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.

I don't want short travel, I want long travel up front. Short springs also means stiffer rates. Also, with the stock camber plates I ran out of adjustment because I had to lower it so much the springs actually lost compression at full droop, and pre-loading the springs more meant the car got REALLY high (stock ride height) to get it at acceptable pre-load.



Anyway, My basic suspension philosophy for this car right now is this:

Stiff front swaybar, Softer/taller front springs...
Soft rear swaybar, Stiffer/shorter rear springs...
More quality dampening (shocks) less reliance on stiff springs (IE over-sprung)

The rear suspension isn't capable of a lot of travel, unlike the fronts (Pretty common information bout the design of the Subaru rear subframe they use in this car plus the Imprezas/Foresters) and with the rear suspension unless you are running an expensive clutch pack rear diff, needs as much independence as possible to keep the wheels on the ground (as I learned running the stiffer rear bar).


Some more background information... I used to have a '95 Impreza that was fully built suspension wise with EVERY single bushing in that car being replaced/upgraded (a couple of them took trial and error to reduce NVH) granted I had crummy coilovers for awhile that were over-sprung (Megan Racing, I had one of the first sets for the GC's) that car also had a front Helical diff and a rear viscous which made it VERY grippy and weighed about the same as the twins since I was running it N/A (EJ25 running about 180hp with mods).

With that car, it was all about swaybars being almost even front/back and spring rates being almost even front/back. But that car had a Macpherson rear as well as front so it had a lot more travel in the rear than the BRZ does but wasn't multilink and had static camber. That car was OK to lift a rear tire because it didn't cause snap oversteer with the diffs I was running and I actually run rather mild swaybars for that car and focused more on using suspension settings to adjust the cars handling balance, but I did have to go through a couple swaybars to get that car right too.

What is the spring rate in the front? Also, make sure you double and triple check the math on coil bind vs. damper/bumpstop travel. If you're using spacers to get the desired height with additional travel (perch threaded higher than without spacer) then you may start getting into coil bind territory depending on the setup. Especially since it's a somewhat customized setup.

Did some freeway driving today with the current setup, wasn't that happy with the ride quality... I think the camber plates have compromised the ride enough to where the daily driving quality has gone from "acceptable" to "not comfortable".

As mentioned, I've had coilovers before and have experienced this, and I do personally think a lot of it has to do with the compromise of going from a suspension designed for street use which uses bushings in places to a coilover type suspension with full metal-on-metal bearings instead of bushings for camber plates (and even more so when you start swapping out suspension joints for bearings instead of bushings).


So right now, I'm thinking of three possibilities on what to do next:


1) The all-out route: Go with 6" springs up front instead of 7" and up the spring rate from the ~225 now to ~275 or higher. Swap out the rear stock Bilstein springs for linear springs and go with Raceng rear tophats and go with ~350 6" springs. This would be an all-in approach and probably sacrifice any possibility at good ride quality...

2) The reverse-route: Try the 6" 275 springs up front but with the Group-N tophats instead of the camber plates and see if I can get the ride height OK with the shorter springs. This would be the least expensive option to try and get the car to where I want it with having linear coilover springs with good shocks and keep the Group-N/STI tophats to maintain a good ride quality as well...

3) The start-over route: Sell what I have now, go for Bilstein B8 shocks with either RCE Tarmac springs or another lowering spring that doesn't have even front/rear rates but still are nice and stiff, and use the Group-N/STI mounts. This would be risky with wheel clearance and expensive buying a whole new setup, and lose any height adjustability, but would probably be a good all-around setup...

So your main goal is comfortable daily driving, as well as good performance for the odd AutoX event, is that correct?

Do you have any regulation limitation?

Jerrick

No I'm not shooting for a specific class, that was early last year I was aiming for STX lol

I only do local events and not entire seasons, so specific class rules aren't a big deal. Eventually I'm thinking CARB legal supercharger too which would be SM of course.

As for "comfort" stiff is perfectly acceptable, but harsh is not. Harsh being vibrations and sharp hits from small bumps/imperfections in the road. Once upon a time I could daily drive a harsh car but maybe not so much now.

What a mess.

Did you at least swap the mild steel washers for stainless?

I've only had one other car with coilovers in my life, and those reused the stock rubber top hats, and that seemed acceptable to me. They were quiet, but I think most of my grumbling of NVH came from the coilovers themselves and all the shit they made rattle and creak in the car since they were stiff and overdamped. My passengers would always complain, haha. But, the rates themselves seemed pretty good (I just looked up rates, and holy balls, they were much stiffer than I thought) and that car was decently balanced and could carry itself through corners very well. But, those were the days when I was young and stuck out the uncomfortable ride because I didn't care and didn't have money to play with my suspension–I just wanted the lowered look back then.

On the FRS, I currently have the the OTS B14s and HVT camber plates (stock rear rubber mounts, and all factory bushings). Unfortunately, I installed both at the same time, so I don't have the experience between stock upper mounts and the HVTs, but trying to compare it to my experience in my old car, the solid mounts do add a little bit of NVH, but it doesn't sound as bad as what you're experiencing in your FRS. I think my complaints about the B14s mainly stem from the soft progressive rates and the slightly underdamped(?) valving.


I can't tell you how many times I've considered the "start over" option on my car. Half of me wants to tear into the B14s, the other half wants to walk away from them and just get B6s (revalved) and a set of Swift Spec Rs. I never plan to run anything larger than the 17x8/225s I currently have, and I have no desire or need for the corner balancing capability, so there isn't really a reason why I should have coilovers in the first place. Looking back, I guess I only bought them because the B6/B8s weren't out yet and I wanted Bilstein suspension (for reasons of decent-to-good quality and rebuilding/service). What I want to avoid with building the B14s is having to continually play with spring rates. I don't really have the time to constantly be testing and switching springs (and revalving if necessary). I am slightly interested in the RCE spec B14s coming soon, but I'm turned off by the even F/R rates.

Are you sure that even with the increased travel top hats you aren't hitting the bumpstops with springs that soft?

Didnt run with the washers, pretty much just took the photos and thats it, and they were stainless.

Maybe on speedbumps, but ill find out if they have issues with hard turns during the autox this upcoming weekend. FYI 225 isnt thst soft, the progressive stock springs on these B15's max out around there.


I'm thinking right now ill order some 6" ~275lbs front springs to try. Should I run helper springs though?

fwiw I didn't experience any significant increase in NVH with my camber plates (Raceseng) aside from a minor rubbing of the spring perch at full lock over bumpy pavement (shit parking lot). The stock top hats are remarkably stiff compared to the other bushes on the car.

I think so, I could use helpers on my 8" springs up front right now, but I'm not going super low because I'm prioritizing maintaining suspension geometry.

But why are you doing this? To go lower?

I won't try and pontificate about the bumpstop as I don't have a great understanding of the reality of all the variables at play yet.

But I will say this, it sounds like you can technically go lower on the fronts but don't because you want to have the springs pre-loaded. I say go max low in the front, yeah springs will be free but it's just a test, if that's too low you might be able to use the springs you have now and just add helpers. Note that if it's harsh because of the bump stop, changing spring rate will only have a minimal impact on comfort up front unless you alter the bump stop again.

If you slam it and still want to go lower (and are ok with the harshness if the bump stop is in play) then you'll need to get a shorter spring and I would say helpers are a must.

What I want is the comfort of the Group-N tophats I had, but without the issue of them raising the car so crazy high with the linear springs. With these 7" springs and those tophats, it sat at stock height with the springs barely pre-loaded (and also note, it drove great like that). I solved that by running the Ground Control camber plates, but now its uncomfortable.

I do think the spring rates are a tad soft now, so thats why the 6" springs instead but with stiffer rates. The question is if they need helper springs and which helper springs to go with.


FWIW, I'm very sensitive to changes in suspension. I've been able to notice specific differences with all sorts of parts, from individual bushings to fender braces and strut bars, and of course spring rates. Shocks I'm probably not too familiar with identifying rebound/dampening isolation but thats due to lack of experience with adjustable shocks... I have had single-adjustable shocks before and was able to dial those in (coilovers and those old AGX shocks for Imprezas).

I'm looking into the springs now, and here are a couple pics of some options:

http://i.imgur.com/Z7OwUzx.jpg

I'm thinking 280's for the front with the 6" spring, 336 is probably too much. That was what I was actually thinking for the rears if I go with the "all out" option, run those with Raceng rear 1" tophats.

But if I go with helper springs, I have NO IDEA which ones I would pick! I'm starting to research methods for calculating helper springs, but I'm starting from zero on this so any input is appreciated:

http://i.imgur.com/Vn3Ratc.jpg

i think i have the 6 inch swift springs with helper springs/thrust plates sitting in a box in my garage. let me check the part numbers on them i cant remember if they are 6k or 7k springs. if you are interested i can make you a deal on them.

Go ahead and check what you have.

they are the 7k versions.
https://goo.gl/photos/AhTe4iJe7fgqcdD79

Oh man those are in bad shape. No thanks, but thanks for the offer.

I thoroughly analyzed ALL the strut bars available, and found the FT86Speedfactory bar might work in conjunction with the Ground Control plates...

It just arrived today, and as you can see they BARELY fit! Had to move the camber plates to full caster to do it but it works:

https://imgur.com/UKQC6Yx.jpg

I'm going through the same scenario with the strut travel thing. I have MCS shocks which were originally made for CS and the strut bodies are longer than the versions made for STX. I converted them to normal coilovers with 60mm perches, springs, and Raceseng tophats last year. I'm taking the car to SM next year and want to lower the car more but I'm basically out of travel at this point. The MCS have a slotted ear on the strut so I can gain camber back that way and I'll be using adjustable front arms as well. So I'm not too worried about pushing the strut top inward to get camber.

If you had the GC camber plates with the 60mm perch basically in the middle is there room for the perch to sit fairly far within the hole? I can also modify the opening but I'd rather not.

I would have a billet plate machined to match the exact layout of the GC plates and tap the GC plates and use countersunk screws so the spacer and GC plates are attached to each other.

How much space do you reckon you could raise the GC plates before running into any other issues?

In the Honda world GC actually makes extension pieces specifically for this, similar to the rear Raceseng tops. I talked to Raceseng about making something like this for the BRZ and they have had a lot of interest but didn't think it would work without a complete redesign.

I think the plates could go 1/2" before the strut starts to run into issues. If its sitting in the middle of the hole, you can go pretty damn high though.

But I would say try the GC camber plates (mine might be available eventually depending on how good the new springs I ordered work) and see how much additional travel you get over the Raceng, you might get plenty just via that. Also, the Caster adjustment with the GC plates lowers the car even more because Pythagorean theorem LOL!

The Raceseng plates are recessed a bit so they don't really raise the car much if at all. I'm not too worried, I can also enlarge the opening with the new 2016 rules for SM. The 2016 rules would actually allow you to build an entire new shock tower that is higher. It would let you build in all kinds of adjustment or change geometry if you want, but that's a bit drastic for me at this point.

Did my first Autox of the year today... Wasn't that happy with the car.

I did have one "clean" run, but it was red flagged at the end... UGG

[ame]http://youtu.be/SlyJw1uJD5w[/ame]

I had a nasty spin on my 2nd run, which as you can see was pretty nasty snap oversteer. Previously, I was able to "catch" this kind of oversteer, but it just was done after it started slidding.

[ame]http://youtu.be/0uKxm08YUb0[/ame]

You can see it start to snap at the same corner in this video too...

[ame]http://youtu.be/CkwK0g__2IQ[/ame]

Plus, I had a lot of understeer if I pushed the car too hard, it wasn't rotating as nicely as before.

I also had a bad vibration when understeering that I'm not sure about, as you can see in this vid...

[ame]http://youtu.be/kIdoRqVdO0A[/ame]

I'm probably going to try the 6" springs with helpers I just got combined with the old Group-N tophats up front and see how that works, they are 5k instead of 4k so a little stiffer but also shorter, so the helper springs might help keep it at an appropriate ride height.

I'm also contemplating going the "full on route" and upgrading the rear springs/tophats as well. But that won't be right now, maybe a month or so.

My new front spring setup... 5k 6" Swift springs (Z60-152-050) with helper springs (H60-060-015)

http://i.imgur.com/jaa6Zrz.jpg

I'm re-using my Group-N tophats for normal street use because I wasn't happy with the Ground Control camber plates and how rough they were with harsh roads:

http://i.imgur.com/Z2FdSwg.jpg

I got REALLY lucky (educated guess work mostly) about the ride height. Using the 6" springs with the helpers gets me to EXACTLY where I wanted to be height wise without having to do major adjustment and they have plenty of preload because of the helpers

First driving impression...

MUCH improved! I know most people want solid bearing solid metal camber plates for track events and competitive racing, but IMO so far I have to say they are not right for the street. Too much of a compromise. In order to get the proper use out of camber plates like that, you need significant other suspension modifications, solid metal bearings everywhere and lots of track-worthy upgrades.

I think Subaru had it right with the tS model, and how they use stock mounts with Bilsteins and upgraded springs. Plus the combination of OEM upgraded bushings and you can really have a car that can work extremely well for normal driving but have that extra quality suspension for competition/fun.

I need to do some harder driving (autox) to see how the spring ratios work with the stiffer fronts, and see how much understeer/oversteer the car has. Right now it feels pretty good though so I'm happy for now.

MUCH improved!

Also, I came up with an alternate MATSU strut bar layout using my old strut bar...

Not sure if I want to run this, or the FT86speedfactory full setup I have which doesnt work with the MATSU strut bar (the speedfactory stock replacement bars are too thick) but I like this idea of running double strut bars:

http://i.imgur.com/My1oW8F.jpg

http://i.imgur.com/QxOVx4U.jpg

Any update on how you're liking your last (current?) setup? Still running progressive rears?

Its quite good. Very solid at high speeds, test drove it on some back roads and found it to be very predictable, so I took it to a track day at Thunderhill:

[ame]http://www.youtube.com/watch?v=bCoqQL4Iswg[/ame]

[ame]http://www.youtube.com/watch?v=aQ_wTgdMwJA[/ame]

I had zero issues with snap oversteer or any sort of unpredictable behavior. You can see in the first vid how the car took the hard berm on that corner quite well.

Turn it was very good, and the car had so much traction that the power I'm currently running just wasn't enough. It could easily take another 100hp+ in my opinion in its current configuration and maintain predictability. There were only a couple of times where I felt it needed more front camber, the rest of the time the current alignment was adequate.

I plan on leaving it how it is for the near future, I'm plenty happy with the setup as it is.