General suspension design question

First, I have to say that I've just finished digging and pouring the stair well in to my basement, underpinning the whole damn thing, replacing the original central load bearing wall with a beam AND poured the floor (the whole basement is roughly 27 1/2' x 36' and took about 2 years to do)... so now I'm back to "easy" work and miraculously I'm finding myself being a lot more sane and have time to think about fun things. But basically I'm no stranger to stupid amounts of work.

So with that in mind, I want to design a chassis for a Volvo PV with a widened track (initial thought is around 8". I'm thinking dual A-arms with coilovers front and rear (I've always preferred A-arms). I want to keep the suspenders inside the shell.. so they are going to be on I'd imagine close to a 60 deg angle to the horizontal. I can't make up my mind if this is a good or bad/livable or not livable thing. I just argue myself in circles. Any thoughts?

Thanks for any input.

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Andrew M
Onterrible
30ish

More angle makes need for bigger spring, that's simple enough.

Does anyone think you would see increased shock wear (seals etc) with them on a significant angle?

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Andrew M
Onterrible
30ish

They will certainly work laid over that far but the motion ratio is going to stink. You won't see much difference in wear because shocks are always mounted pin-pin the only side loading you can generate on them is caused by friction in the end bearings. That friction will be slightly increased by the higher spring rate and damping rate.

The bigger problem will be getting something close to a linear spring rate without some sort of progressive spring or linkage. With the layout you described you are pretty much stuck with a falling rate ratio...when you would really like something linear or slightly progressive. With out a drawing it's tough to give you a definitive answer though.

Tim

hudson Wrote:
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> widened track (initial
> thought is around 8"

You'll probably roll over pretty easily with only an 8" track.

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Grant Hughes

I would guess the best thing to get ideas from would be the rallycross 544s

http://www.bendixen.se/ go to bildarkiv Garagebilder 2006/2007 2005/2006

http://www.bostorpsracingteam.se/ bild/film scroll down

Tim Taylor Wrote:
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> They will certainly work laid over that far but
> the motion ratio is going to stink. You won't see
> much difference in wear because shocks are always
> mounted pin-pin the only side loading you can
> generate on them is caused by friction in the end
> bearings. That friction will be slightly
> increased by the higher spring rate and damping
> rate.

Thanks for clearing that up.

> The bigger problem will be getting something close
> to a linear spring rate without some sort of
> progressive spring or linkage. With the layout
> you described you are pretty much stuck with a
> falling rate ratio...when you would really like
> something linear or slightly progressive. With
> out a drawing it's tough to give you a definitive
> answer though.

Yeah I had thought about that. When I've got time I'm going to start doing some
drawings.

The other thing would be finding and deciding on front and rear spindles/hubs.. junkyard sourceable would be awesome.. but whats been around long enough, rwd with a-arms in the back? The only stuff coming to mind is Jag and Corvette.

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Andrew M
Onterrible
30ish

NoCoast Wrote:
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> hudson Wrote:
> --------------------------------------------------
> -----
> > widened track (initial
> > thought is around 8"
>
> You'll probably roll over pretty easily with only
> an 8" track.


no doubt. I meant 8" wider

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Andrew M
Onterrible
30ish

CharlieV Wrote:
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> I would guess the best thing to get ideas from
> would be the rallycross 544s
>
> go to bildarkiv Garagebilder 2006/2007 2005/2006
>
> bild/film scroll down


Yeah charlie, that's what got me thinking down the road I'm on. I hadn't seen the second link though before.

But since 90% of the local shells are all rotten underneath I'm figuring on doing a complete new floor and chassis being the easiest/best way to go about it.

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Andrew M
Onterrible
30ish



Edited 1 time(s). Last edit at 09/05/2007 01:01PM by hudson.

What the reasoning for widening the track I saw that you have a merkur front rack is it to accomodate it.

Jeeezus boys put some piccies up!
These guys cars are the hot sheet!

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

CharlieV Wrote:
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> What the reasoning for widening the track I saw
> that you have a merkur front rack is it to
> accomodate it.


Main reasons for wider track are:

A) More stable.

Look a hell of a lot better. (visually they look a lot taller than wide)

The main reason for going to a fabricated chassis is because most PVs have pretty rotten floors and frame rails etc now. So it will be a lot of work to patch up what's there. So once you're already into a lot of fabrication time and materials, why not just build a whole new chassis the way you want it to be? All new steel and whatever design you want.

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Andrew M
Onterrible
30ish

Spaceframe?

CharlieV Wrote:
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> Spaceframe?


That's surely a possibility.. but I think I'd have a much harder time getting it classed and competing if I did that. I definitely want to rally at some point.. with this car? I don't know. I know it will be a while before I can build a car AND race it.

However, I definitely do want to design a car and drive it daily for a very long time. Hence the choice of a classic and simple shell. I also like that the fenders are separate and can be replaced easily/made out of something that doesn't rust. To be honest I really don't like how disposable cars are, especially in locations where rust is a big factor. So, I'm thinking a PV with glass or carbon fenders a completely new frame with the floor on top and a stainless steel skid plate running tip to tail (in sections of course).. stainless for the no rust, smooth underside for the aerodynamics. Besides if I think it through enough and do it right even if it costs me 50 grand to make that's a bargain if I then drive it for 20+ years (ride comfort, noise and fuel efficiency (I drive a 4x4 V8 Dodge now) would also be big factors in that).

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Andrew M
Onterrible
30ish