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View Full Version : Beatrush PPF compatible with Autoexe Bracing?



Tristan75
03-03-2012, 01:48 PM
Hi...

Do you know guys if a Beatrush PPF can be compatible with an Autoexe Bracing?

http://www.good-win-racing.com/miata/images/items/beatrush_miata_ppf.j pg

http://www.autoexe.co.jp/products/memberbrace/NB1.jpg

I think they share some of the same bolt holes :?:

03-03-2012, 03:10 PM
No idea but given the choice, I'd ditch the Beatrush for the Autoexe in a heartbeat.

Tristan75
03-03-2012, 03:18 PM
Of course, I would do the same... but the Beatrush holds the PPF bar and the autoexe doesn't.

03-03-2012, 05:18 PM
I wouldn't care so much about attaching to the PPF. For that, I'd look into firmer differential mounts instead along with new motor mounts. You cant have worn motor and diff mounts and then think that little brace is going to do anything.

That's why the Autoexe is more appealing to me because it boxes in the rear more. I know it's a different purpose than the Beatrush but if I had to choose one or the other because they share a mounting point, I'd opt for the Autoexe.

2001SE
03-04-2012, 07:40 AM
For the benefit or rookies like me, would you guys take a moment and explain which is which and what the benefits of both are.

What is the intended purpose,
What is the approximate cost,
On what model/year do you see the most/least benefit
Degree of difficulty to install? (How many holes need to be drilled and is it worth it)

If you agree, I will move this (or copy) and the reply into Suspensions as a reference for others.

03-04-2012, 10:37 AM
Well, just finger typing on a pad so a little curt of an explanation:

Two separate forms of bracing being talked about here, one for frame (unibody), one for drivetrain.

Purpose: The Autoexe braces (about $700ish) are designed to frame the body for more solidity and torsional rigidity which is a weakness in the floppy Miata body and generally with any convertible. The Beatrush brace (about $100ish) is designed to reduce side-to-side play in the drivetrain by tying the power plant frame (PPF) to the rear subframe.

The Beatrush is easiest to install with only three points, no drilling required. The Autoexe is more complex (hence more effective at what it does) and requires some drilling in the floorpan. Earlier Miatas are more flexible than later ones and benefit the most from aftermarket bracing. The 2001+ Miatas came from the factory with many braces, trussets on the firewall and even a factory "butterfly" brace underneath. Miatas got heavier over the years because added bracing made the body stiffer.

Nothing wrong with add-on braces until they conflict such as the point of the original question. Each brace in this thread does different things (body vs. drivetrain) but my opinion is that the Beatrush is used more like a Band Aid for most people.

The entire drivetrain is supported at four points: the two motor mounts and the two differential mounts with the PPF connecting the front to the rear. All four points are made of rubber which wear out over time, especially with higher HP upgrades. For example, boosting to 200hp on stock marshmellow motor mounts will not only give you vague shifting feel, it also stresses out the PPF.

Adding a Beatrush brace to the rear that ties the PPF to the rear sub frame does nothing. As a matter of fact, now you're solidifying the PPF to the rear subframe while the motor is still twisting side to side which could crack the rigid aluminum PPF because you've taken away the purpose of the rubber differential mounts to absorb some of the twist.

The moral of the story is if you want better transmission of power to the road, snappier shifting and reduced drivetrain slop, replace the motor and diff mounts to better ones or at a minimum replace worn mounts with new stockers. If you can grab the top of your motor and move it more than an inch side to side, you need new mounts and the Beatrush brace would not only be ineffective, it could be detrimental.

It's harder to check if the diff mounts are worn but if they're old or you're running high HP, again, it would be better to replace them rather than mount a Beatrush brace and hope that fixes anything.

So, IF your mounts are in good shape, THEN the Beatrush brace is nice to have. If they're worn, the Beatrush does nothing and could make things worse. IF you're simply deciding between the Autoexe frame braces and the Beatrush PPF brace (and money is no object), always opt for stiffening the body.

Again, two different braces for two different purposes so it's hard to do a line-by-line comparison but I hope that gives some insight.

Tristan75
03-04-2012, 02:31 PM
Woow... I wouldn't have explained this better!

Hmmm... could the Autoexe be modified to be able to do the same job as the Beatrush, like this you have both things (2 in 1).

Soon soon... big surprise :twisted:

2001SE
03-05-2012, 07:27 AM
Thank you very much. That answers many questions.

Like I said, for the benefit of those, like myself who are getting to know some of the finer points, this is very good information. I, and I assume others, read about different modifications, additions, improvements etc from different sources and sometimes they are bias. Reading the sellers side, every item they sell will make your car run faster, and jump higher (like Wonder Bread). Other forums seem "product loyal" to the extent that they seem to tout one product or one procedure.

One of the many benefits of the Gearheads is that still being small, we get good feedback from people that we know and in many cases actually see the mods in use.

Thanks for taking the time to explain this.