Miata diff to PPF bolts, threaded inserts in PPF?

So the two big bolts that attach a Miata diff to the PPF - WTF are they supposed to thread into?

Clearly I'm missing something

This is what the Mazda dealer parts diagram shows... not helpful.

I take it there's some kind of threaded insert that drops into the top of the PPF for those bolts to thread into. What is it, what's it called, and where do I buy them? Or do I just buy another PPF? Google has been un-helpful.

3rd failed attempt to swap my torsen LSD into my car...

The manual says if those come out you replace the entire PPF. I had one pop out but I just tapped it back in and threaded the bolt back, it has been fine since.

The easiest way to replace them if they are missing entirely would be to buy an entire PPF.

Your car had some at some point!

Or find someone with a PPF and get them to send them to you. We don't have any right now, but I can keep my eyes open.

Any reason you can't just put a nut on the bolts?

Because then the bolts can move around in the PPF and your diff starts to clank around and stuff breaks. Never mind the difficulty in actually getting up there to hold the nut. It's much easier to do it correctly.

Unless this car is a literal basket case and came disassembled, it had those inserts.

The car has the inserts, because the (open) diff and PPF have likely never been separated since the factory. Unfortunately, the bolts holding the two together are perma-seized and not going anywhere. So I have a torsen, I have $50 worth of two bolts from the dealer, and I have another used PPF... but I didn't realize there were inserts for the PPF to be missing.

If you take the diff out properly, the inserts stay with the PPF. If you're a racer in a hurry, you back the bolts off a bit and whack them with a hammer to blow the inserts out the top of the PPF. Much quicker.

I'd contact the source of this PPF and ask for the inserts.

Got access to a lathe?
Seems simple to machine a step into the lower part of a nut, diameter sized to a light press fit into the PPF.
Or make an adaptor flange sized for the PPF hole, and then tack a nut onto it.

erohslc wrote: Got access to a lathe? Seems simple to machine a step into the lower part of a nut, diameter sized to a light press fit into the PPF. Or make an adaptor flange sized for the PPF hole, and then tack a nut onto it.

that's what i was thinking. make a bushing for the holes, tack them to nuts, and maybe throw a bar in between the nuts and weld them together to keep them from spinning while tightening bolts?

Look carefully at what Keith said and get the nutserts out of your old one, it's not so bad. Heck even I did it. Loosen the bolts out about 1/2" and then drive them in with a maul/hammer. They pop right out the top of the PPF and can transfer onto your new one. Or buy a couple new ones from Mazda. Surely they have them in stock.

I even have a pair in my garage now.

KyAllroad wrote: Look carefully at what Keith said and get the nutserts out of your old one, it's not so bad. Heck even I did it. Loosen the bolts out about 1/2" and then drive them in with a maul/hammer. They pop right out the top of the PPF and can transfer onto your new one. Or buy a couple new ones from Mazda. Surely they have them in stock. I even have a pair in my garage now.

Mazda does not appear to sell the inserts separately from the PPF, and a new PPF is $400.

There is always someone on ebay Listing those. Example these aren't mine but Ebay link

Yep, as said Mazda does not sell them separately otherwise I would have bought them too when I spent $50 on the two bolts unfortunately, I also didn't know I needed them. And I can't remove the inserts from the PPF in my car because I cant remove the bolts. A week of soaking in PB Blaster, a torch, and a 4' breaker bar = stripped. That's why I had to get new bolts and another PPF...

Thanks for the tip on eBay, didn't think to check there.

The thread wouldn't happen to be wheel stud size, would it?

Toyota alloy wheel nuts

Well, if the heads are stripped off the old ones can you grind off the heads and drive them out with a center punch?

Is it possible you were PB blasting the wrong end (down at the bolt head rather than up on top where the threads are in the nutsert) and when you get them out you can soak them properly and remove the bolt pieces with vice grips....

Just a thought.

Sorry for the sidetrack, but PPf = punk powertrain frame? Purple powerlube fluid?

Power Plant Frame

Pay for shipping and they're yours.