tim
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| posted on 28/11/02 at 09:36 PM |
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Anti dive / Anti squat
Has anyone any advice on anti dive/squat? I am building a locost based on the seirra 2.8 4x4, with wishbone rear suspension! Have had some advice from
a freind who races a Lotus Elan, that altering the angle of the chasis pickups could make a huge difference! The Alan Staniforth - Supension book
doesnt really give a figure, rather it just says it is personal preferance! That 0.5in on a 16in base is about right. Anybody any suggestions?
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Viper
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| posted on 28/11/02 at 09:44 PM |
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We run anti squat on a TVR tuscan chalenge car, and we found it realy is a case of trial and error a big difference was found between two drivers in
the same car..i would set it parallel and make sure you have some adjustment.
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tim
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| posted on 29/11/02 at 07:54 PM |
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Ah! Was kind of hoping that wasnt the answer! Does anyone know if it is ok to elongate the holes in the chassis pickups? Also will it pass the SVA and
MOT tests if done. Otherwise a rethink is in order!!!
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Viper
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| posted on 29/11/02 at 08:06 PM |
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we use rose joints in the horzontal plane on the inboard side of the wishbones so we can put spacers either side of the joint so altering the
squat...does that help?
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Viper
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| posted on 29/11/02 at 08:07 PM |
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we use rose joints in the horzontal plane on the inboard side of the wishbones so we can put spacers either side of the joint so altering the
squat...does that help?
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Rorty
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 posted on 29/11/02 at 09:09 PM |
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Sorry Viper, I don't follow! Presuming your brackets are welded to the rear of the chassis, rearranging the position of any washers at the Rose joint
pivots, will only alter the castor. I don't see how you alter squat, unless there's something you've ommited.
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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Viper
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| posted on 29/11/02 at 09:21 PM |
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castor is a by product of dialing in squat what you are efectivly doing is tipping the wishbones, castor on the rear shouldn't be a problem. havent
you got an off road jobbie rail or something going by the pics you have posted elswhere, dont you run a lot of squat on that??
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Rorty
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| posted on 29/11/02 at 09:55 PM |
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I understand that rear wishbones with anti squat will alter castor as they rise and fall, but to what end?
I don't run any anti squat on the buggies, but anti dive could arguably be used to increase castor when landing off jumps, thus increasing initial
stability.
But that still doesn't explain your original comments. How does altering the lateral position of the wishbone with spacers induce anti squat, and why
would you want to alter it? The centre for anti squat (or anti dive) doesn't vary.
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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Viper
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| posted on 29/11/02 at 10:12 PM |
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looking back at what i have posted i said ANTI SQUAT my mistake we don't dial in anti squat but we do dial in squat , theory being better grip of
the line etc are you sure squat would change the castor with suspension travel? by tipping the wishbone the rear suspension willl compress when you
apply the power how much it will compress also relies on how stiff the low speed bump is set...i know rom experience that with one driver we had
(leadfoot) by tipping the wishbone he had more traction out of corners and off the line, i noticed the diffeence when i drove the car, perhaps i am
wrong, but there was a definate improvement when we did this..or perhaps i am not explaining my self very well!!
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Rorty
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| posted on 30/11/02 at 12:06 AM |
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I fully understand the workings of squat/anti squat and dive/anti dive, as I've used it in a variety of combinations to great effect, when I had
various tarmac cars. I now race off-road buggies exclusively.
This nomenclature is obviously very confusing, as we were at cross purposes with squat/anti squat, and now you're confusing squat with anti dive.
You said "are you sure squat would change the castor with suspension travel".
What I said was that "ANTI DIVE could arguably be used to increase castor when landing off jumps".
This notion has merit. As the front wishbone rises upon landing (with dive/ anti dive), the position of the top of the front upright will be altered
laterally, relative to the chassis, thus producing more/less castor.
That all aside, I'm still very keen to know how you achieve either squat or anti squat by altering the lateral position of the wishbone pivots in a
horizontal plane. Is there some trick I've been missing?
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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tim
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| posted on 30/11/02 at 02:40 PM |
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Going back to the rose joint idea - I assume you have them in a horizontal plane, so by rearranging the washers, you alter the height? Sorry if that
is a stupid question, this is all kindof new to me!!!
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Viper
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| posted on 30/11/02 at 04:16 PM |
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Tim
that is exactly what i have done in the past,,
i think me and rorty have our wires crossed somewhere.
Rorty
How have you dialed in squat in the past?
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tim
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| posted on 30/11/02 at 06:27 PM |
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Thanks Viper.
Do you have to alter both top and bottom whishbones, or will you get the desirered effect from altering just the lower wishbone? Also by altering
the wishbones, do you have to alter the angle of the damper/pushrod to match the lower w/b?
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Viper
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| posted on 30/11/02 at 06:57 PM |
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our top wishbones have only a single rose joint on the outboard side (upright end) so tipping the top wishbone would make no difference at all, as far
as the damper goes, it shouldn't affect them as you are not moving the wishbone a great deal unless you are worried about the bush in the shock
"eye" ours again are spherical i guess you could be putting an unescesary load on the bush...
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tim
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| posted on 1/12/02 at 10:28 AM |
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Thanks for all the info Viper. Been a great help.
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Rorty
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 posted on 2/12/02 at 06:29 AM |
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I think I've worked out what's going on! In one of Tim's recent posts (although he too mentions the Rose joints being in the horizontal plane) asks
if Viper alters the height of them.
Had Viper stated , that the Rose joints axis was in the VERTICAL plane, and not HORIZONTAL, then it would have all made more sense.
Viper, you stated squat/anti squat could be altered by using spacers either "SIDE" of the Rose joints in the "HORIZONTAL" plane. This will only
alter castor.
Did you mean the Rose joints were mounted in the VERTICAL plane with spacers ABOVE and BELOW the Rose joints? Altering one or both ends in the
vertical plane will indeed alter the aspect of the wishbone, and MAY contribute to squat/anti squat.
To answer your question, If I wanted to alter a car's attitude with regard to assisting/resisting weight transfer, I would incorporate it into the
design at an early stage, as It's possible to work out the parameters on paper or computer. It's usually a fruitless task, trying to make
adjustments to a set-up designed to be horizontal and parallel, without doing some calculations relating to CoG etc. Having sorted out the centres,
then new mounts and/or wishbones are usually required.
Having said all that, the 1/4 mile fraternity use adjustable rear linkages on the rear of their drag cars to shift the weight rearwards, and make the
car "sit", on take-off for maximum traction. But that's a totally different situation, using different suspension.
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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