Technical Speedway Wishbones Caster Angle ?

Speedway Wishbones - I see many installation of Speedway Wishbones. Some modified for caster angle while others are installed bone stock.

Anyone know what approximate caster angle would be if the end of the wishbones (unmodified) installed under the frame like this ?

 

Too many variables to be remotely accurate, ride height to axle, angle of wishbones, any built in angle on axle. Etc.. Etc...

 

Yes, too many unknowns. Tire rake, frame sweep, front crossmember angle, front spring arch, frame depth, all influence your final caster angle.

 

I've done several customer chassis with Speedway bones and as long as I mount them under the frame and the car has about 3 degrees of rake I've ended up with 5-6 degrees of caster without cutting the bones. I've never had a complaint to date.

 

I ordered Boling Brothers 4-10 frame. 4 inch kick up in front and 10 inch in rear and wondering if I can mount the Speedway Wishbones under the frame. Will have 4 inch drop axle.

 

Not sure about all of the rest of your parts, but with the front frame sweep and the dropped axle my guess is that your attachment point will be in the frame rail, not below it. But until you get it mocked up you won't know for sure.

 

So it looks like you need certain amount of rake up front to be able to mount the wishbones under the frame like this Riley frame otherwise it will end up in the frame or too much caster. Correct?

 

Contact Boling Bros and ask how they have set up their own frames.

 

Generally a front frame sweep brings the mounting point upward. But a lot depends how the front crossmember is positioned in the frame. You find anything from flat to 10 degrees. Depending on the style you are going for, many prefer the through the frame mounting location. So again, establish your tire rake (or assume 3 degrees), and get a front end under the frame and then work out your mounting location. Also depends on if you are using fixed or adjustable spring perch. Do you know how the front crossmember was welded into your frame?

 

They take the Speedway Wishbone, shorten them and also cut and reweld up front to achieve proper caster which over doubles the cost of the wishbones!

 

So what exactly do you want to end up with?

 

That truck looks killer

 

Just tack weld it together u til you have all the major components mounted. Then measure the angle and weld it in. Otherwise you are making a stab in the dark.

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Block up your axle to sit at the height it will be with the tires you intend to use. Block the radius rods up until you've got the desired caster. This will show you how far from the floor they should be mounted. Block the frame to the desired ride height. now you can measure roughly where the rods need to be mounted. If you cant find an acceptable location you may have to cut the rods and reweld them, although that is something I would avoid at all costs.

 

Almost always the only way to really get things right is to mock it up. With all your variables on hand and the frame at ride height/rake.

 

Try not to over think it . The frame you have will be built with the crossmember mounted at the correct angle . When you secure the front spring in the X member properly and secure the spring to the axle perches your caster wll pretty much be in the ball park without pulling the wishbone around to much . If it doesnt locate where you want it, then you are faced with the desision to cut and reweld to suit, just as the frame builder does to achieve the look they did . Thats more or less all there is to it .. Just make sure you dont raise the rear end to much so it deceases the caster angle . If you dont mind your steering being a little heavier but more prone to driving straight with hands off the wheel ( on a good road surface ) then treat yourself to a little more caster .