Fitting front strut brace

[h10ndr]

The brace is to control / stop strut/tower flexing. With the car on the deck the brace should then be extended to counter the forces slightly. Doing it the other way means your brace will be under tension just being dropped to the floor never mind loading up through corners...

[wurlycorner]

I've never looked at this before, but just thinking through the way the tower would flex;

Depending on where the car is jacked up from, but assuming it's supported from the sill jacking points...

With the car jacked up, the towers would flex outwards and down (weight of the wheels/suspension would exert a force on them in that direction). So if the brace is fitted with the car jacked up, then when the car is lowered onto the ground, the towers would have a force on them that's upward and inward, meaning the brace would then come under compression.

If the brace is fitted with the car sat on the ground, the brace will be fitted under no load at all and will only come under load as the car corners (or over bumps). This load would be to put each outer tower under extra load upwards and inwards as the weight transfers onto that corner.

So on that basis, fitting it with the car jacked up would seem to achieve the stiffer set up?

I suspect unless you're into really really hammering it on a track though, repeatedly putting the chassis through flex one way and the other, you're unlikely to notice any difference whichever way you fit it?!

[NafemanNathan]

In my mind a brace should be fitted to the car in it's relaxed state (Being sat on level ground as it would have been when it's geometry was set up). The idea is for when cornering the shock tower under compression is supported by the other side. By jacking up the car first before fitting a brace means that as soon as the car is lowered again the brace is under compression already and therefore the shock towers are being pushed out (or the brace flexes if it's jobby). This compression is then increased further when cornering and increases the chances of something going pop. If it's fitted when the car is just sat then the brace only comes under compression when corners, or tension when going over a hump... Basically only when the shock towers are being forced to be anything other than in their relaxed state.

[wurlycorner]

However, there will be a small degree of elasticity in the brace before it stiffens up (however good it is) and pre-loading it takes this elasticity up and ensures when you add cornering forces, it provides the maximum stiffness?

As you say, there is more chance of it failing though (and as I say, in the real world none of this matters a damn anyway!)

[bristol_bb4]

LOUD NOIIISSESSS

[NafemanNathan]

However, there will be a small degree of elasticity in the brace before it stiffens up (however good it is) and pre-loading it takes this elasticity up and ensures when you add cornering forces, it provides the maximum stiffness?

As you say, there is more chance of it failing though (and as I say, in the real world none of this matters a damn anyway!)

Too much preload though and it'll just deflect and flex instead of channeling the force where it's required.

Still, way to much thinking involved for road drivability

[wurlycorner]

[BMCC]

I've bought a few brand new strut braces over the years. The instructions were short and none of them asked me to jack the car up.

[mills]

In my mind a brace should be fitted to the car in it's relaxed state (Being sat on level ground as it would have been when it's geometry was set up). The idea is for when cornering the shock tower under compression is supported by the other side. By jacking up the car first before fitting a brace means that as soon as the car is lowered again the brace is under compression already and therefore the shock towers are being pushed out (or the brace flexes if it's jobby). This compression is then increased further when cornering and increases the chances of something going pop. If it's fitted when the car is just sat then the brace only comes under compression when corners, or tension when going over a hump... Basically only when the shock towers are being forced to be anything other than in their relaxed state.

This I'm no expert by all means. but I did actually question whether the car should be jacked up while fitting an upper brace, even though I thought it was common sense to fit it while the car was settled on a flat surface. After asking a couple of mechanic mates, and doing a bit of research online, it is best to fit an upper brace while the car is in its relaxed state

as for the people who think it is "common sense" to jack the car up 1st.....WTF please explain

[bristol_bb4]

as for the people who think it is "common sense" to jack the car up 1st.....WTF please explain

glad someone else asked this before i did i cant see how its common sense in the slightest