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I recently put an x-link type of modification on the Patrol...... i steer away from calling it that, out of respect for the product that Dobbins are selling. i prefer to call it a PDP Link A mate made it for me....... anyway, i find that with the link on, on right hand side slopes, it leans reallllllll bad..... turning left gives it body roll that needs to be seen to be believed, but going the other way isn't nearly as bad. off-road, turning into a gully, or on a right hand side slope will increase the pucker factor quite a bit! Got to the stage on a moderate side slope on "Ouch Canyon" at Rover Park, that i needed 2 blokes to stand on the passenger side side step to stop it flopping over I spoke to somebody at the Tuff Truck DVD launch yesterday who said that if i were to raise the panhard mount on the rear diff to level it up, it would stop the springs unloading in that direction and pivoting on the panhard mount..... after some advice and suggestions in regards to whether or not that is indeed the problem. And.... do i need to sort it front AND back?
TIA guys
Tony
Last edited by Vulcanised on Mon Jun 25, 2007 8:10 pm, edited 1 time in total.
There is no "I" in Team, but there are 5 in Individual Brilliance
You've discovered why nissan chose a front suspension system with a fair amount of roll stiffness built in.
Without it, brown trousers territory isn't far away.
Raising the panhard rod mounts will reduce body roll a little, but introduce some other handling traits that you won't like. Raising the rear one without the front will probably give you rampant oversteer.
I can't remember the details, but the height of the panhard rod ends does affect the height of the roll centre - so the theory is feasible.
At a guess, I would say the body tends to roll about the "downhill" end of the panhard end, more so if you have variable rate springs. So raising one end sounds like a good option to increase roll stiffness (is that the correct term?)
Any automotive engineer worth his money should be able to confirm it for you with a phone call - who engineered your mods?
KiwiBacon wrote:You've discovered why nissan chose a front suspension system with a fair amount of roll stiffness built in.
Without it, brown trousers territory isn't far away.
Raising the panhard rod mounts will reduce body roll a little, but introduce some other handling traits that you won't like. Raising the rear one without the front will probably give you rampant oversteer.
what sort of handling traits? i am willing to sacrifice things for off-roadability.... it only gets driven once every pancake day these days.
There is no "I" in Team, but there are 5 in Individual Brilliance
I could be way off the mark here, but I tend to think that most of the Japanese manufacturers got their leaf designs pretty right (I think they were mostly copies of the WWII jeep) but for some reason, totally missed the mark with their coils.
Leaf cars tend to run greater roll stiffness in the rear than the front - the rear leaves are more widely spaced (and often have a higher rate, but no always) Both range rovers and the Gwagen are set up with widely spaced coils in the rear - right out near the wheels - to improve roll stiffness.
But both Toyota and Nissan went to springs mounted inboard of the chassis rails and 4 links with minimal bushing bind while the fronts have wide spaced coils and radius arms with bushing bind.
I agree with the notion of needing to take roll stiffness out of the front to make the front end follow the terrain when climbing, every factory coil car seems to suffer with this. However, where I tend to disagree with the way most people set up their coil cars is that I think the rear needs to be fairly stiff and have decent roll stiffness, even if this requires an antisway bar in the rear. Adding some roll stiffness in the rear will allow the rear to stay stable and let the front flex when climbing.
Be careful not to overdo it though, or the oversteer will be a killer.
not trying to tell you how to suck eggs patrolden, but 6" is a lot of lift and the spring characteristics it will create will be amplifying the problem.
Just my 2C worth.
Steve.
[quote="greg"] some say he is a man without happy dreams, or that he sees silver linings on clouds and wonders why they are not platinum... all we know, is he's called the stevie.[/quote]
KiwiBacon wrote:You've discovered why nissan chose a front suspension system with a fair amount of roll stiffness built in.
Without it, brown trousers territory isn't far away.
Raising the panhard rod mounts will reduce body roll a little, but introduce some other handling traits that you won't like. Raising the rear one without the front will probably give you rampant oversteer.
what sort of handling traits? i am willing to sacrifice things for off-roadability.... it only gets driven once every pancake day these days.
Vicious and unpredictable would describe the extreme end result.
Basically as you raise the roll centres (by raising the panhard), the vehicle will want to roll over the top of the loaded wheels rather than compressing the suspension on that corner.
Imagine a vehicle cornering, with a low roll centre the body rolls and the COG gets lower.
With a very high roll centre the wheel starts to tuck under, the body rises, the COG rises and it finishes with the vehicle on it's roof.
Cornering might not worry you, but consider the similarities between cornering and negotiating a sideslope. Your panhard rods don't know the difference.
It may go against all your instincts, but the right sway bar will actually be the best way to solve your problem. Especially a tunable one that you can get the right balance between roll stiffness and articulation.
Or you could four link the rear like Carlton and Dan did to their shorties when they had them. All reports were that it fixed a lot of the bad characteristics lifted GQs have of falling on their right sides.
What's the difference between ignorance and apathy? I don't know and I don't care.
I am an insomniac dyslexic agnostic. I often lay awake all night wondering if there really is a Dog.
A mate made it for me....... anyway, i find that with the link on, on right hand side slopes, it leans reallllllll bad..... turning left gives it body roll that needs to be seen to be believed, but going the other way isn't nearly as bad. off-road, turning into a gully, or on a right hand side slope will increase the pucker factor quite a bit! Got to the stage on a moderate side slope on "Ouch Canyon" at Rover Park, that i needed 2 blokes to stand on the passenger side side step to stop it flopping over 
I spoke to somebody at the Tuff Truck DVD launch yesterday who said that if i were to raise the panhard mount on the rear diff to level it up, it would stop the springs unloading in that direction and pivoting on the panhard mount..... after some advice and suggestions in regards to whether or not that is indeed the problem. And.... do i need to sort it front AND back? 
