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Chassis stiffening - which parts are good?

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Old 07-26-2009, 10:16 PM
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There are some pictures of door bar installs here. I just posted some more of mine recently. A search on door bar should do the trick.
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Old 07-26-2009, 10:21 PM
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Originally Posted by TheBandit
The HD Door Bars don't look very complex. I'm thinking about trying to fab some up with some DOM tubing and a couple pieces of 1/4" plate. Does anyone have any good pictures they feel like sharing?

-Michael
i was looking into this as well. shouldn't be too hard to fab up since the HD bars are just straight with like a 60* bend at the end and two flat mounting plates.
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Old 08-04-2009, 02:59 PM
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Originally Posted by Sam Amporful
It helps tremendously on twisty tracks and in autocross situations. My car feels much firmer with the butterfly brace and subframe braces.
Yah... but its more fun to shimmy and wonder when the car is going to twist in half
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Old 08-25-2009, 08:16 PM
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The dead shall rise.

Has anybody followed up on the triangular diff/ppf brace?
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Old 08-26-2009, 12:26 AM
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Originally Posted by Sam Amporful
and in autocross situations
If you check the fast autocross Miatas going to nationals you'll see them being stripped of all possible bracing. Reason is the weight saved by removing any of those braces is better for cornering than the minor stiffening effects the braces add.
If you want your car be a good street cruiser - the braces are good for their effects on NVH. But not if it is a dedicated racer ...


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Old 08-26-2009, 01:24 AM
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Originally Posted by j_man
If you check the fast autocross Miatas going to nationals you'll see them being stripped of all possible bracing. Reason is the weight saved by removing any of those braces is better for cornering than the minor stiffening effects the braces add.
If you want your car be a good street cruiser - the braces are good for their effects on NVH. But not if it is a dedicated racer ...

I could argue this all day, but in the end both sides will be right and there would be several useless posts. BTW bracing, if done where it counts, doesnt even have to add any more than 30lbs
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Old 08-26-2009, 01:58 PM
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Originally Posted by Sam Amporful
I could argue this all day, but in the end both sides will be right and there would be several useless posts. BTW bracing, if done where it counts, doesnt even have to add any more than 30lbs
30 lbs is huge. People going to Nationals fight for the last pound and the thousands of the second it gives them.
I.e. talk with any CSP national champ in a Miata and you'll see their cars stripped of all bracing possible allowed by the UD/BD rules. Those guys have tested bracing vs no bracing against the clock many many times.

I just read few days ago that Bill even recently removed the flex section from his current header because of weight savings ... that's how serious those guys are ...

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Old 08-26-2009, 02:09 PM
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for Auto-X, the 'flimsy flier' approach is what seems to be winning nationals (csp) repeatedly. Some guys are even shaving bolt heads to save a few oz. For auto-x. no argument. end of discussion.
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Old 08-26-2009, 02:24 PM
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So, anyone compared times on bracing versus no bracing on a 250+ HP Miata?
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Old 08-26-2009, 02:25 PM
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At first I wasn't sure, but I can see how that would be likely. All of those factory braces do probably add up to 40-50lbs, and probably don't have all that much effect on the track. However, for a street driven car, or a car making considerably more power than stock, I would want the bracing. Whats 40lbs when you make 100hp+ over stock. Plus most of the bracing is around the same height as the wheels, so its not making the car top heavier.
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Old 08-26-2009, 02:32 PM
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I don't race often enough to make the Miata even less DD friendly. My mother visited a few weeks ago and commented that I'd "taken a perfectly good car that I (she) liked to drive and ruined it". I need to get some current good pics of Andrew's car so I can show her how much restraint I've shown in the pursuit of speed.
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Old 08-26-2009, 02:34 PM
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Originally Posted by NA6C-Guy
Whats 40lbs when you make 100hp+ over stock.
Those 100hp+ don't help in the middle of a corner.
And the 40lbs hurt your grip.
Then on a straight do you think a 20 lbs ladder brace would help your 100hp+ over car accelerate quicker?

The CSP Miata national level prepped cars are much more violent on the hardware too ... they have less than 200 hp but they break PPF, differential cases, etc. often, generate over 1.5G in cornes and are driven much harder than 99.9% of the turbo Miatas on this forum. When sitting in those Miatas in the middle of a run it feels like they are going to fall apart any moment. And owners have found that all these bolt on braces still hurt times ...

Originally Posted by NA6C-Guy
However, for a street driven car
For a street driven car I agree. One doesn't want his car to feel like it is going to fall apart when driving over a railroad crossing
All I was saying that while making our cars feel more comfortable or help other parts last longer, they don't help with getting faster lap times as many who only test by feel try to convince you



Last edited by j_man; 08-26-2009 at 02:46 PM.
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Old 08-26-2009, 02:50 PM
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j-man, I don't think he was talking about auto-x necessarily. I would argue that riding in an LS1 Miata at Laguna Seca convinced me that it was worth it to have as much bracing and heavy BBK as possible.

koto, I totally feel your pain. I get criticism from the fam all the time for 'ruining a perfectly good car'.
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Old 08-26-2009, 02:53 PM
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This is exactly what i was talking about, hence why im not even gonna argue the point as it has been argued constantly
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Old 08-26-2009, 03:07 PM
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I for one would want a really solid feel to the car while doing 100+ MPH through Turn 1 at TWS

Spec Miata also runs a full cage (right?), which street cars do not, so that in itself would add a lot of chassis bracing.
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Old 08-26-2009, 03:54 PM
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Gee, I guess floppy cars are the way to go. All those automakers building stiffer cars all the time must be idiots. Those full cages in the CSP cars don't help stiffness at all either...
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Old 08-26-2009, 04:00 PM
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Originally Posted by superslow
j-man, I don't think he was talking about auto-x necessarily. I would argue that riding in an LS1 Miata at Laguna Seca convinced me that it was worth it to have as much bracing and heavy BBK as possible.
In my first reply above I quoted the autocross part only since I've talked to those national champs and have first hand info
About the track case - it is all up in the air unless someone of national caliber at a test day does a bunch of laps with bracing then without, then with, then without again and then analyzes the data from the logger ...



Last edited by j_man; 08-26-2009 at 04:22 PM.
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Old 08-26-2009, 04:03 PM
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Originally Posted by cueball1
Those full cages in the CSP cars don't help stiffness at all either...
Cage in a CSP autocrossers? CSP Miatas don't have even rollbars - put in any cage or rollbar and it hurts the times ...
AFAIK they can install such (IIRC safety rules allow it) but they don't because the Miata gets slower ...

At autocross you will see Miata with a cage only if the class rules mandate it or if the owner decided to do it for safety. The weight it adds slows the car down ...

The track case most likely will turn out the same way, but very fast & powerful Miata without a cage starts shifting towards the driver life/death gamble zone


Originally Posted by cueball1
Gee, I guess floppy cars are the way to go. All those automakers building stiffer cars all the time must be idiots.
Designing a stiff chassis from the ground up is one thing.
Throwing extra metal/weight on a Miata trying to make it stiffer is a totally different thing. If you get rid of the unibody and replace it with some space frame both stiffer and without weight penaltry ... sure.




Last edited by j_man; 08-26-2009 at 04:21 PM.
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Old 08-26-2009, 04:30 PM
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Originally Posted by superslow
for Auto-X, the 'flimsy flier' approach is what seems to be winning nationals (csp) repeatedly. Some guys are even shaving bolt heads to save a few oz. For auto-x. no argument. end of discussion.
Yeah, and I would suspect almost every one of them could shave a few pounds of of themselves and it wouldn't cost anything. I never got the shaved bolt/save an ounce thing. Go on a crash diet a month before nats, shave 20 lbs off of the driver and it is better than all of the scrimping that you can on a car. Heck, we had a guy that shaved 20 lbs in a week during wrestling season.

EDIT:

We have guy locally that has sent a bunch of money lightening his camaro for autox. The funny thing is, he is built almost exactly like my av.
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Old 08-26-2009, 04:36 PM
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Originally Posted by Stein
Go on a crash diet a month before nats, shave 20 lbs off of the driver
Most of them do that too

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