Roll centre adjustment - options & benefits?

[ultra]

My car's only lowered 30mm but I'm keen to know more about the benefits and importance of roll centre adjustment on this car. Is this something worth looking at and why/why not?

I've heard about the Moonface MF-R Roll Centres for $300 but haven't seen any actual reviews or real world feedback on them. Does anybody have more information on these any whether they're effective?

Other than the Moonface units it seems that there's only the Robispec front control arms as far as roll centre correction goes. A lot pricier at $750 but you get a ton of other adjustment with them besides roll correction (camber, track). I'd be very interested to hear some feedback on those too.

Big thanks to anybody who can shed some light on this. Seems to be grey territory at the moment which is bit weird considering the amount of lowered cars out there & people tracking them etc.

Reference links:

Moonface MF-R Roll Centers - $300
http://www.ft86club.com/forums/showthread.php?t=35337

Robispec front control arms - $750
http://www.ft86club.com/forums/showthread.php?t=31424

[supramkivtt2jz]

Originally Posted by ultra

My car's only lowered 30mm but I'm keen to know more about the benefits and importance of roll centre adjustment on this car. Is this something worth looking at and why/why not?

I've heard about the Moonface MF-R Roll Centres for $300 but haven't seen any actual reviews or real world feedback on them. Does anybody have more information on these any whether they're effective?

Other than the Moonface units it seems that there's only the Robispec front control arms as far as roll centre correction goes. A lot pricier at $750 but you get a ton of other adjustment with them besides roll correction (camber, track). I'd be very interested to hear some feedback on those too.

Big thanks to anybody who can shed some light on this. Seems to be grey territory at the moment which is bit weird considering the amount of lowered cars out there & people tracking them etc.

Reference links:

Moonface MF-R Roll Centers - $300
http://www.ft86club.com/forums/showthread.php?t=35337

Robispec front control arms - $750
http://www.ft86club.com/forums/showthread.php?t=31424

You should look into the book Race Car Vehicle Dynamics - the Milliken guys have quite a bit to say about it. They explain what it does, why its important, and its overall affect on the rest of the vehicle's dynamics. I would say that if youre not tracking your car, theres no need to consider roll center adjusters.

If youre interested, Milliken talks about roll center in Chapter 12 - Chassis Set Up. Im sure you can find a pdf copy floating around on the net

Maybe @robispec, @Dave-ROR, or @CSG Mike can chime in

[CSG Mike]

While they're nice for rounding off the car, I'd recommend you get the larger modifications squared away first.

We don't use them on our car. Would we like to have them? Of course! Alas, the ROI of roll correction is small enough that the cost is not justified to us at our level of development, so we don't have them.

[Draco-REX]

Originally Posted by CSG Mike

While they're nice for rounding off the car, I'd recommend you get the larger modifications squared away first.

We don't use them on our car. Would we like to have them? Of course! Alas, the ROI of roll correction is small enough that the cost is not justified to us at our level of development, so we don't have them.

This. While RCAs are nice to have, they are far from mandatory.

To put it simply, a lower RC will increase body roll. Raising it back to a stock height will reduce roll. But the amount it changes usually isn't enough to matter.

[ultra]

Originally Posted by CSG Mike

While they're nice for rounding off the car, I'd recommend you get the larger modifications squared away first.

We don't use them on our car. Would we like to have them? Of course! Alas, the ROI of roll correction is small enough that the cost is not justified to us at our level of development, so we don't have them.

I hear what you're saying. I do track my car and I've already done the whole coilovers/bushings/alignment/big brake kit routine. I know that I may not need an RCA but I'm the kind of guy who'll go from 20mm to 10mm spacers just to improve my scrub radius.

To me every bit of feel and handling counts, especially on a car like this which doesn't have the power to bury a bad chassis.

I'm curious to know what the tangible benefits might be, if any, and whether any of the track rats besides @robispec might have fiddled with roll centres on this car, or have anything to say on the subject.

Interested to see the nonchalance towards RCAs on this car so far. They were one of the must-have chassis mods in the Evo/STI track day world.

Thanks!

[CSG Mike]

Originally Posted by ultra

I hear what you're saying. I do track my car and I've already done the whole coilovers/bushings/alignment/big brake kit routine. I know that I may not need an RCA but I'm the kind of guy who'll go from 20mm to 10mm spacers just to improve my scrub radius.

To me every bit of feel and handling counts, especially on a car like this which doesn't have the power to bury a bad chassis.

I'm curious to know what the tangible benefits might be, if any, and whether any of the track rats besides @robispec might have fiddled with roll centres on this car, or have anything to say on the subject.

Interested to see the nonchalance towards RCAs on this car so far. They were one of the must-have chassis mods in the Evo/STI track day world.

Thanks!

This car doesn't suffer from losing camber via compression as badly as the Evo/STI

[ultra]

Originally Posted by CSG Mike

This car doesn't suffer from losing camber via compression as badly as the Evo/STI

Maybe not (not that I'd know lol) but I'm pretty sure I've heard some mutterings about camber curves in the Suspension and Track & HPDE sections of the forum.

Are roll centres really such a non-issue for us? Sorry if I'm being pedantic - just genuinely curious.

[Draco-REX]

Originally Posted by ultra

Maybe not (not that I'd know lol) but I'm pretty sure I've heard some mutterings about camber curves in the Suspension and Track & HPDE sections of the forum.

Are roll centres really such a non-issue for us? Sorry if I'm being pedantic - just genuinely curious.

It's a bottom-of-the-list thing like strut tower bars. Good to have, but not the bang for the buck that many other mods are. So they should be towards the end of the mod path.

[supramkivtt2jz]

Originally Posted by ultra

Maybe not (not that I'd know lol) but I'm pretty sure I've heard some mutterings about camber curves in the Suspension and Track & HPDE sections of the forum.

Are roll centres really such a non-issue for us? Sorry if I'm being pedantic - just genuinely curious.

It's one of those things that need not concern anyone who doesnt intend to utilize them. Theres no point in the average joe spending $5000 on coil set ups when shock dynos and finite adjustments dont matter to the end user. In my opinion, a marginal return to the original roll center height will not make a reasonable return on investment since my vehicle will never be in a scenario where something that finite will be taken into consideration.

[CSG Mike]

Originally Posted by ultra

Maybe not (not that I'd know lol) but I'm pretty sure I've heard some mutterings about camber curves in the Suspension and Track & HPDE sections of the forum.

Are roll centres really such a non-issue for us? Sorry if I'm being pedantic - just genuinely curious.

While we haven't measured the curves, anecdotal evidence would show that it has (for us, at our level of development), a somewhat negligible effect. I CAN feel the difference, but do not think that it hurts the performance of the car enough that the cost is justified with how our car sits now.

You can see the movement of the wheel, and the car's roll here:

[ame="http://www.youtube.com/watch?v=nGBZWkoQO-s"]CSG BRZ Buttonwillow 2:00 lap - YouTube[/ame]

[donutfilling]

Buddy Club has extended ball joints for the FR-S

[autobrz]

Robispec front control arms also come with bump-steerable tie-rod ends. I feel correcting bump steer is perhaps more important than raising the roll center. Also, if you make the suspension stiff enough, you won't need to worry about roll centers, lol...

[mobybrz]

Originally Posted by autobrz

Robispec front control arms also come with bump-steerable tie-rod ends. I feel correcting bump steer is perhaps more important than raising the roll center. Also, if you make the suspension stiff enough, you won't need to worry about roll centers, lol...

The counterpoint is that if you get the rolls centers right, you can run a softer suspension and (especially) softer sway/anti-roll bars while still keeping body movement and weight transfer under control

[ultra]

Wish we could get @robispec in here to say a few words