For the sake of curiosity, i did actually have braces mounted to different points. (only one at a time)

 

First a ran a mates brace that ran between the rear shocks, and mounted at the shock mounting points. This was 3 star improvement on the "riverside scale"

 

I then removed that brace and fitted my boro spec, super bodgy home made brace. This brace was attached at the rear seatbelt mounting points. No adjustment etc. It was simply one bolt at each end attaching it to the car, then a bolt at each end holding a piece of thin walled steel box section. This felt substantially better than the "proper" brace. I rated it a 4 star improvement on the "riverside scale".

 

I don't claim to understand all this sprung/unsprung mass jargon......to be honest, I simply wouldn't have the patience to absorb that kind of information.

 

I base everything on my personal real life experiences.

 

Perhaps you can explain why the bodgy brace felt better? in simple terms of course lol.

 

Cheers

Made the body a bit stiffer.

 

As far as i know, on the modern day sedan/coupe/soft-top (etc) its illegal to cut the parcel shelf cause its now such an integral part of the body strength.

 

But, anywhat, its about what you've done.

 

Where as the brace on the shockie is doing the same thing, but it just doesn't get the same leverage (strengthening) as what your parcel shelf one would.

Whereas, say, a silva s15, is IRS which uses struts and links to both locate and support the rear suspension to the body.

 

A car with struts (from a performance side) needs a strut brace between the towers to stop or reduce camber and or toe (and maybe castor) changes during cornering and uneven road surfaces.

 

All the S series chassis (and all the other Nissan IRS cars for that matter...they all have the same basic cradle design) have a massive IRS cradle. The strut towers merely support the vertical load of the shocks and springs, there is no lateral load on or near the strut towers. A strut brace in the rear of any S13/14/15 is a waste of time and money. Why are they available? They're cheap and easy to make and morons still buy them so theres money to be made. Any "gain" is merely a placebo effect.

Well, i was going to say the front end of a commodore but it wasn't the topic in question

Ahh so you're talking about MacPherson strut not IRS (independant REAR suspension). Yes it does make a difference in the front. Its not massive and its not entirely necessary. I go to the track frequently (thats about all I do with the Silvia these days) and I haven't bothered with one yet.