Street focused suspension advice

[Julian Baynes]

I've done a lot of searching on the forum lately but most of the information is more track focused. I have no plans to track the car. I plan to do some suspension work sometime this winter and looking for any advice on street focused suspension or non power mods to improve the feel of the car.

I have MSS lowering springs with about a 15-20mm drop and Continental ECS02s 275/30 front and 305/30 rear, but currently running stock sized all seasons through winter. Running JB4 custom map on E30 with an AA GESI downpipe, so a healthy step over stock power. After the springs and an alignment the car felt quite nice but as I've gone up in power it feels unsettled. It seems to walk a little on launch and under power. Seems a little unsteady in corners, especially on rougher turns. Some of this may be the alignment drifting as the springs settled. I believe I was around 2.2 front and rear camber after the alignment so not desperate for more camber. Just looking to tighten things up as much as possible.

I'm definitely getting coilovers. KW DDC or RS-R Best*i. Leaning towards the KW as they seem to be stiffer. Also waiting for the Rapid Designs diff brace which I hope will improve launches and response. I considered a full SPL setup, but that feels overkill and if I was going to drop the subframe anyway I would want to add swaybars as well. Seems like a deep hole to get into if it's not a world of difference on the street. Would it be worth it to run a partial SPL setup and if so what parts? I've read that the rear traction arms mostly eliminate wheel hop, but not the squirliness in the back and that is my biggest concern. Front only vs both sway bars seems contentious.

I guess a reasonable, cost saving approach would be in stages. Coils and diff brace. Drive for a bit and go front sway if wanting more. Rear sway to balance if needed and switch the upper arm bolts while the subframe is down. Then look into SPL parts if needed. A little concerned about testing on stock sized all seasons during the colder months. I've looked a bit into the auto solutions short shifter. Haven't seen much in the way of braces that seem worth it but would love options. Any other suggestions suspension or otherwise to tighten up the feel of the car would be greatly appreciated.

Sorry for the wall of text, but I'm trying to be thorough.

Sponsored

 

[i3igpete]

It seems you're adding a lot of complexity, with parts that are either less reliable than stock (SPL) or have no track record at all (Best*i), on a car that you are not planning to track.

Considering you are using all seasons, all of these mods (especially sway bars) make the car twitchier to drive in the snow.

What is your end goal?

 

[itzTang]

i say start small since youre not going to track it. Diff brace 1st sway bars and links 2nd. See how you like it and if still not to your liking go on to coilovers/suspension arms. But i think the first 2 for the street will make a good difference.

 

[Eastwood]

I say go coilovers first and make adjustments from there.

i had springs and hated the bouncy floaty feel on the freeway and some bumpy roads, jumped to KW DDC coilovers and was very happy with the ride quality.

 

[Mattboyd]

Get yourself some good coilovers. I have KW v3 on mine, absolutely planted to the road. (I'm lowered a lot too). Good tires make a huge difference.

 

[Julian Baynes]

I almost never drive the car in the snow. The all seasons are just to get me through the cold months until I can get the summers back on.

My goal is to tighten up the car as much as possible without being miserable to drive. I have a pretty high tolerance for nvh but roads here aren't always great. I never drive on the softer damping setting since I put the springs on as the car feels oversprung. That's why I thought KW DDCs would be a good route to start.

I know SPL is a hot topic with a lot of people here, but I haven't heard many problems with people driving them on the street. That would also probably be the last step I take unless there's reason to do specific arms. Just looking for thoughts or experiences people have had on the road, since so much of the information here is track focused.

 

[Julian Baynes]

I say go coilovers first and make adjustments from there.

i had springs and hated the bouncy floaty feel on the freeway and some bumpy roads, jumped to KW DDC coilovers and was very happy with the ride quality.

This is exactly where I'm at and why I thought coils were a sensible first step. Even in sport the car feels oversprung at times.

 

[mojo_jojo77777]

if you're running 305's in the rear with stock wheels or even 10.5" wide rear wheels, thats going to contribute to poor handling.

 

[Julian Baynes]

if you're running 305's in the rear with stock wheels or even 10.5" wide rear wheels, thats going to contribute to poor handling.

The summer tires are on 9.5" wheels in the front and 11" in the rear. The all seasons I run through the winter are stock sized on the stock wheels.

 

[mojo_jojo77777]

those are more on smaller end of what should be used for those size tires. There will be more pinching than if running a 10" front and 11.5" rear, which are more ideal widths for those tire sizes.

One of the fastest local supras in region for example, runs a 315 on a 12" wheel.

What is your alignment looking like? Alignment also plays a large factor in handling.

And if you have no intent of street driving, you should not consider SPL. They will require maintenance and will not last as long as oem rubber bushing components. They will wear out much quicker street driving and increase NVH. Perfect for track use, sorta crap for daily driving.

 

[Julian Baynes]

It's been a while and I can't find the numbers anymore, but I believe I was around 2.2 camber front and rear. Something like 0.1 toe in on the front and 0.2 rear. Next alignment I plan to go zero toe front and slightly less in the rear.

That is almost the opposite of the impression I've got about SPL on the forum. But in any case that has probably moved to the bottom of my list.

 

[Kobold]

Personally, I don’t really see the point of running zero toe at the front. Especially for everyday driving, I want stability at higher speeds on the autobahn. I often drive over 200 km/h, sometimes 250 km/h or even faster — and personally, above 200 km/h, I don’t want a neutral (zero) toe setup. Why make the car unnecessarily nervous?

I’m not exactly sure what the speed limit is in the U.S. — around 140 km/h? If that’s the case, it probably doesn’t matter much. Sure, for track use or full-on race cars you’d go for a neutral or even toe-out setup to maximize cornering grip and responsiveness. But then you’re also running a lot more front camber and usually different tires (semi-slicks).

After a bunch of testing, here’s what works best for me in daily driving:
– a bit of toe-in at the front
– noticeably more toe-in at the rear
– as much front camber as possible
– slightly less camber at the rear
– and stiffer anti-roll bars

I’ve talked to several mechanics, and they all said the same thing: the stock anti-roll bars on the Z4/Supra are too soft — they’re really just set up for grand touring.

My “test track” is an unrestricted section of autobahn in the Bergisches Land region. That stretch goes quite steeply uphill with a long, gentle right-hander followed by a left-hand curve and some dips in the right lane caused by trucks. With the original anti-roll bars and too little toe-in at the rear, the rear end became extremely unstable above 200 km/h — it started dancing around and couldn’t correct the lateral movements quickly enough, causing it to oscillate. The result was a very insecure driving feel.

With stiffer anti-roll bars, a lot more rear toe-in, and a slightly softer suspension setup, the car now drives much more stable and confident. But of course, everyone has their own preferences and needs to test what works best for them.

 

[Julian Baynes]

Personally, I don’t really see the point of running zero toe at the front. Especially for everyday driving, I want stability at higher speeds on the autobahn. I often drive over 200 km/h, sometimes 250 km/h or even faster — and personally, above 200 km/h, I don’t want a neutral (zero) toe setup. Why make the car unnecessarily nervous?

I’m not exactly sure what the speed limit is in the U.S. — around 140 km/h? If that’s the case, it probably doesn’t matter much. Sure, for track use or full-on race cars you’d go for a neutral or even toe-out setup to maximize cornering grip and responsiveness. But then you’re also running a lot more front camber and usually different tires (semi-slicks).

After a bunch of testing, here’s what works best for me in daily driving:
– a bit of toe-in at the front
– noticeably more toe-in at the rear
– as much front camber as possible
– slightly less camber at the rear
– and stiffer anti-roll bars

I’ve talked to several mechanics, and they all said the same thing: the stock anti-roll bars on the Z4/Supra are too soft — they’re really just set up for grand touring.

My “test track” is an unrestricted section of autobahn in the Bergisches Land region. That stretch goes quite steeply uphill with a long, gentle right-hander followed by a left-hand curve and some dips in the right lane caused by trucks. With the original anti-roll bars and too little toe-in at the rear, the rear end became extremely unstable above 200 km/h — it started dancing around and couldn’t correct the lateral movements quickly enough, causing it to oscillate. The result was a very insecure driving feel.

With stiffer anti-roll bars, a lot more rear toe-in, and a slightly softer suspension setup, the car now drives much more stable and confident. But of course, everyone has their own preferences and needs to test what works best for them.

140 km/h is over the highest posted speed limit anywhere in the US as far as I'm aware. Highest posted in my area are 105-110 even on large interstates. Obviously I occasionally drive much faster than that, but most of my driving is off highway. The time I spend around 200 is almost exclusively short bursts. I'm far less concerned with how it behaves on the highway than I am with how hard I can carve through a series of turns with a 50 km/h or lower warning posted.

 

[Strych9]

Just to clarify, an issue of freeway bouncing is going to be 95% in the damping and not in the spring rate. The other 5% will come from almost entirely negligible sources.

I would advise against dropping rear toe in unnecessarily. Entry stability is #1 and rear toe in is absolutely a component of that.

"Seems a little unsteady in corners, especially on rougher turns."

This needs to be as exceedingly specific as possible to get a good diagnosis. Instability typically refers to oversteer. On entry? Mid corner? Exit? Hard transitions? How cambered are the curves that present the biggest issue? What speed are we talking?


"Leaning towards the KW as they seem to be stiffer."

Don't choose a brand based on spring rate. The hill I die on is that almost all choices in spring rate could stand to be lower. Damping and setup will cure most problems that are commonly patched with higher spring rate.

 

[Julian Baynes]

Just to clarify, an issue of freeway bouncing is going to be 95% in the damping and not in the spring rate. The other 5% will come from almost entirely negligible sources.

I would advise against dropping rear toe in unnecessarily. Entry stability is #1 and rear toe in is absolutely a component of that.

"Seems a little unsteady in corners, especially on rougher turns."

This needs to be as exceedingly specific as possible to get a good diagnosis. Instability typically refers to oversteer. On entry? Mid corner? Exit? Hard transitions? How cambered are the curves that present the biggest issue? What speed are we talking?


"Leaning towards the KW as they seem to be stiffer."

Don't choose a brand based on spring rate. The hill I die on is that almost all choices in spring rate could stand to be lower. Damping and setup will cure most problems that are commonly patched with higher spring rate.

My issues are mostly on entry and hard transitions. On stock dampers and MSS springs the car feels oversprung. It sort of bounces or slightly rebounds on every entry or transition. After that initial settling it handles sweeping turns well, just that initial turn in feels very unsteady. S-turns are especially bad. Makes it hard to get a feel for the limits of the car and I'm looking to get a more solid entry/transition. It also walks a bit when launching or during a pull, but I think some of this is due to the rear springs settling and throwing my alignment off and the rest can be solved with the diff brace.

That bounce or rebound is why coils were high on my list with sways possibly coming after. If I was willing to give up the EDC what coilovers would people recommend? Are Ohlins R&T reasonable for a strictly street driven car?

Sponsored