Evening all well after some playing with the string computer and then some fine tuning in CAD this is what i have come up with (front susp). Only real packaging issue is that the rear lower pivot is a little inboard but that should be ok. All thoughts and comments from those who know better much appreciated.

Thanks in advance

Andrew

[Edited on 8/11/07 by AGK7]

[Edited on 8/11/07 by AGK7]

Bonce

Droop

Combined.

Apologies for the multiple posts but could only seem to attached one at a time.

cheers
Andrew

What uprights is it based on?

What uprights is it based on?

Sorry guys,

Cortina upright, Mcsorley +4 with a few minor adjustments.

cheers
Andrew

Looks sensible :-)

Andew,

Are you using any suspension software to get those drawings?

If so what is it?

I am aware of staniforths string computer but have never seen a software version available.

Thanks,

Doug.

Doug,

played around with the good old string computer and then into AutoCAD to get things a little more accurate.

escort rack will need to be cut down to suit to bump steer is not a problem but i was wondering how these result compare to others who have built. My only packaging concern is that the rear lower pivot point will be fairly inboard but i think i will be able to work around this.

Cheers for now.
Andrew

My theory has always been to widen the front rather than cut the rack.

What do you think?

on the basis of what? i want to get my geometry right and that will then dictate the rack length. The escort is not far off the mark but because i have moved my lower pivot points inboard a little which has seemed to help wheel control the rack will be too long.

Cheers.
Andrew

Cutting the rack is a possiblity.

I placed mine a little bit lower, 3d-calc show that there is no bumpsteer.

Maybe your lower pivots are more inboard so you must short it.

Are there no shorter racks availble?
Mazda MX-5?

BTW the rest looks oke to me.
Wouldn't worry to much about rollcentre at bodyroll, cause would it roll like you calculated on the road?

Grtz

When you finalise your geometry you just widen/close the track to suit the rack.

quote:

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Originally posted by designer
When you finalise your geometry you just widen/close the track to suit the rack.

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First its good to see somebody playing around with the suspension and understanding what is going on.


Are your wheels vertical at static? Ideally under all your anticipated roll your outer wheel should stay negative camber. One way to do this is to start with -1degree camber.

An anti roll bar can restrict the amount of roll so the outer wheel doesnt go positive. Do you have a soft bar and more static negative or a harder bar and less static. Testing will tell you. However 1 deg to 1.5 deg negative with 3 deg roll is a very good starting point.

However if you do a combined roll and bump you will see the situation improves...... which is great for corner entry but when the car settles...............

Your RC seems static under roll. Some people say this is the main consideration others say it doesnt matter.

As regards the lower wishbone being inboard of the chassis....... make the chassis to suit the pickups. Also lift the lower crossmember so it goes between the lower pickups. It is best not to put loads in the middle of a tube.......

Before you narrow your rack, build and mount the wishbones then mock up the rack and try what it is like for bumpsteer. (off set the rack and put the pivot point where you want it) You may find that "in the metal" the rack needs to be a different length.

Widening the track does not alter the suspension geometry; it affects weight transfer.

Independent suspension is, as it says; each corner working independently.

there are a few reason why it does affect it. If you believe in roll centres, it clearly would move these since its related to where the lines on each side cross. Also, a wider car will roll less (in degrees), so it affects changes in roll etc.

quote:

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Originally posted by designer
My theory has always been to widen the front rather than cut the rack.

What do you think?

---

Thanks for the comments,

Have done a little more work. Some minor adjustments (slightly shorter) to the lower wishbones sees the packaging less of an issue and an increase in wheel control with only a slight reduction in RC control. (Staniforth is a big believer in RC control).

As for the steering rack i am not overly concerned as i am comfortable making this to match. certainly comments about double checking in the flesh are very valid and taken on board.

My track and chassis are pretty well fixed unless i get the grinder involved! (probably the wrong way around but i started with a Mcsorley +4 and have been slowly making some minor changes.

I now have only -1.5deg with 3 deg roll and about +2.3deg camb with roll bump combo.

Thanks again for the comments.

Cheers
Andrew