Back End Light? Options

[o0black0o]

Wondering If it just me or not. Anyway, Lets say have to stop really quick and turn at the same time. I think my back jumps up in the air then falls back down, at least it feels like it? I got my spare back there so...

[Hanyo]

you mean, the back tires lift off the ground when you slam on the brakes?

I once saw a mini couper do that in a video. But i dont think the celica has enough weight over the front axles to do that. And the celica is a pretty heavy car. So most likely its just what you feel.

[blu94gt]

My ST's back end never left the ground, but it would tend to oversteer a lot in corners. I did quite a few accidental 180s because the back end wouldnt keep traction.

And for your problem, if you're physically leaving the ground you may need to replace your struts/springs to keep the tires on the ground

[Bigmeanbulldog55]

I've picked the back end up a few times in braking and turning in hard corners. It wasn't flat ground though, it was down hill and swooping. This is normal. You could have bad shocks, wich aren't controling the up and down motion of the back of the car very well. Or some could just be loose.

[Shigexile]

I've picked the back end up a few times in braking and turning in hard corners.  It wasn't flat ground though, it was down hill and swooping.  This is normal.  You could have bad shocks, wich aren't controling the up and down motion of the back of the car very well.  Or some could just be loose.
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something loose? that doesn't sound good.

[o0black0o]

I do have bad shocks... Lol

[Bigmeanbulldog55]

I do have bad shocks... Lol
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If your going to get new rears, you might as well get new fronts too. They might go at the same time. And if your getting in there to replace them, you might as well lower the car wile your at it with some new springs. If you really want to improve, shoot for the sway bars too. They would be an easy install with everything already twor down.

[Kwanza26]

You guys sound like wreckless drivers to me. It's pretty hard to lift off the rear wheels... I mean... even if you lift the car with a jack... the body of the car's gotta be a good 2 feet off the ground before the wheels lift off...

Anyway... what you describe is body dive... which is normal for all cars because of brake bias (front brakes harder and sooner than rear). It has nothing to do with grip... cause it's very hard for the car to lift the rear wheels during hard cornering/braking... and if you think your rear is lifting during a turn... you're going too fast and braking too hard. The rear grip is as strong as the front grip under balanced weight... unless of course it's a very agressive weight-shift... but that only happens if you slam on your brakes from insane speeds to enter a corner... and if you're doing that... you're driving wrecklessly... even under race conditions.

This post has been edited by Kwanza26: Sep 18, 2005 - 12:02 AM

[GT4WRC]

Which comic book did you get all that info from?

It's all down to weight transfer. This is why the rear end of a car can get 'light' and unstable, especially when braking really hard. Brake bias puts most of the braking force to the front where most of the work is done. But front and rear braking happens at the same time. The front does not start braking first followed by the rear
You will always get weight transfer when braking - it's a simple rule of physics. The degree to which it happens is dependent on speed. This is why rear engined cars can easily 'swap ends' when braking heavily as most of the weight is at the rear. Brake bias is also set up so that most of the braking can be at the rear where the weight is.
Other factors need rto be taken into account - especially the road surface. If the surface is uneven when braking hard, it can easily unsettle the rear end of the car even more, causing it to lift up more than it usually would.
Answer is twofold. Get your suspension sorted (shocks AND bushes) and don't drive like a tw@t where you get intoi a situation on a public road where you're likely to get the rear end light.

Gary

[o0black0o]

Damn.. talk about shutting someone up......

Anyway, My idea is to replace all with KYB's and drop it... Just a matter of time and money.

I was just curious why it did it. It happened at least 4 times.

[Kwanza26]

Which comic book did you get all that info from? 

It's all down to weight transfer. This is why the rear end of a car can get 'light' and unstable, especially when braking really hard. Brake bias puts most of the braking force to the front where most of the work is done. But front and rear braking happens at the same time. The front does not start braking first followed by the rear 
You will always get weight transfer when braking - it's a simple rule of physics. The degree to which it happens is dependent on speed. This is why rear engined cars can easily 'swap ends' when braking heavily as most of the weight is at the rear. Brake bias is also set up so that most of the braking can be at the rear where the weight is.
Other factors need rto be taken into account - especially the road surface. If the surface is uneven when braking hard, it can easily unsettle the rear end of the car even more, causing it to lift up more than it usually would.
Answer is twofold. Get your suspension sorted (shocks AND bushes) and don't drive like a tw@t where you get intoi a situation on a public road where you're likely to get the rear end light. 

Gary
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Don't even think I'm, some sort of Initial D fan boy.

So what exactly did I say that was "wrong"? Heh... FWD cars don't get "light" in the rear under any circumstances beyond what I describe (if they did so often... why do they understeer so much huh?)... and it's EXACTLY as you say... unless it's under heavy weight shift (in this case... only during very hard braking)... and if that's happening in a FWD car... you're simply going too fast. You're saying exactly what I'm saying... except I'm thinking about this from a practical standpoint... assuming people are driving on normal roads. Also... what I describe about braking is correct. The front do approximately 80% of the braking, and the front WILL start locking before the rear... and all things considered, the rear applies very little pressure anyway. Now think about it... if the front is doing 80% of the braking, the rears do 20%... the front will be able to lock up before the rear at a given speed. This has NOTHING to do with when the brakes start applying... but only the end result. Yes... the front and rear do start applying at the same time... but because the fronts can do more than 3 times the work of the rears... the fronts can technically lock up sooner... think about it before you try to act "smart". This is done for a reason... and even in Rear/Mid engine cars... the front brakes will be stronger. You're silly to think the rears will brake stronger on a rear/mid engine car. The rears may brake harder in a rear/mid engine car than a FF car or FR car... but it still doesn't mean the rears brake harder than the fronts. That's just dangerous... If rears were to brake harder than fronts, plus that heavy rear (MR or RR)... the car will simply be unpredicatably unstable during hard braking (think pulling e-brake).

*shakes head*... you tend to jump to conclusions before understanding a post. Last time around... it was about a brake rotor dust/stone covers... which you adamently said it was a "stone" guard... NOT a dust cover. Turns out... Toyota calls em dust covers also... Kinda lame to try to pick apart someone's post by saying the exact same thing... no?

[GT4WRC]

You've completely torn apart your own 'arguement' there. How may rear engine cars have bigger brakes at the rear than the front? Quite a few which backs up what I said. Unless, of course, the car manufacturers which spend millions on research are wrong and you're right......
Gary

[o0black0o]

Mmmk... Lets stop this nonsense before my thread gets locked, thanks

[Kwanza26]

You've completely torn apart your own 'arguement' there. How may rear engine cars have bigger brakes at the rear than the front? Quite a few which backs up what I said. Unless, of course, the car manufacturers which spend millions on research are wrong and you're right......
Gary
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Torn apart my own argument? Huh... Are you dyslexic or something? Cause you seems to be reading what I write and then think it all backwards. I said the same basic thing... twice.

As for the MR/RR brake deal... it seems the world tends to agree with me... and the millions spent in your fantasy world can't even buy you common sense.
http://www.fastvoice.de/NSXfiles_engl.html
Notice the NSX with the FRONT big brake kit. Now... also NOTE... later model of the MR2 trubo came with twin piston FRONT calipers.
http://www.v8mr2.com/page64.asp
The world must have gone crazy huh? Now if it was as you say... this would cause a catastrophic break down on the car's physics... Also note... I drive an MR2... the brakes are the same size front and rear, and as I mentioned in my previous post... MR/RR cars do brake stronger in the rear than FF/FR cars (better weight control = better traction), BUT... they are still front biased for stability purposes. Why? Oh why? Why is the world agreeing with me? Have you ever raced a car before? FYI... I am a liscened Club race driver... and have been autoX racing for the better part of 7 years. In racing... there's something called brake bias tuning. It's tuned to the driver... and the basic tuning principle is this: If the car doesn't turn well under braking... reduce front bias. If the car wants to spin... reduce rear bias. If that basic brake tuning law was true... your entire idea of MR/RR cars having stronger rear brakes than the fronts would mean those cars are simply spin beasts... since it's already well known that rear and mid engine cars are snap oversteer beasts.

To close... learn a thing or two before you jump to conclusions.

[Bigmeanbulldog55]

You've completely torn apart your own 'arguement' there. How may rear engine cars have bigger brakes at the rear than the front? Quite a few which backs up what I said. Unless, of course, the car manufacturers which spend millions on research are wrong and you're right......
Gary
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From what I've seen of your posts, you seem to be a rally guy. Rally cars very well might have bigger backs because they use the ebrake so much.

EDIT: You guys keep it up if you feel like it. I'm learning things.

This post has been edited by Bigmeanbulldog55: Sep 19, 2005 - 10:39 PM