Best chissis bracing configation

[simie2014]

Hi folks. Not sure if I should be asking this here on in the body, trim section? I recently bought an Mx5 2000nb. I know the Mx5 has a strong chassis but there seems to be a plethora of different chassis bracings and struts on the market. I can understand the principles of the engine compartment tower strut and the and the searbelt tower brace to stop everything flexing and wanting to fold in. I have also seen the under body chissis rails and the many different types of splade hand type u/body braces.
My guestion is how much bracing is really needed for someone who isn't planning on road racing or really going hard. I personally plan to drive the car spiritedly and perhaps a couple of driver training days eventually. I have purchased an engine brace from someone on this site and also hope to get a seatbelt tower brace...but where to draw the line?? Any opinions would be appreciated. Cheers. Simie

[davekmoore]

Spend the money on driver training, and then on some more driver training, and then on some track days. Unless there are broken things on your car, seat time and tuition is much more cost-effective than modifications to the car.

[Magpie]

davekmoore

Look at getting the alignment on the car sorted out first as well as look at other suspension components, tyres and tyre pressures. This way you will have a point of reference to judge other changes.

With the risk of igniting the strut brace issue, a car with double wishbone suspension does not see similar gains from a strut brace as would a macpherson strut based car. However they do make good hand/arm rests and cable tie off points.

Personally I would look at a roll bar (Automotive Plus single diagonal/Brown Davis) rather than a seat betlt tower brace. The roll bar would allow the addition of a harness as well as provide additional safety for driving the car spiritedly and driver training days.

Frame rails add protection as well as add some stifness, so these are worth considering just for the protection factor. Some are being sold on the forum at the moment http://mx5cartalk.com/forum/viewtopic.php?p=825349#p825349.

Here is one persons post wherein they reviewed braces http://mx5cartalk.com/forum/viewtopic.php?p=809463#p809463, however read with a grain of slat as Da Pain is no longer a poster on this forum (however rumour is that they are using the pseudonym Sunbaker now).

Another topic http://mx5cartalk.com/forum/viewtopic.php?p=827360#p827360

[MattR]

For the use you have said the car will be put to, no need to do anything, the standard will be fine. You most likely will get some scuttle shake and feel the chassis flex on rough roads, but you will get this with most cars and even if they have aftermarket braces fitted.

If you want to really tighten the feel of the car, as Magpie said get a good alignment done and look at replacing the suspension bushes with a mix of rubber and nolathane, depending on location, this will make the car feel a lot tighter and will be of more benefit than just bracing the chassis.

[Lokiel]

Chassis-twist is the biggest stiffness issue with NA/NBs and was one of the improvements made to the NC chassis so start there first.

The Automotive Plus roll bars reduce this noticeably - as far as I'm concerned, this is its main job, the fact that it's also a roll bar is just a bonus (and one I hope I'll never need).

There's a lot of arguing over this, some (like me) swear that it makes a massive difference to chassis stiffness, whereas others claim it makes no difference at all. Not many that have an Automotive Plus roll bar would disagree with me though, its torque box is very chunky and "boxes" the seatbelt towers together, providing additional rigidity (think of it like two posts; on their own they may be reasonably solid but by puting a brace across them they're even more solid since any force against one post is also resisted by the other post). I noticed the difference immediately when doing a right turn at carpark speed, the car definitely felt different.

The rollbar makes a great place to mount a track camera too.

Also, just say NO to Style Bars!

Other bracing options I've added in order of "stiffness feel":
. Boss Frog Frog Arms (reduces scuttle and improves turning sharpness)
. Beatrush PPF Brace (reduces wheel tramp - more an issue when you increase engine power)
. FM Frame Rails (can't really notice/feel these when driving but very noticeable when jacking the car up from a corner, the other wheel raises much earlier; their biggest benefit though is that I can use them to do wheel and brakepad changes quickly since I can do one side by simply jacking up the car from the middle of the frame rail - since I'm not under the car when doing this I don't have to worry about getting crushed)
. Carbing 3-point brace - not really sure where this should be in the order since my SE always had a front strut brace (some say they make no difference at all but the fact that Mazda installed them on all the latest NBs makes me think that their engineers knew better)

As Magpie said earlier though, if you've got money to throw at the car, start with the rollbar, the other options are overkill. Do a few YouTube searches for MX5/Miata rollovers too, you'll see that the A-Pillar is nowhere near as robust as you expect - that may help you decide on the rollbar first.

[KevGoat]

The single biggest change I made to the feel of any of my 5's was when I fitted a Brown Davis roll bar in my NA. Less body shake and felt like an immediate improvement in the way the suspension worked.

I agree with Lokiel though and I'll fit one of the Automotive Plus bars (twin hoop) if I fit one to my SE.

Sent from my GT-I9100T using Tapatalk

[greenltd]

I agree with many above, my NB has SE suspension, a good wheel alignment and an mx5 plus roll bar. The thing handles really well and with a good driver (de Bounce) is really quick, beyond what many expect from it. So far this car is faster than my abilities.

[lightyear]

I don't want to take anything away from the awesome engineering in the MX5plus Rollbar, or Brown Davis.
But if you believe that a Rollbar is going to make any difference to your cars stiffness then that is opinion only. And not fact based.
I have had both, and have not noticed any difference. I also think that any off the shelf Rollbar offers too little protection. Too low, and not wide enough. This is due in most cases to having to leave room for a soft top.
There is a lot of sheet metal between the seat belt towers already, as is there in the area of the boss frog arms.
If you want to buy chassis braces, buy anything that you like the look of. As that's mainly what they do - look good.

Nothing short of a full rollcage is going to make much of a difference - my opinion.

[Magpie]

As an alternative to bracing if you have a welder you could seam weld parts of the car.

For example where Lightyear was talking about instead of frog arms, do some welding



Before seam welding and being cleaned (no after photo yet)

[Vat]

I have the Ultra Racing front shock tower brace and an NA seat belt tower brace. The effects aren't huge but are noticeable - I wouldn't call them performance gains, though.

The front shock tower brace seems to clean up the feel of the steering - it's hard to describe, but having run back to back over Mt Nebo, I prefer the feel with the brace in. Seems to isolate it a bit from the suspension, so you have a bit of a better feel for what the wheels are doing in terms of grip and steering loads independent of bumps.

The seat belt tower brace seems to reduce diagonal flex across the cabin. Sometimes hits will come through the cabin and you'll feel them go front left, and then back right, with a little bit of a delay. The seat belt tower brace seems to considerably reduce that.

I seriously doubt they would make any difference on a racetrack and I think Magpie has mentioned previously he went quicker without them. I personally prefer the feel of the car with the bracing in, though, especially the steering feel which is probably the most important of a car to me.

[Nevyn72]

I don't want to take anything away from the awesome engineering in the MX5plus Rollbar, or Brown Davis.
But if you believe that a Rollbar is going to make any difference to your cars stiffness then that is opinion only. And not fact based.
I have had both, and have not noticed any difference. I also think that any off the shelf Rollbar offers too little protection. Too low, and not wide enough........

Sorry but I have to differ from you here.....

I installed the MX5+ twin hoop and immediately noticed a HUGE difference on my SE (the model with the most factory bracing).
Not only was the steering more direct and responsive but the amount of scuttle shake was dramatically reduced!

Yes a full roll-cage will give better results but isn't very practical on a DD and isn't legal in any case anyway.......

[NitroDann]

Bolting heavy components to the car will change the resonant frequency that the chassis vibrates at due to changes in mass and damping in the flexibility.

This is a noticeable change but claiming that its actually noticeably stiffer AND that its a performance improvement is just silly.

Dann

[hks_kansei]

Bracing gives an immediate difference in the modifications you can list when you post on forums, or blogs.

It means your car is more likely to be picked up and have an article written about it on a blog, make sure to also include other "mods" in the list, such as the brand of tyre fitted, and the brand of oil used.

[Lokiel]

Bolting heavy components to the car will change the resonant frequency that the chassis vibrates at due to changes in mass and damping in the flexibility.

This is a noticeable change but claiming that its actually noticeably stiffer AND that its a performance improvement is just silly.

Dann

I remember a phone call from you commenting about how stiff my car was when you first put it on stands at your place - it really stuck in my mind because you've had many more cars on stands than the average Joe and actually thought to mention it.

[NitroDann]

I think it was the first SE.
Which makes sense.

What additional bracing did it have, it hard to quantify anything with a list but for interest.

Dann