Front suspension

[Dan Noecker]

I am getting the first of my front suspension parts back from the chrome shop. I am piecing things together in mock up mode so I can be sure all brackets are in the right place before welding them on the frame. With the car sitting there does anyone know what the degree of the frame is from back to front? Three degrees, four degrees.?? or whatever? I would appreciate thoughts on this.
Thanks.

 

[old round fart]

That is like asking "how long is a string?". Part of what makes buckets fun is you get to make that decision. Mock it up and see if you like it. If not, change it til it does. Good luck. John

 

[Indycars]

Like ORF said!!! Push it outside and get back 15'-20' and see what you think looks best, but if you need some numbers to think about then assuming......

90" front axle to kick up
sin 2° = .0349, sin 3° = .0523, sin 5° = .0872
D = Distance the back is higher than front of frame.

D = .0349 x 90 = 3.1 inches
D = .0523 x 90 = 4.7 inches
D = .0872 x 90 = 7.8 inches

Just substitute your numbers into the above equation. Hope this helps!

 

[one finger john]

Don't forget header angle and body angle. Also load the chassis with a block, trans, and body to approximate running, loaded weight/ height. Sit in it with approximate seat height to see where you are within the body confines.

 

[2old2fast]

If you're gonna keep the driveshaft under the floor , you'll probably end up at 4-5*, that and how high you want the F.E to sit... Whole bunch of variables..
dave

 

[2old2fast]

Other thing to keep in mind is oil pan clearance ,how far up in the body do you want the engine/trans , which leads directly to foot space & so on...
dave

 

[Zandoz]

The degree of rake is up to your preference, within the clearance dictates. Personally, I'm one who works EVERYTHING out in my CAD program of choice. One thing I've found is that changes of rake is of the things that frequently has unintended consequences. Which is one of the reasons that I waste so much time working EVERYTHING out in CAD.

Just for the record, I tend to favor just a little rake. Right now my plans have evolved to 1 degree.

 

[409T]

The thing I would worry about is where is the bar at the top of the windshield going to fall in your line of sight while driving. Getting this wrong can be very annoying, and it never goes away. The rake you choose will affect this.

 

[one finger john]

Is it better to see through a windshield or see over a windshield ?

Also to think about not having a top bar at all.

John

 

[Dan Noecker]

Is it better to see through a windshield or see over a windshield ?

Also to think about not having a top bar at all.

John

All of you are quite correct in your comments. Thanks to all. With the frame just sitting there with no engine/tranny in it, I will aim for a rake of 1-degree. Knowing when everything else is added the rake will increase. It is to some degree a crap-shoot, but I think I will be in good shape. Thanks again to all.

 

[mcmental]

is it best to set these measurements up when the car is on its wheels or on axle stands?

 

[old round fart]

If you set it up at ride height (spindle at 1/2 final front wheel diameter) it doesn't matter if wheels are there or not.

 

[Zandoz]

is it best to set these measurements up when the car is on its wheels or on axle stands?

This is a little tricky. The wheel and tire combos are going to introduce additional "rubber rake"...unless you are running front and rear tires with the same run height. With the run height taking into account the flat patch where the rubber meets the road. I've seen tire web sites that list run heights for their tires, but I've not kept track of them, and their figures have to be rough averages.

What it all boils down to is that the best you are going to do is a guestimate.

 

[ibfishn]

yes