CSG and RCE tag-team suspension Q&A thread! Ask us anything!

[Racecomp Engineering]

Originally Posted by psyclone07

I am getting a lot of mixed responses when it comes to a question I have and was wondering if you guys could help out.

I have some RCE tarmac 2 going on once the weather gets nice and will be doing some occasional autocross and possibly track days. The car is more of a weekend driver.

I am looking for a decent lightweight rim for autocross and track days/occasional weekend driving. The RpF1's are great rims but I am leaning toward the TsW nurburgrings (simply aesthetics in this case) in a 18x8 w/ 35mm offset(18.6lbs).Would the 10mm difference in offset be detrimental in comparison to the 45mm. Also the 1 inch increase from 17 as well.

I am also looking for tire suggestions as well if you have any. Probably looking to get some Michelin pilot super sports in 225/40/18. (Another mixed area as some people say drop in the widest tire possible and others disagree.)

I appreciate your time and insight. Thanks in advance.

RPF1 is a great classic wheel. Hard to beat the value. It'll perform better for sure than that TSW option.

Pilot SS are a good street tire that's fun for auto-x and track. There are stickier tires but the Michelin's do everything pretty well. For an 8 inch wheel, 235 or 245 would be a good width.

- Andy

[psyclone07]

Originally Posted by Racecomp Engineering

RPF1 is a great classic wheel. Hard to beat the value. It'll perform better for sure than that TSW option.



Pilot SS are a good street tire that's fun for auto-x and track. There are stickier tires but the Michelin's do everything pretty well. For an 8 inch wheel, 235 or 245 would be a good width.



- Andy

Thank you! Going to look into some rpf1's right now. Trying to find a good balance.

[Fleischwagen]

Read every post… such a good thread :respect:

I recently threw my nearly stock BRZ with Tein Street-Flex coilovers, 3/4 tank of gas and some ballast to mimic me in the driver's seat up on some scales.

At a nearly stock ride height (maybe 10/20mm lower), 26 inches from the edge of the fenders down to the ground, it came in around LF:753 RF:780 LR:633 RR:591 with no ballast and weighed in at 2757lbs. After messing around with the coilovers, we were able to even the fronts out for the most part, but still had a hard time getting the RR to get even close. I can't remember the end results because I was enjoying a few too many adult beverages but, the LR was about 680 and the RR was 630.

Long story short, I can use these scales whenever, I'm obviously going to try and get it even better (Cross weight was 50.2%) (Front weight 55.3%) and Left to right was nearly dead on. I was shocked to see just how well this car was balanced…

To bring up that RR weight I'm guessing I gotta lower the ride height minimally on the RF and LR? Thats what I tried and it seemed to work, but we ran outta time and packed it all up.

(I have some pretty basic suspension knowledge, please shed some light!)

[was385]

Originally Posted by psyclone07

Thank you! Going to look into some rpf1's right now. Trying to find a good balance.

I just threw on some gunmetal RPF1s I got from a vendor here on my WRB BRZ and couldn't be happier. Awesome wheels for the money.

And a hat tip to @Racecomp Engineering. Installed RCE yellows with the setup and the difference is night and day.

[psyclone07]

Originally Posted by was385

I just threw on some gunmetal RPF1s I got from a vendor here on my WRB BRZ and couldn't be happier. Awesome wheels for the money.

And a hat tip to @Racecomp Engineering. Installed RCE yellows with the setup and the difference is night and day.

Funny because I'm looking at the gunmetal ones for my WRB brz. Heh your in CT as well! Out of curiosity what size did you go with. I'm wondering if 17x9.5 is overkill or would 17x8 be more appropriate. Or even 18's x ???? for a little aesthetic reasoning.

What offset did you go with?

[was385]

Originally Posted by psyclone07

Funny because I'm looking at the gunmetal ones for my WRB brz. Heh your in CT as well! Out of curiosity what size did you go with. I'm wondering if 17x9.5 is overkill or would 17x8 be more appropriate. Or even 18's x ???? for a little aesthetic reasoning.

What offset did you go with?

Yep. 17x8 +45 for me. I did it for performance and think that 17x8 with 245 tires is the sweet spot and you just start gaining more weight (and losing some in your wallet) after that. 17 vs 18 is all about personal preference for aesthetics but for performance it doesn't make sense. Posted photos here:

http://www.ft86club.com/forums/showp...9&postcount=34

Edit: and I assure you the gunmetal looks much better in person than it does in pictures. They're stunning in person.

[DrDuquette]

Originally Posted by Racecomp Engineering

Total weight transfer for a given corner at a given speed is down to COG, track width, and total weight of the car.

What we're doing with springs/rollbars/dampers is trying to control the rate at which it occurs, the distribution of that weight transfer, and minimize the changes in suspension geometry due to body roll.

With regards to distribution of weight transfer and I think where you might be getting mixed up...we can stiffen the rear which means more weight transfer at the rear. Since total must remain the same, this means there must be less weight transfer at the front. Less weight transfer at the front means more evenly loaded front tires. More evenly loaded front tires means more grip up front. That's why stiffer rear = less understeer. There may be additional affects from a stiffer rear like keeping the rear from rolling too much, reducing positive camber gain, and thereby keeping the tire nice and square on the road for a little more rear grip too, but it depends.

- Andy

I love your explanation. I'm a little confused. Help me out please. So a stiffer rear (ie. sway bar, springs) leads to more grip in the front. Right, so that would mean increase the possible oversteer, so if we feel the car pushes stiffen up the rear? If we feel the car oversteers too much, stiffen up the front.

Is an increase in size of the sway bar enough to so call "stiffen" one end of the car?


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[Racecomp Engineering]

Originally Posted by DrDuquette

I love your explanation. I'm a little confused. Help me out please. So a stiffer rear (ie. sway bar, springs) leads to more grip in the front. Right, so that would mean increase the possible oversteer, so if we feel the car pushes stiffen up the rear? If we feel the car oversteers too much, stiffen up the front.

Is an increase in size of the sway bar enough to so call "stiffen" one end of the car?


Sent from my iPhone using Tapatalk

Yup, a stiffer rear means less push. Stiffening the front can reduce oversteer. A few other variables especially with the front but that's the gist of it.

Swaybar changes are usually pretty noticeable.

- Andy

[leicaboss]

OEM - BRZ
Front: 2.7kg/mm
Rear: 3.5kg/mm

Swift Sport - BRZ
Front: 3.8kg/mm
Rear: 4.5kg/mm

This is more of an alignment question, and I'm trying to understand what sort of settings would be ideal for a 1" drop. I have SPC LCAs and front camber bolts. What would be the recommended setting for an alignment (camber, etc) for someone looking to squeeze out some additional handling?

[wparsons]

Camber should be set based on tire wear and temperatures (requires testing), and will be dependent on driving conditions and tire choice.

Stiffer tires, or less sticky tires will need less camber than a sticky or softer tire, and stiffer springs can increase the need for more static camber (less suspension travel in a corner means less camber gain).

That said, there are some pretty safe starting points. Are you planning on mostly street driving, or more track? What tires?

[mid_life_crisis]

This may be addressed already, in which case just point me to the post.
I would like to lower the car about one inch. Based on what I've read so far, if you could do this with no other changes, it would still improve handling overall. I would also like to not lose any ride comfort (improving it would be nice). There is a company selling coilovers that are designed mostly to improve the ride comfort but they also will facilitate lowering quite nicely. The question I have is based on their springs. What would putting identical soft springs on all four corners do to the handling of a twin? What I have read so far says to me that this is a really bad idea and I should look at a different set of coilovers if I don't want to cause a noticeable deterioration in the handling.

[solidONE]

Originally Posted by leicaboss

OEM - BRZ
Front: 2.7kg/mm
Rear: 3.5kg/mm

Swift Sport - BRZ
Front: 3kg/mm
Rear: 4.5kg/mm

This is more of an alignment question, and I'm trying to understand what sort of settings would be ideal for a 1" drop. I have SPC LCAs and front camber bolts. What would be the recommended setting for an alignment (camber, etc) for someone looking to squeeze out some additional handling?

The swift BRZ spec springs are 3.8k/4.5k f/r.

[fatoni]

Originally Posted by Racecomp Engineering

Total weight transfer for a given corner at a given speed is down to COG, track width, and total weight of the car.

What we're doing with springs/rollbars/dampers is trying to control the rate at which it occurs, the distribution of that weight transfer, and minimize the changes in suspension geometry due to body roll.

With regards to distribution of weight transfer and I think where you might be getting mixed up...we can stiffen the rear which means more weight transfer at the rear. Since total must remain the same, this means there must be less weight transfer at the front. Less weight transfer at the front means more evenly loaded front tires. More evenly loaded front tires means more grip up front. That's why stiffer rear = less understeer. There may be additional affects from a stiffer rear like keeping the rear from rolling too much, reducing positive camber gain, and thereby keeping the tire nice and square on the road for a little more rear grip too, but it depends.

- Andy

how do stiffer springs create more weight transfer exactly? its not intuitive really as i would think a spring would be more of a resistance and the weight would be pushed elsewhere.

[7thgear]

i think the word more is what is misleading, stiffer springs increase the rate at which load occurs, so the stiffer side reacts quicker, reaching its limit before the other end... so its more on that relative end, but the total is unchanged

and please understand that springs to not resist weight transfer, they absorb it, with stiffer springs absorbing the same as softwprings, with the only difference being how it LOOKS like from the outside (softer spring compresison more) and the speed at which it happens.