The dreaded nissan wobble

[big red]

I have a seven inch lift and used to get the wobbles with 35's on standard offset rims and newly balanced tyres.
Wider rims, bigger tyres, big offset rims all made it much much worse.
fixed mine by fitting drop brackets.
The 35's are now out of balance and don't wobble.
Still get wobbles when the 38's on 10" rims are way out of balance [lost weights]
Also get wobbles when running 40 mm offset beadlox with 36 swampers which are not balanced at all.

Other things that can cause wobbles are:
Tyre balance,
Tyre out of round,
Panhard rod bushes,
Wheel bearings,
Caster,
Radius arm bushes,
King pin bearings,
Steering rod balljoints,
Tie rod balljoints,
Steering stabiliser,
steering box slop,
Loose mounts of any of the above.

Nissans seem to be right on the edge of wobbling in stock form and any little thing that is slightly wrong pushes them over the edge

It seems like most people go to a lot of trouble to fix the symptoms but no one tries to fix the cause.

IMHO the cause is the angle from horizontal taken between the chassis pivot point where the radius arm pin is mounted and the pivot point on the diff where the radius arm bush is mounted.
The snake drop arms still have the same angle as a standard arm with the same lift so they still wobble.
Some five link set ups also have the same high angle.
Flatten out the radius arms with drop brackets and lose the wobble
:victory:

[Area54]

Ok, here goes. My opinion has to do with rim offset, tyre size and caster.

It's late, but I need to put this down.I'll try to draw up some rough pics to help explain what I'm talking about.

Steering shimmy is the movement of the wheels from side to side, in a constant cycle ('bouncing' from side to side) not up and down.

First thing is with rim offset, the GQ has a shallow camber kingpin angle(the GU has a more pronounced kingpin camber angle), and with standard rims and tyres the projected kingpin contact point is roughly in the centre (if not slightly outside) the centre of the tyre pivot patch. Add an offset rim and wide tyre combo, this then places the tyre pivot point outside of the pivot point of the kingpin, giving more leverage for the road surface to influence the tyre/wheel combo and less leverage from the steering.

Increasing the tyre size comes in with it's own problems - more sidewall flex and squirm from blockier treads. A larger tyre size - increase in radius lets call it - also throws out your caster (caster is the ability for the steering to self centre - the forward projection of the kingpin puts the pivot point in front of the tyre contact patch - ad in too much and you will get a harmonic vibration) as the centre point of the axle is now further from the ground, increasing the caster. It's not the degree of caster you need to maintain, it's the distance of the projected kingpin pivot point in front of the tyre contact patch you need to maintain.

Many people increase the caster to maintain the centering characteristics, but usually go too far with too much. This creates an aggressive self centering characteristic, enabling the shimmy to appear with very little influence.

The wheels of a shopping trolley have caster in them, the pivot point is projected in front of the wheel contact patch, same thing happens with caster in the front of a vehicle at a less acute angle. Ever noticed how a wheel on a trolley 'shimmies''when it has been damaged at the mount with excessive caster?

Now combine all these things together and you have all the reasons to have a shimmy problem. I'm not saying other things don't influence the shimmy, such as worn out components, but predominantly the mods are done then the shimmy shows up.

I had the shimmy with steel rims, but changed to alloys and it disappeared. I have lifted coils (won't say how tall :D ) I too have drop brackets, but I fixed the shimmy before I fitted the drop brackets. I run very little caster, the 33's and the factory rubber radius arm bushes give me the perfect amount of caster, enabling excellent self centering, no wander and no shimmy, even on the 34 JT2s or the 35 pedes ,and the steel rims with these tyres are pretty average, but I keep them balanced.

Not enough camber projection, too much caster and a tall uncontrollable sidewall is my pick for the shimmy.

Troy.

[big red]

i bet we get more opinions on this subject before we're through 8)

I fitted Link's 37" creepy crawlers on toyota offset 16x8 rims tonight, they have not been balanced at all and were at 35 psi.
Took the truck for a drive to check how bad the vibrations would be as i am going to drive them up to Landcruiser mountain park at low pressure to soften them up for him...
No vibrations and no wobbles at all !!!
I then dropped the pressure to 20 psi and took them for a drive again and found a very slight wobble when slowing down at around the 60kmh mark.

[Ruffgq]

The cure on my GQ was Histeer and level the panhard bars (front & back) back to standard angles, and rotate the ends of the housing to get 2 degrees positive castor, since doing this I've had no problems at all.
Just another suggestion :D

[Area54]

i bet we get more opinions on this subject before we're through 8)

I fitted Link's 37" creepy crawlers on toyota offset 16x8 rims tonight, they have not been balanced at all and were at 35 psi.
Took the truck for a drive to check how bad the vibrations would be as i am going to drive them up to Landcruiser mountain park at low pressure to soften them up for him...
No vibrations and no wobbles at all !!!
I then dropped the pressure to 20 psi and took them for a drive again and found a very slight wobble when slowing down at around the 60kmh mark.

Sidewall flex.

Your rig would now be reasonably resistant to the shimmy with your gu diffs, drop brackets and dropped pitman arm.Your drop brackets look like they give you correct caster for a 6 inch coil (drop distance about the same as mine) so your caster would be about spot on for a larger tyre.

[big red]

troy,
i don't have a drop pitman arm, all suspension mounts are factory so it would be fairly simple to put mine back to stock.
When i was just running the caster plates i used to get wobbles if i ran the shocks soft but since changeing to drop brackets there has to be a fairly large problem somewhere for mine to wobble.

[V8Patrol]

Interesting thoughts here guys ..........

GU's do it .....
GQ's do it ....
MK's do it ....
MQ's do it ....

But Ive never heard of a G60 doing it :roll: ......
what castor/camber do they run ????,......
do the guys that own/drive these old girls, fit larger tyres + offset rims ???


My experiance.........

Five of my MQ's get the shudders up,

1 is fitted with 35" bfg's and a SOA and I have now fully cured it !!! :D
1 is fitted with 31" duellers and is stock, shudders around the 60 - 80 kph mark
1 is fitted with 31" kumo full muds, std height, shudders around the 60 - 80 kph mark
1 is fitted with 750X16 dunlops on split rims.... shudders same as the ones above
1 is fitted with 825X16 dunlop road tyres, same as the above !!!
I have also run 38.5 swampers on the first rig I mentioned and NO SHUDDER ! yet the 35's did ????

I have replaced .......
kingpin bearings-------- zero differance
wheel bearings --------- ditto
idler arm bushes ------- ditto
draglink tierod ends --- ditto
cross over link ends --- ditto
steering damper ------- minor improvment for about 3 months

I have since fitted....
RTC damper ------------ minor improvement
an additional steering damper ------- yep I run 2..... shudder GONE !!
The additional steering damper is a std unit and I fitted it to the tierod arm and it has never shuddered since that day.
The unit is mounted off of my old swaybar mounting bracket and the other end is attached to the actual tube part of the tierod arm ( the big one that goes between the two hubs )

Ok so that stopped the shudder, but its a "cover up" of the problem, I shouldnt need two dampers...... but it works.
The second damper got me thinking..... so I removed it and went experimenting....
I reset the toe-in/toe-out, this had minor improvements especially with toe-in, but it still shuddered.
I fitted new tierod ends to the tierod arm, this saw a major improvement but the slightest shudder was still there.
I fiddled with castor angles......
3 degrees -------- bad shudder
6 degrees -------- slight improvement
7 degrees -------- as above only better
9 degrees -------- as above and again better
11 degrees ------- about the same as above but with heavy steering
15 degrees ------- zero shudder but super heavy steering even with pwr assist !
So I set it at 10 degrees castor.

Tyre pressures were the next thing and I stuck with the same set through out the testing.......
I found that the higher the pressure the less shudder existed, example of this is my 35" BFGs were horrid at 10 psi for the shudder but it was eliminated once they were pumped up to 40 psi !!!

Then there was the rim testing......
alloys made no differance, neither did 7", 8" 10" steels........ yet as soon as I fitted a set with much less offset the shudder dissapeared completly !
I then "made up" a set with the rim being centred in relation to the actual WMS ..... minor shudder
then with the rim centre being inwards of the WMS .... shudder gone !
then with the rim centre being outwards of the WMS .... shudder was back !

The combination I now run is
35"bfg's on 8" rims with the smalles offset I could get clearance on,
35" bfg's aired up to 38psi for road use only.
obviously all the new tierod ends,bearings & bushes,
10 degrees castor & standard setting for toe-in
and the additional std steering damper fitted to the tierod arm

NO SHUDDER AT ALL :D

Kingy

[embryo]

no one can ever answer this eternal question. how ever stuffed shocks can also give you the death wobble, doesnt hold tyre to ground giving you uneven tyre wear giving you death wobble (i dont think anyone mentioned that yet)

[V8Patrol]

Stuffed shockers dont seem to have any effect in my experiance, in fact I'd go the opposite way after a mate ( Juddy ) fitted new shockers and the shudder actually got much worse !
The shockers on my rig arent the greatest but even when I removed them completly the shudder never alltered.
I think its a trial and error thing, some things have an effect on some rigs and do SFA on others.

Kingy

[V8Patrol]

From a G60 owner ....... thread link .....
http://forum.patrol4x4.com/viewtopic.php?t=190

from a vintage 1960 Nissan service manual for the 60 series P-troll...I imagine it changed slightly over the 20 year span of the 60 series.

steering angle
-inside: 28*
-outside: 25*32'

toe in: 3-4mm
camber: 1*30'
caster: 1*30'
knuckle inclination: 7*30'

caster & camber is established at time of manufacture and cannot be altered by any adjustment

I myself have never had shimmy or wobbles in the steering on a 60 series P-troll. The only exception being bent rim. Steering box is a Hindley style worm and roller, they last forever. Plenty of slop and play in the tie rod/draglink though if the system is old. New steering system parts and it is as good as a brand new car. I have experienced bump steer but this was with lift kit and no swaybars/limiting rods. Corrected the bump steer with shackles set up better. Never fitted anything over 33/34" tires and nothing real wide, i.e over 11". Usually I run about a 32/33" tire on solid 16" rims that are fairly narrow. Tall tires on a stock G60 are shiat....It doesn't have a low enough low and gearing in diffs is stuck at 4.10.

Driven a SOA G60 with 34's and power steering. No shimmy or wobbels but lot's of slop in the front end and handled on road like crap. Off-road it was excellent...I feel reverse shackle would greatly help a SOA G60's road handling.

That is my 2 cents...

Ok so where's the differances :roll:

[embryo]

yeah its defanatly trial and error, but what i ment was worn shocks dont hold the tyre to the ground and so the tyre wears uneven, 'lumpy' or 'feathered' and the worn tyre is what gives you wobble, so you could replace the tyre and in X amount of time it would come back and so the problem is your shocks and the tyre and wobble is the simptom

[big red]

there is a few different ways tried to combat the wobbles.
drop radius arms from chris's 4wd accessories
http://www.4wdlinks.com.au/albums/album171/abq.sized.jpg

drop radius arms from snake racing
http://www.4wdlinks.com.au/albums/misc/abc.jpg

i would imagine you would get the same articulation but it would start further down so you should get better down travel at the expence of up travel.
drop brackets do the same.
caster plates have less down travel.

because the mounting points are in the same places there would not be any difference to the wobbles [same with caster plates]
[ i am presuming they have built in caster correction ]
drop brackets would improve the wobbles.

the resistance to climbing [eg: a rock ledge] would be the same as caster plates but not as good as drop brackets.

there would be better clearance than caster plates or drop brackets.

just my opinion[/img]

[big red]

drop brackets from wizard
http://www.4wdlinks.com.au/albums/album32/aau.sized.jpg
cure the wobbles.
allow good climbing of ledges.
decrease under chassis clearance.
drop gearbox for better tailshaft angles.

[ozy1]

i myself, started out with castor plates, and had the dreadded wobble, i first had a few different shops balance my wheels up for me, that didnt work, all weel bearings and evryhting was checked, and was still there,

the day i fitted drop brackets, the wobble packed its bags and left, okay, they reduce clearance bo 3" or so, but truthfully only hit them a dozen tims or so, but i am pleased to this date.

[TUFFGU&GQ]

Drove my SWB with the 5" lift for the first time on the weekend, I have 3 degrees caster bushes fitted to the front running 36 'pedes no shudder or vibrations. I'm still running standard panhards and rear control arms too.

[Link]

Drove my SWB with the 5" lift for the first time on the weekend, I have 3 degrees caster bushes fitted to the front running 36 'pedes no shudder or vibrations. I'm still running standard panhards and rear control arms too.
That's a lucky break :D

Before I had drop brackets fitted in my shorty with a 5" lift and 37's, I shook the steering wheel bolts loose from driving it.. :?

[TUFFGU&GQ]

It's strange how this comes about. I had a LWB GQ with stock suspension and it vibrated from day 1. I then fitted a 3" lift and well in short, I gave up trying to fix it.

I had expected the worst with the SWB given front diff is across by 30mm from standard. After I fit F&R Panhards it might vibrate who knows.

[spider]

I've had a 4" lift on my GU ute and put 3degree offset bushes in the radius arms from old man emu and in less than 6 months they're stuffed. :evil: so to combat this problem I looked around for some caster correction for the ute and found that 4" kits aren't really catered for in this area so I just said stuff it and I'm changing everything to 7" :D . We'll see if I can convince the missus to let me do all the other stuff I want to do. Don't like my chances, she's still a tad upset about the bingle in the passenger door from the last little escapade :cry: It's all Big Reds fault for making it look like so much fun. :lol:

[big red]

remind me not to meet your missus then :lol:

[V8Patrol]

Probably a dumb question but ........


Do other makes suffer the same shudders once similar mods are done or is it just a nissan thing :roll:
I have never heard of any other makes doing it except the "older Jeeps"

Kingy

[spider]

Yeah, my wifes pretty dark at you Red. I'll goto explain some of the mods I'd like to do and as soon as I mention your red patrol the conversation usually ends straight away with her saying "OH :evil: THAT ONE :angryfir:




:bigthumb:

[big red]

umm hows it go again ...
"wasn't me"

:oops:

[spider]

Its OK. I'll just have to spend a bit of money on her :wink: . It'll just delay the truck a bit. :cry: