Suberman's guide on how to make the car fix his inability to drive correctly.

[Khorne]

Originally Posted by jebuwh

Is this cjsporl again?

Also in for driving qualifications...

Nah this is Suberman, hard to decide which of them is worse. CJ is funnier though.

[jvincent]

I feel like I have to apologize on behalf of Canada again for UberSuber/Suberman being such an asshat and cluttering the forum with his random babbling.

[wparsons]

Originally Posted by Ubersuber

Then either you're not trying to induce oversteer or you've not driven much in the wet or on ice or snow.

So you're trying to induce oversteer, then complain when it oversteers?

[Ubersuber]

For clarity and, for me at least, finality on this point:

I rely on a post somewhere on this board stating that he measured the free travel of the rear suspension before the bump stop engaged at one half inch of compression. Looking at the shock and bump stop this seems reliable.

Bump stops are not springs but they compress with a spring rate just as a steel spring does.

Bump stops by their nature exert a progressive spring rate, probably very highly progressive.

Bump stops do not extend beyond their designed length when compression force is removed, that is they have no harmonic and do not need to be damped in any significant way.

From the behaviour of this car it seems likely that the bump stop engages too soon and too progressively on these cars inducing a sudden rise in rear roll stiffness, and more irritatingly a hard ride at the rear of the car over sharp bumps with significant amplitude.

Logically, this would only make sense if the engineers were trying to make this car oversteer in roll, as would be needed to drift a car with this low torque output. Since this is what these cars actually do and since the most likely reason is the bump stops I experimented by cutting the bump stop shorter. This as had the desired and expected effect.

If this was not the reason for the long bumps stops then upping the spec on the roll bar(s) would have been a much better solution to the issue of roll control, if you care about driving that is.

Bump stops get their progression from the waists moulded into them. The waists compress first and in the case of this car the lowest waist is softer than the middle waist.

At least one lowering spring maker recommends you cut off the lowest part of the rear bumps stops at this lower waist. This is obviously a good idea if not the best idea. TRD supplies custom sized revised bump stops with their lowering spring kit, which is a better solution. That kit is also a progressive spring kit and I'm betting the compression rate of those revised bump stops is softer than stock but we shall see if we can ever get our hands on a set.

To preserve the same progression of compression I decided to go to the trouble of cutting off the top or hardest part of the rear bump stops. Because the design is such that the top has a concentric groove in the top which keys into a ring on the top of the shock rod and a bevel which engages in a recess in the dust shield I cut one half inch out of the middle of the top part of the bump stop. That way the shortened bump stop fits as per stock, just shorter.

This achieved two things: more suspension travel controlled only by the road spring, roll bar and damper before any bump stop resistance was engaged and, probably, a lower effective spring rate in the bump stop once it was engaged.

The effect of this has been to eliminate suspension hop at the rear when traversing sharp bumps and eliminate the pitching that such disturbances were causing with the stock set up.

Rear roll resistance is now reduced which has the same effect as increasing the front roll resistance but without affecting ride stiffness over single wheel bumps that increasing roll resistance using roll bars does.

Fitting Bilstein dampers (which damp and do not dampen, just BTW) has improved wheel control to such a marked extent I don't know why anyone would tolerate the stock dampers unless very, very short of money. As I previously indicated, the improvement in handling AND ride make this car so much more capable and enjoyable to drive I would add these first even before changing the tires. Subaru seems to agree for 2015 on.

So, I was looking to reduce the absurd tendency this car has to oversteer, particularly in tight corners and even more so in the wet or on snow or ice. I was successful.

I was looking to improve the primitive ride, due entirely to the rear spring rates and dampers, and succeeded there too.

I am quite sure my car is much easier to drive faster than it was before but I have no intention of performing any instrumented tests. These are largely delusional anyway due to the number of variables. Even same day testing gets tricky when the time delta or g increment gets small enough.

But, you guys carry on your interesting debate about stuff this thread isn't about, to your heart's content.

I am finding the misinformation particularly amusing. Perhaps reading more carefully before posting will reduce the entertainment effect though.

[wparsons]

Originally Posted by Ubersuber

Logically, this would only make sense if the engineers were trying to make this car oversteer in roll, as would be needed to drift a car with this low torque output. Since this is what these cars actually do and since the most likely reason is the bump stops I experimented by cutting the bump stop shorter. This as had the desired and expected effect.

More bad assumptions and flawed logic.

You do realize that the front suspension is every bit as bump stop active as the rear, right? That means that as the car rolls in a turn, the front rate also increases. Proper conclusion, the actual reason the engineers use the bump stops like they do is to allow softer spring rates at all four corners for a smoother ride. Without the progressive bump stops they would need A LOT more travel to stay off the bump stops entirely or stiffer spring rates all around.

Even bigger flaw in your logic, if you look at the motion ratios front and rear you would see that if the bump stops are the same rate front and rear, the effective change at the wheel is much lower in the rear. That means as it rolls it actually gets less likely to oversteer. Looks like maybe the engineers aren't as stupid as you claim they are.

In the interest of science, did you cut the bump stops and test on the stock shocks, and compare that to full bump stops on the bilsteins before making assumptions on which change actually did what? Didn't think so.

Kinda related, @CSG Mike @Racecomp Engineering , are the bump stops the same front and rear? I've looked for part numbers, but can't find anything online.

[Racecomp Engineering]

Bumpstops are different front and rear.

- Andy

[Dave-ROR]

Originally Posted by wparsons

Kinda related, @CSG Mike @Racecomp Engineering , are the bump stops the same front and rear? I've looked for part numbers, but can't find anything online.

No.


Edit: Andy beat me.

[Malt]

Originally Posted by Ubersuber

... Fitting Bilstein dampers (which damp and do not dampen, just BTW) ...

They mean the exact same thing in this instance.

Damp: progressively reduce the amplitude of (an oscillation or vibration).
"concrete structures damp out any vibrations"

Dampen: c.1630, "to dull or deaden" (of force, enthusiasm, ardor, etc.), from damp

Dampener: verb (used with object) to dull or deaden

Dampened: verb (used with object) to dull or deaden; depress

For the love of god, if you are going to digress into a semantics argument could you at least know what you are talking about? At least you didn't going into the debate about how damp means to make something moist. Every time I see one of these comments I want to tell someone to look up Homonym in the dictionary.


On Topic: Honestly I'm surprised at the restraint others have shown towards your posts. Clearly you are out of your league here. You want to argue with some very talented drivers about theory and suspension design, yet you offer no evidence or quantitative data to back up your claims. A wise person would step away from the keyboard or admit when they were wrong, you however continue with your diatribe in spite of the fact that you've been shown to be wrong over and over and over again... Ad nauseam.

Just admit you were mistaken and let it go.

[CSG Mike]

This is kinda funny.

A bump stop IS a spring. It doesn't need to be damped because it's a secondary spring in a system, and is typically at it's full extended (free) length.

[7thgear]

[7thgear]

I bet you we're all test subjects of a psychological experiment where by a disturbance is introduced into a generally stable ecosystem and all of our responses and patterns of patience are analyzed and graphed so as to answer the possible hypothesis of how long does it take an average human to lose their minds when dealing with a person who is simultaneously articulate and responsive yet bat-shit crazy and illogical.

[Captain Snooze]

Originally Posted by Malt

For the love of god, if you are going to digress into a semantics argument

Love of which god? What do you mean by "love"? What if you do not digress?

[Malt]

Originally Posted by Captain Snooze

Love of which god? What do you mean by "love"? What if you do not digress?

#1: Which ever floats your boat
#2: The chemicals produced in the brain that induce feelings of euphoria when beholding something you cherish
#3: Then we wouldn't be having this conversation

[finch1750]

This thread is way too damn civil and articulate to be so full if arguing, good information, and terrible information. It's making my head hurt...