Drone From Back Of Mki Gs300 - Worse At 30 Mph

[GS Sport]

Hi LOC USA,

A call for help from the UK.

I have a '97 GS 300 MkI and it has developed a drone from the backend. The noise doesn't seem to increase on cornering so I'm thinking not a wheel bearing, although sometimes it does seem to increase on roads with a steep camber. Braking makes no difference either, the noise remains under braking. It also doesn't change under accelleration. The noise is at it's loudest around 30 MPH. I've checked the level of oil in the differential and this is fine. I did have the rear wheels tracked due to tyre wear on the inner rim. I'm thinking about getting a full geometry check at Lexus but not really sure if this would cause a noise like this droning. If it were geometry wouldn't the noise be simular at all speeds? The car is fitted with the 10.5 inch rears which I guess will cause road noise but this noise wasn't there from when I bought the car. Do the tyres produce more noise as the treads wear?

Sorry so many questions but I'm at a loss with this. Any one with any suggestions would be greatly apprieciated as this noise is driving me nuts!

Thanks in advance.

Ian.

[stroked4.6]

Hi LOC USA,

A call for help from the UK.

I have a '97 GS 300 MkI and it has developed a drone from the backend. The noise doesn't seem to increase on cornering so I'm thinking not a wheel bearing, although sometimes it does seem to increase on roads with a steep camber. Braking makes no difference either, the noise remains under braking. It also doesn't change under accelleration. The noise is at it's loudest around 30 MPH. I've checked the level of oil in the differential and this is fine. I did have the rear wheels tracked due to tyre wear on the inner rim. I'm thinking about getting a full geometry check at Lexus but not really sure if this would cause a noise like this droning. If it were geometry wouldn't the noise be simular at all speeds? The car is fitted with the 10.5 inch rears which I guess will cause road noise but this noise wasn't there from when I bought the car. Do the tyres produce more noise as the treads wear?

Sorry so many questions but I'm at a loss with this. Any one with any suggestions would be greatly apprieciated as this noise is driving me nuts!

Thanks in advance.

Ian.

Its sounds to me like this is differential related. Are there any abnormal vibrations while driving? Have you tried putting the car in neutral while going around 30mph? Does the noise change? I was on a test drive with a tech and was listening for a noise so he sped the car up put it in neutral and turned the car off to track down the problem. You might want to try this. I’ve heard a couple bad differentials and this is what it sounds like. A droan coming from the diff. With your symptoms you could us a process of elimination and everything points towards the differential.

[GS Sport]

Hi LOC USA,

A call for help from the UK.

I have a '97 GS 300 MkI and it has developed a drone from the backend. The noise doesn't seem to increase on cornering so I'm thinking not a wheel bearing, although sometimes it does seem to increase on roads with a steep camber. Braking makes no difference either, the noise remains under braking. It also doesn't change under accelleration. The noise is at it's loudest around 30 MPH. I've checked the level of oil in the differential and this is fine. I did have the rear wheels tracked due to tyre wear on the inner rim. I'm thinking about getting a full geometry check at Lexus but not really sure if this would cause a noise like this droning. If it were geometry wouldn't the noise be simular at all speeds? The car is fitted with the 10.5 inch rears which I guess will cause road noise but this noise wasn't there from when I bought the car. Do the tyres produce more noise as the treads wear?

Sorry so many questions but I'm at a loss with this. Any one with any suggestions would be greatly apprieciated as this noise is driving me nuts!

Thanks in advance.

Ian.

Its sounds to me like this is differential related. Are there any abnormal vibrations while driving? Have you tried putting the car in neutral while going around 30mph? Does the noise change? I was on a test drive with a tech and was listening for a noise so he sped the car up put it in neutral and turned the car off to track down the problem. You might want to try this. I’ve heard a couple bad differentials and this is what it sounds like. A droan coming from the diff. With your symptoms you could us a process of elimination and everything points towards the differential.

Thanks for the response.

No vibrations while driving. I've tried putting the car into neutral at 30mph and there's no change in the sound - if it were a diff problem would the sound lessen or dissapear? A couple of people have suggested a wheel bearing and have said that even with the car jacked up there may not be any noticable movement in the wheel, don't know if this is true?

Thanks again for the response - i'll post when I finally track it down.

Ian.

[rdefabri]

Ian,

I have a 2000 GS400, exact same problem. Mine occurs at 40 mph, even in neutral. Mine sounds a lot like radio interference, but of course the radio is off. It doesn't increase in pitch, but gets louder once I hit 40 then goes away at like 42 mph...it's very high pitched.

No vibrations or anything when driving, just this noise.

HELP!

Rich

[dcfish]

Ian,

I have a 2000 GS400, exact same problem. Mine occurs at 40 mph, even in neutral. Mine sounds a lot like radio interference, but of course the radio is off. It doesn't increase in pitch, but gets louder once I hit 40 then goes away at like 42 mph...it's very high pitched.

No vibrations or anything when driving, just this noise.

HELP!

Rich

Have you guys changed your diffy fluid ? Go to synthetic, It definetly helps smooth things out.

[rdefabri]

That sounds logical - my noise goes away as the car warms up...so it's worth a shot (and a cheap fix for sure).

[dcfish]

That sounds logical - my noise goes away as the car warms up...so it's worth a shot (and a cheap fix for sure).

Don't forget to loosen the fill plug before you drain. And you have to use a pump to get the new oil in.

[rdefabri]

Hmm, I may not have the tools...any idea of what a dealer might charge?

[dcfish]

Hmm, I may not have the tools...any idea of what a dealer might charge?

You need a 10mm allen socket, And they sell the pumps for the gear oil containers wherever they sell the oil. It's easy as pie.

[rdefabri]

Oh, good - I have the Allen wrenches, just need the pump...I'll check that out!

Thanks!

[nc211]

rdefabri, I agree with DC on the synthetic oils. I just recently switched over to the synthetic stuff in my 95 LS, and what a difference it has made!! I used Valvoline's 80w-90 full synthetic, it's in a blue bottle. I also used a hand pump to get the oil into the differential. I have something like looks like a painter's caulking gun that has a plastic tube on the end. It worked great, and you get them at any auto store for like $10 bucks.

On the bolts, they can be tough to get off. I recommend a long handled wrench, so you can get some leverage. I have one of those cheapo' Husky hydrolic floor jacks "$20 bucks +/-". I had to use it to initially get the bolt to break loose. Make sure you've got the fill bolt loose before the drain bolt. Last thing you want is a drained differential with no way to refill it!

[GS Sport]

Just as an update I thought this may help if anyone else has suffered this problem.

The answer lay in the geometry and worn rear tyres. I got a full geometry check with tony (wheels In-motion) and he found a number of areas which were quite a bit out. Most of the noise disappeared once the geometry was right and the remaining noise disappeared once the rear tyres were replaced, There was severe wear on the inner edges of both rear tyres.

Hope this helps anyone else who may be getting the droning from the rear.

GS Sport.