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02-10-2014, 06:47 AM | #1 |
Major
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Rear ARB - A Bad Idea Without LSD?
Hi all,
While I install my Front & Rear Powerflex inserts into the rear subframe in order to stop that horrid bouncing around and also changing my Front ARB to that from an M3 in order to dial out some body roll, I wonder whether I should bother with upgrading the rear ARB? I have heard that without a (mechanical) LSD this is a bad idea to upgrade to a thicker rear ARB (unsure why, increased tendancy to squirm/slide?) but I can't help thinking it's also detrimental to change the roll charcteristics of the front and not the rear. Any advice? |
02-10-2014, 07:04 AM | #2 |
Colonel
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Firs of all you need to choose right stiffenes rear ARB. I think best would be 15mm thickness from 3er xi models.
If you will get M3 rear ARB you will loose traction on turns. |
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02-10-2014, 09:04 AM | #3 | |
Captain
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Quote:
The front ARB and the rear ARB on most street cars work quite differently because of different suspension designs at each end. One big reason is that how camber changes with roll at each end is different. So a street car generally does not respond to ARB changes in strict accordance with simple theory like a purpose built racecar, which confuses a lot of people. It becomes as much art and trial and error as science. On this subject in particular, people's actual experience is probably more valuable than their theoretical musings. Note, however, that transferring their experience to your car requires consideration of differences in spring rates, which also affect roll resistance. On even that purpose built racecar, ARB tuning is trial and error, though the racecar responds somewhat more predictably to changes. Trotting out the late, great Carroll Smith. "If all this seems to say that we're going to be spending a lot more time at the race track adjusting the car instead of drinking beer and chasing girls, you've got the picture". Suspension tuning is tricky. Everything affects everything else. Pro race guys with extremely competent and experienced dedicated suspension tuners go out sometimes and then complain that the car is utter crap. ARBs on street cars are one of the trickier bits. All of which explains why people may be better off getting a package from BMW or, if they feel they can ID a good one, a professional tuner. It's either that or spending some time learning to tune suspension yourself, and being prepared to make some expensive mistakes. Last edited by 128Convertibleguy; 02-10-2014 at 09:40 AM.. |
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