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Why Have The Rear Lower Than The Front?

SS8_Gohan
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SS8_Gohan Grand Master

SS8_Gohan

Posted
Posted

Just noticed in some of the threads, people are running their cars lower at the rear compared to the front. Ie, from centre of the wheel to the guard might be say 340mm and the front will be 350mm...

just wondering what the idea behind running different heights, front to back, is?? I think even the SK group buy might specificy different heights front/back

EDIT: sorry, thought i was posting in the suspension section, mods feel free to move if you think it's not in the best area

BHDave Grand Master

BHDave

Posted
Posted

it's because the front guards are typically cut 20mm higher than the rear.

So by running the center to guard heights 10mm less at the rear you actually end up with about 10mm of rake as the front is lower

260DET Experienced

260DET

Posted
Posted

Measuring and quoting comparable heights front to rear by the wheel gaps to the top of the guards is a bit off. Its usually and more accurately measured from under the body/chassis where a part is level with the ground front to rear eg sill panel.

Thanks for asking the question SS8.

djr81 Grand Master

djr81

Posted
Posted
Measuring and quoting comparable heights front to rear by the wheel gaps to the top of the guards is a bit off. Its usually and more accurately measured from under the body/chassis where a part is level with the ground front to rear eg sill panel.

Thanks for asking the question SS8.

It allows people to ignore the tyre diamater. Just about every Skyline ever built is running something different. They may only be 10mm out or whatever but it is enough to make a nonsense of the measurement. Unfortunately it makes the camber settings influence the result where previously they would not.

salad Veteran

salad

Posted
Posted
Unfortunately it makes the camber settings influence the result where previously they would not.

How so? I'm struggling to picture it... Camber makes the wheel pivot about the lower ball joint (for upper arm adjustment), so there's bugger all height change in the centre of the wheel, not even 1mm.

260DET: Sill measurements are best used to measure rake, but for actual ride height, centre of wheel to guard is better. As djr81 said, it neglects all differences in rolling diameters, so this includes things like wheel/tyre size and even tread wear (new tyres have 8mm tread)

Thunderbolt Rising Star

Thunderbolt

Posted
Posted (edited)

If you measure a stock car, you will probably find that the measurements are less on the back than they are on the front. When you lower a car, it is usually best to lower the car an equal amount front and rear. That is why you have probably observed this.

Edited by Thunderbolt
260DET Experienced

260DET

Posted
Posted
..............................................

260DET: Sill measurements are best used to measure rake, but for actual ride height, centre of wheel to guard is better. As djr81 said, it neglects all differences in rolling diameters, so this includes things like wheel/tyre size and even tread wear (new tyres have 8mm tread)

Get it now, thanks for the explanation.

It seems some people get confused, I've heard the 'lower at the back' claim before concerning rake. And thought WTF :dry:

salad Veteran

salad

Posted
Posted

I THINK the rule of thumb is lower front = better turn in. Quite happy to be corrected though.

I think it's to do with the centre of gravity heights front to rear, but then obviously suspension geometry starts playing a pretty big part in it too.

djr81 Grand Master

djr81

Posted
Posted
I THINK the rule of thumb is lower front = better turn in. Quite happy to be corrected though.

I think it's to do with the centre of gravity heights front to rear, but then obviously suspension geometry starts playing a pretty big part in it too.

Upside down Miss Jane.

Lowering the front will tend to generate more initial & indeed midcorner understeer.

Raising it will tend to allow the car to turn in better.

Sometimes it is a matter of balancing the turn in with the mid corner grip.

260DET Experienced

260DET

Posted
Posted

Rake helps the aero, providing of course it does not put aero aids such as wings out of alignment. High back particularly helps beneficial air flow under and out the back of the car.

SS8_Gohan Grand Master

SS8_Gohan

Posted
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Posted

ok ok... i haven't heard of rake before

so rake refers to the height of the front relative to the rear? So could you say a car has "positive" rake if the front or rear is higher?

To the cars have a default rake from factory??

So it's not such a bad thing to have the rear a little lower compared to the front? I like this as i've got a real low front spoiler, but my rear guards have the biggest "gap" between them and the tyre. So in terms of wheel guard gap, i could even it out a bit, but actually have the rear lower.

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