Topic: Rear differential problems + other noises

[MomsSol]

 

31 psi is way to high.   29 is the recommended pressure for our cars.

Unless you enjoy the 'go cart' feel on OEMs.

I think he is using different tires, which could do better with the 31 psi 

[elff]

It depends on the tire and the tread.

[Sol Asylum]

Given that he is not running stock tires and the link he posted is about others having problems balancing the tires that he is running, the problem is probably the tires themselves and not so much the pressure.

[elff]

I have Hancook Tires on the Truck and they SUCK!!!
I have a wobble at 65mph that we have tried to balance out twice.
We are going to flip the tires 180 degrees on the rims this time and if that doesn't work I am just going to buy 4 new tires.
These came with the truck when I bought it and have at least half the tread left, but between the balance issue and how bad they are in the wet and snow, it's just not worth it.

[LatinVenom]

Yes, you are running them to high.

[Critterman]

Somewhere on this forum I posted a formula that allows you to figure out what pressure you should run depending on the tires you have purchased.

[ToniCipriani]

Thing is, I measured when the tires are hot. And yes I think I meant to say 29, but somehow said 31. I just know 1 off from 30, since my G6 was 30, and somehow I said 31. But I meant whatever stock was.

I'm thinking trying to do a road force balance to see if it helps.

Given that he is not running stock tires and the link he posted is about others having problems balancing the tires that he is running, the problem is probably the tires themselves and not so much the pressure.

Actually no... I started this thread about my diff leaking and diff replacement, then I started noticing vibration at highway speeds. Just that I noticed the vibration changes by changing tire pressure (and that one tire way higher than others), I started factoring in the new tires I got, and the complaints with the same tire.

[DaveOC]

Somewhere on this forum I posted a formula that allows you to figure out what pressure you should run depending on the tires you have purchased.

http://www.kappaperformance.com/forum/index.php/topic,4068.msg97141.html#msg97141

[elff]

I never run anyone elses formula with tires.  I take some recomdations and then see what works best in my driving.
I will say that AuotX requires higher PSI than normal street driving and Drag requires less on the rears but more on the fronts.
4 Wheeling in the jeep is 6-7 psi

[ToniCipriani]

OK so in the tire formula, this is what I got for Hankook Ventus (max load 1764lbs/50psi) on my N/A:

3350*0.35/1764*50 = 33.23 psi

I measured the tires they were around 32-33 hot, so I guess I'm underinflated?

[DaveOC]

GVWR on my '06 Solstice is 3279 pounds,

3279*0.35/1764*50=~32.5

That is a cold tire pressure, and should be treated as a starting point in determining the proper inflation.

[Sol Asylum]

Tire pressures can change quite a bit just from temperature changes that the tire experiences from driving.  The tire pressure monitoring system I have on my car will display the temps as well and no joke the pressures can be more than 5psi different during driving even though the cold temps are all the same.  In fact if one side of the car is in the sun even on boring straight roads, which is every F'n road here in central Hellinois, you can see big differences in pressure.

Tire pressures are always measured cold because all four tires will have different temps after driving thus different pressures.  So stop taking hot pressures as they won't really tell you anything.

I can't say that I have ever heard vibration being caused because a tire was 1-2 psi more or less then another tire or outside of the recommended pressure.  So either your tires are shit and out of balance causing the problem or you have some other mechanical problem.

[ToniCipriani]

Tire pressures can change quite a bit just from temperature changes that the tire experiences from driving.  The tire pressure monitoring system I have on my car will display the temps as well and no joke the pressures can be more than 5psi different during driving even though the cold temps are all the same.  In fact if one side of the car is in the sun even on boring straight roads, which is every F'n road here in central Hellinois, you can see big differences in pressure.

Tire pressures are always measured cold because all four tires will have different temps after driving thus different pressures.  So stop taking hot pressures as they won't really tell you anything.

I can't say that I have ever heard vibration being caused because a tire was 1-2 psi more or less then another tire or outside of the recommended pressure.  So either your tires are shit and out of balance causing the problem or you have some other mechanical problem.

Oh I know I shouldn't take hot pressures, like I said it was a spur of moment thing to check it.

But my dilemma remains... I have the V12s that seemingly there are reports of being unable to be balanced properly, and also I got my diff replaced recently. So the head scratching continues.

[Sol Asylum]

If you have another set of tires for the car put those on and see if the vibration remains.  If the vibration is gone it's the tires replace them.  If the vibration remains take it back to whoever installed the diff and make them figure out what is wrong.  If they won't fix it tell them you'll never do business with them again and go somewhere else.

[Gentleman Jack]

This isn't a complicated problem. It's a complicated solution. Or maybe it's the other way around.

[ToniCipriani]

If you have another set of tires for the car put those on and see if the vibration remains.  If the vibration is gone it's the tires replace them.  If the vibration remains take it back to whoever installed the diff and make them figure out what is wrong.  If they won't fix it tell them you'll never do business with them again and go somewhere else.

I was about to put my winters on to try, but then I remembered the weights on that fell off so I need to get those balanced first...

Went to try the tire pressure check, this time cold to 33 psi as calculated. Same situation, still there but dampened. Two strips of highway, on the way out it was there but on the way back much less.

I'm about to give up and just make an appointment with the dealer next week...

[ToniCipriani]

Update... At the dealer now.

3 out of 4 of my tires out of balance, it turns out. That was corrected and now significantly reduced. Foreman's looking at it now, hoping for the best...

Update 2: Foreman said my driveshaft is out of balance, suggested I do a balance test. Guess I'm glad it's not the diff.

[ToniCipriani]

Think I found what my exhaust noise is: http://www.solsticeforum.com/forum/f12/exhaust-buzz-gm-bulletin-solstice-issue-5290/

Does anyone have the full bulletin for this? I saw it at the dealer yesterday but forgot to grab a copy.

[ToniCipriani]

OK so back from the dealer, they said it's still there, and it comes and goes, they found it's more prominent at low RPMs. Re-assured me nothing wrong with the diff or the entire drivetrain, installation was correct and retorqued everything.

At this point I'm pretty sure it's the tires, so I'm just going to leave it at that until my winter tires go back on.

Thanks everyone for helping me out!