Outer Limits 4x4 Board

i have read a lot of posts about shimmy and have corected everything that has been yhe sugested cause (bushes, steer joints , adj steer box made panhard parallel with drag link etc) i have also decreased castor to what i measure as 1.5 degrees but am curious whhether the steer knuckles are the best place to measure from or should i rremove them and measure from the bearing cups



any other ideas will be appreciated


for those who ont know the truck it is a 94 disco with gq diffs

May not be the solution but a mates GQ had the dreaded "shimmy" and after doing pretty much every bush in the front end and a wheel alignment/balance we put in a new steering dampener and problem solved .
May be worth a try.

tried 2 diferent dampners 1 rancho and 1 tougj dog rtc it also now runs tough dog big bore adjustables

I'm sure you've already been down this track but my steering box was leaking and hydraulic oil would leak down chassis and onto top panhard rod bush.

I was well overdue for adj panhard rods anyway with a 5" lift and having twice bent and straightened the rear one.
Anyway, new bushes, shimmy went away. s/box still leaking

within a week it was back

I replaced every damn bush,even on control arms, repacked wheel bearings, checked cv's and swivel hubs, you name it, nothing

Then i noticed top panhard rod bush had excessive movement. i hadn't bothered checking this again because it'd just been replaced.

sure enough, power steering fluid had destroyed the nolethene bush within a week. i fixed the leak, replaced bushes with gen rubber nissan's, no shimmy!!

onto second set of panhard bushes still no fix but something i have noticed is that with the shocks let down i feel every bump and groove in the road even through a good rancho dampner?


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that to me says too much +castor but i could be wrong i often am
but by putting my angle gauge on the king pin plate there is only 1.5 degrees + castor

Have you gone and got a wheel alignment. That should tell you exactly what your castor angle is. Eliminating one problem area.

king pin bearings replace them and pull the shims out

Leading arm bushes and panard bushes are the major causes. Very badly balanced tyres another. Bearings need to be checked to make sure no wobble in wheels. Use genuine rubber bushes.

LudaCris

IMO the bearing cap preload is not right in the specs.
Ive removedthe shims top and bottom and the slight chnage in the bearing load dramatically drops the shimmy.

Of course this assumes adequate alignment/ balance and true geometry.

Ive done this on GQ that have shot steering dampers and it still makes a huge difference

how are your wheel bearings???

all bearings and bushes are newwill get alignment done this weekend and see what they say to me i think it is castor
my main q was where do you measure it when u have?

i have 35's on mine and it gets the hippy hippy shakes at about 90kph.... intensifies up to arounf 100kph and dissapears at about 110..... i have a brand new rtc damper on it, made no difference at all..... it did slow down a little when i put the 5 degree castor plates on... all my bushes are ok, no play at all.... i suspect i may have some dodgy MT/Rs on it..... I'm going to get all 5 re-balanced and put the best 4 on the patrol.... somebody suggested getting them balanced on the vehicle.

RoeDao wrote: somebody suggested getting them balanced on the vehicle.

Bob Jane I think it is do a Silver and Gold balance or different levels of balance.
Its been a while Bazzle mentioned it. But basically they keep takin tire off rim to get the balance best to use minimal weights.

yes my GU had bad shake in the wheel from 80 up to 95 k's...

Tried a few things & asked around.

Took it to a tyre place who knew what they were doing where they balanced the tyres properly (33's). shake no more!!!

If your running 33-35's + i strongly suggest you try this!

Coey suggested a place that balances from the stud holes and not the centre hole...... there is a place in town here that does that.

my tyres ar notthe prob as i have tryed 3 sets of tyres and rims no difference

cooter wrote:my tyres ar notthe prob as i have tryed 3 sets of tyres and rims no difference

mate you should have 3 degrees postive castor with gq diffs, Try rotating the tyres front to back.
I personally measure castor of the top swivel hub cap and hav'nt had any problems.
Also i know this has been said but check the wheel bearings swivel hub bearings and tie rods for any movment.

all bearings and bushes are spankin newcastor is 3 degrees toe in is 5mm

still shakey i mean tear the wheel from ur hand shakey

cooter wrote:all bearings and bushes are spankin newcastor is 3 degrees toe in is 5mm

still shakey i mean tear the wheel from ur hand shakey

What speed?

who balanced the wheels? have you tryed rotating the front wheels to the back?

My brother had that problem on his gu replaced drop arm bushes tightend
wheel bearings. Made minimal difference. Looked past panard bushes. Gave the steering wheel a bit of a lft hand down,right hand down real quick the panard was sloppy as. Replaced bushes problem gone.

I have had the problem in 2 cars a MQ (really bad!) and a GQ (not so bad could drive out of it), as kirragc advised the swivel hub preload makes the biggest difference bar none, that is the starting point then move on from there, just my experience and it worked straight up on both cars with only a small amount of fiddling with other bits, on the MQ it needed to torque the spring plate's up and on th GQ the tie rod ends needed replacing. The most of the MQs bushed were near buggered but didn't get replaced also the GQs bushes were in great condition.

From that point on the only time the MQ ever did it and only slightly was fully loaded and towing at speed with the nose of the car pointing up with less weight on the front tyres. Just my experience.

If you do attempt it make sure the shim spacing top/bottom is identical or else the oil seal can leak early.

cheers fnq

i will be romoving the thick shims this week and will check if there is change

May bit of a long shot but I had a problem with the chasiss cracked around panhard/steering box mount. Was a problem on early GQ's(88-91). Was on way to Cruiser park when it let go, was only 5min down road luckly, couldn't drive it over 40kph. Just a thought mate.

Have the same prob, 88gq stock everything (yeh yeh boring). Have a bad shake just before 60ks, goes away at around 70 then comes back around 90-100 and goes away beyond 110.
New tyres, wheel align, balance, bearing adjustment etc, saving pennies for suspension lift.
Was sure the wobble came from the back, blew a brand new rear tyre that ripped shreds off the gaurd, thus the new tyres all around again.
Be interested to know what the prolem is..

cooter wrote:i will be romoving the thick shims this week and will check if there is change

Dont just remove shims (thick).
If loose remove thin ones equally top and bottom. Check load on housing as you rotate.

Wheel bearings may be new but preload can be incorrect.
Check panhard bushes again using hand wrapped over bush as someone wiggles steering wheel to feel for play.
Most of these issues are
1. Wheel balance or radial runout
2. Panhard bushes

Caster issues just amplify probs in other areas.

Bazzle

yeh panhard bushes are a bastard specially nolathane as they are hard to fit withoutb tearing them but there is no movement there

set toe to +1 still shakey
removed some shims still shakey

Sounds like the shims might be a dead horse. Did you measure the preload after?, the right setting ends up stiffer than than one might expect if they had not measured it before.

cheers fnq

was 5 Lb after removed went to 10 or so

when your looking for movement in the panyard bushes, with neoprene style fitted how much movement should there be?any at all..i have some,but has had leaky steering box fluid on them..gone soft??

i have shimmy i can not get rid of,and its bad too.hit a hole over 50mph and its brown pants time!!

car is a range rover,but suspension is the same really..i have renewed and adjusted EVERYTHING to do with wheels,bushes,swivel preload tyres steering etc..

this suspect bush is my last hope before replacing complete front end.(which i dont want to do!!)

any thoughts?