Daily Archives: October 6, 2020

Still thinking about improvements

Yep, mind still churning about the Sprint-T. This time I’m thinking about how to mount the steering box.

There are two orientations the box can take and still turn the front tires in the correct direction as commanded by the steering wheel: the kit orientation was pitman arm pointed forward controlling a steering arm pointed back, or the OE orientation of the pitman arm pointed back controlling steering arms pointed forward. The problem I’m trying to solve is making room for the engine and radiator and also sneaking the steering shaft from the steering wheel to the box around the radiator without hanging out in the breeze.

Aero is not critical but it is important for freeway fuel economy. I mean there is going to be a lot of junk hanging in the breeze simply because T-Bucket, but that’s still not an impediment to decent but not fantastic aero. For examples of decent aero and exposed wheels see https://www.google.com/search?rlz=1C1CHBF_enUS809US809&sxsrf=ALeKk02olFWp4zhsrQs1tNKIuVFdAMTU0A:1602022917053&source=univ&tbm=isch&q=images+lakester+racers&sa=X&ved=2ahUKEwiP3JG3gKHsAhUEKawKHdSNBDoQjJkEegQIChAB&biw=1517&bih=694 “lakester racers” that are required to have exposed wheels. The old belly tank racers are a good example of that.

Anyway, I have been thinking about it and there is a 1½” gap under the radiator because it sits on top of the frame that would be good to sneak the steering shaft through without hanging out in the breeze. The closest to a problem would be clearance for the U-joints to turn that close to the bellypan. And something to block the air from going under the radiator, but that would be a great place to mount the bearing that guides the steering shaft under the radiator. I really need to find out how big are those U-joints that connect to the steering shaft. I may need to make a relief bump in the pan for the U-joints to swing, but if I need one it wouldn’t be very big.

The other problem is properly bracing the top of the box to prevent it from rotating in reaction to the forces from the pitman arm hanging off the bottom of the box. Side to side is easy, just weld the mount to the top of the frame rail. Boom, you’re done! The other is a bit more tricky, because there has to be something to brace against to do the top part of the mount. On the kit the mount welds to the side of the frame rail, so the twisting moment from the force through the pitman arm is close to zero and is resisted easily by the sheer mass of the frame rail and the extremely short arm the force has to act through. It’s basically all sideways against the rail for the kit mount. Now there is another frame rail to run a brace from on the same side of the frame, plus its mirror on the other side of the frame for slightly better angle on the force. Which brings us to the actual point of the post, the reason why I mentioned the OE orientation of the steering box: I’m thinking of attaching the steering box mount to the front bulkhead with the drag link under the steering shaft and ahead of the axle.

If I move the box in front of the axle, then I could brace the top of the box against the front bulkhead at whatever place is convenient to mount the brace. The bottom of the mounting bracket still mounts to the frame extension that also acts as the mount for the panhard rod. As a point of fact, that was the original reason for the frame extension in the first place, someplace to mount the frame end of the panhard rod so the panhard rod could be the same length and parallel to the drag link for no bump steer. And now it looks like I only need to make a slight adjustment to the front of this extension to mount the steering box, because there are braces from the bulkhead in two directions to locate the front and triangulate it in two dimensions, and the vertical one can be used as the actual place to weld the mount.

So these are the pros and cons of moving the steering box in front of the axle:
Pros: simplifies the top mount of the box, lighter, gets the drag link completely away from interfering with any suspension links.
Cons: puts weight in front of the axle, increases to moment resisting changes in direction, susceptible to damage when hitting curbs while parking.

And that last one is only mentioned because it is a slight possibility, not because it’s likely to happen, and a curved skid plate in front of the box will prevent even the slight possibility from coming true. Or it might not even be a possibility because of how high the box has to be mounted for the drag link to be level, especially if I don’t drop the drag link at the steering arm on the spindle. I think mounting the drag link to the top of the pitman arm and the bottom of the steering arm will give enough offset to prevent binding. This will raise the bottom of the box to about 9-9½:” above ground with the street tires. Considering the frame is about 6″ above ground with the street tires that would be a very tall and vertical curb to hit the steering box. It would have to be a really tall and narrow parking bumper that didn’t block either front tire, a freak of parking bumpers.

And I still haven’t gotten this editor down pat, because I have no idea how to insert text to a link and not leave the URL all over the page, so I’m going to quit fighting it and publish the post.