Well, if unsprung weight is a concern, build your short driveshaft with an early mopar style ball and trunion on both ends and mount the motor/trans to the chassis and swing the QC rearend however you like...
What about a De Dion tube? The super 7 guys love 'em. Packages spacewise like a tube axle, but the diff is hard mounted and uses driveshafts to reach the wheels. For a belly tank it could be set up for a transverse leaf and a set of wishbones. You could scavenge uprights/axles/diff from a factory IFS car of the right track width and fab the rest. Early miata or tons of older European cars come to mind as good donors. It's a wierd suspension, and in a belly tank it would be wide open for the world to see. Might look super sweet, might look awful. Would depend 100% on your execution.
Well at least in those diagrams there is way to much stuff hanging out in the breeze for an areodynamic type car. That's why guys went to toursion bars in the older days. A smart guy can tuck them behind the axle tubes and out of the wind. It's a tank, not an autocrosser. Coil overs and their mounts are to much trash in the breeze. What next? Air dams and spoilers?
The salt can be rough too,some years its smooth,some years it rough as a cob. You need suspension at both places,Maxton and B-ville. I have raced at both locations.
Listen to Rich and keep it simple !!! The Lynde lakester built in 1964 had a rearend setup very similar to the Markley Bros tank. Instead of torsion bars a 1953 Mercury rear spring was mounted on top of the hard mounted QC bracket and connected to the outer ends of the swing axles and the shocks were mounted at 45 degrees. This lakester has been 260 and handles great.
Ok here is the sketch of what I cam up with. Its just one idea and may not even work. My idea was to have the rear axle piviot around its horizontal center line, instead of moving in a vertical arc. As the chassis moves up and down the rear axle would piviot, with in the limits of the u-joint and the sliding spline. There would be very limited suspention travel (1-2in max maybe) and as mentioned before a limiter would have to be used (ie. rubber blocks, straps). The entire suspention would be located inside of the tank which would cut down on wind drag. PS. I know that the bottom bar would have to be located more towards the end of the frame, to prevent it from hitting the rail. It was late and didnt feel like making another sketch. So, what do ya think will it work? or is it a disaster? Mike
Those drawings are for full fender cars, I just hoped they showed the basic function. Just like a live axle, you can package it lots of ways. Look at the last drawing, that's the solid structure boiled down to it's essence. It's the same shape as a front axle beam with stripped down spindles welded on the ends. If using a transverse leaf and wishbones, no more stuff exposed than normal except a pair of driveshafts.
DeDion will allow the differential to be solid mounted and the wheels to move like a live axle. That's not bad. Still more parts in the air than the old Ford Swing Axle deal which also allows one wheel to react without affecting the other. But this cat has been skinned lots of ways. What works for you is the right one.
Can anyone see flaws in the drawing that I posted? I am no designe expert. Also RichFox you had offered to take a pic of a suspention you had. Would it still be possiable to see that picture?
Where does the drive shaft or coupler allow for any movement? Looks like the rear end is mounted solid to the trans. Even with a short drive shaft or that single u-joint, it would limit the movement regardless of how it is sprung or the length and location of the 4-bars. That looks like it will do nothing but bind, followed by a severe break. Mounting the engine, trans, and axle on one whole pivoting assembly seems like the way to go.
All the movement would be in the u-joint itself. I know there isnt much, but there is some. As the top of the rear pivots forward the drive shaft will need to extend, this is where the sliding spline would come into effect.
hey fordrat could you use a watts link set up that runs parallel with the frame rails that way there is no pinion clime or fall it would be very smooth and slap some coil overs on it? That way there's no need for a sliding coupler and most of all it would be very easy to make
Why not mount torsion bars laterally behind the axle tubes and have the lever side and adjustments on the chassis? Then the only thing in the wind is your shocks...you could locate the rear with a very short wishbone and panhard bar...I agree that on a street car that has to corner it's probably not an effective system since your center of pressure for your suspension is so far inboard of the ends of the axle, but for your needs it seems to fit the bill...
Ok, after some thought, have the axle OVER your main frame rail and hang the frame from it using the torsion levers, then run some cage tubing OVER the axle to trap it in case of suspension failure, it stays with the car, and you can also put rubber limiters on the tubing...still using a fabbed short wishbone locator and panhard bar...I REALLY like the potential of this system, it's tuneable, efficient and cheap to make...the only down side is using your axle tubes to support the rear of the tanker's weight, you'd almost have to have custom heavy duty axle bells and tubes made to handle the stress and mount the torsion bars to...
Why don't you go look at a bracket dragster, they have 4 link suspension with either single or dual coil-over shocks with wisbone locator is very tight packages.
I like your idea but I still dont see how the drive shaft wouldnt bind? I dont think I would have to worry too much about the rear tubes becoming over stressed. If my calculations are correct the tank will weigh less than 1000 lbs. Also dont most vehicles use the axle tubes to support the entire vehicles weight?
If your thinking of Bonnevile or Maxton you want to consider a LOT more weight. The saying at Bonneville is weight is your friend.
I guess I am not too familiar with a watts link. How would it allow the rear to move with out putting the u-joint into a bind? The shaft between the trans and the rear is only a max of about 8 inches, just enough to get one u-joint and a slide spline.
I can't pull the deck off the roadster right now. I will soon. In the mean time look at the links on the Landrace site for Purple Sage, I think. There are 3 or 4 tank builds photographed there. Lots of ideas and ways to do stuff.
Right but even if the car did weight 3000+ I dont see why the rear tubes would have a problem supporting the weight. Is there somthing I am missing?
1000lbs is pretty light...like "good luck getting traction over 100mph" light...mount the engine, trans and QC on the single trailing arm with a swivel pivot on the front trailing arm mounting point and the torsion bars behind the axle tubes...gives you suspension, no driveline bind, and more leverage on your rear tires to sustain traction...
In fact, if you make the trailing arm mounting point adjustable heightwise on the chassis, you can experiment with angle of inclination on your driveline/axle which might give you different traction results at speed, as long as you adjust your torsion bars every time you move the trailing arm mounting point up or down...
Here is our rear set up for our tank (so far). Swing arm mounts to the quick change bell area. There will be some webs added between the arm plates. This set up has no body roll.
I like that setup a lot, simple, compact and looks like it will get the job done...seems like the OP has less driveshaft length though...I say just run a clutch and a driveshaft straight to the QC with no transmission, push start the sucker and wind it out 1:1 and adjust QC gears accordingly...
If you're set on keeping it traditional – as I see it – you need to look at the suspension on the Beatty tank. Swing axle made entirely from early Ford bits. It is a featured how to in one of the little books and I think someone has scanned it and posted here before. I think pretty much anything else you do would require some drawn out disclaimer about what technology was actually available somewhere at that time and, "some hot rodder would have done this because, blah blah blah." EDIT: Okay here's a couple. Markley Bros. tank And the previously mentioned Beatty tank
I really like the idea of the swing axle. But how would I go about making a Halibrand 301 champ case into a swing axle?
That, is a beautifully thought out and executed arrangement. Anyone who is THINKING of building a tank would do well to swallow their pride and pay very close attention to how that is done. Economy of design is the essence in tanks, hanging stuff out in the wind defeats the whole purpose....but fitting everything in is real hard. This design nails it.Very tidy work. Don't try and re-invent the wheel Fordrat,and, use uni-joints in pairs , or carry lots of spares. <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden"><input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
The Jalopy Journal
