New tire sound(s)

[Pomorza]

Hey guys
Today I invested in a set of new tires. 215/70R14 in the rear and the stock 195/70R14s in the front. Car drives great but I've noticed that when I decelerate I get a thud thud thud sound from the rear passenger's side. The best way I can describe it is it sounds like I'm crossing a bridge. (and hitting the spacers on the bridge once in a while). The tires don't rub.

Three things that I've thought of at the moment. One, for some reason they used different lugs on the one tire. don't know why, but it could maybe make a difference. Secondly, the struts on the rear are gone, literally I don't think they "absorb" any kind of impact anymore. They are leaking fairly badly and make noise. Thirdly, the rear tires are misalligned. They are pointed inwards towards the front of the car. If you look at them from the top, they are about 2-5 degrees pointed inwards.

Any ideas.

Thanks greatly
Jan

Happy 4th to everyone.

[mlc240z]

Bad tire?
Might have belt separation internally.

[Gary in NJ]

Bad tire?
Might have belt separation internally.

Assuming that nothing else has changed, that's what I was thinking. Swap the rear tires and see if the noise moves to the left.

[d240zx2]

You may have some "burping" going on in the strut, too. If they're leaking as badly as you describe, air has supplanted the oil and you may be hearing air getting by the seal.

Just a thought...

[Zedyone_kenobi]

I was not aware that the Z's could adjust toe in the rear?
Before you start blaming anything else, I would recommend a new set of struts, and replacing your bushings in the rear end. Under braking or decel the weight transfers to the front of the car to some degree, leaving the rear suspension somewhat unloaded. It may be enough to upset something. Just a thought.

It is hard to diagnose something when you have known rear suspension bits that are shot. I would recommend parking her and fixing the bits that are worn or tired.

[Carl Beck]

I'd pull one lug from each rear wheel - and check to see that they are the same length. If you use too long a lug on an aluminum wheel it will hit the rear drum before it actually clamps the wheel to the hub/drum.

Better to be sure..
FWIW,
Carl B.

[Pomorza]

Thanks guys for all your input.

I drove on the tires for a good hour last night to wear them in a bit. The noise only occurs when I decelerate or brake so I'm leaning more towards the suspension or lugs rather than a bad tire. (as wouldn't the sound be continuous if there belt was bad inside?).

I sadly can't stop driving the car as it is my daily driver. I try not to drive it much as the suspension is in dire need of repair but when I have to I really have no other choice.

Thanks again
Jan

[Smokey]

Check around the wheel well opening front to back, and top to bottom, and inside out. With the suspension so bad in the rear, you will be getting more movement front to rear than you would normally. This is supported by the toe issue you mentioned. When you are decellerating or braking, the diff will put a load on the wheels in a different direction then when its under power. This could be shifting the wheels and causing them to come in contact with some part of the body. You will notice scrub marks if this is the case. The tires you are using are both wider and taller than what was there before which would support why the new tires caused you to hear the noise. The smaller tires wouldn't be big enough to make contact.

It might also be your U-joints on the rear axle going bad. The extra mass of the bigger tire could have put week joints over the edge. They would make a knocking sound under different loads similar to a CV joint in a front drive car when turning.

[Inf]

I had the same symptoms before with a front tire. Turned out the tire was coming apart on the inside. It had one part that was slightly out of round, and I only noticed the lump while rolling the tire along the garage floor with my hand sliding on top.

The whump-whump-whump only showed up at low speeds, like when rolling up to a stop sign.

At least dismount the suspect wheel, and do some close examination of the tire.

[Pomorza]

Check around the wheel well opening front to back, and top to bottom, and inside out. With the suspension so bad in the rear, you will be getting more movement front to rear than you would normally. This is supported by the toe issue you mentioned. When you are decellerating or braking, the diff will put a load on the wheels in a different direction then when its under power. This could be shifting the wheels and causing them to come in contact with some part of the body. You will notice scrub marks if this is the case. The tires you are using are both wider and taller than what was there before which would support why the new tires caused you to hear the noise. The smaller tires wouldn't be big enough to make contact.

It might also be your U-joints on the rear axle going bad. The extra mass of the bigger tire could have put week joints over the edge. They would make a knocking sound under different loads similar to a CV joint in a front drive car when turning.

Thanks for the advise.
I went out for another drive today to see if the sound was there. It was but only after a few minutes of driving over 35mph. I took a look at the tires and suspension and I'm in dire need of new struts in the rear. They are in horrid shape.

By u joints on the rear axle I'm assume you mean the half shaft u joints? The drive shaft has brand spanking new u-joins (actually the whole thing is new).

Thanks again guys
Jan

[Smokey]

Yes, I am talking about the half shafts. Didn't even think about the actual drive shaft, although that could also cause some thumping. Since you have new U-joints there, that should be just fine.

I thought of a test that you could do to see if you have enough slop in the rear end to cause excessive movement. With the car in gear and the parking brake set, you and a buddy get behind the Z and start pushing it in a rocking motion. While the car is rocking, you should not see any front to back movement on the rear wheels relative to the fender openings. Then try the same trick with the parking brake off. With the car in gear, you should still have a lot of resistance to the rocking motion. If you hear clunking, it is likely your half shaft U-joints.

[Pomorza]

Guys you are going to fall over this. Apparently my mechanic, who I've been going to for years, was no aware (or forgot) that I have staggered rims. (that is one is 1" wider than the other). Well to my amazement (and fright) I found that the rear has one thin rim (driver side) and one wide rim (passenger side) on. The tires are the same size (215/70/R14) but the rims are not. Assuming that the wider rim is heavier (which it is) I found the problem.

I'm going to avoid driving at all costs until this can be fixed as a weight difference can really mess with the diffy and really pretty much everything else back there.

Thanks guys for all your help
Jan

[Pomorza]

Yes, I am talking about the half shafts. Didn't even think about the actual drive shaft, although that could also cause some thumping. Since you have new U-joints there, that should be just fine.

I thought of a test that you could do to see if you have enough slop in the rear end to cause excessive movement. With the car in gear and the parking brake set, you and a buddy get behind the Z and start pushing it in a rocking motion. While the car is rocking, you should not see any front to back movement on the rear wheels relative to the fender openings. Then try the same trick with the parking brake off. With the car in gear, you should still have a lot of resistance to the rocking motion. If you hear clunking, it is likely your half shaft U-joints.

Apparently the rims were not the problem. I did do the test you asked with the parking brake on and off. With it on the car did not move period. When you take it off it would move but there was no sounds at all that I could tell.

Any other ideas mates? I took it to my other mechanic to get an alignment and asked him to take a look at the suspension to see if he can figure it out.

[Zed Head]

Apparently the rims were not the problem. I did do the test you asked with the parking brake on and off. With it on the car did not move period. When you take it off it would move but there was no sounds at all that I could tell.

Any other ideas mates? I took it to my other mechanic to get an alignment and asked him to take a look at the suspension to see if he can figure it out.

It might help you if you try to separate the drivetrain issues, from the suspension, brakes and wheels, as far as you can. Even if it's just down to fine details of the noise. You said decelerate originally and then later you said decelerate and brake. It's not clear if you're using engine braking, brakes or a combination of both.

If you decelerate just using the transmission and engine braking, is the noise different than using just the brakes with the clutch in or transmission in neutral?

With just brakes you're only loading the wheels and suspension. With engine braking only, you're loading the half-shafts and driveshaft, along with the wheels and suspension.

You might even try stopping hard using just the parking brake, to put more load on the rear wheels.

It might give a few more clues.

[Pomorza]

It might help you if you try to separate the drivetrain issues, from the suspension, brakes and wheels, as far as you can. Even if it's just down to fine details of the noise. You said decelerate originally and then later you said decelerate and brake. It's not clear if you're using engine braking, brakes or a combination of both.

If you decelerate just using the transmission and engine braking, is the noise different than using just the brakes with the clutch in or transmission in neutral?

With just brakes you're only loading the wheels and suspension. With engine braking only, you're loading the half-shafts and driveshaft, along with the wheels and suspension.

You might even try stopping hard using just the parking brake, to put more load on the rear wheels.

It might give a few more clues.

The noise does not differ from the method of driving I have. I put it in neutral, or keep in gear or hit the brakes the noise remains constant. When I drive and do not put load on the rear end (that is I'm no accelerating) the noise is there very loud. When I put a load on it it diminishes in volume but it's still there but harder to hear.

Jan

[Pomorza]

A bit of an update and I hope you all can help here:
I took the Z to my other mechanic to get the alignment done. In the process he found that there is movement in the rear right wheel (the one that makes the noise) and advised me that the bearing is bad. (loose). He reconfirmed that the rear struts are worn to bits and they need replacement.

Secondly we found that the rear end wheels have a 5/8" toe in on both sides. As these are non adjustable does anyone know what could cause them to do this? I took two pictures so you all can see what I'm dealing with.

On a side note, the front tires also had toe in of 5degrees (roughly) on both sides. That was fixed but the rears are still a bit odd.

Any help would be great
Jan

[Zed Head]

A bit of an update and I hope you all can help here:
I took the Z to my other mechanic to get the alignment done. In the process he found that there is movement in the rear right wheel (the one that makes the noise) and advised me that the bearing is bad. (loose). He reconfirmed that the rear struts are worn to bits and they need replacement.

Secondly we found that the rear end wheels have a 5/8" toe in on both sides. As these are non adjustable does anyone know what could cause them to do this? I took two pictures so you all can see what I'm dealing with.

On a side note, the front tires also had toe in of 5degrees (roughly) on both sides. That was fixed but the rears are still a bit odd.

Any help would be great
Jan

Getting closer! I was going to say bearing. Seriously. Anyway...

Your transverse link bushings determine the alignment of the rear wheels (assuming that their mounting points to the body are not misaligned). Are they worn? There are two inner, where the wide part of the link attaches to the frame, and two outer, where it attaches to the strut/bearing housing (the cast iron piece) via the spindle pin. If the inner ones are worn, I've heard (read) that you can get quite a bit of movement of the whole assembly. I think that it would give toe-out under braking, toe-in under acceleration.

There is an account out there from someone about being able to move the whole wheel assembly by hand because the bushings were shot.

There is also talk of poorly drilled bearing housings, from the factory.

I still have my stock bushings though, and my rear alignment seems pretty good, so can't offer much more.

[Pomorza]

Well if the transverse link are the rather large A looking parts of the rear suspension(that hold the wheels to the frame) then I don't think the word "worn" gives justice to what I have left. On all eight I have maybe an inch or two of "bushings" left. These "bushings" are broken, cracked and torn all over. Could having bad rear bushing really cause 5/8ths of an inch of toe in?

To be more specific, pretty much all the rear bushings on my car are shot. The mustache bar bushings are gone so when I shift I get the dreaded "thud". The drivers side strut is leaking oil.

Hope that sheds light on my Z. Its not exactly "perfect" but what can I expect for a care that wasn't really taken care of properly.

Jan

[Zed Head]

Well if the transverse link are the rather large A looking parts of the rear suspension(that hold the wheels to the frame) then I don't think the word "worn" gives justice to what I have left. On all eight I have maybe an inch or two of "bushings" left. These "bushings" are broken, cracked and torn all over. Could having bad rear bushing really cause 5/8ths of an inch of toe in?

To be more specific, pretty much all the rear bushings on my car are shot. The mustache bar bushings are gone so when I shift I get the dreaded "thud". The drivers side strut is leaking oil.

Hope that sheds light on my Z. Its not exactly "perfect" but what can I expect for a care that wasn't really taken care of properly.

Jan

Yes, the transverse link is the A shaped piece. Also called a control arm by many.

If I remember correctly,the guy who had the worn bushings found them because he had a noise from the rear end. If yours are as bad as you describe, they could also be a part of your "thud thud" sound. If your mechanic is not familiar with the these suspensions he might even be mistaking bushing movement for wheel bearing wear.

Each rear wheel assembly is held on to the car by three contact points with the body. The top of the strut and the two inner bushings. They take up all of the turning, braking and accelerating loads.

You really need good bushings to have a good solid car.

[Pomorza]

Yes, the transverse link is the A shaped piece. Also called a control arm by many.

If I remember correctly,the guy who had the worn bushings found them because he had a noise from the rear end. If yours are as bad as you describe, they could also be a part of your "thud thud" sound. If your mechanic is not familiar with the these suspensions he might even be mistaking bushing movement for wheel bearing wear.

Each rear wheel assembly is held on to the car by three contact points with the body. The top of the strut and the two inner bushings. They take up all of the turning, braking and accelerating loads.

You really need good bushings to have a good solid car.

If the noise I'm getting isn't from the bearing, wouldn't I get it on both sides and not just one if the bushings are all worn out? The exact phrase I was told was that rear right tire has movement (that is when it is in the air he can move it around by pulling and pushing on it).

Jan

[Zed Head]

If the noise I'm getting isn't from the bearing, wouldn't I get it on both sides and not just one if the bushings are all worn out? The exact phrase I was told was that rear right tire has movement (that is when it is in the air he can move it around by pulling and pushing on it).

Jan

No offense intended, but I would find someone who knows these cars and let them crawl under it and look around. I know a little about cars and most mechanical things and I spent quite a while under my car after I got it thinking "What the heck is that and how does it work?" and "Is that all that holds the rear wheels on?" and "It's just a big chunk of rubber!" as I searched for my own "clunk" (it was the diff mount and a bad half-shaft u-joint and loose moustache bar bushings).

You can't really tell by looking alone, that the bushings are bad. You have to torque parts around while someone looks (or vice versa). My diff mount looked like it had new rubber, but it was half split and worthless.

Yours should be fairly easy since you have visible wheel movement. Just watch the link mounts while someone moves the wheel. Watch the joint at the spindle pin also. As far as one side to the other, they might not have worn evenly.

[Pomorza]

No offense intended, but I would find someone who knows these cars and let them crawl under it and look around. I know a little about cars and most mechanical things and I spent quite a while under my car after I got it thinking "What the heck is that and how does it work?" and "Is that all that holds the rear wheels on?" and "It's just a big chunk of rubber!" as I searched for my own "clunk" (it was the diff mount and a bad half-shaft u-joint and loose moustache bar bushings).

You can't really tell by looking alone, that the bushings are bad. You have to torque parts around while someone looks (or vice versa). My diff mount looked like it had new rubber, but it was half split and worthless.

Yours should be fairly easy since you have visible wheel movement. Just watch the link mounts while someone moves the wheel. Watch the joint at the spindle pin also. As far as one side to the other, they might not have worn evenly.

I'm going to take it up to some Z expert(s) to ask their opinion. I've heard from a number of sources that bad bushing can cause that type of issue though.

Thanks
Jan

[Samuel]

Hi,


Nice to see the thread which is good from my and others point also and can be important also

car ECU