Knocking Noise

[GSSPORT]

Hi All,

I was wondering whether someone could help?

I have a GS 300 Sport MK2 2000 model. There is a knocking noise from the front suspension in a straight line when going over minor bumps and imperfections in the road, but I will always hear in when driving right into my drive over a hump. I have had mechanics (non-lexus) check and they can't find the problem.

They have said that the ball joints and shockers are fine and I have tried to move the calipers by hand through the alloy wheels to see if there is any movement, but I can't see any (I could be doing this bit incorrectly ).

Oh and I do have warped brake discs (vibration from 30 mph onwards) this could be factor (to be replaced next week).

Any help or experiences from fellow lexus owners would be really useful. :)

Many Thanks

[maneesh]

Sounds like the control arm bushes are worn. What's the mileage on yours?

[GSSPORT]

Sounds like the control arm bushes are worn. What's the mileage on yours?

Hi

The mileage is exactly 100k. If it is the control arm bushes how can I check them???? I have also read that it could also be the anti-roll bar and if so how can I check it??

Thanks Maneesh

[Damer]

I have a similar thing on my IS200. Been to dealer a few times can't find what it is, my wife thinks I imagine it.

[maneesh]

At that mileage, all GS and LS models suffer from worn bushes. Most owners don't notice worn bushes, as they wear out so slowly over time.

I don't know myself how to check them. If you are handy with DIY, then your best best is to ask on the US forums, as they do this day in/day out there.

It sounds like the upper control arms, from what you have described. Lexus will only supply complete control arms (at great cost), you cannot get the bushes separately from Lexus.

However, companies are offering alternatives. TM engineering in the States sells polyurethane bushes as an alternative to replacing the entire control arm, which can save you a huge amount of cash. See website.

http://www.tmengineering.net/suspension/daizen/make/gs.html

They sell replacement bushes for all front arms for approx 60 quid. Same for rear arms. You can also get anti-roll bar bushes off them too.

Bear in mind that if the central bush (i.e. upper ball joint) in the upper control arm has worn, then you have no option but to replace the entire arm. With worn lower control arm bushes, the ball joint is available as a separate unit, so it's only the lower ball joint you would need to buy from Lexus, the other two bushes you could replace using the Daizen kit.

It doesn't sound like anti-roll bar bushes to me, but here's hoping that's all it is, as those are pretty cheap, even to get hold of from Lexus UK.

[maneesh]

Forgot to add, if you fit the Daizen bushes, you will need to burn the old ones out!

[GSSPORT]

Thanks Maneesh,

I'll check out the US forums and if necessary buy from the US too. Any ideas on how much the labour would cost..seems like a big job?

Thanks

[maneesh]

If you can find a decent mechanic who can burn the bushes out, then shouldn't be that expensive. Perhaps a few hours labour for each side? The anti-roll bar bushes are quick, you could even do them yourself.

Make sure you get them to put lots of grease if you go with the Daizen bushes, to stop them squeaking. Whilst the new control arms would come with new rubber bushes, the polyurethane replacement bushes are firmer and have less "flex" so ride quality may be a tad firmer, but handling will improve significantly.

[GSSPORT]

If you can find a decent mechanic who can burn the bushes out, then shouldn't be that expensive. Perhaps a few hours labour for each side? The anti-roll bar bushes are quick, you could even do them yourself.

Make sure you get them to put lots of grease if you go with the Daizen bushes, to stop them squeaking. Whilst the new control arms would come with new rubber bushes, the polyurethane replacement bushes are firmer and have less "flex" so ride quality may be a tad firmer, but handling will improve significantly.

Many Thanks Maneesh,

I have bought some anti-roll bar bushes to spice up the handling abit, which I will be fittting in a couple of weeks. Whilst I'm under the car I will check the central control arm bushes

Many Thanks for the excellent advice

[GSSPORT]

If you can find a decent mechanic who can burn the bushes out, then shouldn't be that expensive. Perhaps a few hours labour for each side? The anti-roll bar bushes are quick, you could even do them yourself.

Make sure you get them to put lots of grease if you go with the Daizen bushes, to stop them squeaking. Whilst the new control arms would come with new rubber bushes, the polyurethane replacement bushes are firmer and have less "flex" so ride quality may be a tad firmer, but handling will improve significantly.

Many Thanks Maneesh,

I have bought some anti-roll bar bushes to spice up the handling abit, which I will be fittting in a couple of weeks. Whilst I'm under the car I will check the central control arm bushes

Many Thanks for the excellent advice

Hi All,

I thought it would be useful to provide an update on the saga.

I changed my disks and pads together with the anti-roll bar bushes (front and back). The mechanic charged me £70 and the new parts were Lexus.

The good news is that it worked, there is no knocking noise from the front and the car handles the road alot better. However, the problem could have been that the bottom slider pin on the caliper was a little lose, the mechanic feels that it could have been either the brakes or bushes. The buhes were a little soft but no completley worn.

One more question. Would anyone know how long it takes to bed in a new set of pads and disks. I have been told "not to work them hard". But its pretty difficult when your always on the motorway.

Thanks

[maneesh]

Some reckon 200 miles for bedding-in.