Next A-V8 caster question

[cuzncletus]

My A-V8 build is on a Model A chassis with a 4" dropped A axle and reversed spring in front, a 2" Z ala Tardel and T spring in back. I'm going to run big and littles on 16" wheels. This will cause the frame to sit at a few degrees tilt from front to back. My question is how will this "downhill" attitude affect the caster settings, if at all. Relative to a horizontal surface the caster angle will decrease but relative to the car frame the angles won't change. Which should I pay attention to?

By the way, purists, this car is entirely from cast off parts with a Brookville body. No Model A's are being damaged in the process.

[Bruce Lancaster]

Relative to the surface. What wishbone and crossmember are you using?

[CT AV8]

Caster is set with respect to the horizontal plane on which the front tires are rolling.

[mrtexas]

I had big(16 inch 700 tires) and little(16 inch 195 70 r16 radials) on my 28 pickup. No caster problems. Too big in the back and caster will be not enough.

Had caster problems on my 49 woodie with fatman front end which lowers the front end considerably. Solved with 2 inch lowered springs in back and 14 inch tires in front/back instead of 14 front/15 back. Couldn't be aligned otherwise. The guy who built the the car was very nice guy but clueless as to building a hot rod!

BTW need 2-35 wires with 700r16 BW new from Coker?

[cuzncletus]

My wishbones turned out to be 37-41's. When the wishbones are level they have approx. 10-12 degrees positive caster measured using a cheap Sears angle finder. What I'm trying to avoid is long split wishbone mounts. I'll make some clamp on temporaries, but until I get the chassis fully loaded weightwise I don't know if there's an accurate way to determine the spread of the mounts from the frame to the ball joints.

If all works out right, the mystery 37-41 split bones may prove to be a blessing. It looks like the tie rod will clear with no heating and bending of the spindle arms. I'll post pictures if it works like I think it will. Bending will be minimal at most.

[CT AV8]

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10-12 degrees sounds like a lot. I think you want to be looking for 7 deg fully loaded with tires on the ground.

[Randy in ca]

What style/type of spring perches are you using? Unless you're using a non-stock adjustable type, the caster angle is pretty much determined by that of the front crossmember and the spring when it's firmly clamped in place. Attempting to set it to anything else is going to result in something binding somewhere.

[cuzncletus]

Randy, thanks. I'm using the stock crossmember with spring perches from Speedway. Nothing exotic. CT AV8, I figured some of the 10-12 degrees would come out when everything was firmly bolted together, plus the angle of the radius rods and the downhill slope of the chassis.

[CT AV8]

Originally Posted by Randy in ca

What style/type of spring perches are you using? Unless you're using a non-stock adjustable type, the caster angle is pretty much determined by that of the front crossmember and the spring when it's firmly clamped in place. Attempting to set it to anything else is going to result in something binding somewhere.

Cuz,
I agree with Randy. When the spring is seated and clamped tightly, the caster will set itself. The cross member spring seat creates the caster. I know some do chamfering and wedging of the starter leaf there to adjust, but I'm not a big fan of that. A stock wishbone unrestrained at the ball end will float right where it needs to be. If you move it up or down you will feel it binding at the spring. And I bet you will end up around 7 degrees regardless of the amount of rake. I personally wouldn't bind up the spring for half a degree of caster.

[bdave_mcc]

Yes, those 37 wishbones are a blessing, with stock wishbones you usually end up with not enough positive caster and you have to either have really long mounts or pie cut the wishbones. In your case you should be able to have short wishbone mounts close to the frame and still have enough caster. On the subject of your spring, while 7 degrees +caster is optimal, your spring can easily handle a degree or two one way or the other.

[pooch]

Originally Posted by cuzncletus

My wishbones turned out to be 37-41's. When the wishbones are level they have approx. 10-12 degrees positive caster measured using a cheap Sears angle finder. What I'm trying to avoid is long split wishbone mounts. I'll make some clamp on temporaries, but until I get the chassis fully loaded weightwise I don't know if there's an accurate way to determine the spread of the mounts from the frame to the ball joints.

If all works out right, the mystery 37-41 split bones may prove to be a blessing. It looks like the tie rod will clear with no heating and bending of the spindle arms. I'll post pictures if it works like I think it will. Bending will be minimal at most.

I am playing with an AV8 with a 4 inch drop and rake ATM , and am planning on bending arms down and using 42-48 bones with the upwards hump to clear the tie rod going under.

I am guessing you are going over the bone ?

Are you re-tapering the arm and also putting the tie rod on top of the arm ?

Pics will be good .

BTW, this thread would be better in the traditional hot rod forum.

[cuzncletus]

Pooch; I am going under the bone. The 37-41's look upside down compared to a stock A. Even the welded seam is on top. I just ordered my tie rod so I can't verify it, but using just the 7d tapered rod ends it looks like there will be adequate clearance without any modifications. At worst I'll have to bend the end of the tie rod arm only a few degrees.

I thought about the traditional hot rod forum. I know there's a lot of interchange between this and the HAMB but it seems like you get better tech info over here in the Ford Barn. Just my opinion.