8 replies to this topic

[ptk]

I was able to remove the PPF rear bolt at the diff with PB blaster, heat, and wax ok, but I rounded off the front bolt.  I took the diff and PPF out of the car, cut off the head of the bolt, and have now finally been successful in pressing the bolt and spacers out of the diff.  I thought the joint would be made up of the bolt, the top threaded spacer/cap, the bottom spacer/cap, and a long sleeve.  In addition to those parts, I see a shorter spacer sleeve that’s still attached/corroded on the body of the bolt.  This isn’t just the stepped portion of the bolt.  What is this piece and should it be still inside the diff housing?  I am wondering if I can just buy a bolt and lower spacer (since I cut them) and put it all back together or if I need to do something further.  See the picture for a better explanation.  Thanks

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[Bench Racer]

Here is a video which should explain the diff. to PPF connection. Please not that the spacer with the two holes has a top side and a front end. Everything in your picture has a home when it's all fully assembled. When you assemble the upper nuts please look at the PPF and you'll find there are some groves in the PPF created when the nuts were initially assembled. When re-assembling these nuts with gloveless fingers rotated these nuts feeling for said grooves, push nuts in place in said grooves. Please message any question within this post or send a private message.

 

[ptk]

Thanks for the reply.  I do have all of the pieces shown in the video, but if you look at the bolt I have an extra spacer that is still attached to the body of the bolt.  I am attaching another pic for better clarity.  I assume it is corroded onto it and the bolt was supposed to just slide through it, but it came out with the bolt. I have not seen this part in any of the writeups that I have found on PPF bolts, and I have looked at more than a few because I had such a hard time with this.

In the picture, you can see the regular step shoulder of the bolt, and a little ways below that, there is another bulge on the bolt body...

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[Bench Racer]

Take a picture of the lower sleeve. Fits in the lower front hole of the PPF. I don't have a clue what that in my words "extra part" is as shown in your second picture attached over the shoulder of the front long bolt other than the nose being broken off the lower sleeve. When you view the video at 7:40 you don't view said "extra piece" on the long bolt shoulder.

[Steve Scheifler]

It appears that someone was missing the correct bolt and sleeved one up to fit.

[ptk]

Here is one more picture including the lower sleeve.  It’s still intact.

After looking a little more at the extra spacer and the position of it on the bolt, it seems like it came out of the diff casting.  I guess I thought the casting was just solid, but it looks now like this was a sleeve inserted in the through hole in the casting and it got rusted to the bolt and pulled out of the casting.  I will probably try to separate it from the bolt and reinsert it to the diff casting.  I don’t see any reference to that part and don’t see any way to order a replacement if I cut it..

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[Steve Scheifler]

Right, there is a sleeve back there which can make disassembly difficult, I’m trying to recall which hole. I don’t think the video above even has one. And the video doesn’t even mention proper alignment of the PPF before tightening the front long bolts and mount. Terrible.

[ptk]

Just to close the loop on this thread, I ended up pressing the small sleeve off the bolt (it was corroded enough to need a press to do it), cleaned it up, and pressed it back into the cast portion of the diff. It sits in the upper half of the lower casting through hole.  It would have stayed there if I had been able to pull the bolt down from the top. Instead, because I had to cut the bolt head and press the rest of the body up through the top of the diff, the sleeve /spacer had nothing stopping it and it slid out of the casting…

I know they want a nice, rigid attachment at that joint, but it seems like an overly complicated design that’s clearly prone to gathering crap and rusting based on all of the forum discussions I have read

[Steve Scheifler]

Just to close the loop on this thread, I ended up pressing the small sleeve off the bolt (it was corroded enough to need a press to do it), cleaned it up, and pressed it back into the cast portion of the diff. It sits in the upper half of the lower casting through hole. It would have stayed there if I had been able to pull the bolt down from the top. Instead, because I had to cut the bolt head and press the rest of the body up through the top of the diff, the sleeve /spacer had nothing stopping it and it slid out of the casting…
I know they want a nice, rigid attachment at that joint, but it seems like an overly complicated design that’s clearly prone to gathering crap and rusting based on all of the forum discussions I have read

They are victims of extreme reliability, most Miatas go decades and hundreds of thousands of miles without needing those removed.