Technical pressure required to tilt front axle back 8 degrees?

I'm trying to get my front axle tilted back 8 degrees so I can mount my radius rods in place. I'm using a pipe wrench with a floor jack to hold it in place. seems like it takes a decent amount of force . I'm worried it's to much pressure on the shackles and spring. the spring is tightened down . should i loosen it ? or is what I'm doing just how it feels?

 

The 7-9 degrees should have been built in to the front cross member.You cant tweak it against its will,and not break something later on.If you don't have the cross member at the correct angle you would at the least need adjustable spring perches so you can make adjustments then tighten them down.

 

If you managed to get it tilted back that far the tension on the radius rods would be excessive. How much caster does it have as it sits right now? If caster is where it needs to be then the radius rods need their length adjusted to fall into place.

With all that being said.... What are you working on and what spring setup are you using?

 

I had a friend of mine with a straight up perch welded on a T-Bucket he bought so back when I had access to a machine shop I made him a shim with the proper angle to go between the perch and the spring and when clamped up it put the spring at the proper angle.

 

it's a 30 model a. it was pretty much at 0 degrees. I split the bones . I'm trying to mount them . it took a little pressure to tilt it back to 7 degrees.

 

A shop that does front end alignments on over the road trucks will have a "castor correction shim" available that will allow your spring to be tilted to the back to correct some of the bind in the spring shackles ...It is installed between the top leaf of the spring & the crossmember before the U-Bolts are tightened ...The same as Rambling Dans explanation above .....

 

something is wrong your A should sit right with minimum effort

 

I had this same issue.
The original builder of my car used a bone stock Model A frame and never changed the front crossmember and I had about 0 degrees.
I installed adjustable spring perches and was able to dial in 8 degrees without to much trouble.
Chappy
https://www.speedwaymotors.com/Forg...ABbX4NDfThssnpAfnRyZw7emPe7hBjxhoCj9MQAvD_BwE

 

thanks chappy444 and to everyone else. a shim or those spring perches will help a ton.

 

I suspect you need to pie cut the radius rods to make it work. The Model A front cross member is automatically set at 7 degrees.

 

As stated 7 * is a ton to load the axle . Adjustable perches are made to correct the issue easily . If you choose not to use the adjustable perches , a shim will have to fabled to cure the issue . Spring shops do sell shims , but I’m thinking they are to correct parallel leaf spring issues not a transverse spring issue.

 

The front crossmember is set properly in a stock frame to achieve the desired amount of caster but, if you use smaller tires on the front and you drop the front more than the back resulting in a "rake" you then change the amount of caster. Remember that caster is measured from a level surface not from the frame rail. My '30 A has the same problem, only about 2 degrees caster. A shim would work if the spring wasn't so tight in the crossmember that I doubt if it would rotate in it. so the adjustable perch sure sounds like the real answer.

 

A stock A crossmember probably won't have enough space inside to put too much extra tilt with a shim.

I just did this job, adding about 5 extra degrees. I had a custom made shim, welded it into the crossmember, bent the front and back faces of the crossmember to match the spring's new angle, and also bent the clamp bolts to match.

 

Wait a minute...if I understand you correctly, you want to tilt your axle BACK 8 degrees? Unless I misunderstood, that's 8 degrees NEGATIVE caster.,,which will be undrivable. You want 6-8 drgrees POSITIVE caster which is tipping your axle forward.

 

He may mean back as in towards rear of car

 

yes I mean back, towards the rear. but now I'm getting confused a little. the top of the king pin is supposed to go towards the back of the car which in turn would make the bottom go forward towards the front bumper ( if i had one). yes I have a rubber rake. 700 in the rear and 550 in the front

 

To get an idea of what caster looks like look at a picture of a rail dragster.The axle leans way back,and the wheels look like they are flopping over in a turn.Way more than we run on the street,but in a straight line perfect for control.

 

I gather it's an I-beam axle and not a tube axle, PHOTOS. Something sounds amiss! Plenty of Model As out there with split bones

 

The degrees are relative to the frame, not to to the ground. If you put an angle gauge on the spindle boss you aren't doing it right. Same thing as measuring the pinion angle, you can't measure it to ground, it is relative.
If you have stock crossmember and frame you're good to go.

 

You are wrong. The degrees are relative to the ground. An angle finder on the kingpin is the perfect way to determine the caster.

Now, you are correct on the pinion angle though.

 

Just a note after building 300 chassis, set the frame @ 3 degrees rake & MAKE the front x member (reposition) at 7 degrees + -. (caster). Set the axle up with main leaf only to get apx. ride height. Yes, put a spacer under the leaf & use C clamps (tight). That way after u v cut the wishbones they won't b n a bind when fitting. I use adj. ends in welded bungs sandwiched between tabs under frame. Several other options of course. PLUS read all these suggestions again from members. Alan

 

Check out your alinement shops that do big trucks. They have angle shims that may be big (wide) enough to go under your perch. They may be too long, but can be cut back.






Bones