strut braces

[Okibi]

An NA at The Putty.

[EGG80X]

An NA at The Putty.

oh my

[smiles]

So ... Um ... how much are those Brown Davis Roll Bars worth?

[EGG80X]

is that a NB8B or NB8A underside?

seems like i m missing all those braces

[Okibi]

B

[EGG80X]

B

phew.....

man got ripped off lol should have got a nb8b

[CT]

I think you'd notice the effect of a strut brace more on the road than on the track.

There's one off camber corner near my house where i can definitely feel the car sitting flatter.

Most race tracks might be too smooth to have these sort of corners.

I think you'll find the cornering forces on the chassis in an MX5 with slicks and 400lb springs on a track exceed anything that is capable on the road by a factor of many. Generally, the track amplifies issues that road speeds and tyres will barely display. In my car, I've not found it to make a noticeable difference - the underbody bracing on the other hand made a noticeable difference both in directional stability and high speed handling, ie, turn one at the creek flat in 5th ~180kph is a doddle now whereas before I added the bracing it was a little scary and very twitchy.

See the extra braces on the NB, especially the longer one in front of the diff - good shots of the NC also show the attention paid to the underbody section of the chassis. That's what I was talking about. Good pics.

[StanTheMan]

So ... Um ... how much are those Brown Davis Roll Bars worth?

they are worth every cent. It will also add some extra bracing
you will also notice the suspension doing exrtra work around corners

about $790 for a bling polished one from mania
little less for ther Stainless steel.

[Okibi]

I think you'll find the cornering forces on the chassis in an MX5 with slicks and 400lb springs on a track exceed anything that is capable on the road by a factor of many...

I wasn't doubting that, i was talking more about the road surface.

[CT]

I think you'll find the cornering forces on the chassis in an MX5 with slicks and 400lb springs on a track exceed anything that is capable on the road by a factor of many...

I wasn't doubting that, i was talking more about the road surface.

I see - then I don't get your point. Poor surfaces will not give the mechanical grip required to put the load on the chassis. They will however increase NVH which may relate to chassis stiffness but probably relate more to shock, spring and bushing compliance. Sometimes we forget that a degree of compliance is required to actually establish grip - stiffer is not necessarily better. On the track, FIA kerbs and "shortcuts" mean that there's plenty of times a track car uses it's full suspension range too. Add to that that Australian tracks are sadly some of the bumpiest in the world. It's a large can of worms this one but I think the best approach is a balanced one - a sum of all things.

[Okibi]

It's a little hard to describe, but on the road the camber changes a lot more during cornering.

You don't need tyre grip to put load on steering, you also have a ton of car.

While the springs move to plant the tyres on the road the front of the car also twists.

The "strut brace" makes the front of the car more rigid.

It's much easier to flex the sides in on a U shape than a square.

As you mention in some cases it doesn't help because they car can't flex to match the road surface and give you more grip.

But with a strut brace you also get a more precise steering feel.

[CT]

Okibi - I'm not trying to be argumentative or a pr!ck on this topic, but I think it's very important that people understand exactly what it's about. I hope you don't think this is a personal vendetta because it's not. It's just that suspension fundamentals are exactly that and the MX5 is subject to them the same as any other car.

Camber change is a result of changes in suspension travel which is caused by changes in road surface. Due to the design of the suspension, it will change the same on the road or track with the same suspension components at the same compression. Road shape but not surface is the variable factor.

Apart from weight, the grip tyres provide transfers load to the chassis via suspension components. Jack up a car and see if you can move the steering via the wheels - you can. Now on the ground, you can't. Weight and tyre grip provide resistance and when moving without tyre grip( ice), there is much reduced load transferred to the chassis the weight of the car has nothing to rebound off - ie, grip.

OK, so if a car is designed correctly, when hitting a bump, suspension compresses and extends to keep the tyre in contact with the surface. The chassis may deflect but I will assure you, if it did by a noticeable factor, the sides of the bonnet would be bare aluminium as they'd be rubbing against the front guards every time you drove the car. Now we know that doesn't happen.

Why I believe a strut brace will have no affect on your steering? The steering rack is connected to a massively strong steel subframe. If it flexed, then not only will the engine move, but also the gearbox and PPF which are all connected to it move. That subframe is then bolted to the chassis rails which are sizeable box sections either side of the car. When you refer to the engine bay as a "u", is' actually a cup shape. The firewall and radiator panel box in the chassis rails and subframe to make a very rigid, compact shape that has immense strength. If your steering rack was mounted to the top of the engine bay, between the shock mounts, then I believe another brace may improve steering. But considering it's mounted at the strongest part of the engine bay, I can't see how it has any affect.

A brace between the upper A-arms I can see would stop deflection - if it was found.

So what will now seem like a contradiction, a stiffer chassis is better as it allows more compliance to be built into the suspension which then keeps the tyres in contact with the road and provides better grip. So, get rid of the rubber suspension components, weld in braces and then we are starting to talk. But yes, that's why I think the "strut brace" probably doesn't do what we all think it does.

I hope that makes sense. Happy New Year to all!

[Okibi]

...Camber change is a result of changes in suspension travel which is caused by changes in road surface. Due to the design of the suspension, it will change the same on the road or track with the same suspension components at the same compression. Road shape but not surface is the variable factor...

I'm talking about the camber of the road, not the wheels.

Set the length of your strut brace, now remove it and jack up one side of your car. Try and place the strut brace again and you'll see how much the chassis flexes between these points.

[Okibi]

To explain myself a little better (to avoid further confusion); road surfaces changes to suit the landscape, they’re designed so that water runs off and hopefully so that a car can safely hold a higher speed through the corner. (Yay for well engineered roads?)

I notice the difference of the strut brace most while moving from the peak of the roads surface (the middle of the road when turning right) down the slope (across the oncoming lane) then onto the intersecting road (sloping toward the gutter on my left).

During these kind of corners I noticed the front of the car sits flatter.

On a race track you don’t often have intersecting sections of track, you don’t often have “off camber” corners, and most track surfaces seem flatter than the convex of a suburban street.

We should also make note that there are marked differences between a fairly stock street MX-5 and a track car.

By adding a proper roll cage you’ve dramatically increased the cars rigidity, a strut brace wouldn’t be so noticeable and therefore might be negligible.

Perhaps with the rigidity of the NB8B and NC you might not notice the difference as much either.

The strut brace was possibly the first mod I did to our NB8A so the car was dead stock.

The byproduct of less chassis flex is better feel through the steering wheel.

[StanTheMan]

so..... what was the consessus....i'm still confused


*gone hiding*

who opened this can