castor specs for front end?

[rickjohnson356]

I have an SR prepped FST front beam that needs to be mounted on the clone chassis that I got a while ago. I would like to know what the correct castor value (degrees?) should be for this type of car.

The zero-roll chassis I have was sold to me as being a Caracal, but it isn't. It may have been an early Lynx FV zero-roll version, before Fred Clark became the company owner/manufacturer. The body looks like it has a place for one of the early clear windscrreens that were used on these cars.

In any event, the front vertical square chassis tubing is angled back a little, to provide castor. Additionally, there is a small square steel bar (about 1/4" square) that is welded on the top of the bottom frame rail, just in front to the vertical frame member. the beam rests on the top of the bottom frame rail as one major support and slides back until the lower tube hits the welded-on block There are holes in the vertical chassis tubes that are very close to the holes in the vertical mounting brackets (stock) on the axle beam. I suspect that the blocks on the lower frame rails are there to prevent the lower axle tube from being positioned directly under the top tube and to provide additional caster.

From just looking at the setup, with the beam resting in place, there appears to me to be a whole lot more caster than what I am used to seeing on a regular FV with zero-roll rear suspension.

Does anyone have an expected range of values for the castor angle required for a FST?

Another question: do the vertical mounting brackets that are factory-welded to the beam have different spacing (left-to-right) on a link-pin (FV) axle tube than those on the ball-joint style axle tube? My ball joint ones appear to be a little wider than one set of holes in the chassis, but match the other set of holes very closely.


Any advice will be greatly appreciated.

TIA

Rick Johnson

[problemchild]

The beam holes were the same width on KP or BJ beams. Relative to the tubes in each beam the holes are all consistant vertically .... which is my awkward way of saying that the extra distance between the tubes on the BJ beam is the same as the extra distance between the holes on the BJ beam.

Most people decide whether they want the lower or upper tube to match the location where the KP beam tubes were. I expect that the Lynx will require you to match up the lower tube location. That means you will use the lower holes in the BJ beam with the lower holes in your chassis. You can then drill two new holes in your beam to match up with your upper chassis holes. These new holes will be about 3/4" lower than the existing upper original holes.

You will get different opinions on castor. I had my beam laid back at 8 degrees. I think others were using much less. I think many FVs are 4-6 degrees.