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Discussion Starter · #1 ·
Re-found this site again today and noticed the suspension tech: http://e30m3performance.com/myths/Weight_T...ht_transfer.htm

On the second page-

"The key point is that as a MacPherson strut suspension is lowered, the length of this lever arm increases. Just compare A1 to A2 in the figure above. Thus even though the car is lower, it will tend to roll more! This is not what many people expect when they lower their cars."

There's two sides to that story, of course, but the article is definitely worth a read!

Adrian W~
 

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Damn ... now I'll obviously have to throw away my Bilstein kit and go back to standard suspension!

Seriously though, the article doesn't seem to account for the fact that most lowering kits make use of stiffer springs, which alone provide a greater force to oppose roll. When you choose stiffer springs it's also wise to fit matched dampers.

Maybe the writer is approaching the subject from the view of lowering American cars, many of which still use leaf springs? I'll admit I have no idea how leaf-sprung cars are lowered, but I can guess that lowering leaf-sprung cars may not be as beneficial as lowering coil-sprung cars.

However, I'll admit that there are a lot of ricers out there (in the US and Europe) who are primarily lowering their cars for aesthetic rather than dynamic reasons. I can believe those guys would be likely to choose a kit which didn't necessarily improve the cars handling.
 

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Discussion Starter · #3 ·
Originally posted by Jason (Mr Torque Steer):
[qb]Seriously though, the article doesn't seem to account for the fact that most lowering kits make use of stiffer springs, which alone provide a greater force to oppose roll.[/qb][/b]
Actually, it's a very well ballanced article. I just pulled that quote out because I like playing devil's advocate.

You must have missed this part at the end (understandable):

"If you stiffen the front springs at the same time that you lower your car (this is usually the case) then the stiffer springs offer an increased roll rate to counter-act the increased roll couple. In this case you get reduced weight transfer without necesarilly increasing roll. And often the reduction in weight transfer will offset the reduced camber curve and bump steer effects enough that the car will ulitmately be faster around a track. However, you should not lower your car without at least being aware of the possible negative consequences."



Adrian W~
 

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i think the main thing is that for al those 'boy racer' types that use coil locks to lower the car will notice more roll than uprated,lower springs.
 

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Another bit of car-handling physics I never quite manage to get to grips with is about the relative positions of the roll centre axis and the CoG, where lowering usually (but not always) helps!

You could argue that fitting wider or offset wheels will also increase the lever length and therefore increase roll...but it worked having reverse rims on tons of old 60s & 70s stuff...
 

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Discussion Starter · #7 ·
Originally posted by Grentarc:
[qb]i think the main thing is that for al those 'boy racer' types that use coil locks to lower the car will notice more roll than uprated,lower springs.  
 [/qb][/b]
Well, it's also worth noting that buying the lowest set of uprated springs may not give the car the best handling. It's quite possible that a set of uprated springs which maintain stock ride height could do quite well.



Adrian W~
 

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but if you just cut or lock standard springs lower, on say, a celica which has McPherson struts all round, this will increase roll, than using purpose made lower springs (which would usually be stiffer springs) according to that writeup.
 

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Discussion Starter · #9 ·
True. But a purpose-made set of control arms to raise the roll-center and decrease the roll-couple after you've lowered the car, would do better still.

It's just worth knowing, which is why I posted it.

Adrian W~
 
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