My BRZ ST* Autocross build

[lordtakuban]

Not sure if it's been mentioned before, but I wouldn't change your Diff for the OS Giken 1.5 Mech LSD. The car comes with a helical gear type LSD which will provide much better grip in corners vs. the locking clutch types that you would use for drifting or drag or something like that.

As for coilovers, I've been pretty happy with my BC Racing set on the MR-S. I think they are making or already have a set available for the FR-S/BRZ. But I'm not sure.

Good luck with your progress.

[Vanguard]

If you are going ST, neither would be ideal. Camber is important and the bolts might not get you enough. For ease of adjustment from street to track, plates would be better. That puts you toward the ASTs, but if they are single adjustable it might not be best. I've played with SAs before and there has been improvement...but all the pros I invited to run my car said that it could be so much more quick with extra bump. And from what other pros tell me, the suspension isn't something you want to skimp on. Maybe save up your pennies for Motons that would work with plates?

[Scooby South]

Originally Posted by lordtakuban

Not sure if it's been mentioned before, but I wouldn't change your Diff for the OS Giken 1.5 Mech LSD. The car comes with a helical gear type LSD which will provide much better grip in corners vs. the locking clutch types that you would use for drifting or drag or something like that.

As for coilovers, I've been pretty happy with my BC Racing set on the MR-S. I think they are making or already have a set available for the FR-S/BRZ. But I'm not sure.

Good luck with your progress.

in the plan actually..

Bill

[apexaddict]

Originally Posted by lordtakuban

Not sure if it's been mentioned before, but I wouldn't change your Diff for the OS Giken 1.5 Mech LSD. The car comes with a helical gear type LSD which will provide much better grip in corners vs. the locking clutch types that you would use for drifting or drag or something like that.

Actually, a clutch-type has a number of advantages over a Torsen in terms of handling, primarily end-user customization of power/decel locking rates, quicker response, and the fact that it doesn't go open when it becomes unloaded. Therefore, you don't have to set the car up around the Torsen to keep it working. With my old STR Miata, there was quite a big difference going from the stock Torsen to an OS Giken, in that I could put power down just about anywhere without nearly forcing the car to push to keep the rear wheels down.

As far as the coilovers go, I highly recommend the ASTs. Vorshlag should be able to valve them how you want and can spring them how you want, and they will also be able to be upgraded to doubles in the future. Avoid the instant gratification factor of the KWs and skip them for now. V3s are very street-oriented and they are often relatively softly sprung, usually with some sort of progressive rate in the back. I don't know what the BRZ/FRS rates are off-hand, but in my previous experience you typically need to do a lot of extra work to a set of V3s to make them competition worthy (i.e. the Tarmac 2s that RCE sells for WRXes). Additionally, it's an absolute PITA to adjust the compression on them with the dumb little allen key.

Also, the ASTs (at least in my experience of owning 5200s) do not have separate pre-load/body length adjustment, unless this is a new feature on the 4150s. On good shocks that are the correct length, it's unnecessary. Just throw on helpers/tenders to keep the main springs in place during droop and you're good to go.

[blur]

I vote Tanabe Sustec Pro Z40 Coilovers

http://www.tanabe-usa.com/z40.asp?id=22

http://www.tanabe-usa.com/rnd/post/S...cion-FR-S.aspx

[lordtakuban]

Originally Posted by apexaddict

Actually, a clutch-type has a number of advantages over a Torsen in terms of handling, primarily end-user customization of power/decel locking rates, quicker response, and the fact that it doesn't go open when it becomes unloaded. Therefore, you don't have to set the car up around the Torsen to keep it working. With my old STR Miata, there was quite a big difference going from the stock Torsen to an OS Giken, in that I could put power down just about anywhere without nearly forcing the car to push to keep the rear wheels down.
...

This sounds like you needed to set up your suspension/alignment differently. The reason you achieved less pushing with the clutch-type LSD is because both wheel speeds were locked the same. with the helical, it allows the outer wheel to still rotate faster keeping grip without sliding.

[Scooby South]

Suspension Choice has narrowed down considerably... looks like I am probably going with ......KW ... Lifetime warranty is kinda hard to pass up.....and the fact I have dual adjustment...and 'soft' springs are oK...I can change those as necessary...and the length...they also already come with helper springs.. its not that AST isn't on the map ...they are just a bit behind my schedule... First tour event is PERU...kinda want the car setup before then..so I can tweak as needed... 375/300 is what I hear for spring rates on them.. going to try that and see how it does..
Order being Placed as we speak..

Bill

[VCMC-STC]

I have to admit, I think it would be worth the wait for the parts from Vorshlag. Just my $0.02 though. Great build! I've been following this thread closely!

Richard

[Miniata]

I'd also recommend waiting on the AST's. I've had KW coilovers in the past on a Neon ACR, and currently have AST's on my Miata and Mustang. The KW's were a good compromise coilover for the street and occasional autocross use, but were just too soft for serious autocross use. Can the KW's be easily revalved (and rebuilt) to handle stiffer spring rates like the AST's can? Some things are worth waiting for.

[ubersoph]

Originally Posted by Scooby South

Suspension Choice has narrowed down considerably... looks like I am probably going with ......KW ... Lifetime warranty is kinda hard to pass up.....and the fact I have dual adjustment...and 'soft' springs are oK...I can change those as necessary...and the length...they also already come with helper springs.. its not that AST isn't on the map ...they are just a bit behind my schedule... First tour event is PERU...kinda want the car setup before then..so I can tweak as needed... 375/300 is what I hear for spring rates on them.. going to try that and see how it does..
Order being Placed as we speak..

Bill

I dunno bill, those seem kinda soft for a BRZ - I ran 550/350 on my Miata and felt that was on the soft side of what I wanted. With the mcstrut suspension we have I'd consider going far stiffer in the front?

Did you try talking to RCE? Maybe they will revalve a set for you before sending them out, and putting stiffer springs on?

[track_warrior]

Im waiting on JIC to release something man, they make great coilovers had them on my evo x and loved them.

[ultra]

I've had KW V3s but getting them set up was a PITA and I never found adjustable top hats that fit very well with them (tried Whiteline Max Cs, and HKS camber plates...both had top nut issues, even after uaving custom top nuts machined to fit and/or tons of clunking from the spherical bearings). Of course that was on an Evo IX, not a Subie or 86.

I'd wait for the KW Clubsports or ASTs to come out...ideally something engineered to work pretty well with the car out of the box, so you have a decent starting point to get dialed in faster and/or fall back on.

I hear you though...I'm also an impatient type.

[Vanguard]

Originally Posted by VCMC-STC

I have to admit, I think it would be worth the wait for the parts from Vorshlag. Just my $0.02 though. Great build! I've been following this thread closely!

Richard

"Money spent well is money spent once." - Some Guy

[simpleisbest]

I would vote to wait for AST. It's all about the quality of the shocks.
Swap the diff with the OS unit first (ask for any autocross+street tire base setting), as it will greatly change corner acceleration and rear grip. Select your spring rates based on how the car feels from there. Biggest mistake many make is choosing to upgrade the diff last. They're usually left scratching their heads trying to re-invent their spring rate combinations and alignment settings to find that last ounce of speed. Do it right from the start and save headache later is my $0.02.