prado steering wander

[Heath]

I am considering selling my 96 SWB Prado but have an issue with the steering wandering and want to get it sorted before selling (and if it doesn't sell for a while I may as well be comfortable).

My steering rack failed at last Warrant of fitness (6mths ago - buggered beyond repair - didn't notice seemed fine to me) so was replaced with second hand unit (in good condition I was told) and all was good for 6 mths. Went in for a Wof last week and the steering rack was buggered again, but repairable this time. Also got failed on rear tyres (one had a slash down to the steel belts - didn't see it) so I replaced the rears with some near new tyres (Nangkang Mudstars 265/75/16 - fronts are same size but khumo kl71 almost worn out and need replacing soon). A Wheel align was done and all good.

The steering feels like it is wandering all over the place now when driving and I am having to make constant corrections to steering to keep going straight. It's like I am driving down train tracks and the wheels are diving left and right incrementally.

Could this be the difference in the tyres causing a problem (rears fighting the fronts due to slightly smaller rolling diameter or different tread pattern) or should I look more at the steering rack area? Tyre pressures are all good (actually since I set them all up at 41psi it is worse/ more noticeable - thinking tyres might be the issue) and where I always had them with the original set of kl71's.

If I had just done the rack or the tyres then it might be easier to pin down but now I am confused as to which is the cause of the wander.

I have tried to get the rack to move (wiggle on its mounts) but it feels tight. I assume that when the rack was out the rack mounts were checked and all was tightened back up to spec.

Might see if I can grab another pair of tyres tomorrow to replace the front ones so I have near new tyres all round.

Heath.

[churchill]

Check the lower hub ball joint, these have a habit of wearing and dropping out.

[Jerry]

the bushes on the steering rack are a common wear item on the 90's and can cause this, bout 80-100 for new ones

[mud_slinger]

post up your last wheel alignment print out

[Heath]

Left Right
Camber -0deg40' 0deg03'
caster 3deg51' 3deg15'
toe 1.3mm 0.8mm
SAI 12deg36' 10deg35'
Incl Angle 11deg56' 10deg38'

Cross camber -0deg43'
cross caster 0deg 36'
total toe 2mm

the bushes on the steering rack are a common wear item on the 90's and can cause this, bout 80-100 for new ones

Is that the mounting bushes? I would have thought this would be picked up during removal and install.

[Jerry]

i had to do mine in the green playdoh at 140k

[Heath]

I would've thought these would degrade slowly, not just fail overnight.

[zukmeista]

40psi sounds a bit high for the size of the truck to me.

[Heath]

Sounds like putting the new tyres on the rear are the problem, which I made worse with the tyre pressures I am running. The new tyres need a lower pressure than the old ones. I'll get another two tyres and lower the pressures.

[Heath]

Well two new tyres to match the rears, pressures dropped to 36psi and its better but still there. So its back to the mechanic so they can check what they did is all good and tight. I'll be pissed if the bushes are buggered and they didn't pick it up the two times they have had the rack out. Feels like something is loose.

Guess I drive carefully until I get it sorted on Monday. Hope it doesn't cost me more fore something they should've picked up.

We'll see I guess.

Of course I could just be so used to driving on what were essentially road tyres (due to lack of tread) that I have forgotten how squirmy MT tyres are.

[Heath]

Steering bits and pieces all checked out and all okay (tight and as they should be).

Chatted to a mate last night and he runs the same tyres (diff size) as muds . Has two sets so he swaps back and forth as required with the highway terrains. He says I have been spoiled with the road manners of my old kl71 road tyres (not enough tread to be anything else) and should get used to the new muds with time as his squirm around a little compared to his road tyres.

I'll get the wheel align rechecked just to be certain, but it looks like the taller tread blocks flexing is the cause of the issue. I wish I had had the chance to do the rack and then the tyres separately so I could keep track of changes and what caused them.

Feel a little foolish to be honest panicking but wanted to be sure all was good and safe before selling.

[mud_slinger]

i can do ya wheel alignment heath if you want, but the catch is im in goon tho

[Heath]

i can do ya wheel alignment heath if you want, but the catch is im in goon tho

Cheers for the offer.

I rang the guy who did the one last week and he said to bring it back in and they will have another look. If they don't make any difference or bother trying then I'll be happy to go for a drive over the "northern moat" (and get a second opinion - I'll PM you for details if it gets to that).

Heath.

[mud_slinger]

i think the camber on the left is to negative and the camber on the right needs to be more positive

[Heath]

i think the camber on the left is to negative and the camber on the right needs to be more positive

Cheers for that. I'll mention it.

Is that something that would've changed when the rack was done? I guess the old tyres were worn to suit the difference so it wasn't noticeable until the tyres were changed.

[mud_slinger]

no that would have had no effect on it at all, unless they had to remove the arms but from memory you dont need to

[Heath]

no that would have had no effect on it at all, unless they had to remove the arms but from memory you dont need to

Okay, I guess its been like this for a while then and the old tyres must have been hiding the effects (must have been worn to suit) and the new tyres are less forgiving?

[mud_slinger]

your tyres would have worn to suit the way the alignment was

[Heath]

Alignment checked - all okay.

Steering box is a bit tight and is restricting the return to centre of the steering so is the problem (not so much wandering as not returning to centre freely). The test driver described it as a dead feeling. Been told to drive it for a few more kms and see if the box frees up a little. If not I'll take it to the power steering guys who did the job and they can sort it.

[mud_slinger]

wat year is the prado? pretty sure they rack and pinion so essentially no steering box

[Heath]

wat year is the prado? pretty sure they rack and pinion so essentially no steering box

96 - yeah sorry old school term from me (still think in inches and yards although I was a metric kid - dads influence I guess),it's a r & p setup.

[Heath]

Done a couple of hundred Kms since the align check and it is better. Less wandering (which was the steering sticking due to tightness of the rebuild), so I guess I can call this problem sorted and be confident when I sell it that the new owner will have no problems.

[00falcon]

Unsure if this is going to help, but my ,99 wrangler does the same.
I noticed it today especially i the high winds...

It doesn't want to track in a straight line.
it wanders a bit.

I have had it in my mind for some time now, that my caster is to light...

I think spec caster, for a ,99 wrangler is 7deg +-1deg
and mine is sat at about 5.5deg.

I just need to shorten my upper control arms... (next weekend)

What has made me comment is your caster at just over 3deg...
i dont know what prado caster spec is...
But hey...

Also, off topic sort of.
But i think, tire size affects what your caster should be...
Caster changes your SAI relative to the ground, and tire size alters this...
But im still trying to get my head around the math behind that...