Yaumeister Posted January 27, 2010 Report Share Posted January 27, 2010 Tony, Do you have any particular advice on upgrading anti roll bars for FWD vehicles? I'm considering getting a set for my Focus. From various articles I read on the net, the general recommendation is for FWD to have a stiffer rear bar then front, and some even recommend just upgrading the rear bar. Would you mind sharing what your view is? Thank you. The ARBs I'm planning to use are 22mm versions from Whiteline. http://www.whiteline.com.au/do_segue.php?m...s+LS+06%2F05-On Quote Link to comment Share on other sites More sharing options...
Tony Posted January 27, 2010 Report Share Posted January 27, 2010 By reducing body roll as the cars inertia transitions during a turn the bar helps reduce understeer, that said if you boot it on the apex in the wet nothing will save you. Quote Link to comment Share on other sites More sharing options...
Yaumeister Posted January 27, 2010 Author Report Share Posted January 27, 2010 More specifically, would you recommend upgrading both front and rear, or should the rear be stiffer then the front? Quote Link to comment Share on other sites More sharing options...
Tony Posted January 27, 2010 Report Share Posted January 27, 2010 Depends how you want the car to handle, just the front would invite oversteer, both should keep it neutral. Quote Link to comment Share on other sites More sharing options...
Yaumeister Posted January 27, 2010 Author Report Share Posted January 27, 2010 Got it, in simple terms if I don't have an existing understeer problem, I should maintain a balance between front and rear. Quote Link to comment Share on other sites More sharing options...
Tony Posted January 27, 2010 Report Share Posted January 27, 2010 Yep .... The balance of body roll tunes how the front/rear/both gains geometric positions, this invites or belays the under/oversteer. one thing that will remain regardless is the polar moment of inertia however you tune the bars. Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 4, 2012 Report Share Posted April 4, 2012 Depends how you want the car to handle, just the front would invite oversteer, both should keep it neutral. Sorry for digging up old topics Tony, but could you expand on this comment a bit? Are we talking about the Focus chassis specifically? Based on load transfer alone a front upgrade would generally increase understeer, how do the geometry effects counter this to produce oversteer? Quote Link to comment Share on other sites More sharing options...
Tony Posted April 4, 2012 Report Share Posted April 4, 2012 A true explanation would need many other factors but distorting the rear tyres contact patch geometrically will change the tyres saturation limits. Obviously pneumatic slip angle and actual saturation limits cannot be measured but that's where experience comes in. Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 5, 2012 Report Share Posted April 5, 2012 A true explanation would need many other factors but distorting the rear tyres contact patch geometrically will change the tyres saturation limits. Obviously pneumatic slip angle and actual saturation limits cannot be measured but that's where experience comes in. Yes tyres are certainly a bit of a black art. As far as I have learnt though, it is generally accepted that load transfer results in a loss of grip on an axle due to tyre load sensitivity. More roll resistance at one end, either from springs, dampers, geometry or bars, will result in more load transfer at that end with a resulting reduction in the total lateral force available from that axle. Not arguing experience of course, if you have fitted a front ARB to a Focus and found increased oversteer then fair enough, however I added a large rear bar (from 14mm to 24mm) on my Civic and found it greatly increased oversteer, thus I would expect a front one to increase understeer. Different chassis and suspension designs admittedly, but this is what got me wondering whether this trait was specific to the Focus... Quote Link to comment Share on other sites More sharing options...
Tony Posted April 5, 2012 Report Share Posted April 5, 2012 My analogy is theoretical based on load transition, camber migration and tyre saturation limits. Quote Link to comment Share on other sites More sharing options...
Bazza Posted April 5, 2012 Report Share Posted April 5, 2012 on the Starlet I found that by uprating the front alone it produced more understeer when matching the rear to the front it reduced it, but didnt overcome it by then reducing the front to below oem size and ratings it produced a neutral handling with no dramatic over or understeer by experimenting you find things out, that on paper shouldnt work ! Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 6, 2012 Report Share Posted April 6, 2012 on the Starlet I found that by uprating the front alone it produced more understeer when matching the rear to the front it reduced it, but didnt overcome it by then reducing the front to below oem size and ratings it produced a neutral handling with no dramatic over or understeer by experimenting you find things out, that on paper shouldnt work ! On paper, that works perfectly! Quote Link to comment Share on other sites More sharing options...
Tony Posted April 6, 2012 Report Share Posted April 6, 2012 How? Quote Link to comment Share on other sites More sharing options...
Kozy Posted April 6, 2012 Report Share Posted April 6, 2012 Uprate front bar = More front roll resistance = More front axle load transfer % = More understeer. Uprate rear bar = More rear roll resistance = More rear axle load transfer % = Less understeer. He claims that shouldn't happen on paper, but it does. Quote Link to comment Share on other sites More sharing options...
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