TOYBARU STX Build 2.0

[cjd]

Why start with sway bars of you're still working spring rate? I haven't added bars yet, though that may just be me not realizing I could use some... Tein SRC on 10/12k rates so higher than you've yet reached.

I need to remove some rear camber I think... Or drive harder, which is clearly true.

[DocWalt]

Originally Posted by cjd

Why start with sway bars of you're still working spring rate? I haven't added bars yet, though that may just be me not realizing I could use some... Tein SRC on 10/12k rates so higher than you've yet reached.

I need to remove some rear camber I think... Or drive harder, which is clearly true.

Softer bars & stiffer springs to counter the loss in roll stiffness lets the inside tires do more work.

[Silverspeed]

Originally Posted by cjd

Why start with sway bars of you're still working spring rate? I haven't added bars yet, though that may just be me not realizing I could use some... Tein SRC on 10/12k rates so higher than you've yet reached.

I need to remove some rear camber I think... Or drive harder, which is clearly true.

I am back to the stock rear bar. With enough spring I could go without one at all possibly. That will be tested this year for sure. On the front I'm as soft as I've ever been regarding the bar. I also may try the stock bar there later in the year, but based on feedback from others, and my own limited experience, the car does need some sort of front bar.

I'm not a chassis engineer, but with a front motion ratio of near one (McStrut) you'd have to run a bunch of spring to compensate for the loss of the front bar entirely. Bars add spring rate, or at least roll rate. Bars do a lot more work than you think and play more into the amount of wheel rate than the springs do in most set-ups. Check out this link/thread:

http://www.ft86club.com/forums/showp...&postcount=107

I was running really big bars, but the focus for me this year is smaller (or no) bars and more spring. The bars are advantageous because of the flexibility (provided they are adjustable) and ease of tuning. Also, as noted above, the bar adds rate that is only applicable to containing roll (mainly) while allowing for softer (more comfortable) springs. But, with bars, encountering a bump or roll affects both sides of the "independent" suspension. The larger the bar the less independent each side is. Or at least that's the theory.

[cjd]

Originally Posted by DocWalt

Softer bars & stiffer springs to counter the loss in roll stiffness lets the inside tires do more work.

Right. I guess that's the quandary, and why I'm still running stock swaybars. I'm not a good enough driver at this point to know if I still need more front bar... So I was curious why tuning would start with more bar, because everything I've read says to get the roll resistance from spring if you can. Then add sway...

I suppose I should just try it. which one to get... My issue remains confidence, so I'm not even pushing the current setup to its limit - but perhaps a front bar would help me gain that. It does seem that everyone runs with a stiffer bar in front. Regardless, I'll be watching and hoping to learn before shelling out for more parts.

C

[Silverspeed]

Originally Posted by cjd

So I was curious why tuning would start with more bar, because everything I've read says to get the roll resistance from spring if you can. Then add sway...
C

If you're running coilovers with 400+ spring rates I'd start small, and adjustable. Always adjustable if possible. The ability to change a bar without removing the bar is a great thing. I am back to trying the stock rear bar and I very well may end up going back to the stock front bar.


Another thing to try is just swapping endlinks. Good links will add stiffness to the existing bars and allow for pre-load changes. Although they also typically add some noise and some required service from time to time. Stiffer bushings are another option to add roll stiffness without a complete bar swap.

[cjd]

Roughly 560/670 rates... A bit over 400 I think I'd definitely go for adjustable bars that include stock in the range, or a whole set, but... I guess it's harder to justify the spend if you might not use the part. that is likely silly...

[heeltoe86]

Hey @Silverspeed how are the RCE Clubsports legal for STX with a separate reservoir? I thought they are disallowed for the class?

[conedodging]

Where do you get that idea?

14.5 SHOCK ABSORBERS
A. Shock absorber bump stops may be altered or removed.
B. Any shock absorbers may be used. Shock absorber mounting brackets which serve no other purpose may be altered, added, or replaced, provided that the attachment points on the body/frame/subframe/chassis/suspension member are not altered. This installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed. The number of shock absorbers shall be the same as standard. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as original equipment. MacPherson strut equipped cars may substitute struts and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel.

[Silverspeed]

Originally Posted by heeltoe86

Hey @Silverspeed how are the RCE Clubsports legal for STX with a separate reservoir? I thought they are disallowed for the class?

As per SCCA rulebook for Street Touring class....

B. Any shock absorbers may be used. Shock absorber mounting brackets which serve no other purpose may be altered, added, or replaced, provided that the attachment points on the body/frame/subframe/chassis/suspension member are not altered. This installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed. The number of shock absorbers shall be the same as standard. No shock absorber may be capable of adjustment while the car is in motion, unless fitted as original equipment. MacPherson strut equipped cars may substitute struts and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel.

They would not be legal for the street class as they are 3-way adjustable. Only two way of less is allowed there.

[Silverspeed]

There is a winter RM Solo event this Sunday so I'll get a chance to try out the new set up for the first time. I haven't had much seat time but initial impression is that I am set up for a bit of a push. That was just from horsing around on some side roads. I'm wondering if swapping to the stock front bar is a good move?? I'll probably just leave it alone for this event.

I will say that a couple of click of adjustment on these shocks seems to go a long way to changing the attitude of the car. I need some experience with the 2-way compression adjustments before I'll grasp what does what to the car entirely. Sunday's event should be interesting. It's also in a location I've never run before - well kind of.

It's funny but when the FR-S came out Scion did an event there where you could show up and drive one on an autocross course which was created out of essentially huge walls of cones. They really didn't want you pushing it to hard. But I loved the car then although I wasn't really thinking of buying one. The car I drove there was exactly like the one I have now other than it was an auto.

[cjd]

I have different spring rates but a similar ratio, and push is something that I found to be my fault... Try that stock front bar!

[Silverspeed]

So I completed my first autocross this past weekend with the new setup. Overall my impressions are good. It needs some fine tuning to compensate for a bit of a front end push. It's been awhile since I finished 3rd locally but but it was a really cold day (40 - 45 degrees) and I was the only guy in STX without a co-driver. Waa waa... Somebody's gonna ask me now if I want some cheese with my whine, I know. But seriously, I think I was a bit handicapped as I never got any heat in the tires.

I played with the shocks a bit during throughout the day. I mentioned this before but making changes to the Tarmac 3's seem to result in more pronounced changes to the attitude of the car. I won't bore you with the run-by-run change list, but essentially I ended up reducing front rebound and adding some compression front and rear with some success in reducing a corner entry push and corner exit loose condition. I do think a reduction in front spring rate may ultimately be needed to balance the car, so some new springs are on order.

At the event I met up with my co-driver from last year, who also is a pretty much a car set-up guru. When I asked if he had any recommendations on setting up the T3's he suggested bringing the shocks down to the race shop he works at, 3R, to run them on their shock dyno. He then would have confidence in providing suggestions for baseline settings and preferred range of adjustment. So I did just that....

Here are the results from the dyno. The RCE Tarmac 3's have a very large window of adjustment. As was my experience from behind the wheel, each click has a very noticeable effect. The rears have noticeably more rebound and compression range, no doubt due to the motion ratio associated with the rear vs. front. I am not a suspension engineer, but the 3R guys were very impressed with the results. The comment was made that for a the price, a higher quality 3-way could not be found.

Apologies for the less than stellar scan quality.

[Silverspeed]

So I mentioned in the intro to this thread that I would have some changes coming for the exhaust.

Nothing ground shattering mind you, just a home brewed attempt at keeping the peace at national autocrosses where a sound limit exists. At previous events I would run my Berk single outlet track pipe, saving maybe 25 pounds (more probably) over the stock system. I really like to hear the car when I'm autoxing. It provides some additional feedback that I can't get unless I watch the tach, which I don't. If I'm accelerating and the rear breaks loose it helps me realize it maybe even before my butt does. I have an old numb butt... TMI?

Anyway, last year at Spring Nats I was warned that my car hit 99 dB's with 100 being the limit. I never did exceed 100, but it was a bit too close for comfort so I had Granby Truck Shop weld me up a single exhaust from a used Berk dual outlet track pipe I purchased. Added a Dynomax muffler and all was well, albeit a bit heavier than with the track pipe. I had also had a few complaints from the local events that I might be pushing the envelope a bit as well so I was time to make nice. But I still really wanted to run the lighter track pipe...

So this is the solution. Muffled track pipe using the old un-muffled Berk + a 2.5" muffler built for a NE Dirt modified. Or sportsman modified or something like that. Anyway my son helped weld this up with his new MIG welder he got for X-mas. It's not a thing of beauty, but so far I'm really happy. Much lighter than the Borla pipe, a bit louder but noticeably quieter than the track pipe alone. I think the turn down built into the new muffler helps as well. I actually sounds really good. Boxer rumble! I think the muffler was around $50 so it was cost effective as well.



I also made another purchase last week. I found a used half shaft for sale locally for $75 so I grabbed it. My left side shaft seems to be increasing in the amount of play it has so it's reassuring to have a spare.

[Silverspeed]

And for reference, the quiet version of the axle-back, built from a Berk dual-outlet, converted to single.