Projects Looking for front axle degree of lean.

Hello,Have a 1930 Av8 build going.Im trying to find the angle of lean back on the front axle to get the bracket length needed after splitting the wishbone. Thanks

 

I kinda like 6-7 degrees; but you will find a lot of other opinions.

If you are retaining your Model A wishbone; you will likely find the back will be hanging low enough below the frame along with the length of bracket needed will be unattractive. Pie cutting the bones behind the yoke is way of tuning the appearance so it looks good.

 

Thank You, I've stretched the a bones 9" ,your right the stock length doesn't look that nice.

 

I use 3 to 5 degrees...

 

It's called caster by the way.

 

I have only done one. My car drives great at 7 degrees. No issues at all.
Go Maine, go

 

I'm with @RICH B , 6-7 degrees.

 

The more you have the harder to steer but the easier it comes back to center. Just things to consider.

 

Thanks... I'm running on a public school edu.

 

The Model A crossmember has about 6-7degrees built into it, adding more with the bones can bind things up, do a mockup and let your eyeball tell you whats what.
I never knew there is a Western Maine, I'm from Ashland.

 

Peru, in the western foothills near to Sunday River/Bethel area

 

I believe you have to weld the A crossmember into chassis with 7deg. caster. Welding in the 7 deg should eliminate any bind if the axles is same angle. Shackle mounts thru the axle are available with or without swivel to eliminate bind also.

 

If building the frame level but plan running it with the nose down (rake)that needs to be considered.
If ya built it level with a 6-7 degree caster angle, you lose caster when you raise up the rear.
Just something to consider.
Frames at our shop would usually sit in the jig at 3*
The front axle and spring crossmember would usually be 6-7*

 

When I worked in a machine shop I used to make shims at whatever degree angle someone wanted that would go between the spring and the cross member so when you tightened them down they would put the spring to desired angle. It was pretty popular with the guys with T-Buckets.

 

I usually use 5-7 degrees, but for vehicles with shorter wheelbase I often go as much as 10 degrees. Especially for a drag car that's short wheelbase and might see speeds over 100 mph, as things can get spooky with short wheelbases and high speeds.
I have an 89" wheelbase Austin gasser and I set it at 10 degrees, and well over 100 mph I can let go of the steering wheel and it tracks straight.

 

This ones a flathead powered prewar speedster,something my fathers generation were building ,cut off is 1939 ... 100 mph blasts probally not an easy task.

 

Just did the alignment on my mew deuce sedan. Car has between 3&4 degrees of rake and the caster ended up at 6.5 degrees.

 

Speedway motors has adjustable spring perches.
910-33042

 

Changed the 32 over to an drilled i beam and adjustable spring perches a couple of years ago. It made a tremendous difference in the driving and ride of the car. I think front end was in a bind with the fixed perches. The adjustable perches allow you to adjust caster with out binding anything.

 

You are correct; however, this brings up an outstanding issue.

The position of the crossmember has nothing to do with setting caster, so stating this only serves to reinforce the mistaken belief that some hold (not you).

For clarity, caster is set by the axle position in-relationship to the ground.

The front crossmember is set (originally) on a radius line that has the same length as the front-to-rear run of the wishbone.

This is done to minimize leaf spring twisting on suspension cycling.

The two numbers roughly should agree, but one does not set the other.

 

My 1946 Motor manual says 4-1/2 to 9 for 35 to 48 but the actual setting for you has more to do with how you are going to drive the car most of the time.
Simply cars that don't get outside of the city Metro areas and don't see speed limit and above out on the long wide roads for hours on end don't want or need as much caster as those who are more likely to do 3/400 mile road trips as a norm. The more caster the more arm strength and Chest muscle action that you are going to use in town. That 3-4 is great around town but may take a bit more attention to keep in a straight line at 80 running across 80 in Wyoming on the way to Bonneville. At the same time the 7 or 8 that some guys like is great out on the long roads and on the straight ones the car will track straight for miles but when you are cruising in town and doing a lot of steering your arms know it.

 

A model A wishbone has the least amount of built in caster compared to a 32-48 wishbone. You might kept this in mind if pie cuting the wishbone becomes an issue.

 

Positive or Negative caster

 

Really ?

 

With split bones I usually set the caster at 7° HRP

 

For those who don’t know, tilting the top of the axle towards the rear of the car (the correct way) is positive caster . Tilting it toward the front would be negative caster.

 

Its called caster for future reference. (@RICH B knows this already ) 6-7 is common, I have seen them run on the street as much as 11 degrees but it makes 'em a little sluggish and is not optimum for cornering. Anyway Rich nailed it down for ya, he knows his chit.

 

I would limit it to seven degrees.
I had to back mine down from 11 degrees because that induced death wobble on rough roads.

 

Lucky 7 is what I always have used

 

7. Period. (not always on everything) But, all my early Fords get 6-7. (Actually, 7; My F100 has 7, except when hauling a Hemi and other stuff...Then I have to settle for 5.5-6, until I get the tail back up.
And YES, it sure steers nice carrying Chryslers...(Hauling Hemis)
Front end gets lighter, too.