STUT BRACES ON STi8
#1
Having owned an STi4 Type R for 4 years and recently changed to STi8 Type UK there is a blatent lack of front strut brace (knew that when I bought it before anyone says). They tell me (other people) that this model is stiffer anyway than the older models and therefore doesn't really need a front strut brace. Is this a true statement or just some sales bullsh!t as I know many performance cars have these fitted?
Ady
Ady
#3
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Quoted from Damian Harty, Prodrive handling guru
Hope that helps
Strutbrace Q: There is an awful lot of mythology around this stuff that goes back to body-on-chassis beam-axled racers in the 20s - I'm not kidding. There are two effects that are important. Basically, the body structure is like a "fifth spring" between the front and rear suspension. If that spring is not stiff enough then the body relaxes out any redictribution of roll moment that the anti-roll bars were trying to make and so the car is unresponsive to handling balance tuning with springs and bars. However, once the body is "stiff enough" then making it stiffer offers no benefits. A good rule of thumb is that the torsional stiffness of the body (between suspension mount points) needs to be about ten times the roll stiffness of the stiffest suspension end (usually the front). If you chase the numbers through you end up with about 5-7 kNn/degree as the requirement for a body structure. Most modern monocoques comfortably exceed that and the Subaru with its bonded screens both ends does too. Somewhere I have a figure but can't recall it right now. Anything over 10 is good, 15-17 is current "state-of-the-art". So in that case, a strut brace does very little. The second effect is a bit more complicated. The body moves on the suspension but the wheel also moves on the tyre - the tyre is in many ways a "secondary" suspension system. That movement is partially controlled by the tyre and partially by the suspension damper and happens 10 to 15 times a second. The body is a flexible thing that has its own resonances and because of the shape of most cars at the front - they need a hole to put the engine in - it can get quite flexible in just about this frequency region. If the body goes flexible - goes into resonance - then the damper just moves with the body and can't contribute to the control of the tyre and in fact can do something bad called "mass loading" where the tyre is carrying not only itself but also part of the body _while it resonates_ (it's important to separate the static 'weight carrying' from dynamic things in your mind). In those cases, the strut brace can help because if it is a good design then it stiffens the front end usefully.
What all of the above means is that the effectiveness of a strut brace is strongly connected to the stiffness of your suspension. So for a Scoob that is fairly standard, the strut brace probably doesn't do a great deal, but as they get modified and stiffened the brace will contribute more to a well controlled feel over less-than-perfect surfaces.
The final point about strut braces relates to the emporor's new clothes - having bought a flash one, not many people will admit they can't really tell the difference.
Sorry for such a long answer but it isn't straightforward, especially when I'm denied my usual engineering shorthand of "Hz" and "modal damping" and so on...
What all of the above means is that the effectiveness of a strut brace is strongly connected to the stiffness of your suspension. So for a Scoob that is fairly standard, the strut brace probably doesn't do a great deal, but as they get modified and stiffened the brace will contribute more to a well controlled feel over less-than-perfect surfaces.
The final point about strut braces relates to the emporor's new clothes - having bought a flash one, not many people will admit they can't really tell the difference.
Sorry for such a long answer but it isn't straightforward, especially when I'm denied my usual engineering shorthand of "Hz" and "modal damping" and so on...
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#10
got my carbon fibre/aluminium strut fitted after 12 on a saturday at stan palmers by ian and nik-no fitting fee and got for a lot less than £375 although he made me test drive his sti with 18" wheels and made me buy a road angel
martin (skint again but very happy)
martin (skint again but very happy)
#12
Ady, you work at BAE ? parked outside 2 shed ?
If so, why you not parkin with the other scoobies any more ?
Just bought a new WRX from Wildings Kendal Mica blue. Parked at back off 1 shed. give us a wave next time - wouldnt mind a look round the STI sometime.
If not oops !
cheers
Andy
If so, why you not parkin with the other scoobies any more ?
Just bought a new WRX from Wildings Kendal Mica blue. Parked at back off 1 shed. give us a wave next time - wouldnt mind a look round the STI sometime.
If not oops !
cheers
Andy
#13
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Hi McScoobydoo,
I work at BAE (Prestwick Regional A/C), are you at Salmsbury? I know a few guys down there.
Ady, on the strut brace, the new age shells are significantly stiffer than classic and I seriously doubt if you would notice a marked difference. However they do enhance the engine bay looks.
If you want genuine Sti then have a look at www.japanparts.com or go to DR Motorsport, David will sell you a Cusco aluminium version with blue steel strut mounts for £95!! Looks better than STi version IMO. Pictures are shown on the website.
You might be better getting the suspension settings altered by your dealer which will increase neg camber on the front and reduce understeer.
I work at BAE (Prestwick Regional A/C), are you at Salmsbury? I know a few guys down there.
Ady, on the strut brace, the new age shells are significantly stiffer than classic and I seriously doubt if you would notice a marked difference. However they do enhance the engine bay looks.
If you want genuine Sti then have a look at www.japanparts.com or go to DR Motorsport, David will sell you a Cusco aluminium version with blue steel strut mounts for £95!! Looks better than STi version IMO. Pictures are shown on the website.
You might be better getting the suspension settings altered by your dealer which will increase neg camber on the front and reduce understeer.
#14
Thanks guy's for all the useful info and a merry xmas to you all. Andy Mcscoobydo, the reason I have not parked my car with all the other scoobies is that at the moment we have had an influx of morons who rather than look at your pride and joy form a distance, they want to feekin climb all over it just to varify that yes it does have a steering wheel and speedo just like any other car, in the process the works pass and other objects dangling from their person are scraping a layer of paint off the car bodywork doh! so thats why I hide mine away M8. Anyway buddy I will come and show it to you sometime now you own a real scooby. See ya later M8. By the way I bought mine from John Wildings as well.
Ady
[Edited by Ady 1 - 12/10/2003 8:58:15 PM]
Ady
[Edited by Ady 1 - 12/10/2003 8:58:15 PM]
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