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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 12:48
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ok, this is one for those of you who know what you're talking about (keep uninformed opinions out please  )
I'm suffering a bit of lift off oversteer in the supra at the moment. Now while I dont actually let the power off much in the corners, as I usually judge them pretty well, it is a serious problem when I do misjudge corners, because it means tricky braking and steering to counter it, all while keeping the car going round the corner.
has anyone experienced this with their supra? And could it have something to do with a front shock being rooted? (because I cant imagine toyota designing lift-off oversteer into a rwd car. not on purpose anyhow)
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Registered:
August 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 12:55
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Can you describe "lift off"?
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Location:
Carlingford, Sydney
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 13:02
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dont lift off? 
...sorry
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 13:47
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"Lift off" as in taking foot off the accelerator suddenly. Common trait of FWD cars when pushed hard.
It suggests that when you back off, there is a significant 'weight transfer' to the front, reducing grip at the rear and resulting in a rear that wants to swing like a pendulum. I think it might help if you stiffened the front, by increasing spring rates or better shockers....
Also check to see that the full travel of the rear suspension is available at the rear. Sometimes incorrectly matched rear shock absorbers may have been fitted and these may limit the full amount of droop available. It happens with unusual cars (read Corona Mk2). This can make for 'interesting' handling....travelling backwards at over 100kph is very unnerving.
I suggest you pose this one on PF in their handling section.
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Registered:
August 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 14:07
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ah ok then.
Well in that case im going to be unhelpful and say no i never experienced this in my supra.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 14:15
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to define it a little more, when you lift off, and weight transfers to the front, are the front wheels getting more bight and pulling the front of the car round, and that causes the car to oversteer?
or is the weight transfer to front lifting weight from the back, causing back wheels to slide without front wheels turning that much more?...
i had a similar thing in my rolla when it had positive camber  both cases actually, it'd roll onto front sidewalls and hoik the car round, while at the back one wheel would lift and it'd slide... farkin scary...
so. is the frotn turning in, or the back sliding out? or both?
Cya, Stewart
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 20:04
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well... both, but the actual cause is taking the power off.
might be worth noting a little bit of lift-off oversteer is actually a good thing ina a FWD car, find you dont have power oversteer available as an option (assuming you dont panic in a bad situation, take your foot off the accellerator, and then go oversteering into a tree)
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Location:
Brisbane
Registered:
June 2003
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Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 22:38
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Also a solution worth a side note would be to change your driving style, If you become so concerned about oversteer take the corner slower...
OR.
Dont accel off during a corner... brake first power through the corner, it works as a pricipal of rally drivers its bound to work for you.. either that or take the corner with an engaged clutch blip the throttle through the apex and try to match gear / revs of the exit - (however this is more likely to promote a power shift on exit and therefore create oversteer if you are not straight.)
just a thought
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Location:
Cabramatta, NSW
Registered:
May 2002
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 Re: how to eliminate lift-off oversteer in an ma61
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Thu, 28 August 2003 23:18
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I assume this is happening when you lift off before the apex?
Normally, if you lift off after hitting the apex, it's a lost cause...
Is the oversteer sudden?
How extreme is it?
What tyres do you have?
There's a lot of factors involved.
Could be the shocks, do you get snap oversteer (ie: powering through the apex and once you pass it, the rear just snaps out)? I had that when I had a rooted shock.
GT: When I did my advanced driving course, the only cars that locked up their rear brakes first were utes, Excels, and a Corona MkII.
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Location:
Brisbane
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 01:06
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MA61's are known for this sort of behaviour. Most cars are set up from the factory to understeer at the limit (it's safer for the average driver), but the MA61 will oversteer instead. There are ways to minimise this, and I think GT is on the right track: minimise weight transfer as much as possible. Another thing I might add: get a wheel alignment done. If the rear wheels have too much toe-out, the car will be excessively tail-happy. Last time I had this done it made a huge difference!
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 01:22
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just a few ideas
a friend wanted to promote lift off oversteer in his sss pulsar, so he fitted a harder swaybar, seemed to give him what he wanted.
from what little i understand, oversteer is caused by the rear camber changing to positive, or more positive on "outward boody roll"
have you fitted a harder rear sway bar? could this be a problem?
maybeye fit a harder front swaybar, this will tend to increase understeer, so it might all come out in the mix.
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Location:
Hobart, Tas
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 03:09
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There is a FANTASTIC book I am reading at the moment, for the second time, that I suggest you (and everyone else!) reads. It's called.... "Car handling and roadholding" or something similar, written by an engineer in the mid 80s who designs car susp and tests it, and reviews cars. It doesn't tell you how to drive, but talks all about car chassis/susp designs, physics of suspension & chassis dynamics, all about the interplay & tradeoffs between different suspension (and car) design considerations, rwd vs fwd vs awd, roll centres/ moments of intertia/what happens when a car goes through a corner, etc etc etc etc. I can't really summrise it well but it really is good, and I think it would give a good understanding of exactly what your car is doing and why, and what you could do about it.
I'll get the full reference & proper title sometime if anyone is interested.
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Location:
Hobart, Tas
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 03:21
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| shinybluesteel wrote on Fri, 29 August 2003 11:22 |
just a few ideas
a friend wanted to promote lift off oversteer in his sss pulsar, so he fitted a harder swaybar, seemed to give him what he wanted.
from what little i understand, oversteer is caused by the rear camber changing to positive, or more positive on "outward boody roll"
have you fitted a harder rear sway bar? could this be a problem?
maybeye fit a harder front swaybar, this will tend to increase understeer, so it might all come out in the mix.
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Bear in mind that an SSS puslar is FWD, so take that into consideration. Different beasts. For example, in a fwd, the inside rear tyre lifting off the ground isn't such a bad thing - in a rwd, it is! But yes, a stiffer rear swaybar should make a car oversteer more.
rear camber changing to positive is just one thing that can effect oversteer, and is one thing that can be built into rear susp design when tuning suspension (at the cost of deliberatley sacrificting some [overall grip, not correct word])
The relative hights of the front and rear roll centres have an effect too, as will weight transfer, as will a lot of other things.... i am by no means an expert, what I am trying to say is don't pigeon hole terms in black and white - how your car behaves mid corner is due to a LOT of interrelated things!
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 05:55
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mmm. well driving style isn't the problem. as I said, I dont usually have the lift off oversteer problem, 'cause I don't usually lift off 
thanks for that GT and max - new shock and a front swaybar first, then I'll find if anything more drastic needs to be done
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 14:47
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stefan, i agree with you, was just throwing in some ideas.
ill leave any more advice giving to supra owners.
i think the book is called "roadholding and suspension" or something, has a picture of an old wire wheeled morgan or something on the front cover? FANTASTIC book, not over the top in tech stuff, but gives you a really good idea about all the different systems that are out there.
i'm a huge fan of De dion tube rear suspension now, thanks to that book.
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Location:
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Registered:
July 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Fri, 29 August 2003 17:34
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Hello,
If i can throw in my two cents worth here's some advice,
There are two basic causes of lift-off oversteer;
1. Poor technique - Slow in/Fast out is the quickest way to get through a corner although it feels a little slow at first. You should be off the brakes and in the correct gear before turn-in. People who are overdriving a vehicle tend to come in too hot and roll around the apex which often results in oversteer.
Assuming your technique is ok.......
2. Front suspension too soft- In a left hand corner for example you will be tucking in the right front wheel thereby raising the left rear. Obviously your rear traction becomes limited due to only one tyre having proper road contact resulting in slide. To cure this you would need to have a look at front shock absorber condition and spring stiffness. Front swaybar changes should be considered after checking shocks/springs. On a race-car attempts are often made to increase front track width over rear track width using wheel spacers at front and introducing front negative camber. This would also help a lot as the contact patches of tyres are no longer square which prohibits the front wheel from tucking. There are other benefits from increased front track and negative camber also.
This advice comes from several years of circuit racing and the last three years teaching young people how to drive race-cars as part of a high-school racing program.I'm not saying it is the only answer but perhaps something you should consider.
Good luck and don't prang before you sort it out !!!!!!!
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Location:
Hobart, Tas
Registered:
May 2002
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Re: how to eliminate lift-off oversteer in an ma61
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Sat, 30 August 2003 12:23
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Just another thought... what struts/shocks do you have, and what springs? If you have lowered springs, without RCA blocks the front roll centre will be lower which should make the car oversteer more, just a shot in the dark. Also... if your rear shocks are worn/leaking, that's nasty and it may be costing you contact. As stated before, I am no suspension expert at all, these are just ideas from my own limited expereince.
I happen to like the balance of my ra65 now. I don't drive like a maniac but if take a familiar right hand turn too fast, the front slides a little and the back slides a little more. The only thing I don't like is the fact it is underdamped (monroe GTs!), and the fact the front end stays flat *to a point* then in a really sharp 90* turn seems to roll a bit more than it should. I think this is because of the lower front roll centre due to lowering the car.
I am getting RCA blocks to put the front roll centre back where it should be, so if that makes it understeer more (it should) and I don't like it maybee I can play with the stiffness of the rear shocks (got some secondhand slightly-shorter stroke Koni reds to put in the front, and will buy some rears sometime down the track)
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Registered:
August 2002
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