I get a substantial wobble through the steering wheel at around 60mph. It's not so bad at less or more than that speed. Also I sometimes get a judder under breaking, though not always.

I've changed the front pads and disks in case they were warped. I've had the wheels balanced and ensured correct tyre pressure. Still the wobbles and judders persist.

Any tips on what else to check ?

I would check the balljoints next, top and bottom. And probably check the track rod ends for play too.

It's easy to spend a small fortune trying to sort this one out. I've been there.

Take my tip. Get the front and rear wheels swopped and see if it disappears. One front wheel with a slight buckle will cause this and it doesn't necessarily show up on a balancing machine.

Im with Tigerfish, get the ball joints checked

My GS has been balanced countless numbers of times and spent 4 whole days at a dealer who couldnt work out what was wrong with any of the suspension / steering.
Even tried balancing the wheels on a hunter 9700 road force balance machine ...and a visit to WIM to check the geometry - solved the prob for a while but its back.

Consistent advice seems to point to the non OEM rims I have and the fact the offset is different (35 vs 50) - Ive eventually bought some this last weekend and having them fitted and road force balanced tomorrow.
As the wrong offset alters the geometry im also having a geo check tomorrow too.

Hopefully the end of my woes.

Mine is worse some days than others and particular road surfaces seem to make it better/worse.

By all means get the ball joints and track rod ends checked out but also consider looking for a road force balance machine - they are pretty rare - I have a link for UK garages with one (http://www.pro-align.co.uk/amc/centrelocator.htm) but not Ireland unfortunately.
Go to the Hunter website to see all the reasons why they are better.
Another member on the site had same issues with his GS - and after going to have his road force balanced he was happy as anything. He had oem rims.

Also - If you dont have OEM rims then could be to do with the incorrect offset - but I'll know more about that tomorrow ;o)

Good luck - and let us know how you get on.

Another thing - check the torque on your wheel nuts and ensure they are tightened in the correct order - Lexus wheels have a low torque spec compared to most cars and the idiots in most garages use impact wrenches or dont torque at all so then end up being at ~160 - way above what they should be. This can also cause vibration issues

Ive had the exact same issues with my Aristo. It appears to be the ball joints on my car...........replacements arrive Friday from Chris at Cheaptoyotaparts.co.uk

Good Luck

Anees

Anees- that site is poo! Cannot view all items so I have emailed them instead!

I have the wobble myself but my brake disc is warped so will get that changed first!

Anuj you are right, you can't view anything on the site. But they are very quick at replying to emails and Chris is very helpful on the phone. You basically make sure you have what you want, then they send you a paypal link via email to pay (you don't have to have paypal to pay). Front ball joints for my car were £65 delivered, which is pretty good I thought

Find a road force balance machine it sorted mine out and never had a wobble since, thanks to Mark W.

did all 4 wheels at a cost of £40 and well worth it.

Im in touch with Ravi from Japarts.co.uk

£51 per ball joint! so will go for these IF my wobbles aint sorted

Just bought 2x front discs, 2x front brake pads

All OEM genuine Lexus

£195 delivered.......saving of around £35 from buying from lexus!

"Apart from the usaul CLUNCK noise when turning" how else would you know that a ball joint is fooked. .ive got the same sort of wobble at 50mph + all wheels are fine,all been balanced at WIM..Geo is spot on & had new front Mintex disc`s and pads fitted but still got the wobble`s..

Are they genuine Lexus parts?

My first GS did exactly the same thing. I went through all the usual checks and found the fault by accident. I had a sticky front brake caliper. I stripped both of them, cleaned off all the muck and put it all back together. Wobble cured and never returned.
I found it when one of my front wheels felt warm compared to the other one after a run home from Blackpool I think. It wasn't sticky enough to cause a pull on the brakes but it did stick on to cause a wobble at a certain speed that I could drive through.