Upright Dimensions

[mreddaway32518]

I'm in the planning phase of my kit car fantasy. It'll probably be some time before this is turned in to a reality but you've gotta dream right?!

I was thinking of using an mx5 as a donor, including the front uprights. To plan the suspension I need the dimensions so that I can get the angles correct.

Does anyone have the distance between the top and bottom mounts on the uprights as well as the location of the steering arm ball joint on the upright?

Failing that I'll have to use my E46 as a donor (which could be interesting) seeing as I can't sell it (nudge nudge)...

Thanks for any information.

[flyerncle]

Saturn have all the parts to hand as he has just built one using an MX5 donor.

[minicountryman1961]

Hold on for just a bit, Saturn is about to release a set of drawings for an MX5 based Roadster. Look in this thread.

http://www.haynes.co.uk/forums/showthread.php?t=5753


I'm in the planning phase of my kit car fantasy. It'll probably be some time before this is turned in to a reality but you've gotta dream right?!

I was thinking of using an mx5 as a donor, including the front uprights. To plan the suspension I need the dimensions so that I can get the angles correct.

Does anyone have the distance between the top and bottom mounts on the uprights as well as the location of the steering arm ball joint on the upright?

Failing that I'll have to use my E46 as a donor (which could be interesting) seeing as I can't sell it (nudge nudge)...

Thanks for any information.

[trick-kit]

http://locostcadfiles.wikispaces.com/Spindles+and+Hubs

If you don't have Solidworks I'm sure if you give Jason an email he'll export it to a file that your software can support.

There's more to suspension design than making it "fit" the Haynes chassis. My dealings with the Haynes's supension shows that as the car rolls it goes into positive camber, not ideal.

Spend a bit of time to get it right, you'll be far more satisfied with the results.

ATB

Will

[Bonzo]

There's more to suspension design than making it "fit" the Haynes chassis. My dealings with the Haynes's supension shows that as the car rolls it goes into positive camber, not ideal.

Spend a bit of time to get it right, you'll be far more satisfied with the results.

ATB

Will


Perhaps you would care to enlighten us with your dealings of the Roadster suspension !!?? :confused:

Rather a strange first post to make on the forum ( Sorry if that comes over as a tad hostile, it's not meant in that way )

Perhaps an intoduction to yourself would have made better subject matter for your first forum post ;) :)

[trick-kit]

Perhaps you would care to enlighten us with your dealings of the Roadster suspension !!?? :confused:

Rather a strange first post to make on the forum ( Sorry if that comes over as a tad hostile, it's not meant in that way )

Perhaps an intoduction to yourself would have made better subject matter for your first forum post ;) :)

Indeed Bonzo, please accept my humble appologies for not introducing myself first.

However my first post was actually to supply the OP with the information he asked for, as no-one else seems to have answered his question, but when you've quoted me you seem to have deleted the important part of my reply and just concentrated on the obsevation I've made about the design. which I have said isn't ideal, nothing else.

Here is what my observations are, please study the drawing below


http://i1187.photobucket.com/albums/z399/trick-kit/HaynesRoadsterinroll.jpg


I have simplified the drawing to show what is important, the pivot points on the chassis and the hubs are represented by the circles. The drawing represents a car to book dimensions on 195/50/15 tyres with a ride height of 4" (as seems to be most popular for it) in static, 1 degree & 3 degrees of body roll. And no, I haven't doctured any drawings to exagerate this.

As you can see the outside wheel (the one loaded in cornering) gradually lifts the inside edge of the tyre clear of the ground, pictures on the Saturn website back this up, the reason the car may feel "balanced" is because both ends do the same.

What I am saying is that the design can be improved, if you are building using the MX5 upright then with a little time and patience you can achieve a design that will provide good wheel control in roll, it's always a balancing act but it is possible to get very close to ideal.

[minicountryman1961]

Perhaps you can show us what happens with a real tire that distorts under load, instead of your depiction of a solid inflexible tire?

I have never seen a rectangular tire in the real world, which is where we drive our cars.



Indeed Bonzo, please accept my humble appologies for not introducing myself first.

However my first post was actually to supply the OP with the information he asked for, as no-one else seems to have answered his question, but when you've quoted me you seem to have deleted the important part of my reply and just concentrated on the obsevation I've made about the design. which I have said isn't ideal, nothing else.

Here is what my observations are, please study the drawing below


http://i1187.photobucket.com/albums/z399/trick-kit/HaynesRoadsterinroll.jpg


I have simplified the drawing to show what is important, the pivot points on the chassis and the hubs are represented by the circles. The drawing represents a car to book dimensions on 195/50/15 tyres with a ride height of 4" (as seems to be most popular for it) in static, 1 degree & 3 degrees of body roll. And no, I haven't doctured any drawings to exagerate this.

As you can see the outside wheel (the one loaded in cornering) gradually lifts the inside edge of the tyre clear of the ground, pictures on the Saturn website back this up, the reason the car may feel "balanced" is because both ends do the same.

What I am saying is that the design can be improved, if you are building using the MX5 upright then with a little time and patience you can achieve a design that will provide good wheel control in roll, it's always a balancing act but it is possible to get very close to ideal.

[Talonmotorsport]

Bet me too it. How ever if your that worried about front end goings on mid corner you should be looking into this sort of set up.
http://www.daxcars.co.uk/start.htm

[trick-kit]

Predicting what a tyre does in deflection is a bit of a grey area, as the amount of distortion varies from one make to another, the reason a lot of the more performance orientated vehicles use tyres designed specifically for them, it's not so prices can be fixed but because the chassis designer would have worked closely with that perticular tyres characteristics to fine tune the suspension.

[minicountryman1961]

Predicting what a tyre does in deflection is a bit of a gray area, as the amount of distortion varies from one make to another, the reason a lot of the more performance orientated vehicles use tyres designed specifically for them, it's not so prices can be fixed but because the chassis designer would have worked closely with that particular tyres characteristics to fine tune the suspension.

So you agree that since real cars have real tires, suspension design is a bit of a gray area, not easily proven by simplistic rigid drawings.

[spud69]

You're correct to some extent the pics on my website do show excessive body roll but these where taken a long time ago and the suspension, ride height and springs have been since setup accordingly, mainly being stiffer springs on the rear which has improved the balance of the car significantly. All cars need to be fine tuned and can only be compared to other track cars, I and others have been very pleased and surprised by the Haynes as a driving experience off and on the track.

Suck it and see may be the answer.......Andrew

[Bonzo]

Ok, Ok not my absolute last word on the subject ( Read, so I lied ) :o :D

TK

Thanks for taking the time to post a comprehesive reply, tis refreshing for someone to illustrate what they mean :)

Firsly, sorry for taking your post in the wrong context & yes of course I do realise that you made a reply to the OP re: MX5 geometry.

As said I am by no means an expert on steering & susspension geometery, that said, I do understand your illustrations.

Are these based on the Sierras geometry ?

In my simple mind by looking at your illustrations and as you have stated " the reason the car may feel "balanced" is because both ends do the same "

Surely this by its very nature is what you can term as some form of ballance ( The cars handling will remain predictable )

Is this not consitently common with all 7 type cars ?

Ideal for the track ? ( probably not ). Could it be refined further ? ( Probably yes )

From a very quick glance, I can see that some form of anti roll bar would certainly go a long way towards optimum handling !!

I am sure those folk building Roadsters & are fully conversant with the design principals of suspension geometry will alter thier builds to suit their own tastes.

Do we really want to encourage novice engineeers to ring the changes without fully understanding what they are doing !!??

Just to point out

The pictures on Saturns web site are of a Sierra based Roadster .... As far as I know, Andy has not done track testing of the MX5 based Roadster as yet ;)

[mreddaway32518]

Didn't quite expect a simple question about dimensions to snowball in to that!
And there I was thinking this wouldn't be like other forums...

Anyway I think someone asked me a little about me somewhere in that. Well I'm 23 and drive a mk1 MR2 which is a fun little car. I've become more interested in cars over the last few years and really fancy building something a little different. I was thinking of an every mans caparo T1. But having little mechanical knowledge it will probably be like something on topgear, ambitious but rubbish. So long as I have fun along the way hey?

Thanks for the post regarding saturns build. I'll be sure to check it out.

As for the rest of you, stop bickering on my first thread!

[Bonzo]

Didn't quite expect a simple question about dimensions to snowball in to that!
And there I was thinking this wouldn't be like other forums...

Anyway I think someone asked me a little about me somewhere in that. Well I'm 23 and drive a mk1 MR2 which is a fun little car. I've become more interested in cars over the last few years and really fancy building something a little different. I was thinking of an every mans caparo T1. But having little mechanical knowledge it will probably be like something on topgear, ambitious but rubbish. So long as I have fun along the way hey?

Thanks for the post regarding saturns build. I'll be sure to check it out.

As for the rest of you, stop bickering on my first thread!

Sorry :o

This thread is not typical of this forum .... Honest :)

Bye & large this is a happy, friendly place to be.

If I have not done so, please may I welcome you to the forum & enjoy your build :cool: :)

[TSM Locost]

All mreddaway32518 wanted was a little help to try and build himself a small sports car that he could enjoy and be proud of by saying i built that.

If you want to race or use your car for serious track days then you have to modify and set up to your own personal tastes for your style of driving.

How many people race production sports cars without making some alterations to at least the suspension set up ?

Could a full race car be driven in relative comfort and safety on the road without some degree of compromise ?

Welcome and good luck with your build mreddaway32518. May you have many happy hours building and driving your pride and joy.

After your first drive you will have a big grin for hours. :D :D :D

[AshG]

My car is built to book. it self centres fine as for handling since it was setup properly its awesome. there are lots of different cars / sevens i have met on track and go out for runs with and there are very few that can out corner me. i have been out on track with several strikers and riots, indys, la golds, phoeneix's, furys, mnrs all known known to be up there in terms of handling when correctly setup and never had a moment where i thought i was driving something inferior

[leroybrown911]

Lets et a grip here guys. Alot of good 'conversation' but we are essentially home builders of differenent requirements and capabilities.

There is no such thing as a 'one size fits all roadster' but what you will get is a very quick and good handling car should you make the car to the standard in the book. Should you further improve this (as most people do in one way or another) then all the better.

I have seen 2 other roadsters in the flesh. Both of which are different to mine!

Anti roll bars are a good example of a chassis upgrade that is certainly required for serious track use. A Lotus 7 kit car has its limits!

Haynes roadster aint perfect, but what is?