Front end Geometry for 66 Mustang

[jjamieson]

I'm working on my Corvette C6 front end pans but all I have to work from right now is a generic book on racing geometry. I'm thinking some of these angles will be too extreme for the road. I'm basing my build on the Roadster Shops sub frame pictured.
[imgurl url=http://http://roadstershop.com/suspensi ... ossmember/]http://wwwhttp://roadstershop.com/suspe ... ossmember/[/imgurl]

I'm using 8 x18( I think?) "Bullit" wheels from a 2004 Mustang. I will have some adjust-ability as to caster/camber of the spindles but the one critical angle that I am unsure of is at the upper shock position relative to the connection point on the lower A arm. ( the shock itself)

It also appears that the most of the C-6 conversions have cut the original steering arm off(which connects slightly inboard of center)and replace it will a new one ( as pictured) to line up with the spindle which lengthens the steering tie rod arms a bit.....wondering if that is necessary?

any thoughts or experience would be appreciated.

J

[boofhead]

I am likely stating what you already know..... how ever to help the discussion.

After the static position and initial angles are set up - the location points of the upper and lower arms determine the Caster curve, Camber curve when the suspension moves and has an influence on the roll centres. In addition, this movement relative to the position of the tie-rod end position and location to the (in this case) rack determines the toe curve aka Bump steer (which is not great anyway in a standard Mustang). Lastly the position of the steering arms and the rotation point of the axle determines the Ackerman angle. These are the basics. Your most pressing point in my view is the toe curve with the goal to remove as much bump steer as possible then you can feel confident for normal driving - the rest applies to how you want it to behave under higher loads and corning conditions. How much natural understeer or oversteer you design in etc. If you spring it tight then the affects of the change in angles when the suspension is reduced though you loose comfort. So it is all an engineering exercise. I have not looked into your specific one though the Detroit Speed front cross member looks to me to be very nicely designed. Though keep in mind I have not tried one though I can see engineering considerations and design behind it.

Edit: Note: The standard mustang suspension can be made to work very well with minor changes here and there. Far less expensive and no engineering certification needed (which appears not to apply in the US).

Edit 2: Had a look at the system. Looks very nice - I can see this as a further improvements call it phase to of the front end system available. Not sure the price makes it work the effort though. Cool to see several vendors taking the next step in this area.

[ozbilt]

I looked at fitting C6 suspension in a 68 Camaro back in the early 2000's. However I was going to use the frame (chassis) to hold the suspension & drop the Camaro shell on it.

Ended up using C4 front & rear suspension because I found a bolt in kit (sub frames) to fit it.

What I liked about the front suspension (besides the huge brakes) was the way the top & bottom arms fitted inside the wheel. It then had a perfect scrub radius as the center of the tyre (tire) was the mid point on turn. Stock Mustang is the inside of the tyre, so a lot more "scrub".

What boof said is correct though, a well set up standard type Mustang suspension will be just as good as what you are intending to use. I have proved that point time & time again with my customers. You are going to spend a LOT of time (& money) for little gain (if any).

[jjamieson]

Thanks for the input.....every little bit helps. As far as expense....I already purchased everything I need to build it except for the hubs. All the parts I needed came from E-bay for a total of $500. Lots of used Nascar parts from S Carolina. I think the teams liquidate used parts for cheap locally and guys buy them up to resell. Most times you get very high quality parts that may have only been used in a single race or two.....(sponsors give the teams their parts for free many times). I found a Penske shop that will custom build the shocks I have for $300 any way I want to meet my needs (that's the price for one new....I have 6 that I paid $300 for). So I'm into the system so far for $800 minus stock material. I can live with that.

Anyway......I thought since I will never be able to afford the kind of car that these parts come on(aside from a used Corvette)......I'll put them on my Mustang so I can say I did and learn from the experience just for the hell of it.

It also gives me the freedom to make adjustments to ride height and structural improvements at the same time....as well as being different which is part of going with the 250l xf head on a 200 six.....WTF?

FYI: I'm also considering copying Maer Racings cantilever extreme rear end suspension too. This is all for fun anyway...the car itself I picked up for $1000 (which is straight, rust free with new wheel wells and floor panels already installed) so I'm also seeing what I can do for as little money as possible......a side fun goal. why not eh?

[jjamieson]

Lastly the position of the steering arms and the rotation point of the axle determines the Ackerman angle. These are the basics. Your most pressing point in my view is the toe curve with the goal to remove as much bump steer as possible then you can feel confident for normal driving - the rest applies to how you want it to behave under higher loads and corning conditions. How much natural understeer or oversteer you design in etc. If you spring it tight then the affects of the change in angles when the suspension is reduced though you loose comfort. So it is all an engineering exercise.

That answers the question about the custom steering arms. Looks like I will need to get very familiar with the Ackerman angle. I had already considered building in as much adjust-ability in the entire system since I predict the need based on my experience and ability.

I fabricate and use CAD at work so I know all too well about things not fitting the first time around.....actually, 2nd , 3rd, 4th, 5th, 6th.......ha ha.

Thanks for the straight forward insight....I need straight forward and simple to get this process narrowed down.

J

[Shaunp]

One thing to consider with the ackerman angle is you may wish to give it less. It's common on drift cars to reduce the angle to make them snappier.