Technical AV8 Late Model Banjo Spring Over Conversion

Okay, you gave my post a like so here's a shot of the chassis with the body off. I'm not a Preacher or a Teacher but think your making yourself a lot of unnecessary work. Think T Bucket front spring perch, then apply it to the back of your frame be it a bolt on or weld on and hang the spring on your stock 2 speed hangers. No kick or Z and it drops you I think 4.5" and no floor pan surgery. No one will see it and it will work just fine.

 

that looks good mr wizzard! 35-40 X members? now that columbia, i cant believe any one would need a 1000 dollars to shorten the tube. i did my own in my lathe, 14" swing. not a big deal. john stooksbury is the guy in Tennessee, sorry, no contact info, but any machine shop could do it if you provide the math

 

I think shorting the tube would be the same as a torque tube. I made checker to see if mine was straight. It was just a piece of pipe that fit inside the trans end. I would rotate the tube and work on it so the pipe dangled the same.

 

Being in Michigan, I am at a disadvantage sometimes when it comes to custom built and rare parts. Most of it is in Cali. Luckily I do have some resources for most of what I need, other than the Columbia, which I may have to tackle myself. I have an education in automotive, but a career in aerospace, so I think I can handle most anything. But back to the point, I have had many things damaged or lost in shipping. I can't afford to loose this axle. My rims are 4 inch wide fives from a donor 36 ford chassis where I got the front axle parts from. I have a local machine shop that can widen and true the rims as needed. My engine machinist had this done at this shop. He said it worked out great. I'm really trying to keep the spirit of "build it with what I have available" and I'm treating the internet as my virtual junkyard. What I would give to be in my 20's in 1949 building this car from new dealer parts and local junkyard parts and with all the little specialty shops that used to be on every corner. If only right.

 

Wizzard, that chassis is cool. I love all of the Ford hardware repurposed in a way that looks as if it was meant to be. With the frame sitting that close to the axle tubes, how much travel is left? Rust Valley and Andy, I don't have a quote on getting the Columbia shorten, just swapmeet here say, but I haven't found anyone around here, unless I road trip to Tennessee, which is a possibility. I hate to let just anyone take a knife to this axle. I've definitely got some homework do and some calls to make. Thanks.

 

For an update, I did contact Posies, and they said they don't have a spring that would work. Their "A" spring will only operate at a perch range of 48.5 to 49.5. They do not have a custom option. 100% Matt did suggest Millworks Hot Rods for the springs. The measurements online are promising, and I'm waiting to here back from them to confirm. They have options for the front and rear springs. More to come.

 

Thanks you and good question. I thought I had a photo of Axle to frame spacer in place. Can't seem to find it. When I do a chassis like this I determine final ride height and then build to it, not build the chassis then try to get it sitting right. Final tire size is selected then total travel. In this case it is 2.5" before contact. I'm using 32 Ford axle snubbers that are 3/8" thick. I then made 2.750 spacers and tack welded them to the frame and let them sit on the Axle. After centering the Axle housing I tacked them to it. The spring if you noticed is just the main leaf in place. Same thing in the Front. Now I move on to building the car. Once everything is in place and I have curb weight I then stack leaves till the care is sprung and sits in place without the spacers. No guess work or luck involved.

 

I didn't notice it was only the main leaf. That sounds like a good plan. The spring from Millworks appears that it might work from behind the axle or on top. It is a hybrid spring combining the "A" and "T" springs. If this works out, I could potentially mock up both ways to see how it works out. I'm using a 36 Ford front axle, so this does limit the amount of drop in the rear. This is unknown at this point. I'm using a 36 axle in front because it has a factory drop, good turning radius if I decide to split the wish bones, and keeps with using junk yard parts. My car won't be slammed or have a channeled body, but should have some attitude. Thanks for the tech.

 

Did you try to contact Eaton spring? Don't know much about them, but my impression from their website is that they'll make a custom spring to your specification, and they know what they're doing. As well as the expected weight on the spring center, and the obvious dimensional information, tell them what the static angle of the shackles and shackle length will be; also the magnitude of "bump" (2 or 3" ?). They should be able to tell you the resultant spring length at full bump, so you can determine if the spring eyes will bottom out against the perches.

 

You really need to talk to Jon at Columbia two speed parts stand up guy that does quality work. He shortened mine housing a year or so ago I think the price was $250 not just anybody with a lathe and welder can do that. He is a retired machinist and has a special fixture for that. 15 minutes on the phone with John will answer all your questions. Please give him a call and clear up all the miss information about Colombia to speeds.

 

Dan, what ever you do don't let T.M.I. make you over think things. Should you decide to have a spring built to mount on the rear Axle as is just tell who ever it is doing the job the change in width difference between what you have and the Stock Model A hangers. If you don't know Spring Technology don't try to tell them how to do there job. It would be like you telling your Cardiologist how to do surgery on your Hart. No matter what you end up with you will do a little fine tuning for ride by adding or removing a leaf or two.

 

Did you notice the shackles in the photo are about an inch over shock length? That increased shackle length will allow for the dimensional issues when using the Model A spring behind on a 42-48 rear end. With spring on top the spacer and drawing shown is a good option.
You could be overthinking this, and just lengthen the frame 7 inches, and use the spring behind rear end as it was designed...

 

Good eye on the shackles. However they are a stock Ford item. Just not stock for Model A. I actually think they are front shackles for 46-48. Not rears at all but correct for what I'm doing.

 

Way cheaper than a new longer spring.

 

All good information guys. I apologize if I spread any rumors about Columbia 2 speeds. Not my intention. This is very new to me. It's my first project in the 30's and 40's. My other projects have been from the 50's on up to present. Sounds like I should talk to John at Columbia 2 Speed Parts, however the freight shipping scares me going to AZ, but worth looking into. Thanks.

 

For an update. Millworks Hot Rods seems to believe their AV8 rear spring will operate at my perch width of 51.25 and should give a drop of 3 inches to 4 inches. They could not verify an actual spring rate, but felt confident it would work, because of their past projects they used it in. There spring is 42.5 inches static eye to eye. The spring would have to flatten 5.75 inches to connect with a 1.5 inch stock shackle. This seems possible. I did send an email to John in AZ at Columbia 2 Speed Parts. I won't make any decisions before I here back from John and then I will post an update. Thanks.

 

For an update, John would like me to get the drivers bell and banjo gear set off of the Columbia first. Then we can talk more about the modifications. So, I'm going to mix this up a bit and work a little on the axle before a continue with the chassis set up. Lots of good info in this thread. I will update after some progress has been made. Thanks guys.

 

Seems like everyone talking about shortening the Columbia specifically speaks of the "tube". There is, incidentally, an axle involved as well, which I'd guess is by far the most costly aspect of the operation. I have no idea if the axle adjacent to the splined end or tapered end has enough O.D. so that this is just a machining procedure, or if a new bespoke axle would be required ($$$).

 

Clarification -- "good old steel" has virtually identical "springiness" as "spring steel".

Spring steel has a much higher carbon content, which substantially increases its yield point, aka, allowable stress. Consequently, spring leaves can be much thinner and narrower and shorter than would be necessary for mild (low carbon) steel, for the same "spring constant". Tensile strength, toughness (sort of opposite of brittleness), and hardness (wear resistance) is generally enhanced after the spring shape and eye is formed (hot) by oil quenching. Heating spring leaves in your garage for recontouring results in some losses in characteristics achieved by the oil quench, but you still have high carbon steel, not mild steel.

By the way, you can oil quench at home in old motor oil. You can Google DIYs on the net.

 

Assuming a final installed shackle angle of 45 degrees, increasing the shackle lengths by 1" translates to allowing a spring 1.4" shorter, eye to eye, vs with "standard" shackles.

As an aside, let me clarify something that I suspect is not well understood, or even thought about:

Consider two cars that are identical, including identical Model "T" type rear springs, except on Car X, the perches are further apart, such that the shackles are at 45 degrees, vs vertical shackles in Car Y. If you measure the installed eye-to-eye spring length, it will be significantly longer in Car X. Also, Car X will be a bit lower.

Why, you may ask if you're still awake? In both cars, there is an identical vertical load (tension) in each shackle of, say, 700 pounds. However, in Car X, there is an additional, horizontal load of 700 pounds, pulling outward on the spring, with additional resulting flattening of the spring. (The magnitude of this load depends on shackle angle; it would be zero with the vertical angle in Car Y. Also note, these forces would likewise exist with a flat spring, but would not result in any measurable spring deformation.)

Because of all this, I am quite leery of loaded dimension of springs in various catalogs. Did they test for spring constants by setting on a floor with roller skates under the eyes (simulating vertical shackles), or did they hang the spring on very long (so the angle wouldn't change as load was applied) sloped shackles, at what angle?

As an aside, the horizontal load created by shackle angle must be considered when designing spring perches. I get really nervous when I see perches connected to vertical flat plate "bat wings" on front axles, with no gussets. (Is "bat wings" still an acceptable term, regarding political correctness?)

Their will be a quiz on this Tuesday morning.

 

I have noticed there is not a lot of technical information on a lot of aftermarket parts. Being in aerospace, this drives me nuts, the lack of tech on hot rod parts. I think its just part of the territory. Hot rodders generally fabricate what will work and test 5 miles at a time. I guess that's why most of us leave it up to the professionals or trust our gut not really understanding what the science is. Thanks for the perspective and thought.

 

The information that I delineated in above Post #39 is the responsibility of the "buyer" to provide to the "designer". I did omit "spring constant", as the designer probably has better judgment for this than the typical rodder, based on spring load. If you want to tell him to give you the same spring characteristics as a Model "A" spring, but make it X" longer (on the shelf or installed?), and you think you're going to take leaves out willy-nilly to get the height that you want, you won't have much recourse when the car rides like an empty dump truck, or bottoms out against the spring perches, or just simply breaks. Have a discussion with the spring designer; he should be able to guide you through this process. If he doesn't understand why you should mutually agree on these parameters, turn and run.

Springs are designed to accommodate a static load, at an allowable stress level with sufficient margin to allow for increased deflection in "bump". Removing leaves to achieve desired ride height subjects the spring to overstress and potential failure. I know, your cousin Charlie removed three leaves from his T-Bucket seven years ago, and hasn't had any problem. Well if the car is lighter than the spring was rated for, or if he drives 900 miles a year so that fatigue is not a consideration, that could well be.

Why would anyone want a cardiologist to work on their skis? Or did you mean my pet male red deer?

 

Nope. The R/H (Columbia) housing needs to be narrowed and then assembled with an earlier L/H tube, and a pair of earlier axles. The axles in a Columbia are just regular Ford axles.

 

F.Y.I. Ford closed drive rear Axle shafts are not splined as well as tapered. The inner end has the spider gear made as part of the shaft. Nothing you can do there from my perspective. Only the tapered end can be modified.
Odd as it may seem Columbia 2 speed in a Model A isn't all that new. I took these photos yesterday after doing a little digging in the Barn. I know that this unit was built sometime in the 40's and was run till around 1970. In some eyes it shouldn't have made it around the block but did that and more. I just wanted to see exactly what was done after moving it countless numbers of times. It ran stock Model A manual brakes, has stock Model A radius rods and Model A torque tube. All the mods were done with a Stick Welder. The V-8 ends seem to have been cut off and Model A ends replaced them at proper width of the Model A rear Axle. The model A inner drive shaft had the V-8 coupler WELDED to it and the V-8 flange was welded to the Torque tube. In todays world of Engineers and Micro Scrutiny this would never happen. Back then nobody new any better so things just got done and worked fine and we moved on. This is kind of standard in the Hot Rod world. Are you building a Rocket Ship or a Hot Rod? I'm not advocating cutting corners but sometimes it's okay to just do it and move on. Enjoy the photos.

 

That is a neat piece of history you have there. Who ever made those mods with yesterdays tech did a pretty nice job. Thanks for sharing.

 

Great thread for traditional builds. Thanks.

 

@Pist-n-Broke "Micro Scrutiny" gotta love it!

 

There are those that do stuff and some that only talk about How to. Total perfection is an imaginary place.

 

Rich B & Pist-n-Broke:

I am aware that standard Ford axles have integral side gears on the inner end. As had been described to me, the Columbia had a bespoke two-piece axle on one side, which would have included the outer axle having a splined inner end.

I had always understood that the principle of the Columbia was similar to the Miller/Ford front drive Indy car 2-speed "rear" (front) end. In this, I understand, there were gears on one axle only; high gear was direct, and low gear (for pit exit) went through the step down gear on the two piece right axle. Therefore in low gear, even when driving in a straight line, the differential spider gears would be turning, as dictated by the rotative speed difference between the left axle, and the inner right axle. (The outer right axle would be turning at the same speed as the left axle.) In thinking about this, when in low gear there would be more torque delivered to the right wheel when in "low" gear, which would be OK for pit exit in a '20s Indy car, but not acceptable in a road car.

I couldn't find a clear cutaway on the 'net of the Columbia internals, but apparently the step-up planetary gearing is in effect between the ring gear and the differential carrier, although it is physically located around one side's axle. In "high" gear, the entire differential carrier is rotating faster than the ring gear, and the spider gears would not be turning when driving straight, regardless of "low" or "high" gear selection. Likewise, torque split would always be 50/50. Aparently, as you say, both axles would be standard Ford.

Now I'm wondering if my understanding of the Miller/Ford design is correct. I saw an internet cut on this some time ago, but I can't find it now.