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I have bent the hell out of my stock rear subframe brace. I have an 01 SE, so that means the giant ladder brace that comes with the Sport package. It goes from the rear tub, to the rear subframe, to the lower control arms. The very front section has a horizontal section that is a U-channel. That is the lowest part of the car and it caught on several speed bumps over the years.
My stock catalytic converter plugged up, so I took off all the stock bracing and put on an FM exhaust. I drove around for a few weeks without any of the bracing on and I must have gotten used to it, because I didn't think it was that bad. Last week, I put all the front bracing back on and that is when I discovered the back section doesn't fit anymore. Now I can't put both rear braces back on because they hit the exhaust pipe. The front braces made a massive difference in NVH and the response of the front end, so now I definitely need to figure something out for the rear.
I just got back from a 1500+ mile road trip through the NM and AZ mountains and the lack of stiffness in the rear and all the shaking is really annoying me now. I have found the Beatrush rear brace and the FM rear cannon brace. The Beatrush rear brace ties into all the stock mounting points and lacks the cross-bar that is preventing me from bolting up the stock brace, so that should work and it is $234 at Goodwin. The FM cannon rear brace ties the lower control arm mounting points together and into some stuff above it. It goes for $169.
Does anyone have any direct feedback between the two braces or which one would be better for my application?
Last edited by Chilicharger665; 04-12-2017 at 10:29 PM.
OK, so truth is I have been thinking about rear subframe braces a ton. I have miata2fast to thank, I can't remember where he said it, Pat, Scaxx or Six's thread.
I think the beatrush brace is closest to what I want but they box in the diff with the rear subframe. I want to make a sort of slapper bar for the PPF, bracing the front of the diff forward. I think this is to combat wheel hop more than anything else.
The bars that extend forward from the sub frame are similar to mustang steeda sub frame braces, although not as beefy. They are meant to make the sub frame more of a unit with the entire car instead of just bolted to the small rectangular area, that it is bolted to. So these would be pretty important, as well as the bars connecting side to side.
I think the factory ones are pretty flimsy and you could probably make something just as good with a couple of junk chromoly bike frames, a hammer and a drill. I probably would just try to make the original fit again with some brute force. I often see people trying to sell them on CL and ebay but you would likely have the same problem.
I will be making some braces soon, but again I am going to try to combat wheel hop more than anything else.
I can verify the lack of the rear subframe brace is allowing excessive wheel hop. I drove it yesterday and the damn thing was wheel hopping just leaving stoplights. I wasn't taking off hard or anything. I know my motor mounts are shot, but just letting out the clutch used to make the rear wheels shudder, not full on shake like crazy.
On the Beatrush piece, it sounds like you are talking about their PPF brace? That is not what I am talking about, I am talking about Beatrush Rear Performance Bar- (NB) for Miata 1999-2005. It looks like the PPF brace bolts on to the bottom of that brace and then to the PPF. I bet that would make quite a large difference for wheel hop.
Canon brace only ties the rear inner control arm mounts of the subframe and the sway bar bracket. It lives on my car still, but I don't have front mounts to utilize the OEM U-brace thing because 1992.
beatrush brace. no street use or launching from stop/etc. track only.
-made 6 spd livable. was ready to go back to a 5 spd otherwise, and didn't want to spend the $$$ for a miataroadster shifter.
-noticeably more NVH
On the racetrack you noticed more NVH from the Beatrush PPF brace? Damn, it must be pretty bad then.
You should definitely re-think not buying the Miataroadster shifter. They are 10% off right now, I think. I have bought two. One standard height for my old 04 MSM and one extended height for my current 01 SE. It completely transforms the shifting. I always hear everyone complain about the 6-speeds shifting and I share none of those complaints. I literally have only kept the car this long because of that shifter. The car is slow, rattly, and looks like ****, but I love shifting the thing.
w.r.t canon brace, I'm not sure what made a bigger effect. I swapped from a rotting NA subframe with a torsen to an NB subframe with an OS Giken. Stiffness might have been inherent simply because the subframe was updated and 10 years newer
Ok, the brace you linked does look like my 99 factory rear brace, but a bit nicer. I was thinking of the PPF brace.
I plan to connect the ends and middle of the U shape, like a B shape. Then I will use one of the new cross braces to limit upward movement of the PPF. If all goes as I imagine, which is unlikely, there will only be contact/noise on hard launches. I will dampen the noise with some sort of bushing, but I would like to hear it, so I know if it's working or not.
Does your 99 factory brace have a perpendicular upside down U-shaped brace connecting the front of it? I don't know the differences between all the factory braces on the different years.
No those are from a later year, you mean connecting the ends of the U right. I have seen them and I want to make one that will basically catch the PPF if it bends up.
So this is a representation of my 99 rear sub frame brace. The wood block represents the rear section of the brace and would sit just behind the rear axles, my feet would be where the rear bumper is. The green stakes represent the braces going forward which bolt to the sub frame just in front of the rear axles and further forward at the frame rails.
The 2 braces will be used as follows, with an additional brace reaching up from the front one to catch the PPF.
I will most likely space them away from the chassis with bushings of some sort.
Would you happen to know the size/thread of those bolts?
Ok, what you are building is basically the stock Sport brace. It has 3 cross braces, instead of the 1 like you showed in the first pic. I will be interested to see how you brace the PPF.
I have the bolts, but I have no idea of the size. Any quick way to check?
Maybe just a ruler across the diameter of the threads if it's 1/2" probably M12, bigger M14, smaller M10 which I doubt. Not a big deal, I will know soon enough, just wanted to make sure my holes are big enough.
I'm basically going to weld a small piece that reaches up above the bottom of the PPF, so it can only bend up a small amount. Hopefully it won't have unintentional consequences, like wadding me into the wall.
03-26-2017, 09:11 PM
I need a new rear subframe brace
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