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Jimny chronic understeer
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Author:  Rockhopper [ Sat Apr 16, 2011 7:32 am ]
Post subject:  Jimny chronic understeer

As most of you know by now, I bought myself a little 2003 Jimny a couple of weeks ago. Apart from the 215/75R15 all terrain Sime tyres that came with the car, and me removing the sway bar the minute I got it home, the car is standard. Today is the first time I've driven it in the rain, and going around a round-a-bout near home, I pointed the wheels right and the car went straight. After this happened, I tested this out a couple of more times, going both left and right, and sure enough, the understeer is pretty bad. Now, I wanna know is this just a Jimny thing, or is it these Sime tyres or the fact that I removed the sway bar that is causing this problem. Personally, I would'nt of thought it would be the sway bar, as I've owned 2 2.5 tonne coil sprung GQ Patrols with sway bars removed, and had no drama's with them. My thinking at the moment is the Sime brand tyres. Anyone else shed some light??

Author:  bcgal0004 [ Sat Apr 16, 2011 7:34 am ]
Post subject:  Re: Jimny chronic understeer

when i had stock tyres on my jimny, i got heaps of oversteer not understeer on wet roundabouts.

Author:  steak_knife [ Sat Apr 16, 2011 7:34 am ]
Post subject:  Re: Jimny chronic understeer

Put your sway bar back on, Jim's are not like sierra's.......
get a wheel alinment to 0deg
how old are the tyre's???

Author:  alien [ Sat Apr 16, 2011 7:45 am ]
Post subject:  Re: Jimny chronic understeer

sime tyres arent the best you can buy by any means...

also, what pressure is in them?

Author:  Scrawny [ Sat Apr 16, 2011 7:52 am ]
Post subject:  Re: Jimny chronic understeer

steak_knife wrote:
Put your sway bar back on, Jim's are not like sierra's.......
get a wheel alinment to 0deg
how old are the tyre's???


I would have picked tyres over car. But then I've never driven a Jimny so purely speculation. Condition and pressures would be my first checks

Author:  woody1 [ Sat Apr 16, 2011 7:53 am ]
Post subject:  Re: Jimny chronic understeer

My Jimny has always suffered major understeer.
I've tried alignments and stuff but never fixed the problem
so I just got used to it.
Wet roundabouts are always alot of fun.

Author:  monley [ Sat Apr 16, 2011 7:57 am ]
Post subject:  Re: Jimny chronic understeer

woody1 wrote:
My Jimny has always suffered major understeer.
I've tried alignments and stuff but never fixed the problem
so I just got used to it.
Wet roundabouts are always alot of fun.


X1000000000 but it dose get a bit hairy with the sway bar off an 80mm lift with muddies. But Yeh i do get under steer in the wet....and if i fell like having some fun over steer on the way out

Author:  squizzytaylor [ Sat Apr 16, 2011 8:19 am ]
Post subject:  Re: Jimny chronic understeer

Sway bar made absolutely no difference when I removed it, none at all.
Mine is pretty neutral in regards to oversteer or understeer but if you really push it it will oversteer long before it will understeer, I would consider this normal for any car with such a short wheelbase.
How much pressure in the tyres?

Author:  monley [ Sat Apr 16, 2011 8:20 am ]
Post subject:  Re: Jimny chronic understeer

squizzytaylor wrote:
Sway bar made absolutely no difference when I removed it, none at all.
Mine is pretty neutral in regards to oversteer or understeer but if you really push it it will oversteer long before it will understeer, I would consider this normal for any car with such a short wheelbase.
How much pressure in the tyres?


:blink: Mine did.

Author:  smiffkid [ Sat Apr 16, 2011 8:48 am ]
Post subject:  Re: Jimny chronic understeer

i think its just the tires, mine has a auto locker 31s and some added power and it steers fine wet and dry roads,
if i want to push it then i can get under steer and over steer happening but other then that there is no problem
id swap the tires for a better set, or check the pressures they may be way to high

Author:  squizzytaylor [ Sat Apr 16, 2011 8:56 am ]
Post subject:  Re: Jimny chronic understeer

monkey wrote:
squizzytaylor wrote:
Sway bar made absolutely no difference when I removed it, none at all.
Mine is pretty neutral in regards to oversteer or understeer but if you really push it it will oversteer long before it will understeer, I would consider this normal for any car with such a short wheelbase.
How much pressure in the tyres?


:blink: Mine did.


I had mine on from when I purchased the car, left it on when I did the lift, for some reason the sway bar always "wandered" toward the passenger side.
While I had it off trying to rectify this I had a call and had to go out, with some apprehension I took the car without the bar on and was gobsmacked by how well behaved it was. Having said that the suspension was and is still pretty new so coils are all still nice and firm.
Correct me if I'm wrong but running a sway bar on a lifted car (unspaced) will further limit the travel difference from left side to right side due to the exaggerated angle on the link pins so rather than the body moving as it should it is being restricted and the weight is transferred to the outside tyre, which could cause understeer.

Author:  monley [ Sat Apr 16, 2011 9:01 am ]
Post subject:  Re: Jimny chronic understeer

squizzytaylor wrote:
monkey wrote:
squizzytaylor wrote:
Sway bar made absolutely no difference when I removed it, none at all.
Mine is pretty neutral in regards to oversteer or understeer but if you really push it it will oversteer long before it will understeer, I would consider this normal for any car with such a short wheelbase.
How much pressure in the tyres?


:blink: Mine did.


I had mine on from when I purchased the car, left it on when I did the lift, for some reason the sway bar always "wandered" toward the passenger side.
While I had it off trying to rectify this I had a call and had to go out, with some apprehension I took the car without the bar on and was gobsmacked by how well behaved it was. Having said that the suspension was and is still pretty new so coils are all still nice and firm.
Correct me if I'm wrong but running a sway bar on a lifted car (unspaced) will further limit the travel difference from left side to right side due to the exaggerated angle on the link pins so rather than the body moving as it should it is being restricted and the weight is transferred to the outside tyre, which could cause understeer.


I think you are correct there. But once i took mine off the back wheels wouldn't go up into the arch as much cus the front not forcing the rear down, but it made the front more lively.

Author:  Gwagensteve [ Sat Apr 16, 2011 9:13 am ]
Post subject:  Re: Jimny chronic understeer

More front roll stiffness will ALWAYS increase understeer.

Try adding some caster. This generally improves turn in and front end "bite"

If it's a tyre effect, then its affecting the rear too - what I'm saying is the effect is less grip altogether - more oversteer and understeer.

Bear in mind that manufacturers will tend to set up cars to understeer - it's considered safer.

Author:  smiffkid [ Sat Apr 16, 2011 9:15 am ]
Post subject:  Re: Jimny chronic understeer

with my sway bar in, the car handles super well, (for a jimny thats 9 inchs over factory height) and the rear flexs great

Author:  alien [ Sat Apr 16, 2011 9:30 am ]
Post subject:  Re: Jimny chronic understeer

Gwagensteve wrote:
Bear in mind that manufacturers will tend to set up cars to understeer - it's considered safer.


really? far out... i'll take oversteer over understeer any day of the week. what do you think their rationalisation on that is??

Author:  Rockhopper [ Sat Apr 16, 2011 10:35 am ]
Post subject:  Re: Jimny chronic understeer

Thanx for the replies guy's. I'm tending to lean towards a tyre issue, as these tyres seem to behave pretty shit. I don't know how old they are as they were on the car when I purchased it from a car yard, but they've got plenty of meat left on them. To start with, they're very noisy as opposed to the Mickey Thomson MTZ's I had on my old Sierra (and these are only all terrains), and if I exceeed 110km/h, the car starts to shake to the the shitter. I have had a close look at the tyres and they're not feathered or out of round. I think they might just be a shit tyre. In the dry, going around corners, they seem fine, but shit, it was all over the shop in the rain today. I took they sway bar out, because I've taken all the sway bar's out of every 4wd I've ever owned. Wether they've being coil sprung or leaf sprung, it's never been an issue. My last Nissan was 6" over standard on really soft springs, and it still handled corners fine. I've got a set of stock wheels and tyres off my old Sierra out the back. There's not much tread left on them, but the next time it pisses down, I might swap them over and see if it makes a differance.

Author:  Rockhopper [ Sat Apr 16, 2011 10:38 am ]
Post subject:  Re: Jimny chronic understeer

alien wrote:
Gwagensteve wrote:
Bear in mind that manufacturers will tend to set up cars to understeer - it's considered safer.


really? far out... i'll take oversteer over understeer any day of the week. what do you think their rationalisation on that is??


I think the reasoning for that is it's easier to regain of control an understeering car than it is of an oversteering car. In my younger stupider days I over corrected my oversteering Mazda on a busy Parramatta Rd in peak hour and my car became a pinball bouncing off three semi trailers and coming to rest on a Volkswagon Passat :oops:......
...... right outside the police station I might add :oops: :oops: :oops: ....

Author:  royce [ Sat Apr 16, 2011 10:44 am ]
Post subject:  Re: Jimny chronic understeer

alien wrote:
Gwagensteve wrote:
Bear in mind that manufacturers will tend to set up cars to understeer - it's considered safer.


really? far out... i'll take oversteer over understeer any day of the week. what do you think their rationalisation on that is??


understeering car, back off and continue arond the corner

oversteering, back off its too late your in a tree


Rockhopper, rotate front to rear and see what happens?

Author:  BAZZOOK [ Sat Apr 16, 2011 8:47 pm ]
Post subject:  Re: Jimny chronic understeer

royce wrote:
alien wrote:
Gwagensteve wrote:
Bear in mind that manufacturers will tend to set up cars to understeer - it's considered safer.


really? far out... i'll take oversteer over understeer any day of the week. what do you think their rationalisation on that is??


understeering car, back off and continue arond the corner

oversteering, back off its too late your in a tree


Rockhopper, rotate front to rear and see what happens?


Yeah, oversteer on a short wheel base is pretty hard to round up. once it goes it's goodbye momma

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