Engine Torque Brace
 

I did a search for these and the most recent thread was 2008.
Anyone still making them? Any verdict on which style is best? ie mounting near the brake pipes or off of the alt bracket.

Why do you want an engine torque brace?

IMO they are a bit of a ricer mod unless your making massive power with really soft engine mounts...in which case you should get harder or solid engine mounts.

If your engine moves too much without loads of power then replace your mounts

Hey buddy, haven't seen you in a while!

Yeah, the other issue with the torque braces is I've seen them strip out and destroy the aluminum threaded holes on the UIM where they bolt to.

It gives the UIM and LIM hell because the brace normally comes off the UIM and goes to the body- the shaking and rocking tends to try and flex the upper manifolds (which are not designed to take loads) and you get all sorts of problems with not much of any benefit at all.

A few of the JDM cars I've imported here from Japan have had them on and it was pretty obvious the damage they eventually did to mount holes and UIM/LIM joints, gaskets and mating surfaces...

I think the best type of Engine Torque Brace is the kind where you just replace your engine mounts with some good condition ones, and don't worry about throwing a bandaid on an issue that won't be fixed like that.

Ok maybe I should explain my situation. I already have new solid engine mounts that will be going in.
The flange on the hot side of the turbo housing cracked and the previous owner did a quite terrible job welding it. I had all the old weld ground out and did it properly.

I'm trying to prevent this from happening again by reducing the movement. Option 1 is to add another hanger to the exhaust so there is less weight on the flange. Option 2 is to reduce the movement at the source by adding an engine torque brace.

If you have any other suggestions I am open to discussion.

Option 3 may be to add a flex section to the exhaust to keep the whole system from putting so much stress right into that area.

^ I'd go with Andre's suggestion.. if the DP hasn't got a flex section you may def want to add one.


And Solid Engine Mounts? :scared: Is this a street car? If you've never run solid engine mounts before you *may* want to reconsider... they transmit a LOT of vibration... I had some in my car once... They lasted for 1,000-2,000 miles before I had to chuck them! I went back to some low mileage/good condition stockers..

Putting a flex section in the exhaust is a good idea that will lower one stress to the turbo to downpipe v-band section.

The main cause of initial cracking is welding the v-band flange to cast iron. The expansion rates are different and the constant heat cycling is what causes the initial crack that the exhaust stress spreads.

You say it was welded properly now so it should last longer/indefinitely depending on use.

The real proper "weld" is to heat all the metal involved to dull red and then braze weld it with nickel filler so the weld and the area around it is a gradient of cast iron/cast iron + nickel/nickel + v-band steel/v-band steel and then beat the metal as it slowly cools to alleviate stress.

Even done this way these welded on v-band joints are notorious for failing and that is why the manufacturers now machine the v-band flange into the turbo housing.

That is the method this was redone. I just want to add some more margin to prevent it from cracking again as it will be a PITA to unbolt once its in the car. There is also a large radius now to help with some of that stress.

I agree that if you have bad motor mounts I would replace them. If you are still looking for a brace I have one I am no longer using. It is all SS and would sell it to you. Just PM me.

WOW, how far have we come.
I remember when these torque braces came out, you needed one for smooth gear engagement, prevent missing a shift, save engine mounts, reduce vibration?, etc.
They were high priced and everyone had to have one, but the right one.
Adjustable with internal rubber bushing vs. fixed solid length (Garfinkle one), and you had to get on a waiting list for one.
Now, it's the other way around, you don't need one because it tears the UIM/LIM.
LOL

^Was kinda thinking the same thing.
I had one but it was never intended as anything but a Band-Aid for the typical OEM mount failure. As soon as I was able to install some Noltecs I got rid of it. Always thought it looked 'rice' and had to fuss with it constantly to keep it from rattling.
We've come along way from the cut-down hockey pucks some used to replace the failed mounts too.

^ had to make a comment because I bought the Noltec mounts used from CrispyRX7, and they were likely the first part I purchased for the car.
Very neat design that has the mounts isolated and free floating, until you get on the power then they lock together.

Solid mounts shouldn't be used in anything but a full race car in my opinion. You want some give. Myself and several other vendors sell quality polyurethane motor mounts. I offer different stiffnesses as well. A torque brace is a bandaid. Plus most of them mount to the thin sheet metal of the fender which really isn't strong enough. If your exhaust/turbo is cracking it either wasn't welded properly or inferior materials were used. And yes a flex will definitely help.

Interesting thread. Back in 2008, I had every suspension bushing replaced in my car. Steering rack bushings, engine mounts, pillow balls, diff mounts, etc. All available Mazdaspeed bushings available were used FWIW. At, or about the same time, I had the Banzai Racing diff brace installed. The car felt very solid, but a peculiar thing happened that I could only attribute to the diff brace. When in gear and slowing down that the revs dropped to around 1500 rpms, the car would start to buck pretty hard. Sort of like when your slowing down in gear but at very low rpms to the point of the car wanting to stall. I had the ETB, installed and it corrected the problem. However, after looking back at a dyno session I filmed, I noticed the brace and mount flexing under load. I've included the link.


It's very fast and not too noticeable, but watch the ETB at the moment the throttle is lifted. I really don't like that it does that and have contemplated removing it, but I don't want that bucking to return. I may need to remove the diff brace as well. Thoughts, opinions?

Ihor, I'd like to bring the car in soon for some minor stuff, perhaps you can take a closer look at it then.

I have the exact same problem, but never thought to associate it with the diff brace

^^^^^^^^
I had the same experience to your vibration/hesitation event, but mine was with the transmission brace.
My car had new engine mounts, differential tower bushings and the engine torque brace and I had no vibration/hesitation issues on the track or the street.
I add the transmission brace and the car vibrates like a Mexican maraca.
I had to stay on the gas on idle at the grid and street lights to avoid vibration and the feeling of stalling.
When I took the tranny brace off, vibration was gone and problem solved.
I still have the engine brace, but after seeing your video, it is coming off too. :nod:

People have spoken about the Mazda engineering design of the PPB and the reason for needed flex in the system for the transmission of power to the wheels.
Others advocate the stiffness in the system, in order to transmit the power to the wheel efficiently and quickly.
After my experience, I will side with the Mazda engineers.
Most, if not all of the aftermarket designs have no data to prove or back their claims. They are mostly based out of race car designs and then, translated to the RX7.
Following the principles or philosophy: "It's big, it's strong, I could feel the difference on my butt dyno, my cousin has one with no issues, it's painted red; therefore, it must be functional, good and fast".

Thanks for your response RedBaronII and TomU. I was thinking perhaps I needed the trains brace as well, but now it looks like I'll skip that. The ETB is coming off and perhaps the diff brace as well. IIRC, the diff brace was intended more for the drag people. Although I don't drag my car, I've witnessed several FDs brake their diffs at the starting line, even with simple bolt ons and moderate launches. While we know of of several design flaws in the FD, I do agree it's hard to fault a chassis design team that had a near unlimited budget when designing the FD. There were some under chassis braces from Mazdaspeed several years ago but that was it.

The trans brace was designed to solid mount the trans to the chassis, it was no secret that it transmitted vibration. We specifically stated "this brace can transmit vibration into the passenger compartment. If you have any concerns about noise or vibration, we do not recommend installation of this product" https://www.rx7club.com/banzai-racin...-brace-918218/

We discontinued the trans brace quite some time ago.

Do not confuse the trans brace for the Transmission Crossmember which does not transmit vibration, since it utilizes the Energy Suspension polyurethane trans mount Transmission Crossmember

In my experience engine "bucking" is typically tuning related. Most tuners spend a lot of time in the high RPM areas of the map but very little attention is given to low rpm driveability. Often times the fuel cuts are set way too high to prevent stalling which can result in bucking. However I can't say this is your specific issue without actually seeing the car in person. I can say that it is highly unlikely that the diff brace is causing your engine "bucking", it may be highlighting the real issue.

Don, you should let John Renna get his magic fingers on the keyboard in your FD and work his magic ;)

Thanks for your input, however my car was still on the factory ECU at the time.

Rich, yes, I'd like that very much. Especially if I go with AI in the near future.

You have been living with engine bucking for 7 years and think it is due to a part attached to your diff, that is removable in 5 minutes. Sorry but something is not adding up here.

No, hasn't been 7 years, I did the ETB about the same time or very soon after the diff brace(it's clearly stated in my original post). It was someone's recomendation to do so. Even that video clip is about 5 years old already. Looking back I should of just posted that I added a diff brace and noticed an "anomaly" and not used your company name as it seems to have struck a diminished chord with you which is understandable. Wasn't my intention to knock your product or business in anyway.

I installed the trans x-member a while ago as the only suspension mod on an completely stock and original suspension. I very much liked it. It provided a more solid feel and seemed to improve shifting. Since then I have completely replaced my entire suspension with aftermarket poly bushings and motor mounts. I also installed the diff brace, but have not yet reinstalled the trans x-mbr. The ECU is stock and the engine is a reman rebuild with an aggressive street port. I experience "bucking" when the rpms start falling below 2k. I attribute this to the suspension and not the tuning. I plan to install the tran x-mbr and see how that does, then if it continues, will remove the diff brace to see if that is in fact the culprit. I'm thinking with poly diff mounts, the brace may be overkill anyways. Use is street/track BTW with emphasis on track

I let my friend borrow my stock auto RX-8 and he mentioned the bucking in that car when it was cold.

I told him just let off the gas all the way or put it in manual and go up a gear and give it more gas.

Its a rotary thing as far as I can tell.
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On tuning my TII I found adding crazy amounts of fuel at low load/rpm stops the bucking.

If the car hesitates, backfires and shoots flame you have too much fuel, just dial it back a hair from there. You know you are getting close to lean enough when it starts machine gun backfiring and accelerating smoothly instead of hesitating and a single big backfire.

When you get it spot on it will just accelerate smoothly away even when cold with just a big puff of hydrocarbon smoke and a trail of dead animals and birds falling from the sky.