PPF replacement
 

Just got my FD 2 days ago and it comes with quite a bit of problems, the PPF is broken and there’s another part that’s broken which I think is the Diff brace, what causes these to break and can y’all see anything else that might need to be replaced?
https://cimg2.ibsrv.net/gimg/www.rx7...7d9662320.jpeg
https://cimg5.ibsrv.net/gimg/www.rx7...6a4eabac6.jpeg
https://cimg0.ibsrv.net/gimg/www.rx7...bdb021ec4.jpeg
https://cimg8.ibsrv.net/gimg/www.rx7...c8b95aeb0.jpeg

That usually starts with a broken motor mount- check those too.

I bought my new motor mounts and ppf from Mazda. Tried poly motor mounts first, but I didnt like them.

Ended up with Banzai trans brace with stock motor mounts.

That can be welded back together. Just need someone competent to do it.

Alright, I’ll check out the motor mounts, was planning on getting the sikky ppf/diff brace but read that it’s pretty much made more the swapped fds so I’ll look at other stuff

I think I’ll just get aftermarket ppf and diff brace instead

An aftermarket ppf is incredibly rare and aggressively expensive. They all start out as stock ones and then they just reinforce them. The same yours would be if you got it repaired by a competent welder. From the pictures it doesn't look like you have a diff brace at all. The ppf is also the diff brace on a stock fd.

Looks like it was repaired before and broke on their weld. From the pictures looks like the penetration was poor and likely the reason it failed. Fit a good used PPF and look at engine mounts and potentially additional bracing if you're modifying the car.

+1

Many times PPF's break from hard launches on cars making a lot of power. I've also seen bent PPF's as well.

I wouldn't try and repair that, it maybe could be done but there's a lot of geometry there. Most likely if it is fixed you'd have your shifter hard against the firewall tunnel or something dumb like that.

Get a good used one and be done with it.

Dale

The diff brace also snapped

Yeah thats what I figured, I will be taking a look at engine mounts after my PPF comes in, also the stock diff brace

I ordered, the PPF and diff brace, should come in next week, after that I will probably be checking the engine mounts, before the PPF and diff brace broke off there were clunking noises coming from the back so I'm going to have to see if those parts fix it.

Thanks yall!

The clunk noise was quite likely the cracked ppf before it let go. There is no diff brace stock, that aluminium brace is not connected to the diff, it's just the rear most tunnel brace :icon_tup:.

If you wanted a diff brace, Banzai make a good one that goes in this location

Does anyone have pictures or diagrams for a reinforced PPF? I'm wondering where it needs extra bracing and how to go about it

Ill eventually get the diff brace from banzai, I’ll be working in my garage with a jack and jack stands, is it possible to replace the ppf with just that or should I tow it to the shop?

Not a difficult thing to do with the car on jackstands on the floor. Will need some larger deep well sockets to get to the PPF nuts I believe they are 23mm

Oh alright, would I need to have the jack on the diff or anything?

It's held in the air by rear subframe, and aligned by the driveshaft, will be just fine while changing out the PPF. If you end up taking off the driveshaft then the front nose would want to rotate down and would then be held by the axles, so having somehting under the front nose at that point would be good to not put too much stress on the CV Joints

The diff will be held up by the diff mounts through the whole procedure so you are fine there. Yes, you can do this on jack stands, it's not that bad. Probably hardest thing is just removing the main cat or midpipe if you have rusty old bolts. If you have the main cat you will want a jack under it as it's quite heavy and bulky, like 40-50 pounds.

It also helps to have someone else help out, it's an awkward job but not too bad.

I could probably swap a PPF out on jack stands in my driveway in an hour. Having impact tools helps a LOT as well, the bolts and nuts for the PPF are really on there.

Dale

Also, per the FSM new PPF nuts are needed, but I think most everyone accepts using loctite on used nuts. They are lock nuts that yield during torque and will not lock as well after the first use.

^In theory, but in practice I've re-used PPF nuts many times with zero problems.

They aren't an exotic torque-to-yield bolt for a head or something. Just tighten properly and you are good.

Dale

Yeah. May not actually be true. But I feel like there is a big difference between torque to yield bolts vs nuts. If I had to re-use one can the other, I'd rather reuse nuts and would be more cautious reusing bolts.

HPP 2in1 Diff Brace & Cradle
Cradle protects diff case from cracking.....high HP cars
Brace protects PPF from cracking and makes car launch like a bandit

https://cimg3.ibsrv.net/gimg/www.rx7...014fb32154.jpg

A separate diff girdle and front mount/ppf attachment point to body brace, in addition to a gearbox/ppf mount to body brace are both more serviceable and provide strength where it is actually needed.

I bought a brace like the combo one pictured. You are asking for diff leaks/housing torsion, an independent girdle that fits under the diff cover is better, with a separate diff nose to body brace, likewise a gearbox to body brace. You will get a bit more driveline noise but the whole thing will respond better on turn in and to driveline torque.

Marcus Read in Australia makes rubber mount, stainless gearbox and diff braces and green Brothers in New Zealand do a diff girdle if you don't want to make then or can't source them there.

Au contraire
To-date there are over 265 very happy users of the HPP 2in1 Diff Brace/Cradle.