STX BRZ/FRS Setup-Discussion Thread

[Scooby South]

Anyone think getting a Mech Diff will be better than the torsion Diff??? I personally think I can get to the gas quicker and brake later with a clutch type diff.. What do you guys think??

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[Splash]

IMO, Torsens are better at getting into corners while clutch-types are better at getting out of them. Which you do want to see improved more?

[MNbiker]

Originally Posted by Splash

IMO, Torsens are better at getting into corners while clutch-types are better at getting out of them. Which you do want to see improved more?

Not necessarily, it depends on how the clutch diff is designed, and how it's tuned.

Taking initial cost and ongoing maintenance concerns off the table, I'd choose an OS Giken diff over a Torsen every time for a no-compromise RWD autocross car.

However, it's hard to not like the "install and forget" nature of a Torsen. I had a Torsen in my old XP Miata that survived 280WHP and 5 years of hard autocross use without a single failure, while the car fragged 3 transmissions and a couple halfshafts.

-Steve

[Scooby South]

Originally Posted by MNbiker

Not necessarily, it depends on how the clutch diff is designed, and how it's tuned.

Taking initial cost and ongoing maintenance concerns off the table, I'd choose an OS Giken diff over a Torsen every time for a no-compromise RWD autocross car.

However, it's hard to not like the "install and forget" nature of a Torsen. I had a Torsen in my old XP Miata that survived 280WHP and 5 years of hard autocross use without a single failure, while the car fragged 3 transmissions and a couple halfshafts.

-Steve

Thanks Steve..
Interesting points. I am actually going to a Gaurd Transmission diff that setup on Ratio's vs. Percent.. Supposedly I can stay on the gas longer going into to corner.. and get to it quicker coming off, which means time.. Kinda trying a different approach on this one. As A Guard Transmission Diff is on its way with expert setup of Matt Monson.. I am looking forward to shaving some time. Hopefully that translates to me being a better/faster driver. .. We'll see as I know there's still room to tighten the nut behind the wheel ..

Bill

[dwx]

Max has made some comments on ft86club about his OS Giken. Now he is sponsored by them but he said he felt the car was a lot more stable under acceleration with it coming out of corners.

I'd probably use the OSG but definitely don't plan on doing it this year.

[Scooby South]

Originally Posted by dwx

Max has made some comments on ft86club about his OS Giken. Now he is sponsored by them but he said he felt the car was a lot more stable under acceleration with it coming out of corners.

I'd probably use the OSG but definitely don't plan on doing it this year.

understand that. .its a helluva expense for sure. but somehow I feel it needs to be done... to be at the Rules limit. Which, for me, is VERY close right now.. I hope it makes a difference.. doing LCA's at the same time .. Should be about it.. for me..

Bill

[MNbiker]

Originally Posted by dwx

Max has made some comments on ft86club about his OS Giken. Now he is sponsored by them but he said he felt the car was a lot more stable under acceleration with it coming out of corners.

I'd probably use the OSG but definitely don't plan on doing it this year.

When properly tuned, a clutch-based diff definitely has some advantages on corner exit. Power application out of corners with a Torsen can be a bit abrupt. Another consideration that may not be an issue with the Twins is that Torsen diifs don't work right if one wheel is off the ground - so it's important to set your car up to keep the tires on the ground at corner exit.

[Scooby South]

^^^^ agreed... Don't know of any lift on the 86's that I am aware of.. unless its a uneven contact patch on exit. but that will soon not be an issue either as the new diff goes in. I wonder how much suspension adj is going to have to be made with the new diff. None??? minimal??? Huge??? I expect some Rebound and Comp adj. just hope its not spring rates also..

Bill

[Splash]

My comment was based on the fact that only a 1.0-way clutch-type can enter a corner like a helical can. The others will provide some resistance to differentiating on turn-in, the 2.0-way ones do this the most. IMO, the abrupt power delivery on exit also applies to the 1.0-way clutch paks, though I find the transition not quite as obvious as on helicals. I've had the best luck with 1.5-way clutch units but I also realize much of this is personal taste.

[MNbiker]

Originally Posted by Scooby South

^^^^ agreed... Don't know of any lift on the 86's that I am aware of.. unless its a uneven contact patch on exit. but that will soon not be an issue either as the new diff goes in. I wonder how much suspension adj is going to have to be made with the new diff. None??? minimal??? Huge??? I expect some Rebound and Comp adj. just hope its not spring rates also..

Bill

Bill,

I expect you'll want to make some minor to moderate changes to take full advantage of the new diff. First, it's likely the car will understeer a bit more on corner entry, unless you're getting a true 1-way diff. Ideally, it would be nice if you could set the car up with enough rear brake bias to make trail braking effective, but I'm not sure how far your braking system will let you adjust bias, before the electronic nannies freak out. (I'll be experimenting with this same adjustment on the WRX this year). Second, assuming you have the clutches set up for progressive power delivery, the car should oversteer a bit less at corner exit. This may allow you set the car up a bit looser to deal with item #1. I'd be surprised if the change required major changes, but I've been wrong before.

[mccanixx]

I'm thinking you'll end up messing with toe.

[Scooby South]

Thanks Steve and Greg...
Greg, how much are you thinking??? more in, I assume..

[mccanixx]

Originally Posted by Scooby South

Thanks Steve and Greg...
Greg, how much are you thinking??? more in, I assume..

More in I'd assume. Without knowing the diff.

[UWMechEngr]

Just to satisfy my curiosity because I'm really considering giving up on the WRX. What's a better base to start a build, the FRS or BRZ?

[ABQautoxer]

FRS is a little tiny bit lighter and cheaper. I much prefer the BRZ styling so I would pick that if price was close enough used.

[UWMechEngr]

Good to know. Not really a whole lot of used ones in my area... But this may be a post-Nationals decision...

[dwx]

Yeah the heaviest BRZ (Limited) is only 16lbs heavier than the base FR-S, so really it doesn't much matter, there is more variation in driver weight than that usually.

If you are looking new they are widely available now. In a month the car will have been available for two years but I know used ones are still not too easy to come by.

[Scooby South]

Current Weight on my STX BRZ is 2575ish... Depending on gas.. and I have the limited. I have also done considerable upgrades to get it to that weight also. Danny Kao's and mine are VERY similar in Weight. he's down to 2550ish. so a 25lbs difference at the Full limit of the Rules...right now.
power is even on both platforms.. Subaru IMO has better amenities..with the Heated Seats, fogs. and alcantara suede. (since then I have replaced the driver seat with a fixed back raceseat). it really is a matter of preference. Used are Scarce still .. but pay attention to Danny Kao....as he or Annie could sell their STX Car at any given moment. Danny's is Ex-AndrewPalotta car.. and Annie's is on her 3rd 86.. sooo Hope that helps.

Bill

[UWMechEngr]

Which Annie are we talking about? Gill?

[Scooby South]

Originally Posted by UWMechEngr

Which Annie are we talking about? Gill?

Yes ...sorry...

[UWMechEngr]

Originally Posted by Scooby South

Yes ...sorry...

I'll keep my eye out for a "For Sale" sign at the local events

[CopperTopNWOR]

Did Holly sell her FRS or move to STX? I know she had her stock size wheels from last year for sale.

[Scooby South]

Originally Posted by CopperTopNWOR

Did Holly sell her FRS or move to STX? I know she had her stock size wheels from last year for sale.

Don't think so. maybe Jay Storm can fill us in. She's a service advisor for Toyota now..

Bill

[CopperTopNWOR]

Oh if all else fails I will likely see her at our first event at the airport. Just wondered since she was selling the CS wheel setup.

[Scooby South]

She's registered in a HS Mini Cooper for Wilmington..
co-driving with Tim Carrite..

Bill