DaleClark

iTrader: (55)

Hey guys -

Working on my buddy Jon's car, we have been rebuilding the car from ground up. Finally got the engine back in, now the whole drivetrain is in there. After installing everything we noticed the shifter tower where the shift lever bolts to was substantially over to the passenger side, being off center by a good inch or two.

The car has brand new IRP motor mounts and aftermarket poly diff mounts. The whole drivetrain sits on those 4 mounts. With the PPF off, the engine can easily be moved to center the trans in the tunnel. Also, it's obvious the engine is sitting flat in relation to the subframe and was sitting as it should on the mounts. Same goes for the diff.

When installing the PPF, even using the proper technique in the shop manual (diff first then trans) it would push the trans to the side as soon as it was tightened up onto the trans.

Looking at the PPF there are no obvious cracks or signs of trauma. I looked online at some PPF pictures and it did look like it could be bent. Found a good deal on a used PPF and bought it.

We installed the replacement PPF today - no drama, bolted it right up and the trans went dead straight in the tunnel. The shifter is now perfectly centered in the hole when looking from inside the car.

I have seen other threads and pictures of people with a similar issue. It looks like the PPF will bend to the passenger side when it does, my guess is from drag launches or very high HP cars. I think this may be more common than thought so I wanted to document this.

BTW, with both PPF's right next to each other you could see the difference. Unfortunately we were in a big hurry today so I didn't get any pictures. I may end up pulling the good PPF and taking pictures to try and figure out some way to identify a bent PPF without having to install it in a car.

Dale

TomU

iTrader: (11)

Was the driver side motor mount arm replaced with a steel arm? I don't think they are the same in regards to how the engine sits. Aftermarket motor mounts and oil pan brace may compound the issue.

Unless there is history of hard launches

Sgtblue

iTrader: (16)

Good info, thanks. And it would be interesting to see side by side pictures and if you can figure out a way to 'know' if the PPF is bent out of the car. For the more powerful cars I can see some Christmas wish-lists include transmission and diff braces.
The only noted effect a pan brace had on my car was to raise the engine the thickness of the arm, not move the engine to one side or the other. I also added a steel arm to the driver's side engine mount but I didn't notice any change in center.

DaleClark

iTrader: (55)

The car is a 94 and has both steel motor mount arms. The IRP mounts are both the exact same height. There is an oil pan brace on the motor as well (Chips Motorsports). But, with no PPF installed the motor does want to sit nice and level, it only ***** to the side when the PPF is attached.

Next time we get a chance to work on the car I'll pull the good PPF and get side by side pictures. It may be a while since this is going to be a busy month for me, won't have much wrench time.

The history of the bent PPF is unknown, the car was purchased as a roller and the PPF was thrown in with the deal. The car came from Allrotor and I think he just grabbed a PPF from his parts pile. The car itself had a single turbo in a previous life, but again there's no guarantee the PPF went to this car originally.

We tried EVERYTHING with the bent PPF at first to get it to line up - tightening the bolts as per the shop manual, loosening the motor mounts and picking the motor up with the engine hoist, prying on things with a pry bar, etc.

Remember, the drive train is located by 4 mounts only - 2 engine mounts and 2 diff mounts. If the engine mounts are funny, like an aluminum arm on a thick mount or something like that, in theory that could push the stack one way or the other. But, at the end of the day you would have to have the supposed to be straight drivetrain warped to the side to produce these effects.

Dale

IRPerformance

iTrader: (41)

Although they usually crack, I've seen a couple bent power plant frames over the years. Usually its if the car was in an accident.

DaleClark

iTrader: (55)

Old style with notch New style, no notch
Difference in exhaust hanger, newer on left, older on right

OK, update time.

We had a chance to work on the car today and put the drivetrain together. Pulled the good PPF off the car and compared it to the bad bent PPF.

Unfortunately even with both side by side I could NOT detect a difference or where it's twisted. So, unfortunately there's no easy "smoking gun" to look at a PPF and diagnose whether or not it's bent. We studied both for a good 15 minutes and they really looked the same. The big thing is it doesn't take much to kick it over to the side, a small change can push the transmission over to the side.

One thing I did notice was there was a difference between the two PPF's. I'm thinking that Mazda must have revised the design at some point. The good, non-bent PPF had more metal on top. Also there was a minor difference in the exhaust hanger, one was round all the way through one was flattened where it was welded to the PPF - the newer style is round, older style is flat.

The extra material in the pictures is on the back, top diff side of the PPF. Also neither PPF had a part number or anything. Does seem like you could easily use the exhaust hanger as an easy way to tell if you have the older or newer style.

Dale

j9fd3s

iTrader: (3)

one other little minor thing is that the motor mount arms are not the same side to side. i compared a few in the pile, and there is a small difference. due to the lengths involved, moving the engine 1/16" at the mount, moves it a fair bit at the alternator.

7krayziboi

iTrader: (15)

That is a new cool fact , thanks you sir.

Sgtblue

iTrader: (16)

Yes, appreciate the research. Can't help wondering how the MS PPF falls into all of this. Last I knew, no one had found anything significant about it. Was it a non-notch and does it have the additional material like the later designs?

jalava

I noticed with oil pan brace and aluminium driveshaft, my driveshaft clearance to PPF was very very small (less than 1mm) and I had lot of trouble trying to align the PPF as per instructed on manual. Also getting PPF to tranny bolts were a pain as I was in the threshold of adjustment due to slightly changed angle between transmission and PPF.

I solved this by adding square washers ground to fit inside as shims between PPF and tranny that were about have the thickness of the brace, solving all my fitment problems.

DaleClark

iTrader: (55)

It is possible that yours is bent a bit. The car that we found this problem on has an oil pan brace. With the good PPF it fit PERFECTLY with no fooling around or adjusting - tighten all the nuts up, and the shifter was dead center in the hole and everything bolted up perfectly with no drama.

That's interesting, though, it is possible if a PPF is bent that using shims could help out. But, if it IS bent, it's possible that it has a weak spot and will continue to bend or break.

It does seem though that you need a car making a good amount of power to bend or break a PPF, I don't think it's going to happen on a stock or near stock car. I don't have firm evidence on that but that's my thought.

Dale