A discussion on improving ride quality

[Ubersuber]

Originally Posted by wparsons

Hitting the bump stops isn't a bad thing, they're designed as part of the spring/shock package and are VERY progressive. You'll hit them at like 5mm of bump travel, and not even notice it.

Now, more travel would give more room before a hard bottoming, but I imagine that nasty bumps would still fully bottom out unless you added lots more travel.

Incorrect. The bump stops on this car are "engineered" to allow an amateur to initiate a drift.

Indeed, given the suspension on the BRZ is just an Impreza I am dubious much engineering was ever applied to the BRZ. The front struts are fitted at a steeper angle to get them under the desired hoodline with minimal effect on actual handling, the suspension settings are identical to the Impreza apart from a modest difference in ride height, the alignment is identical. I suspect the spring rates aren't a lot different and the ride height is less than 1 inch lower. Curb weight is virtually the same, a BRZ with two passengers weighs the same as an Impreza with just the driver.

I'm betting the BRZ fits the exact same bump stops as the Impreza and the engineers understood that removing the fwd would make the car more tail happy without much alteration to anything.

[Ubersuber]

Originally Posted by wparsons

I wouldn't listen to his suggestions too much... he thinks he knows more than everyone about handling/suspension/everything.

If you want reliable advice, talk to the guys at CSG, RCE, etc. They're knowledgeable and have experience to back it up.
@CSG Mike @Racecomp Engineering @ZDan

Correction, you think I think I know more than anyone when actually I just think I know more than you do. There is a difference. And I do, BTW.

[jebuwh]

Why are you back?

[Ubersuber]

Originally Posted by pantdino

Is the problem primarily in the rear? I hadn't really thought about it but it does seem the jerking motion comes mainly from the rear. One sits so far back in this car it would affect one disproportionately.


If so, could one start with replacing just the rear shocks?
Any specific Bilstein shock you recommend?

I replaced only the rear shocks with Bilstein B6 initially. The ride improvement was marked. The handling was also much better. Changing the front struts improved the steering feel but I'd say the stock front dampers are fine. I like the inverted struts Bilstein makes.

The stock rear dampers do not control the spring correctly. They allow jounce too easily and damp rebound incorrectly. The high speed control (high stroke rate) is awful in both directions. Some may say this was deliberately engineered and I say it was a mistake. I think Subaru just decided to save money. It'd be interesting to know if Subaru actually changed much from the Impreza except shortening the effective damper stroke.

The way this car can be provoked so easily into oversteer is a real pity, and robs the car of some of its true potential especially for fast road driving on bumpy roads. The ride is truly appalling and unnecessarily so as it yields no advantages.

[Trettiosjuan]

Originally Posted by Ubersuber

The way this car can be provoked so easily into oversteer is a real pity, and robs the car of some of its true potential especially for fast road driving on bumpy roads. The ride is truly appalling and unnecessarily so as it yields no advantages.

Don't know how your bumpy roads look like and mine is the Toyota version, but bumpy back roads is the main type of enthusiast driving I do. Some of them are so bumpy and bad shape I have them to myself as other joydrivers avoid them.

And I do not recognise your complaints. It does not step out easily, nor does it bounce of the road for nothing. Well of course I could provoke that, you learn the limits, just saying that when colouring within the lines, this car is pretty impressive compared to other off the shelf sport cars that have to do it all. In such driving, the damping works pretty well and body control is just fine. It's not a WRC rally car of course and could be improved a lot for such driving, a lighter wheelset with more sidewall was one such improvement. But for a car that has to do all kinds of driving, it's good.

I do recognise the rear suspension stroke is a bit short (I would not lower it on stock struts) and I notice the overdamped front especially when driving over small fast undulations, but those are relatively minor complaints related to ride comfort when cruising. It's a sports car after all.

[Captain Snooze]

Originally Posted by Ubersuber

Depends what you mean, dampers have two separate functions.
Four if you count two rebound and two jounce.
The Bilsteins control the rebound much better than the stock dampers and are more forgiving in jounce.

What does this mean? 2 rebound? I don't understand this at all.
Jounce is is the derivative of jerk. Do you mean compression?
Edit. In Australia jounce is a physics/engineering term but having looked at 3 online dictionaries the definition of jounce as
to move in an up-and-down manner http://www.merriam-webster.com/dictionary/jounce
to make short up-and-down movements http://www.merriam-webster.com/thesa...unce%5Bverb%5D
to move joltingly or roughly up and down; bounce http://dictionary.reference.com/browse/jounce

Originally Posted by Ubersuber

They allow jounce too easily and damp rebound incorrectly.
The way this car can be provoked so easily into oversteer is a real pity,

I suspect you mean compression which is widely understood.
Your use of hyperbole is interesting. Of course it is easy to provoke; you turn the steering wheel and adjust the throttle. Nothing easier but I am suggesting you have to induce it. It is not going to oversteer if driven smoothly. All 3 models understeer on constant throttle.

Originally Posted by Ubersuber

The ride is truly appalling .

More hyperbole. You are making a value judgement but are making an objective statement.

Originally Posted by Ubersuber

I think Subaru just decided to save money.

Inane comment. Most cars are built to a budget. Of course better dampers could have been fitted but 99% of buyers wouldn't care or know the difference. A better sound system could have been fitted, lighter wheels, a lighter battery fitted, where do you draw the line? Oh look, the $38k car has just become a $48k car.

[wparsons]

Originally Posted by Turdinator

Could you not get some Bilstien B6 shocks custom valved for the stock springs to improve the comfort? To me it seems like you won't improve comfort without custom valving as almost everything on the market (at least that i have seen) is designed for performance driving rather than passenger comfort. I would also imagine it would take a few tries to get it where you want.

You definitely could, but it wouldn't be a cheap exercise at all.

Originally Posted by Ubersuber

The Bilsteins control the rebound much better than the stock dampers and are more forgiving in jounce.

Have you compared shock dynos of the B6's to the stock shocks, or are you just talking out of your ass like usual?

Originally Posted by Ubersuber

The proof is in the performance, the stock dampers suck and the Bilsteins are just about perfect with stock springs and bars.

You're the only person to claim the stock shocks suck, and that includes a lot of people that spent a lot of time doing REAL testing on them.

Originally Posted by Ubersuber

Don't think the rear bump stops are correct either way, they are way too stiff way too early in the compression. The rear bump stops are much stiffer than the fronts and only 1/8 inch shorter.

Did you also notice that the rear springs are stiffer? Did you look enough to see the rear motion ratio is very different from the front, which is why the spring (and bump stop) rates are higher than the front? Front motion ratio is essentially 1, rear is ~0.75.

You know what else the rear motion ratio means? It needs less shock travel for the same amount of wheel travel as the front.

Originally Posted by Ubersuber

Incorrect. The bump stops on this car are "engineered" to allow an amateur to initiate a drift.

Based on what facts/evidence? I'll bet you A LOT of money that I could pull the bump stops out of your car entirely without your knowledge and you would complain that they're still making it too easy to drift.

Originally Posted by Ubersuber

Indeed, given the suspension on the BRZ is just an Impreza I am dubious much engineering was ever applied to the BRZ. The front struts are fitted at a steeper angle to get them under the desired hoodline with minimal effect on actual handling, the suspension settings are identical to the Impreza apart from a modest difference in ride height, the alignment is identical. I suspect the spring rates aren't a lot different and the ride height is less than 1 inch lower. Curb weight is virtually the same, a BRZ with two passengers weighs the same as an Impreza with just the driver.

So because they have similar ride height and similar weights, everything else must be identical? You really are an idiot.

Spring rates aren't even close, weight distribution isn't even close. Look at how much further forward the engine sits in an Impreza/WRX/STI to make room for the AWD gearbox.

Further, the suspension isn't all Impreza. There are some shared parts, but not everything is a full carryover, especially the springs/shocks.

As for the strut angle, what evidence do you have to suggest that the angle is actually different, and if it's different that the only reason was to reduce the hoodline height? Stop taking what you think the engineers did and spreading it as fact.

Originally Posted by Ubersuber

I'm betting the BRZ fits the exact same bump stops as the Impreza and the engineers understood that removing the fwd would make the car more tail happy without much alteration to anything.

Good thing you're not putting money on that.

Originally Posted by Ubersuber

Correction, you think I think I know more than anyone when actually I just think I know more than you do. There is a difference. And I do, BTW.

You've contradicted CSG, RCE and other vendors/manufacturers on pretty much every topic you get involved in, and yet you're trying to say you don't think you know more than them? There's some sound reasoning.

As for me, I'm giving information based on facts. You're just spreading your opinions, which contradict facts. Start citing your sources on all the BS you claim is fact.

[Captain Snooze]

Originally Posted by Ubersuber

Incorrect. The bump stops on this car are "engineered" to allow an amateur to initiate a drift.

Indeed, given the suspension on the BRZ is just an Impreza I am dubious much engineering was ever applied to the BRZ. The front struts are fitted at a steeper angle to get them under the desired hoodline with minimal effect on actual handling, the suspension settings are identical to the Impreza apart from a modest difference in ride height, the alignment is identical. I suspect the spring rates aren't a lot different and the ride height is less than 1 inch lower. Curb weight is virtually the same, a BRZ with two passengers weighs the same as an Impreza with just the driver.

I'm betting the BRZ fits the exact same bump stops as the Impreza and the engineers understood that removing the fwd would make the car more tail happy without much alteration to anything.

This is so full of contradictions.
"The front struts are fitted at a steeper angle"
"the suspension settings are identical to the Impreza apart from a modest difference in ride height"
"spring rates aren't a lot different"
"less than 1 inch lower"
"Curb weight is virtually the same, a BRZ with two passengers weighs the same as an Impreza with just the driver"
BRZ castor 5°54’, current Impreza castor 6°30′. BRZ front toe 0±3mm, Imp 0±2 mm. BRZ rear toe 2±3mm, Impreza 0±2 mm.
Yep, look identical to me.

[Ubersuber]

For our friends down under:
http://144.162.92.233/faculty/djones...suspension.pdf

Used primarily in USA. Means the same as bump for UK speakers.

Ride is subjective but only to a point. I prefer the stock ride in the BRZ to the stock ride in the Cayman for example. It is still appallingly bad given how easily and cheaply it can be improved simply by fitting Bilstein shocks to the rear axle. You are welcome to enjoy your "sporty" ride that achieves nothing useful or measurable. Some people even enjoy the hole in the firewall that lets engine noise into the cabin. It seems some people like tatoos and nose rings. Each to his own.

I prefer a car that handles well and rides properly. I also prefer a car that corners better than the stock BRZ. I am very sure the initial market for this car was snapped up by those who enjoy a little oversteer just after breakfast. I'm equally sure that market has been pretty much satisfied and from 2015 on Subaru and Toyota are improving the car to capture more serious and knowledgable customers before releasing a revised model.

If this car rides and handles so well why on earth did such an active aftermarket spring up so quickly? This whole suspension topic is about what is "wrong" with the stock car. For the informed enthusiast the most serious deficiency is the ride and the second most serious deficiency is the handling balance. Both can pretty much be fixed with better designed and built shocks and struts. Not sure about the bump stop problem yet but in about four weeks I should have better information about that.

BRZ manufacturer's weight figures show it to be 66 kg lighter than a four door base Impreza. So if you are comparing occupant numbers a BRZ with two adult occupants will be heavier than an Impreza four door with a driver, on average. For three occupants in the BRZ to equal one in the Impreza you'd need at least two kids if you want to make a point, though what that point might be escapes me. Then compare the 0-60 times to see how relatively sporty the two models are....

I might as well also throw in the opinion that the Torsen fitted to this car could benefit from a reduced bias ratio. Doesn't affect the ride though.

[Mikem53]

Originally Posted by Ubersuber

Correction, you think I think I know more than anyone when actually I just think I know more than you do. There is a difference. And I do, BTW.

You just think you know more.. That's the real difference..

[gramicci101]

Originally Posted by Trettiosjuan

Don't know how your bumpy roads look like and mine is the Toyota version, but bumpy back roads is the main type of enthusiast driving I do. Some of them are so bumpy and bad shape I have them to myself as other joydrivers avoid them.

Instead of just upgrading struts, you may want to look at higher end coilovers that have separate rebound adjustability that will allow the wheel to drop quicker while still absorbing sudden impacts. @CSG Mike or @Racecomp Engineering can probably suggest some that can maintain the OEM ride height, or maybe a little taller. Most of them are designed to lower, so maintaining or elevating the ride height will pull their strut to its upper limits.

[Trettiosjuan]

Originally Posted by gramicci101

Instead of just upgrading struts, you may want to look at higher end coilovers that have separate rebound adjustability that will allow the wheel to drop quicker while still absorbing sudden impacts. @CSG Mike or @Racecomp Engineering can probably suggest some that can maintain the OEM ride height, or maybe a little taller. Most of them are designed to lower, so maintaining or elevating the ride height will pull their strut to its upper limits.

What I miss is info about the stroke length, most coilovers (always lowering?) I suspect have a reduced stroke and would be sub-optimal when maintaining OE ride height and kind of missing the point...

[wparsons]

Originally Posted by Ubersuber

I prefer a car that handles well and rides properly. I also prefer a car that corners better than the stock BRZ.

I would LOVE to see quantitative results to support that your "upgrades" actually make it corner better. I would bet that it's all placebo. Especially since the changes you made (stiffer damping) don't support the effects you claim they had on handling and ride.

Originally Posted by Ubersuber

If this car rides and handles so well why on earth did such an active aftermarket spring up so quickly?

Because OEM suspension is always a compromise. It has to meet legal requirements in all markets, and satisfy a wide range of buyers. The aftermarket is about tweaking it to your taste, although the majority of aftermarket options are all about lowering it without concern for anything else.

Originally Posted by Ubersuber

BRZ manufacturer's weight figures show it to be 66 kg lighter than a four door base Impreza. So if you are comparing occupant numbers a BRZ with two adult occupants will be heavier than an Impreza four door with a driver, on average.

A 66kg difference is a substantial difference in weight. No clue why you're comparing different occupant loads to try to make it seem less significant though. You might as well claim that a Lotus Elise with two people and towing a trailer weighs the same as an FRS.

Originally Posted by Ubersuber

I might as well also throw in the opinion that the Torsen fitted to this car could benefit from a reduced bias ratio. Doesn't affect the ride though.

Oh please go on about how you know more than the engineers in yet ANOTHER area of automotive design.

I'll wait patiently for another of your replies where you completely avoid providing any evidence, data, sources, etc and just blabber on with your, incorrect, opinion.

[gramicci101]

Originally Posted by Trettiosjuan

What I miss is info about the stroke length, most coilovers (always lowering?) I suspect have a reduced stroke and would be sub-optimal when maintaining OE ride height and kind of missing the point...

You can also talk to Paul at Primitive Racing. He tends to focus on more rally-oriented products, so he might be able to come up with a solution for you.