427TTA4

Okay heres the story I've owned my c5 since it had 60k on it now it has 100k and my Torque tube is going out.That I know I can fix and I know what are the symp. but on the other hand the other day I moved it and when I was trying to take off easy I heard this grinding noise like all the way in the back.My first impression was WTF my first though was that the rear diff is giving out but once I take off no more noise???Its like it runs perfect well in the end if its bad im out like 1k but on the other hand 4.10's are going in if its bad.Just wanted to see what you guys think it is before I empty my bank acount.Thanks for looking.. ps (Anyone have a rear diff for sale lol)

tricep

May as well just empty your bank account now...


Your'e going to anyway.


The "rear end noise" in my Z ended up costing about 5K and some change.

seamus2154

A brand new GM rear is only 1600 dollars. Rebuilding is silly unless you need to be overbuilt due to mods.

427TTA4

But if it was the rear end wouldnt it make noise all the time???

Tim01Coupe

When was the last time you changed the rear diff fluid with slip additive?

T5Mika

I got a similar question about my A4, but I think the noise comes from the front. I only hear it top down when it reflects from concrete walls etc. There no noise when the engine idles, but when I give it a little gas it starts. I don't think it matters if it's on gear or not. It's been there as long as I've had the car, so I don't know if it's normal.

The noise is kind of scraping or grinding, not squealing like a belt, or ringing.

tricep

Supposedly, but not necessarily...

427TTA4

(Whats that???)Guess that answeres your question....I never even toched it to tell you the trutt because for the last two years I barely put 1000 miles on it I know the first year I put like 30,000 lol but after that year it was just parked....

Tim01Coupe

I used Red Line synthetic 75W90 High Performance Gear Oil (2- qts, until it runs out the check plug) and one bottle of their Friction Modifier (also synth. put this in, between oil bottles so you have room) There are posts here on how to do it, if you can't find them, I can help you find them. Get the rear end in the air (level), drain it, and with a Harbor Freight $4 pump, get the new stuff into it. It's a 50k mile duty and when you mention possibly intermitent noise, this may be the source. Basically an oil change, except pumping oil upwards!
Check your manual for GM spec for other brands, but I am swearing by Red Line.

Tim01Coupe

C6 posted in the C5 section, it's basically the same.

http://forums.corvetteforum.com/c6-c...s-for-faq.html

Tim01Coupe

This is the friction modifier, 4oz, do not change diff fluid without some sort of GM spec modifier with gear lube:
http://www.summitracing.com/parts/RED-80301/

Jet-Jock

I'd do a fluid swap first with additive and see what happens.

KorbenDallas

Try a fluid swap, but it's probably too late for it to do anything. Start looking into differentials