cinky Posted August 22, 2011 Report Share Posted August 22, 2011 just playing around with the truck and just wondering how much negative camber can be safely run on the fronts with putting my self or others in danger? Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted August 22, 2011 Report Share Posted August 22, 2011 Well, there are plenty of cars running around with -3deg, however.... Under braking the nose-dive give you even more camber and hits the inner edges of the tyres more. It gives you less tyre contact from the increasing camber. Camber gives the very inner tread a hard time and can strip the inner tread to nothing without touching the outside ones that you see. A problem of Altezzas/IS200, you add more toe-in to spread the wear, so the tyres still wear faster but evenly across the tread. I think more -ve camber gives more bumpsteer, but other factors come into that too. But it obviously works for V8supercars! Quote Link to comment Share on other sites More sharing options...
ke70dave Posted August 22, 2011 Report Share Posted August 22, 2011 I think more -ve camber gives more bumpsteer, but other factors come into that too. I don't see how, bump steer is purely a difference in the radius of rotation of the steering arm and the LCA. But it obviously works for V8supercars! -1billion degrees works on v8super cars becuase of the tyre and car setup. my understanding on camber on tyres is the following: a tyre performs maximum lateral grip with some camber angle because of the deformation of the sidewall on cornering that causes the contact patch to sort of rotate around flat onto the road when lage cornering forces are applied. keywords in the above sentence being sidewall and contact patch which are TYRE DEPENDANT. other keywords are the large cornering forces, going 200km/h around turn 2 at queensland raceway, is a little differenent to a quick hills run on your local windy road. not to mention the weight of a v8 super car (which will cause alot more weight transfer to the outer wheels). so comparing a v8 super car (12"+ wide full on slicks with a rock hard sidewall) to your every day tyre (be it a truck or a car)...is somewhat useless! my understanding is that there are a few ways to judge if your camber setting is correct: pick a setting and: -compare the wear marks on the tyre, if the tyre isnt wearing all the way across evenly you need to adjust. too much inner wear, and thats too much camber, too much wear on the outer edges, maybe add a bit more. problem is here you need to drive a bit to get an indication of wear, and if its set wrong...well youve just wasted a bit of your tyre i guess. -do a few hard corners, then measure the temperature of the tyre at say 5 places across the tyre (using one of those infra red things), doesnt matter if the temperture isnt accurate, you are looking for differences, not absolute values. It is ALWAYS a trade off between straight line grip and cornering grip. -1 camber is what is factory on s15 on all 4 corners, and it seems to pull up fine. not to mention I'm flatout locking up these toyo t1rs, my face goes straight through the windscreen before they lock up!!! Quote Link to comment Share on other sites More sharing options...
irokin Posted August 23, 2011 Report Share Posted August 23, 2011 I don't see how, bump steer is purely a difference in the radius of rotation of the steering arm and the LCA. I can't see how it would either. On a MacPherson strut though you'll wreck your roll center by moving the upper pivot too far in. -1billion degrees works on v8super cars becuase of the tyre and car setup. They run a full spool diff. Must be a bastard trying to get them to turn in nice on 280 slicks. We don't need no god dang witchcraft LSD! I've run somewhere around 4 degrees camber on the silvia before (old struts had bolt settings that let you lean the knuckle in). It was stupid, reduced braking grip massively, always wanted to lockup and didn't really help handling at all. Currently running about 2.5deg which is about all I can get with the current struts but it looks like heaps. Could do with a little more to stop the tyres wearing on the outside but I can add more castor yet. Quote Link to comment Share on other sites More sharing options...
cinky Posted August 23, 2011 Author Report Share Posted August 23, 2011 so it doesnt look like a totally meaningless question i will show you what I am working with. its '74 F100 with twin I beam front end, my issue is that if i fit lowered springs it produces negative off set, there is an equation for how much drop to how much camber but i can't find it right now, the next step after lowered springs is to get a set of drop beam from the states but thats atleast a 6 week wait, ive already got the rear sitting at the right height with a 7 inch drop but I can't quite get the front low enough. I hope to have the truck back on the road within 6 weeks but can't do it with the front sitting so high. for those of you that are good at maths the I beams are 130cm long from mounting bolt AKA pivot point to the centre of the wheel. if i drop the springs 3'' how much camber will that cause? Quote Link to comment Share on other sites More sharing options...
irokin Posted August 23, 2011 Report Share Posted August 23, 2011 Very roughly it will add 2 degrees. Could be wrong. Quote Link to comment Share on other sites More sharing options...
ke70dave Posted August 23, 2011 Report Share Posted August 23, 2011 (edited) mmmmm i get about 3.4deg tan^-1 (3*25.4/1300) = 3.34deg either way, i think its a bit much for truck tyres? not htat i know anything about truck tyres, but they don't look like the type of tyre that would respond well to negative camber, especailly in straight line breaking. Edited August 23, 2011 by ke70dave Quote Link to comment Share on other sites More sharing options...
cinky Posted August 23, 2011 Author Report Share Posted August 23, 2011 street tyres will be fitted once resto is close to being completed, its currently fitted with 31'' muddies. just been drawing up a full size scale of it and the horizontal line between point F and point D is actually lower at point D by 2.5'' so if it drop it 3'' it will only just have N/C sso they will be room for more chop and drop later once it get the new wheels on set the ride height to a level i am happy with Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted August 23, 2011 Report Share Posted August 23, 2011 I don't see how, bump steer is purely a difference in the radius of rotation of the steering arm and the LCA Dave, what do you all the effect when you roll a wheel along the driveway and if it is upright it goes straight, but if it leans over it rolls in a circle? The more it leans, the tighter the circle radius. That's the effect I meant, the difference in camber caused by one wheel riding up a hump and trying to turn in a circle. Quote Link to comment Share on other sites More sharing options...
Mitch-12 Posted August 23, 2011 Report Share Posted August 23, 2011 supercar tyres don't have steel belts they only have the string stuff (i don't know thw proper name for it) and under braking the tyres flatten out and the whole tyre touches the road and around corners the tyre tries to peel itself off the rim and the whole tyre touches we run around 5-6 degrees on our au supercar, and irokin they are a handful to turn in just need to use the kerbs to get the weight off the inside rear tyre or our FPR BF with $40 000 sachs shocks has enough grip to do it without hitting kerbs. so on the street i wouldnt want anymore then 2 degrees neg. Quote Link to comment Share on other sites More sharing options...
irokin Posted August 23, 2011 Report Share Posted August 23, 2011 I used this Dave: y = acos((1300^2+76^2-1300^2)/(2*1300*76)) 90 - 88.32 = 1.68deg increase Ignoring the fact the movements in an arc and slightly longer than the drop. I slept through trigonometry though so I might be way off the mark. Quote Link to comment Share on other sites More sharing options...
irokin Posted August 23, 2011 Report Share Posted August 23, 2011 supercar tyres don't have steel belts they only have the string stuff (i don't know thw proper name for it) and under braking the tyres flatten out and the whole tyre touches the road and around corners the tyre tries to peel itself off the rim and the whole tyre touches we run around 5-6 degrees on our au supercar, and irokin they are a handful to turn in just need to use the kerbs to get the weight off the inside rear tyre or our FPR BF with $40 000 sachs shocks has enough grip to do it without hitting kerbs. so on the street i wouldnt want anymore then 2 degrees neg. Bias or cross ply/Rag tyre. Interesting but, didn't know that! Quote Link to comment Share on other sites More sharing options...
Mitch-12 Posted August 23, 2011 Report Share Posted August 23, 2011 Bias or cross ply/Rag tyre. Interesting but, didn't know that! i was gonna say rag but didnt know if you would know the terminology haha Quote Link to comment Share on other sites More sharing options...
ke70dave Posted August 23, 2011 Report Share Posted August 23, 2011 Dave, what do you all the effect when you roll a wheel along the driveway and if it is upright it goes straight, but if it leans over it rolls in a circle? The more it leans, the tighter the circle radius. That's the effect I meant, the difference in camber caused by one wheel riding up a hump and trying to turn in a circle. gravity?:P Quote Link to comment Share on other sites More sharing options...
cinky Posted August 23, 2011 Author Report Share Posted August 23, 2011 ive been trying to reconstruct this as a full scale model using masking tape, a texta and a tape measure but I can't actually measure the angle. any one out there feeling creative and what to get measuring for me? Quote Link to comment Share on other sites More sharing options...
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