Slight knock from front

The-Acre · March 31, 2018

Does this sound familiar to anyone? When I drive over slightly uneven roads I hear what wouldn't necessarily be called a knock, but it's the only way I can describe it. It's not loud, just annoying. Its not one knock but continuous over that kind of surface. Definitely coming from front drivers side. I'm booked in somewhere on Wednesday but thought I'd ask in case others have had it. Maybe I'd say it's more of a muffled rattle. I can't feel it through the steering. Thanks

rayaans · March 31, 2018

29 minutes ago, The-Acre said:

Does this sound familiar to anyone? When I drive over slightly uneven roads I hear what wouldn't necessarily be called a knock, but it's the only way I can describe it. It's not loud, just annoying. Its not one knock but continuous over that kind of surface. Definitely coming from front drivers side. I'm booked in somewhere on Wednesday but thought I'd ask in case others have had it. Maybe I'd say it's more of a muffled rattle. I can't feel it through the steering. Thanks

Top suspension mounts or bushes I would have thought.

Britprius · March 31, 2018

I have the same problem on the GS450H. I have replaced the anti roll bar links, fitted refurbished front shocks, and it passed the MOT with no advisories. I cannot feel the knock through the steering, and although not a metal on metal noise the only way to describe the noise is as a knock from the drivers side.

I am about to replace the rear roll bar links just in case, but I really do not think it's them. All the bushes look in good order, and there is no play in the ball joints or roll bar bushes.

The noise comes from low down on the suspension,and it is not caused by worn caliper pins. The noise sometimes will be evident from the drivers side when the passengers wheel goes over rough a surface.

John

ColinBarber · March 31, 2018

If you can find a road that will induce the sound, try driving over the uneven area with your brakes lightly applied - if it still does it then that rules out play in the calliper / brake pads.

The-Acre · March 31, 2018

47 minutes ago, Britprius said:

I have the same problem on the GS450H. I have replaced the anti roll bar links, fitted refurbished front shocks, and it passed the MOT with no advisories. I cannot feel the knock through the steering, and although not a metal on metal noise the only way to describe the noise is as a knock from the drivers side.

I am about to replace the rear roll bar links just in case, but I really do not think it's them. All the bushes look in good order, and there is no play in the ball joints or roll bar bushes.

The noise comes from low down on the suspension,and it is not caused by worn caliper pins. The noise sometimes will be evident from the drivers side when the passengers wheel goes over rough a surface.

John

Well that sounds like the same thing. When my calipers were being re-greased a couple of weeks ago I got the mechanic to check and he said nothing has any play at the front end. I'm driving to Austria in three weeks so I need to be sure it's safe. It'll be interesting to see what the other place comes up with on Wednesday. Like you, I'd definitely say it's not a metallic sound. I can't hear it with the door open or window down, and it wasn't there when I bought it in January, and I don't really notice it over big bumps, just on the slightly uneven areas (of which there are many in Sussex!)

The-Acre · March 31, 2018

1 hour ago, rayaans said:

Top suspension mounts or bushes I would have thought.

I must admit, I do have the feeling it's suspension related.

The-Acre · March 31, 2018

39 minutes ago, ColinBarber said:

If you can find a road that will induce the sound, try driving over the uneven area with your brakes lightly applied - if it still does it then that rules out play in the calliper / brake pads.

Thanks Colin, I did try that but it made no difference.

Britprius · March 31, 2018

1 hour ago, The-Acre said:

I must admit, I do have the feeling it's suspension related.

Check the anti roll bar links to be sure it's not them. You can best check the by undoing the top ball to roll bar joint as this can be reached without removing the wheels or jacking the car up just turning the wheels on full lock.

If after removing the top ball from the roll bar either ball joint can be articulated easily with your fingers the joint is worn out. It should be very difficult to move with your fingers almost as if they were seized.

John.

ColinBarber · March 31, 2018

1 hour ago, Britprius said:

My previous reply seems to have disappeared, but my GS450H has the same problem so I will repeat below.

There appears to be two threads for the same topic.

I've now merged them.

Edited March 31, 2018 by ColinBarber

Sherra · March 31, 2018

I had a similar problem on my 1998 Camry Sport which took years to find but turned out to be the anti roll bar links as mentioned by Britprius.

The-Acre · April 4, 2018

While I was getting my 02 sensor fitted today I got them to check the knocking and they say anti roll bar links. I haven't got time to do it so it's going in on Friday. I'll report back on the outcome. At least the warranty covers this... apparently.

Britprius · April 6, 2018

On 4/4/2018 at 5:30 PM, The-Acre said:

While I was getting my 02 sensor fitted today I got them to check the knocking and they say anti roll bar links. I haven't got time to do it so it's going in on Friday. I'll report back on the outcome. At least the warranty covers this... apparently.

I hope that will cure the problem for you.

I have also traced the problem with my car. This turned out to be the anti roll bar rubber bushes. It is difficult to find movement in these as the slightest loading from side to side of the car loads the bushes.

I have done a temporary repair "until new bushes arrive" by removing the bushes then increasing the gap in the bush with a hacksaw by about 2mm then fitting a square of plastic about 2mm thick under the bush then tightening the "U" bracket back up. This has completely eliminated the Knock.

I would suggest changing these bushes when replacing the roll bar links.

John.

The-Acre · April 6, 2018

1 hour ago, Britprius said:

I hope that will cure the problem for you.

I have also traced the problem with my car. This turned out to be the anti roll bar rubber bushes. It is difficult to find movement in these as the slightest loading from side to side of the car loads the bushes.

I have done a temporary repair "until new bushes arrive" by removing the bushes then increasing the gap in the bush with a hacksaw by about 2mm then fitting a square of plastic about 2mm thick under the bush then tightening the "U" bracket back up. This has completely eliminated the Knock.

I would suggest changing these bushes when replacing the roll bar links.

John.

Thank you for that. It seems the anti roll bar links were a misdiagnosis so the knock remains. I don't mind as it wasn't an expensive job, and at least it's something less to go wrong in the future! Who did you order the bushes from and how much?

Britprius · April 6, 2018

2 minutes ago, The-Acre said:

Thank you for that. It seems the anti roll bar links were a misdiagnosis so the knock remains. I don't mind as it wasn't an expensive job, and at least it's something less to go wrong in the future! Who did you order the bushes from and how much?

I ordered the bushes from a local motor factor. They have quoted £16 for the pair, and that seems a good price going by eBay prices. The dealers are 100 mile round trip for me.

Shimming out the play as in my previous post works well, and is easy to do even "if only done for elimination purposes". It is very easy to do the hardest job is removing the plastic shield over the mounting bracket (three 10mm self tappers). The brackets are held by two 14mm socket size bolts.

John

The-Acre · April 6, 2018

2 hours ago, Britprius said:

I ordered the bushes from a local motor factor. They have quoted £16 for the pair, and that seems a good price going by Ebay prices. The dealers are 100 mile round trip for me.

Shimming out the play as in my previous post works well, and is easy to do even "if only done for elimination purposes". It is very easy to do the hardest job is removing the plastic shield over the mounting bracket (three 10mm self tappers). The brackets are held by two 14mm socket size bolts.

John

I've ordered a pair so they should be with me in a couple of days. So presumably you do it just by removing the wheel, no crawling underneath? Strange really, of all the jobs I've done on cars over the years I've never done this one. It'll be nice to get rid of the noise, especially as I've more or less taken car of the creaks. It's also nice not to have the VSC check light on now!

Britprius · April 6, 2018

29 minutes ago, The-Acre said:

I've ordered a pair so they should be with me in a couple of days. So presumably you do it just by removing the wheel, no crawling underneath? Strange really, of all the jobs I've done on cars over the years I've never done this one. It'll be nice to get rid of the noise, especially as I've more or less taken car of the creaks. It's also nice not to have the VSC check light on now!

You can change the bushes without removing the wheels "just turn them either way on full lock", but it is easier with the wheels off. You can then reach them through the wheel arch without getting under the car.

There is a plastic cover over the "U" brackets held by the three self tapping screw, and one clip. You can then unscrew the two bracket holding bolts to remove it. The bush will then slide along the anti roll bar, and opened up at the split to remove. Takes about 15 to 20 minutes per side.

Shimming mine has definitely stiffend up the front end. Less body roll, and a tighter steering response.

John.

The-Acre · April 6, 2018

8 minutes ago, Britprius said:

You can change the bushes without removing the wheels "just turn them either way on full lock", but it is easier with the wheels off. You can then reach them through the wheel arch without getting under the car.

The is a plastic cover over the "U" brackets held by the three self tapping screw, and one clip. You can then unscrew the two bracket holding bolts to remove it. The bush will then slide along the anti roll bar, and opened up at the split to remove. Takes about 15 to 20 minutes per side.

Shimming mine has definitely stiffend up the front end. Less body roll, and a tighter steering response.

John.

Thanks John, I really appreciate it. I'll let you know how I get on.

The-Acre · April 11, 2018

The bushes arrived today but sadly I still have the "knock". A strange one this, no-one can find anything wrong/worn. Still, at least I have new links and bushes! I can only think shock absorbers next, although they feel fine over bumps. Maybe I'll just live with it for a bit.

Odysseus · May 10, 2018

I’m following this thread with interest as my GS450 has developed what I’d call a knock/clunk from the suspension in the last few months. It’s definitely more evident when the car is fully loaded or if you encounter a bump on the road while taking a corner while the suspension is loaded.

The car is booked into Lexus in a few weeks for a MOT and I’ve asked them to look at it then.

My car is 10 years old this year and has covered 70,000 miles.

What are the symptoms of worn out shocks?

Sent from my Iphone using Tapatalk

The-Acre · May 10, 2018

1 hour ago, Odysseus said:

I’m following this thread with interest as my GS450 has developed what I’d call a knock/clunk from the suspension in the last few months. It’s definitely more evident when the car is fully loaded or if you encounter a bump on the road while taking a corner while the suspension is loaded.

The car is booked into Lexus in a few weeks for a MOT and I’ve asked them to look at it then.

My car is 10 years old this year and has covered 70,000 miles.

What are the symptoms of worn out shocks?

Sent from my iPhone using Tapatalk

I think what you describe sounds different to mine. I don't hear any difference when loaded or cornering. I've covered 2.5k miles since my first post and it hasn't worsened. Two mechanics have looked and neither can find anything amiss. I would have thought signs of leakage might be the first evidence of shocks going to meet their maker. You may be lucky and find it's as simple as anti roll bar bushes as suggested to me. I'm due for a service soon so I'll get them to dig a bit deeper.

is200 Newbie · May 10, 2018

Could this be an issue with a broken suspension spring?

Hadrian · May 10, 2018

In my experience with (2) broken front springs, I only got a grinding noise when reversing.

The-Acre · May 10, 2018

1 hour ago, is200 Newbie said:

Could this be an issue with a broken suspension spring?

That could certainly be the case with Andrew's GS, mine sounds more like the exhaust just slightly touching but it isn't.

is200 Newbie · May 10, 2018

Another point - the IS had an anti rattle rubber shim on the slide pins - pretty sure its the top one on the front callipers only.

Put on there to prevent rattle I found out a while ago. But, I removed them anyway with no issue on an old IS200 I had as they split while greasing the pins and when re-assembled they did not rattle

just a thought though

The-Acre · May 10, 2018

1 hour ago, is200 Newbie said:

Another point - the IS had an anti rattle rubber shim on the slide pins - pretty sure its the top one on the front callipers only.

Put on there to prevent rattle I found out a while ago. But, I removed them anyway with no issue on an old IS200 I had as they split while greasing the pins and when re-assembled they did not rattle

just a thought though

I've tried just lightly applying the brakes in case it's the calipers but it doesn't make any difference. I only notice it up to 15-20 mph and only over the slightest road imperfections. I'll find it eventually as it can spoil an otherwise quiet ride.