quattromike
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| posted on 10/11/05 at 09:06 PM |
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parallel to the center
I was just looking through some previous topics about front suspension and I noticed one post saying that the front A-arm pickup points on the chasis
must be parallel to the center line of the chasis, Is this true, or is it misguideing? 
This will be the next area of my build I will be concentraiting on just trying to do some homework on the subject, you know what they say ask twice
weld once
Mike
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JoelP
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| posted on 10/11/05 at 09:32 PM |
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if they arent parallel, they will move forward and back in bump and droop. Not the end of the world, just make sure you have taken it into account.
With bushes the eyes must always be in line too.
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quattromike
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| posted on 10/11/05 at 09:40 PM |
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quote:
Originally posted by JoelP
With bushes the eyes must always be in line too.
I understand that one , so that they don't twist then selfs to bits. but I was going to try to add some anti dive on my bottom A-arm so
it'll be going forward a bit on bump, on that same note do you think if I take the front pick up point inboard more to dial out the forward
motion so it's more stationary on bump and droop?
if that makes sense!
Mike
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907
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| posted on 10/11/05 at 09:41 PM |
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And if your using book bones, move the top ones back a bit to correct caster, (IMHO)
Guess who didn't, and has got to remake his top bones. Doh.
Paul G
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quattromike
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| posted on 10/11/05 at 10:00 PM |
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It's also been mentioned that i should make the front track width of the car a tad narrower that the back track width.
Is there a reason for this too?
Mike
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JoelP
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| posted on 10/11/05 at 10:19 PM |
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ive not heard it recommended myself, and can think of no reason why it should be narrower at the front. It would be interesting to hear the reason why
people have recommended this.
I personally wouldnt be concerned about the minimal change in castor or camber caused by either antidive or unparallel bones. My next car will have an
antiroll bar and stiff springs, so it wont matter much anyway. My rosejoints also wont be in line or parallel!
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kb58
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| posted on 11/11/05 at 01:49 AM |
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quote:
Originally posted by quattromike
It's also been mentioned that i should make the front track width of the car a tad narrower that the back track width.
Is there a reason for this too?
Mike
I've never heard that either, but it won't hurt, unless you're after top handling. If so, you want a very wide front track, even
wider then the rear...
FWIW I believe the classic Mini's front end is wider then the rear.
[Edited on 11/11/05 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Rorty
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| posted on 11/11/05 at 04:36 AM |
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Having a narrower front track promotes better turn-in - over do it and that translates to oversteer.
If you're stuck with a narrower front track, a front anti roll bar or stiffer front springs can help.
Don't read that as a cure, it's just the effect; you really don't want to stiffen the front springs any more than is necessary to
hold the car up.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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quattromike
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| posted on 11/11/05 at 04:28 PM |
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quote:
Originally posted by Rorty
Having a narrower front track promotes better turn-in
I remember now thats what the guy said when i was talkin to him about it , but it doesn't seem that any of you guys do it so I might do a
10/20mm a side . My rear track from hub face to hub face is 1700mm so a tad narrower won't make much difference if any.
Mike
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907
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| posted on 11/11/05 at 08:08 PM |
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Ooo err,
Either, I've had a serious measuring accident,
or, I've misunderstood this thread completely. (more than likely)
By track we mean tyre centre to tyre centre, left side to right side; yes?
I have a book chassis, dimension wise, with book wish bones.
Admittedly it's 100mm wider, but that's all the way down, i.e. back +100 and nose cone +100
The back wheels are (centre to centre) 1455mm.
The fronts, 1375mm.
So an 80mm difference;
so IF I haven't cocked up, all book chassis with book bones should be narrower at the front.
 Yes / No
Paul G
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Rorty
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| posted on 11/11/05 at 09:35 PM |
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quote:
Originally posted by 907
Ooo err,
Either, I've had a serious measuring accident,
or, I've misunderstood this thread completely. (more than likely)
By track we mean tyre centre to tyre centre, left side to right side; yes?
I have a book chassis, dimension wise, with book wish bones.
Admittedly it's 100mm wider, but that's all the way down, i.e. back +100 and nose cone +100
The back wheels are (centre to centre) 1455mm.
The fronts, 1375mm.
So an 80mm difference;
so IF I haven't cocked up, all book chassis with book bones should be narrower at the front.
Yes / No
Paul G
Don't panic Mr. Mannering! You haven't made a mistake and it's all OK. 
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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quattromike
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| posted on 11/11/05 at 09:42 PM |
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Sorry my rear hub face to hub face is actually 1600mm dunno where i got the other size from.
Paul the book is made with the escort width in mind but i think your useing the sierra width are you, because 1455mm sounds like sierra.
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907
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| posted on 12/11/05 at 12:20 AM |
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That's a relief
Yup, Sierra dif & drive shafts, not cut down.
So is a true book Locost with Escort back axle wider at the back, if so, by how much?
Paul G
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scotty g
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| posted on 12/11/05 at 08:51 AM |
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Escort axle is 4" narrower than a sierra rear end. More and more poeple that want a live axle set up are using Cortina/Capri axles or Sierra
stuff with a de-dion tube as these are all 4" wider than the escort and in my oppinion looks much better with the fatter rear arches.
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Marcus
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| posted on 12/11/05 at 12:12 PM |
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Capri axles are a mid point between Escort and Cortina and are a good bet for a 'book' Locost as the wheels fill the arches better. Use
the Cortina one if you want wide arches. I personally prefer the narrower arches on a book chassis.
BTW I agree with Rorty, don't put stiff springs AND anti roll bar unless going for serious track use. It will bounce about like a good 'un
on the road. An anti roll bar allows the use of softer springs, compensating for the additional roll generated, for a smooth ride.
Marcus
Marcus
Because kits are for girls!!
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quattromike
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| posted on 15/11/05 at 12:37 PM |
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This may be a bit off post but has anyone used anti-dive on their front A-arms, If so how much off the horizontal would you say would be best?
Mike
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JoelP
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| posted on 15/11/05 at 06:36 PM |
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if you work out your 3d centre of mass, and aim the pivots up towards it, you *should* get no dive. Its entirely possible though ive not quite
hammered out the details in my head though, so if anyone thinks different, please say!
As a small aside, in my locost on track last weekend, i didnt notice any dive with a normal setup. Obviously it did to a certain extent, but it wasnt
noticable. Also, antidive geometry causes the pivots to get a little stiffer when braking than normal, so bumps will hurt it more when braking
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