corresponding to how thick the strut bar is. I first test fitted it with my current strut bar for proof of concept:

http://i.imgur.com/2FBHLyf.jpg

This strut bar however is WAY too thick, so I looked and looked and the Carbing strut bar is VERY close to allowing the Ground Control camber plate to still fit, so I ordered one of those. It came in today, and here are the pics:

http://i.imgur.com/qOjAOBC.jpg

There are some clearance issues:

http://i.imgur.com/JUGPdUs.jpg
http://i.imgur.com/Z3nsFc2.jpg

I've tested it with washers and it does clear with these in place:

http://i.imgur.com/RF3UT9p.jpg

My biggest concern now is structural rigidity... The question is if whether running something between the Ground Control plate and the chassis compromise the mounting location, especially if there are spacers/washers in there with smaller surface area than the camber plate actually mounts... Tommorow, I'll be doing some actual mockups with the new camber plates to see how it goes.

I've been considering both a thinner, lighter 16" setup and a wider, heavier (but still with light wheels) 17" setup. Can you expand on your thoughts on the comparison between these a little more?


Are the GC plates solid from top to bottom or do you have a long bolt that is only supported at the car's body and the top of the plate?

The 16's I had (still have actually, they are in a shed) were 225/45/16's and actually really improved straight line acceleration with the extreme light weight and smaller diameter (thus increasing the gear ratio, same as you would with a new final drive) and were actually better than stock for daily driving and back roads driving with the slight increase in sidewall. But they are only OK on the track because of less overall grip.

There is a plate with bolts welded on you can actually see in those pics.

Some zip ties to hold that together and you're set!

Everything is bolted up now with the strut bar in place and using extra spacers/washers to get clearance with the strut bar and the plate. I had to grind a smidge off of the bar for clearance with the plate.

You can see there is still plenty of room for moving the strut inwards for camber adjustment, its not that high yet. And actually, this might even be TOO low for me... I'm thinking of ditching the strut bar/spacers and trying just the camber plates to see how low it sits with just that.

What the plate mount looks like under the fender:

http://i.imgur.com/ehUb5ds.jpg

With the spacers in pace and everything bolted down:

http://i.imgur.com/kKDo22c.jpg

More under fender view:

http://i.imgur.com/6EuOChP.jpg
http://i.imgur.com/unfnQRT.jpg

Engine bay with everything assembled:

http://i.imgur.com/BIdxi63.jpg
http://i.imgur.com/hg5KIiT.jpg

How low its sitting right now:

http://i.imgur.com/k4AF8D2.jpg
http://i.imgur.com/Bcpj3ou.jpg

My only substantial concern is that the washers (and maybe the strut bar) would flatten over time and cause the whole thing to have more lateral force on the bolts,which could lead to something breaking.

C

You could raise it to get some compression travel back. But I'm learly if lateral movement in the system, it just doesn't seem stiff enough to me.

Also, it amazes me there's that much room under the hood.

Thats pretty much my concern too.

I think I'm going to try it without the strut bar/washers for now and see if I can make a more serious piece of steel to serve as a spacer.

Honestly, I'd key the pieces if possible so everything above the strut mount on the car moves as a unit. I tend to over-engineer, especially where I don't have an actual knowledge of the potential issues; talk to someone that does this stuff more regularly IMO.

And not the kid next door using washers to make his car look broken... er, slammed, or whatever it is. :)

I went ahead and removed the strut bar and washers to check and see how the ride height is with just the camber plates (only took 30 minutes lol) and running the amount of spring compression I though should be correct, and it works just fine:

http://i.imgur.com/FgmsqjP.jpg

And the ride height is just where I want it! Shouldn't be too low to require a roll center kit, but I might get one later anyhow.

http://i.imgur.com/PV5UT8L.jpg

Thought this photo was interesting, shows about where the shock was sitting in the tower with the strut bar/spacers installed:

http://i.imgur.com/ZCTsEFF.jpg

I think I'll go ahead and order a Ground Control strut bar that goes with this kit, and go for a corner ballance/alignment in a week or two.

I'm going to have to raise the fronts a bit for sure, which is awesome cause thats what I really wanted was to be able to raise the suspension a little more and not have the car back to stock height.

I test drove it around a bit, and it feels REALLY good. I do notice the camber plates instead of the group N mounts up front though during low speeds. Cracks and such in the road hit much sharper and louder now, but high speed stuff is really good.

Turn in is VERY nice and smooth, I'm going to order the Ground Control strut bar right now and just use that. I'm going to focus on paying attention to the rear now and see if I need to do anything with the rear and if traction stays down during Autox. Should be interesting...

http://i.imgur.com/UWjha7N.jpg
http://i.imgur.com/7aNW2Ac.jpg
http://i.imgur.com/CC4CDlH.jpg
http://i.imgur.com/zaHAkj9.jpg
http://i.imgur.com/uEOnFN8.jpg
http://i.imgur.com/oABdvIo.jpg

What rear sway bar/tires were you running with the 18x8/9 stagger and rce yellow setup?

What spring rates/sway bar setup do you have now?

Federal 595 RS-R's in 245/35/18 and I had a Perrin adjustable rear bar.

What spring rates/sway bar setup do you have now?[/QUOTE]
The front springs I have are 225lbs and the rears are the stock progressive Bilsteins which are ~275-350lbs I believe.

Front bar is Strano, rear is stock currently.

Maybe you aren't giving all the information, but my obvious question is why not use shorter springs? Are you running out of shock travel? It looks like you have plenty of room on the shock body for adjustment.