Stripped Threads in Differential - Need Advice
 

PO overtorqued differential fill hole so tight that the washer wedged upwards 360 degrees around the bolt.

Anyway, when I tighten the bolt, it just keeps spinning. Fluid is slowly leaking too.

Helicoil? Or is there something else better? I've never done this before.

Thanks.

Is the fill hole on the dif cover or on the main pumpkin? If cover, then call PlanetMiata and get a new one. If body, and you can get the bolt out, then just use a cork from now on.

Take the plug out, go to autozone, see if they have a "oversized" plug. If they look at you stupid, go and look on there "HELP" rack.

It's the top bolt hole. The bolt is out, but the hole is stripped.

http://www.miata.net/garage/trans/13.jpg

worst case, you sorce a new housing. 1.6 diff should not be more then 40 bucks.

To address your "better than a helicoil" question, there is nothing better than a helicoil. That's a whole 'nother thread though. Don't be afraid to use one.

What's a 'cork'? Does it still thread into the hole?

Hmm, If it were my car, I'd measure the diameter of the hole, and drill and tap it the next size up. You could also try runing the correct tap through it to "chase" the threads and see if that's enough to get it to bite again. I've never heard of an oversize plug, but if they make them try that first for sure. Oh yea, no VLSD in there.

just put some jb-weld on it. there is no pressure or anything crazy going on there

Very true. And you only have to monkey with it every 50,000 miles or so.

Ended up putting 2 washers on it. Seemed to grab the remaining threads well. Hasn't leaked since last night. Only time will tell.