Solid front axle mounting options

[JimL]

I am sorry, but we built that car before the "all digital cameras" era, and the old prints are far away.  The clamp was made from thick flat strap, a couple inches wide, that was bent to look like a C with tongues sticking out the ends of the C.  Those tongues were boxed and a large pinch bolt served to clamp the axle tube, with the lower section of the C welded into bosses on the support.  It was overkill, actually.

  You could certainly use a saddle clamp design, with two bolts.  Just have plenty of width to support the axle itself and radius the outside, inner edge of the clamps.  We used a top mount, double bolted rear axle arrangement similar to your idea.  The good bolts held it well.

That has been a great handling car, and still setting some great records after an excellent rebuild by the current owner.  Over the years, all of us have had over 180 mph rides on rough salt, water puddles, side winds.....always ran straight after I got the scrub radius improved.

Hope this helps,
JimL

[Stan Back]

"after I got the scrub radius improved"

There's a comment more people should listen to.

[lsrjunkie]

Jim, makes a lot more sense now! Thanks for the clarification. And for the record scrub radius is one of my concerns on the front end. I am going to have a fairly short wheel base and I really don't want any handling surprises out in the salt!

Still curious what tech would say about a short stub axle on each side of the frame. Probably equipped with some sort of trailing arm to keep it rigid. Any ideas??

[JimL]

Stay with a full width tube.  It spreads upper compression load and effectively lengthens the tension strength of the bottom of your tube, beyond the mount point.  When you butt into something, all the loads are concentrated.  Example:  you can pound the head of a stuck chisel into a mushroom, but you cant pull that chisel apart with a clamped slide hammer....know what I mean?

When them little crystals finally start letting go holding hands, they give up easier when everybody is REAL close to the strain!  When in doubt, spread them out....thats what I was told.

Regards, JimL

[Rex Schimmer]

"Still curious what tech would say about a short stub axle on each side of the frame. Probably equipped with some sort of trailing arm to keep it rigid. Any ideas??"

My guess is that they would call it an "unsprung A arm front end" rule 3.T. which means illegal. This is to avoid using present day top fuel and funny car type suspension. A couple of years ago there was a beautifully built 34 rear engined modified roadster that had a front end that looked similar to the funny car/top fuel front ends except he did not use "aero" tubing, although it looked like it, he actually CNC from 4130 bar the "suspension" parts it was a great design and beautifully fabricated. He had endless problems getting it approved, so I would avoid your thought of welding a stub to the chassis with a support strut, you will be spending time in tech for sure.

One of the things I don't like about having a solid mount front axle is that you then have zero adjustability as far as setting corner weights except for working with the rear end. A little adjustment on the front makes it much easier to get the weights square. That said I am planning to run a solid mount front axle on my little lakester but I am also going to use Strange Engineering funny car front spindles which have the ability to be moved vertically on the king pin to do weight jacking.

Rex

[JustaRacer]

"after I got the scrub radius improved"

There's a comment more people should listen to.

What is "improved"?  More negative?

[Glen]

I think all of you need to spend a day or more on the salt in the inspection lines and wandering the pits. There are a lot of solid mounted front ends on different classes of cars, well maybe not diesel trucks.

[Stainless1]

"after I got the scrub radius improved"

There's a comment more people should listen to.

What is "improved"?  More negative?

close to zero... 

[JustaRacer]

"after I got the scrub radius improved"

There's a comment more people should listen to.

What is "improved"?  More negative?

close to zero... 

Thanks!

[JimL]

Generally, rear wheel drive cars work well with a little postive scrub radius because it gives a little steering feel to the driver.  I used about 3/4" after my first mistake. For front wheel drive we use a little negative scrub, to reduce the tendancy to pull too strongly toward a tire with less traction.

This is right out of the technician training manuals.  I never paid enough attention to it, fixing production cars most my life.  I thought it wouldnt matter too much on a flat, smooth surface.  That was until I drove the roadster at Muroc in '98.  Got my eyes opened, talked to the veterans, fixed the car.

[SPARKY]

Where were your veterans when I need them--- lol  I have run both sprung and unsprung.

I chose to build the new car with a solid that has a small amount of adjustment.  You can get to ZERO scrub radius with early Ford spindles and 21" tires---but I had to work at it: moved the bearing closler to the kingpin on the spindles--Marsh was able to pick some up with a special center section, and Mourer Mach. made special hubs---this is the expensive way---others have made their own wheels various ways.  At B'ville with a light front end car I would have no problem with that form a stress point of view.  The old truck salmesman in me wanted the safest combo  because of the G loads from "depression holes" at the speeds I hope to run!!  YMMV

PS  I also have a .250 frt tube "GASSER" axle from Speedway---I should have had a custom axle made as this one has too much CAMBER--  it was made for street radials not bias race tires.

[lsrjunkie]

I appreciate all the input guys! Thanks!    Now maybe this build can take a few more steps toward completion!

[lsrjunkie]

All right... So much for input! I have officially over thought my front end. Again! Can't get the ride height I want and still have the clearance for the engine. Probably should have started with a longer wheel base car! Anyway, What are everyone's thoughts on the stub axle idea similar to what Stainless has. Unsprung, with the stub inserted through the middle of the frame rail. Load point to king pin will be less than 5 inches. Any ideas? I'm thinking having the shorter stub will make it a little stronger and eliminate the need for any type of trailing arm.

[Stainless1]

Junkie, just so you understand my picture, that is a straight axle, you are looking at the attach point, the doubler on the axle is just to spread the load of the suspension attachment
here is a shot of the underside of the doubler.

[SPARKY]

sweet talk one of the engineer types on here into figuring the bending moment at the speeds you are hoping far.--- the stub is going to try to twist that frame or break off  when you hit one of those "Pot Holes" at speed.  It is not that hard to lengthen stuff