thegodplato
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| posted on 3/5/10 at 03:34 PM |
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Anti-Dive Suspension
Hi, confused here as I have read 3 books now which all say/show something different in relation to the wishbone pick up points for the front
suspension.
Build Your Own Car For £250 seems to have the brackets horizontal.
Build Your Own Tiger Avon has the brackets angled up towards the front of the car
The Sports Cars & Kit Car Suspension & Brakes manual has them sloping downwards to the front of the car.
The latter is to achieve anti-dive and therefore better handling.
Having never done this before can anyone agree with any of the above and recommend a good route to go?
If you've never done anything wrong, you've never done anything
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designer
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| posted on 3/5/10 at 03:42 PM |
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For a road car parallel, no anti dive/squat.
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dnmalc
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| posted on 3/5/10 at 03:59 PM |
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I have 5 deg anti dive in mine still building though. the wishbones follow the 3rd case so that when you brake the forward momentum of the car has a
component (circa 8.5%) that is trying to lift the nose of the car. Why avon has it the other way defeats me.
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Mave
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| posted on 3/5/10 at 04:06 PM |
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It depends on which wishbone is angled. Anti-dive is caused by:
- upper wishbone sloping down towards rear of car
- lower wishbone sloping up towards rear of the car.
A roadcar generally has anti-dive (and anti-squat at the rear)
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britishtrident
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| posted on 3/5/10 at 06:17 PM |
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Or both top and bottom wishbone sloping up towards the rear of the car.
It is really best not to use anti-dive as it can have undesirable side effects and really not required on a light stiffly sprung car with a very low
Cg
A small amount of anti-squat on the rear is more often used as it tends to have less side effects.
[Edited on 3/5/10 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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blakep82
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| posted on 3/5/10 at 06:54 PM |
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my chassis (SHP say it has anti dive facility fitted) can have the wishbone sloping downwards to the front of the car for anti dive, or horizontal if
you don't want anti dive working
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phelpsa
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| posted on 3/5/10 at 11:04 PM |
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In small, lightweight RWD cars where the CoM is back in the car, dive is often to your advantage. Hence soft springs and large ARBs work well.
Saying anti-dive gives better handling without any idea of the setup of the rest of the car is a bit dangerous really.
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thegodplato
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| posted on 4/5/10 at 10:33 AM |
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sorry phelpsa, what I was meaning was that the anti dive element should give a car better handling when under hard braking as the front wheels should
be in the best position for max grip - as far as I understand, a car that dives at the front under braking would change the camber and toe out of the
wheels and therefore not brake as effectively.
I'm only going off what I've read, and will welcome any further comments as I am still learning about this!!
If you've never done anything wrong, you've never done anything
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phelpsa
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| posted on 4/5/10 at 11:33 AM |
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quote:
Originally posted by thegodplato
sorry phelpsa, what I was meaning was that the anti dive element should give a car better handling when under hard braking as the front wheels should
be in the best position for max grip - as far as I understand, a car that dives at the front under braking would change the camber and toe out of the
wheels and therefore not brake as effectively.
I'm only going off what I've read, and will welcome any further comments as I am still learning about this!!
That is very true, but as far as I can see if you're designing a suspension setup you'd be better off trying to counter the current
geometry changes than introducing another geometry change to counter the effects.
What's the car for? Road or track? If it's on the road then ultimate grip under hard braking isn't going to be high on the agenda.
If it's for the track then you'd be better off reducing roll on camber, stiffening the front springs/arbs and running slightly more static
negative camber.
Either way I don't think you're going to see any significant improvement that can't be gained by fiddling with other parts of the
suspension setup.
P.S. I'm by no means an expert! Just done a fair amount of reading, research and chatting on the matter 
[Edited on 4-5-10 by phelpsa]
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MikeRJ
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| posted on 4/5/10 at 12:02 PM |
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quote:
Originally posted by thegodplato
sorry phelpsa, what I was meaning was that the anti dive element should give a car better handling when under hard braking as the front wheels should
be in the best position for max grip - as far as I understand, a car that dives at the front under braking would change the camber and toe out of the
wheels and therefore not brake as effectively.
I'm only going off what I've read, and will welcome any further comments as I am still learning about this!!
You have to offset this against the fact that your anti-dive geometry effectively stiffens the suspension under braking, and this itself can lead to a
reduction in grip (just like running springs that are too stiff). The same problem occurs with anti-squat.
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