Hi

I spent yesterday evening fitting front and rear strut braces to my car, and now I'm done I'm not convinced that I've done more than increased the weight and made the engine bay a bit prettier.

I know that in theory they stiffen up the suspension points, but in the case of the ones I've got (cusco for GC8) they don't seem solid enough to do the job. Specifically the front one only bolts on at two points on each strut top, and isn't positively located. All that stops it from moving laterally is the clamping force of the strut mounting bolts. On the rear the actual bar is an aluminium tube about 25mm diameter with 2-3 mm wall thickness - having seen how aluminium motorcycle swingarms are constructed this seems completely inadequate.


What do other people think? Also has anyone actually measured an increase in torsional ridgity after fitting simple bolt in braces?

Matthew

 

Hi Mathew, i've got a strut brace on my STi 03 and didn't noticed any difference!

 

Some people feel a difference, some don't.

They are not there to stiffen anything. They just help to reduce any movement of the strut tops, which in turn helps to maintain your geometry settings when the suspension is under load.

Oh and I'm not sure how you can compare a rear strut brace with a motorcycle swingarm, they do different jobs and have different forces applied to them.

 

> They are not there to stiffen anything. They just help to reduce any
> movement of the strut tops

Huh? So how do you think they stop the strut tops moving? By stiffening the body shell.

 

Oh god, don't start this debate again

I'm not getting involved.......

I'm sure you will find plenty of 'opinion' along anytime soon......

 

http://bbs.scoobynet.co.uk/showthrea...t=strut+braces

 

And to answer Harveys last question (again) on pg 4 of the thread, it makes your steering 'heavier' because when you turn apply steering lock, it causes the front of the chassis to flex slightly, amongst other things. When you have a front strut brace, some of that flex is eliminated and so the chassis doesn't 'give' as much so the steering feels tighter.

 

Ok, but if they don't stiffen anything, then how do they stop the strut tops moving?

I can't see them doing anything for twisting forces - they are less beefy than the ARB and that still twists (I know the leverage is different). They also have adjusters so any twisting movement would tend to tighten/loosen the adjuster. That leaves the forces pushing the strut tops together/apart which is where the clamping force and positive location is relevant.

I think that in tension (strut tops being pulled apart) the rear bar could do some good as the mounting is much better, and the bar itself is straight. At the front the bar has to be bent around the intercooler so even though it is triangulated it will attempt to twist around the mounting points.

The same applies in reverse when the bars are being compressed, but in this case the flexibility of the bars themselves becomes important. If they bend or slip even a little bit (milllimetres) then I can't see them doing any good.

Regarding the swingarms - the bars look very similar to what was fitted to early 80's sportsbikes. These were notorious for bad handling due to the swingarm (and frame) twisting and distorting. As far as I can see the forces applied by a much heavier car with 3-4 times the power are likely to be more.

When it comes down to it I don't know if they do any good - that's why I asked the question.

Matthew

 

Thanks for that Edcase - I think there's enough info there to answer my question.