[HrZn]4life

Hey guys. I know that every setup is different but I was wondering if in general it's better to have your rear suspension higher, lower, or the same height as your front suspension, to help your rear end rotate around a turn. Thanks.

Back in Black

Depends on many things.

Higher rear rate = more oversteer
Higher front rate = more understeer

Again, depends on many things.

Jason-
who, so far, prefers a higher front rate.

Nuts

I think he is asking about Height, not the spring rate....

[HrZn]4life

yeah, just height not spring rate; let's assume that the front has a spring rate that is a tad bit higher than the rear...in this scenario should my rear end be raised higher, lower, or the same height as my front? Thanks.

sil

do you put things in the trunk??..:0

Wai

Raising the rear higher shifts weight to the front. But I think the amount is really minimal tho. At cornering, a higher rear ride height creates more rear weight transfer so less rear grip --- oversteer.

Asahi

What WAI said.,

I typically put a very slight rake in the car. I do about 8-10 mm higher in the rear than the front . I have been pleased with this pefromance wise and asthetically.

[HrZn]4life

That's where I am at right now also...acutally about ~6-7 mm higher in the rear. I like how it feels but was never sure if the slight rake was better in terms of "physics." Thanks

Asahi

I actually started with the slight rake based on suggestions from the local autocrossers that go to the bigger events and are more competitive. I try to take their advice with a grain of salt since mosrt are RWD nbut this suggestion has been good. The same people also run a performance shop and do my corner weighting . . .

SUPERAUTOBACS

By jacking up the rear, ur allowing more weight distributed in the front tires. There must be weight on the front tires, otherwise they will not do anything. How much front rake is good is a matter of balance. There are pro's and con's to having more front rake...finding just how much is a matter or trial and error.

[HrZn]4life

Thanks for the info guys.

Big Phat R

Uh - you might want to rephrase this. Unless you have some unearthly control of gravity - you cannot control F/R weight bias by ride height - ever - you have to move the engine to do that. The force of gravity acts equally on all parts of the car.

The second statement is false as well. If you increase the height of CG and thereby allow more more lateral weight transfer - the outside rear tire will have MORE weight applied on it than the contra-lateral side and thereby have MORE grip (friction). That is - until rotational inertia swings the body of the car around.

Increasing the height of the rear suspension makes the CG at the rear higher - nothing else.



[Modified by Big Phat R, 12:28 PM 1/17/2003]

Asahi

Ok you edited since I read the email reply but here is what I am thinking.

Correct mne if I am wrong (I am frequently my wife tells me )

You can control f/r weight bias in a crosscorner relationship. Meaning, raise the right rear and it will add weight to the front left. And in turn removes weight from the right rear. This is how i have always cornerweighted my car. Did I misunderstand?

Chris N

What do you guys mean by the term 'slight rake'. ??

Wai

I personally haven't had any experience on corner weighting. But I think it can be shown on a scale that the front total weight would slightly increase when the rear is jacked up higher? But the amount shifts forward isn't really important because the following outcome would have bigger effects:

You're right about the outside rear tire being more loaded, thus more grip on THAT TIRE. But the total rear grip (outside PLUS inside) would be less because a 75/25 left-right weight distribution would have less grip than, say, a 60/40 left-right weight distribution. The weight and grip relationship is not linear.

sackdz

??? You can absolutely change the weight bias by changing the relative ride height Front/Rear. When you raise the rear of the car, you are rotating the weight of the entire chassis onto the front, about the axis of the front wheels....

[e]Consequently, the more you shift weight above the CG, the more this difference is amplified under acceleration/decceleration.


[Modified by sackdz, 3:54 PM 1/17/2003]

Big Phat R

OK - let's talk percentages here. The Type R has roughly a 65%/35% F/R bias.

On a 2800 lb car that equates to 1820 lbs F static weight and 980 lbs in the rear (or 28 lbs per 1%).

Thus to change the weight bias by ONE percent you have to change the weight bias in the car by <edit > TWENTY EIGHT pounds.

Please demonstrate how this is possible by adjusting the spring perches or spring heights. Anyone?


[Modified by Big Phat R, 2:33 PM 1/17/2003]

sackdz

Last time I checked 280 was 10% of 2800



[Modified by sackdz, 5:24 PM 1/17/2003]

Dave-ROR

LOL owned.

I agree with others, but not BPR in this case.

-Dave, who's *** is 5mm higher than his.. uhmm..

sackdz

Whenever you change the car's attitude, weight and consequently traction will not only change under neutral conditions, but even moreso during acceleration and braking.

Example: If you raise only the rear of the car, you are putting more mass above the center of gravity. During braking, the increased mass above the CG will induce a greater moment of torque on the chassis down on the front wheels, in addition to the original increase due to ride height. That is why it is possible to change the cars handling characteristics noticably, while the actual change in F/R weight ratio is less than one might think.

Big Phat R

Yeah I got owned - my bad - this is what happens when you are working and surfing at the same time. My math is bad - but the principle is unchanged i.e. for a 10% change in weight distribution - i.e. 280 lbs - which is an amount you would need to feel a definite difference you still need a ton of weight redistribution. Even a 5% change is 140 lbs - which is not insignificant.

My point is that you cannot change the weight distribution significantly by raising the rear of the car an inch or too.

Sackdz is talking about DYNAMIC weight shift - I'm talking static weight. Any car - either FF/FR/Mid is going to shift more weight to the front wheels during braking - but this doesn't change the nascent weight bias of the car. That's why 50/50 is ideal. Raising the rear of the Type R does nothing to change its weight bias (moving or not moving)



[Modified by Big Phat R, 2:29 PM 1/17/2003]

sackdz

See above post.
That much is true... but for practical purposes thats not nessesarily the goal.

Big Phat R

[QUOTE... but for practical purposes thats not nessesarily the goal.[/QUOTE]

what does this mean?

sackdz

It means who cares what your weight ratio is as long as your car handles the way you want it to. More or less.

SUPERAUTOBACS

Who said 50/50 is ideal??? Is this for a FF, FR, MR?
Doesnt weight bias change under braking and acceleration?