RED MX5

Maybe it's the driveshaft CV joint like Modifry suggests. When you swapped out the diff the CV joint movenet may have redistributed the grease and quieted things down for a while. I'm just grasping at straws here, but if you've taken the diffs apart and they look OK, and they quite and smooth when turned by hand, then I've gotta go with the driveshaft CV joints as the best suggestion yet. It's got to be something upstream of the diff.

Modifry, was the boot on that "Bummer" CV joint damaged? Where did the grease go?

elemental79

I just got done taking off the prop shaft, wiggling it arround and putting it back on. (aligned it to the opposite side of the bolt patern). And it stopped making all noises. I havent had a chance to take it over 70. But I'm sure it would break again. So now im 99.9% sure its the prop shaft and the last 3 diffs that i have purchaced are probably fine.

ShocK

Wow you have WAY too much money lol. The prop shaft is balanced and must be aligned back to its proper position.

RED MX5

Shock is right about the prop shaft, but you can't really mark the old flanges and put them back the same way they came off when you replace the diff or shaft.

At least you've got a couple perfectly good differentials that you can sell to get some of your money back.

rnye

6th diff??? Ever considered doing the R200 swap? Those suckers are bulletproof.

AusS2000

Umm, they've pretty much decided the diffs are fine and the prop shaft is the culprit. Perhaps try reading the whole thread before you post.

3ngin33r1

What's the fun in that?

JDMAPtwo

i had the exact same problem i went through 4 diff's and locked up one going 40 mph i finally sold the car and i later found out the propeller shaft was unballanced and it caused a snow ball effect from there, so have that checked!

ShocK

So when you switch a diff out how do you know where to align it on the Diff again?

3ngin33r1

It goes somewhere in the rear.

(it works with my wife...)