PSA: Think twice before lowering your car

[Tbonem3]

He's got very good points and it's mostly to do with performance, not comfort.

I would say a good rule of thumb is to increase spring rate in equal measure to the removal of travel. Lowering the car by losing travel, but not ramping up spring rate will have you on the bumps constantly and ruin handling.

But as I already said, you can lower the car a decent amount without sacrificing handling.

We can have our cake and eat it too, to a degree.

[jet_dogg]

My first car ever was slammed with cut springs on stock shocks and my wheel never crashed through the fender, guess I got lucky!

[FBloggs]

It is all subjective.
Imo, a stock chassis with stock springs is an imprecise, inert device.
I replaced the bad factory dampers with Bilstein B6 and it handled like absolute crap.
This was a complete shock to me, because 95% of the time, I love tautness of my E36 M3 on stock springs and Bilstein B8.
I had to stiffen up and lower the E46, not for the optics alone.
It is more comfortable now as I prefer it.
I am over 50 y/o.

The "bump stops" btw are actually engineered to be supplemental dampers.
They are designed to have a variable resistance to compression.
They become bump stops once they reach max compression, but they are active and still allow some suspension travel after they first contact the damper body.

my priority is to drive and comfotably operate a responsive and as advertised, an agile sports GT.
For that means a tauter suspension than the factory compromise.

[Obioban]

It is all subjective.
Imo, a stock chassis with stock springs is an imprecise, inert device.
I replaced the bad factory dampers with Bilstein B6 and it handled like absolute crap.
This was a complete shock to me, because 95% of the time, I love tautness of my E36 M3 on stock springs and Bilstein B8.
I had to stiffen up and lower the E46, not for the optics alone.
It is more comfortable now as I prefer it.
I am over 50 y/o.

The "bump stops" btw are actually engineered to be supplemental dampers.
They are designed to have a variable resistance to compression.
They become bump stops once they reach max compression, but they are active and still allow some suspension travel after they first contact the damper body.

my priority is to drive and comfotably operate a responsive and as advertised, an agile sports GT.
For that means a tauter suspension than the factory compromise.

You can be tauter without being lower.

[FBloggs]

You can be tauter without being lower.

absolutely.
My E36 M3 is that way.
The E46 looks good at factory ride height, but a little better with less tire/fender gap.
I'm barely lower on Eibach sports as I do want some comfort.

[tlow98]

How much travel do the turner street camber plates give you back? Seems like a good pairing with the Koni/Dinan setup.

also, doesn’t Dinan advise their alternate bump stops with their kit to get you back off the bump stops?

my main reason for liking the Dinan kit is because it’s so close to the CSL set up.

[Tbonem3]

How much travel do the turner street camber plates give you back? Seems like a good pairing with the Koni/Dinan setup.

also, doesn’t Dinan advise their alternate bump stops with their kit to get you back off the bump stops?

my main reason for liking the Dinan kit is because it’s so close to the CSL set up.

They reduce stack by about 5/8", then you can also remove another 1/8" - 3/16" depending on what washer is in there.

My race bearing Vorshlags reduced stack even more, but I switched back to TMS which I preferred the feel of. GC also reduces stack by a similar 5/8" I believe.

[Obioban]

How much travel do the turner street camber plates give you back? Seems like a good pairing with the Koni/Dinan setup.

also, doesn’t Dinan advise their alternate bump stops with their kit to get you back off the bump stops?

my main reason for liking the Dinan kit is because it’s so close to the CSL set up.

A CSL suspension setup on an M3 weight car will not have CSL results.

[tlow98]

A CSL suspension setup on an M3 weight car will not have CSL results.

Touché.

[Obioban]

I am not sold on the Flat Ride concept. It is based on 2 justifications: referencing OE vehicle parameters (which are compromised), and "fast settling" (which only applies in one very specific vehicle speed/damping situation). I have run a rear-bias stiffness and I'm not in love with the feeling or handling. It feels as though it pivots around the rear while I prefer something more balanced.

Eh...

Non "compromised" OE vehicles (e.g. GT3s) also come with flatride stock.

It's not really "fast settling"-- it's the front and rear of the car settling at the same time. Sure, you're only bang on identical front/rear at one particular speed, but you can tune that speed to be near your average speed... and at all speeds it's MUCH more similar front/rear than any traditional setups.

Flatride was, bar none, the best handling/ride quality upgrade I've ever done to a car. I have zero intention of ever running a non flat ride setup again, on any car.

[Bry5on]

Fascinating. Did you change anything in the rear? What did you feel from shimming the front up?

The rear Dinan springs are pretty nice - linear rate 475lb/in, and barely lower it (only 3/8").
The fronts are too short and too soft. They are only 175lb/in and lower it anywhere from 5/8" to 7/8". They should be more in the 250-300 range, but.... then that wouldn't have worked from a packaging standpoint since they already have 0 preload, and the stock fixed spring perch would not accommodate a helper spring. Shortening their travel internally could have been a solution, but I am 99% sure the Dinan Konis are just regular off-the-shelf Konis.

No changes in the rear and I felt a noticeable difference in the front from crashing less on abrupt transitions. The Dinan springs are great for a wagon to balance ride rates.

I’ve been doing 15-20% higher rear ride rates in my cars since reading Millikan & Millikan while going through mechanical engineering in undergrad many years ago. the physics is old and very much still accurate physics! Dinan is great for an M3 wagon as the extra rear weight brings down the rear ride frequency. It was just a tad too low up front.

[cobra]

It is all subjective.
Imo, a stock chassis with stock springs is an imprecise, inert device.
I replaced the bad factory dampers with Bilstein B6 and it handled like absolute crap.
This was a complete shock to me, because 95% of the time, I love tautness of my E36 M3 on stock springs and Bilstein B8.
I had to stiffen up and lower the E46, not for the optics alone.
It is more comfortable now as I prefer it.
I am over 50 y/o.

The "bump stops" btw are actually engineered to be supplemental dampers.
They are designed to have a variable resistance to compression.
They become bump stops once they reach max compression, but they are active and still allow some suspension travel after they first contact the damper body.

my priority is to drive and comfotably operate a responsive and as advertised, an agile sports GT.
For that means a tauter suspension than the factory compromise.

I guess one way to put it is:
If your priority is handling, comfort, practicality - it's objective.
If your priority is appearance - it's subjective.
If your priority is some balance of the two - it's subjective.

Eh...

Non "compromised" OE vehicles (e.g. GT3s) also come with flatride stock.

It's not really "fast settling"-- it's the front and rear of the car settling at the same time. Sure, you're only bang on identical front/rear at one particular speed, but you can tune that speed to be near your average speed... and at all speeds it's MUCH more similar front/rear than any traditional setups.

Flatride was, bar none, the best handling/ride quality upgrade I've ever done to a car. I have zero intention of ever running a non flat ride setup again, on any car.

Who says the GT3 isn't compromised? A better comparison might be the GT3 Cup since it's purpose built for performance, and it uses a lower ride frequency in the rear. Of course - handling and comfort are two different (overlapping) targets.

I would be curious to ride in your car since you've really said great things about it. I by no means have anything truly figured out, other than the downsides of lowering the car haha!

[Casa de Mesa]

My next big investment is going to be flat ride. Time for the coilovers that came with my car to go the way of the dodo.

Also, I will say my lowered M3 with sub-par coilovers "handles better" than my old man's stock M4. That's driving both back to back, switching up seat time on the same day. Same rubber (Mich PSS4), but we both greatly prefer my car. I'm not talking laptimes, but the feel of the car.

Apples to oranges to a large degree (weight, electronically adjustable shocks, different geometry entirely, etc), I get it. My point is only that lowering a car does not mandate it will handle and/or feel like crap.

[FBloggs]

I guess one way to put it is:
If your priority is handling, comfort, practicality - it's objective.
If your priority is appearance - it's subjective.
If your priority is some balance of the two - it's subjective.

when I bought my chassis, My brief after refreshing the suspension was merely to improve the body control and increase the agility.
It was conservative like yours.
No track activity for this vehicle.
My ideal was my E36 M3 with stock springs and Bilstein sports (B8).
Despite the similarity in suspension layout to the E36, it did not respond the same way to a damper change to Bilstein B6.
Hard to believe +250 pounds makes that much difference, but there is more inertia in the chassis.
I think my ideal would be stock springs and an aggressively valved damper.
I had to go up in spring rate to more closely approach my ideal.

[FBloggs]

My next big investment is going to be flat ride. Time for the coilovers that came with my car to go the way of the dodo.

Also, I will say my lowered M3 with sub-par coilovers "handles better" than my old man's stock M4. That's driving both back to back, switching up seat time on the same day. Same rubber (Mich PSS4), but we both greatly prefer my car. I'm not talking laptimes, but the feel of the car.

Apples to oranges to a large degree (weight, electronically adjustable shocks, different geometry entirely, etc), I get it. My point is only that lowering a car does not mandate it will handle and/or feel like crap.

I drove an M4 on the brands hatch circuit in the UK
The amount of rubber in the suspension made it very sloppy.
All that rubber squirming around meant that my brain had a hard time sorting out all the pitch dive and yaw behaviors when accelerating and braking.
It went like shite off a shovel tho...