RotorMotor

iTrader: (5)

i was wodering if autoexe was the only company which made these style chassis braces? they look relativly easy to make (or copy for that matter)... just wanted to chat about a few ideas i had, and also ask what more we can do to stiffen the FD up. i imagine that stiffer=better but that may not hold true past a certain point. lets talk about it

diablone

iTrader: (2)

Although not a knock off (in fact, probably more expensive ), Mazdaspeed makes these as well.

1point3liter

Are you reffering to the transmission mount chassis brace?

VQracer

a company called gt spec made a set of these for the z33.

they are located in america

perhaps they will take this project.

RotorMotor

iTrader: (5)

sorry, heres what im talking about:


anything else we can do to make the chassis more solid? ive seen some braces that go in front of the doors (behind the fenders) if i remember correctly. can the car be TOO stiff? any downsides?

jimlab

I think the front brace is a joke, personally. The rear-most pieces just duplicate what the '94-'95 cars already had, and the U-shaped bracket in front of the rear subframe does basically what the stock trans tunnel crossbrace did. The only benefit that I can see is that the U-brace effectively ties the rear subframe into more area of the floor pan.

Mike M

Changing the stiffness of the FD will change the crash force distribution. All cars undergo computer modeling during various crash events including frontal, offset frontal, side, and rear. Changing various distribution points will change crash dynamics.

RotorMotor

iTrader: (5)

^agreed, and maximum safety is very important to me in a car like this......

vrmmmpshhh

OPtion magazine did a pretty good test on bodyflex on a few cars, the FD being one of them. They measured the flex between the panel gaps on the top of the door and the body, usually where the door handles are located in other cars. They drew a line bewteen door and body. They jacked up the car behind the front wheel.

Stock the FD had a gap of 1.0mm, s14 had 1.5mm, r32gtr had 2.5mm, toyota supra 0.5!!! IS200 (altezza) had a gap of 1.5mm

s14 they made a brace that covers the hole behind the rear seat. no change in flex.

supra they installed a bar that runs along the front seat belts (both sides). bottom to top. still no change.

IS200 they installed the underbody braces like the ones in the above, there were 5 braces altogether that went under the car. flex changed from 1.5mm to 1.0mm

The R32 gtr they installed a L shape brace behind each front guard. flex changed from 2.5 to 2.0

lastly the FD, they installed a HUGE frotn strut bar, bolted to the 2 frotn stuts and then had 4 other mounting places to the rear firewall. Also replaced the rear strut bar with a beefier one that joined the rear struts and the floor on both sides. NO CHANGE in flex!!!

OHHH there was a older model nissan march that they wetn the whole hog on and did everything to it, braces underneath and full roll cage... change from 1.5mm to 0.7mm

jimlab

I dug up a few pictures...

The front brace (shown below) connects to the rear of the engine cradle by unbolting the eccentric alignment bolts from the rear bushings of the lower control arms and inserting them through the "cups" shown, then re-tightening. The kit includes some cheap hardware that uses pre-existing slots in the floor pan to mount the rear of the brace, 2 bolts per side. On the whole, it's pretty cheesy, and I don't see what good it could possibly do considering the way that it fastens on the car.



The rear section (first picture below) is made up of three separate parts. The rear two are triangular shaped pieces which bolt to the rear subframe and under the stock rear transmission tunnel brace (shown). The third piece is a U-shaped piece which bolts in place of the middle trans tunnel brace, and over the stock rear tunnel brace.

A 1994-1995 rear subframe (second picture below) already includes V-shaped braces which do much of what the rear pieces of the Auto EXE kit does. It should be noted that 1993 subframes do not have the rear mounting points required for the Auto EXE braces (third picture below) and do not have the V-shaped brackets. Instead, they have a single brace per side (silver) which does not tie the rear of the subframe into the body.







That said, I made a welding jig from the U-shaped brace while I had the kit in hand and eventually I'll make a version that has an integral driveshaft loop.

RotorMotor

iTrader: (5)

so jim.... this wont work with a 93 subframe anyway? if so im definatly out of the autoexe boat. id like the extra bracing that the 94 stock frame offers though, so while the car is almost 100% dissasembled i may just swap one in. jim, is it worth it ? -heath

jimlab

Only if you can find a '94-'95 rear subframe used, since a new one is in the $1,100 range, IIRC.

BTW, as part of my Ford Cobra 8.8" IRS conversion kit I had a set of brackets produced which duplicate the '94-'95 rear mounting point for 1993 subframes. I haven't decided whether or not to offer these separately, but I might if there was enough interest.

RotorMotor

iTrader: (5)

in interested .... what range are we talking about price wise?

RotorMotor

iTrader: (5)

basically what im hearing is that all (well most) of these aftermarket bracing pieces do little if any to help the car... is that correct? as far as bracing the drivetrain (transmission brace, diff. brace) id hope that those "upgrades" would have more of a significant impact.

the FD chassis is relativly stiff to start with, but id think that adding any sort of bracing to the car would add to the overall "crispness". when i take my 94 out of our steep driveway (siedways to avoid ripping the bumber off ) i can hear the sunroof and other pannels creeking away. and when that car is jacked up (with just the front in the air) the doors are a bit harder to open. to my knowledge this car has not been in any major accidents. that being said, with the car planted on the ground im not sure how much flex you can really get out of her before the tires will break free (say while cornering). although i am doubting the overall gains from these types of chassis braces, i still feel like tying any extra points together must do some good. is it worth $500? im not sure at this point. the only point of reference i have with bracing would be when i added in the strut tower bar to my 94 a few years ago. the difference was definatly not night and day, but the steering response/feel and cornering did seem to regain some life. it was more that the steering seemed less "sloppy" (not that it was bad before) but just that it gave the settring that extra bit, which was enough for me to justify the price and put a smile on my face.

RotorMotor

iTrader: (5)

and what about integrating a diff brace into the whole thing?

ROTORhead93

Since everyone is saying that these braces dont do anything to help stiffen the chassis, what about the mazdaspeed chassis stiffeners? Does anyone know if these would help stiffen the chassis? I only ask because these are mazdaspeed and they usually make FUNCTIONAL products. Does anyone have these or know if they work?

If you look at the pictures, the autoexe braces and the mazdaspeed braces look almost exactly similar.

jimlab

Well, they both bolt to the bottom of the car anyway.



I still don't think the front brace accomplishes much, if anything. As for the rest of it, who knows? I do know two things, though; 1) Mazda provided the car with lightweight aluminum cross braces that accomplish much the same thing, and 2) the Mazdaspeed and Auto EXE braces add a considerably amount of extra weight.

RotorMotor

iTrader: (5)

not to keep draging this out... but i just was interested in (approximatly) how much you thought all this stuff weighed jim? thanks again

jimlab

I don't remember what the Auto EXE braces weighed when I shipped them, but it was probably in the range of 20-25 lbs. Not a massive change, but if they're providing negligible benefit, definitely something to think about.

I suspect that the new braces I've seen that mount behind the front fenders are probably along the same lines as the "belly braces". An interesting idea, and they probably don't hurt (except for the weight and the effort involved to install them), but the benefits are not easily quantifiable (or disproven). Would most people benefit from them for daily driving? Not likely, and a full race car would probably have a cage of some type installed which would make any tack-on bracing superfluous.

WaLieN

I find it hard to believe that the Supra, of all cars, had a .5mm difference. Are you sure on this information?

RXASSASIN7

okay my only question is:

is there anyway to stiffen up my 93 rx7 other then the pettit power plant sub frame got that but there must be something else thats worth the money to stiffen the ride?

i ahve already ripped through 2 stock power plant subframes until i got the pettit

J.S.J

You can install a solid diff brace as well as a trans brace. I have a diff brace which has a motor mount insulating the vibration. It really helped my PPF which seemed to be a bit soft. The system looks like crap because cutting and drilling 3/8'' by 3'' steel is a pain with out a good saw. You can't make a lot of changes when it takes so much effort to make cuts. I will be making one more which will likely use 2 3/8 ths" by 3" peaces of stock welded together and about 29" long connected to the mount and the body connection will be one 3/8'' by about 16" to attach the other side of the engine mount which will sit just below the PPF behind the cat and in front of where the PPF bolts to the diff. The one I have on now is not as stiff but makes a big difference. I am looking for a way to bend the stock to make a trans mount using a similar mount at where the PPF bolts to the tail of the trans. Just the one system keeps the power- train from pushing the shifter forward like it did before. I will need to but longer studs in the rear PPF mounting point to accommodate the thinker material. I am not a big clutch dropper but do like a secure power - train.

jimlab

The powerplant frame has nothing to do with improving the rigidity of the body of the car.

rotaryextreme

iTrader: (2)

You can put the Autoexe braces on the 93. A Japanese company makes an adapter for the back pieces. My customer has the autoexe member braces on his 93 right now.

Chuck

rotaryextreme

iTrader: (2)

Those fenders braces you mentioned might do something but they might not on the 3rd gen. But it's interesting that WRX comes stock with fender braces.

Chuck