LSD oil

[dannobee]

I'm with Matt on this one. If I see a crack or cracks in the ring or pinion, its getting a new set. And as Matt said, replacing the ring and pinion will likely double (or more) the cost of the overhaul.

As for test driving, pay really close attention to when the noise happens. Accelerate through the gears at various engine speeds. Is it noisy in one particular gear? Does it quiet down in one particular gear? Does the noise remain constant but get louder as the car goes faster? Is the noise a steady drone, or is it a rhythmic noise? Does it sound more wheel speed related, or faster, like engine speed related?

Test drive again and get back to us.

[mhurwitz]

Originally Posted by Matt Monson

The short answer is that a single tooth isn't the likely culprit, but it raises all kinds of alarm bells of it own.

So let's get a little theoretical to aid you in your diagnosis. I want you to think about the function of your gearbox as a variety of things all spinning in a circle, going various directions and speeds. The two you start with are wheel speed and engine speed.

Pay attention to the noise exactly when it happens. Does it go up with wheel speed and get worse the faster you go? If so, it's likely somehow related to the ring and pinion.

Or, does it synch up more closely to the revs of the engine? If so, it's likely a bearing running either on the mainshaft or on the pinion. Furthermore, does it happen in all gears or just one or two? This helps you determine exactly where on the length of the shaft you might have a problem.

Personally, I would have never rebuilt a gearbox with a crack in the ring gear. The job stops being a rebuild right there, and unfortunately for you, doubles the price, at a minimum. I also don't know that I would go back to the prior mechanic with your problem. While the idea of a warranty and some of the work being free is enticing, I seriously question the competence of this "professional" A crack in a tooth is NEVER acceptable.

OK….I took her for a spin yesterday.
The humming happens in all gears.
After the car gets up to speed, if you “goose” the gas pedal, the sound appears on acceleration only, not when I take my foot off the gas.
It doesn’t appear to increase with the speed of the car.
Looking back, like I said, I made the wrong decision not giving the OK to replace the ring and pinion, but the car was never making this sound.

And thank you Pelicans for all your help and knowledge, I really appreciate it.
Mark

[Matt Monson]

Might just be your throw out bearing based on what you are describing. Doesn’t sound like the ring and pinion.

[mhurwitz]

Originally Posted by Matt Monson

Might just be your throw out bearing based on what you are describing. Doesn’t sound like the ring and pinion.

Hi Matt,

That would be a gift if that is what it is.
I’m able to pull the motor and transmission myself.
Is there a way to check the TO bearing once I have it apart?
Thanks,
Mark