We are speaking of keeping the rear straight in relation to the torque tube. it is supposed to be 90degrees, thats what the radius rods do. That gusset won't be able to keep 90degrees. The radius rods locate the rear to the torque tube, they keep it at 90degrees. They don't deal with torque, they keep the rear at right angle to the torque tube. With that gusset the right rear is going to want to drive ahead of the left rear, when you hit a bump the right rear will move back as it looses it's loading and then move ahead again. I am speaking in terms of movement of +/- .060. We don't build for the best possible conditions, we have to build for the worst. Those misaligned edgings going onto a bridge in the middle of a curve when you are the middle guy in three lanes of traffic going 70mph. Anybody can build a car to run on a pool table, the OP is a better builder than that or he would not have asked the question.
Absorbing everything here. My rationalization for shrinking the triangulation on the rear is the Ford 'bones were designed for a car/pickup weighing in at around 3,750 lbs. dry + payload on the pickup. This car should finish out at around 1,600 lbs. I can't without rethinking the whole car, change the ride height as the torque tube, (and the rest of the drivetrain, are above the frame substructure and everything is set up accordingly. Even an inch of change in any direction would require major change. I have a beautiful pair of rear bones but don't like the idea of hanging them several inches below the rear on some fabricated hangers although I do like that look. It would be a shame to s**** this ch***is at this point to build a "belly****on". I don't really care that much for typical T buckets so this one is built to look a bit different and the stance is right for the look I want. Tim-with- a-T and Gimpyshotrods, I know you have your engineering down and I understand your concern with the reduced triangulation. I do think the stresses of this rear are a lot less than a stock Ford. The weak link here is not the torque tube but the flange between the tube and the rear center section. These are both steel, not cast iron, castings. I could not imagine under any acceleration/deceleration in a light roadster coming anywhere near failure on the tube. I've never seen a torque tube on any early Fords fail for any reason. A lot of the old stock car guys would split the bones and mount them to the frame and it usually ripped the "ball " out of the back of the trans or if they were too short, broke the hangers off the frame. This is a very light car. I also would like to note, I misquoted the ride height using the front ride height dimension with 550-16 front tires as the rear is a bit higher for the 750-16. The car does clear scrubline. Even the exhaust, which is not included under Pa.s scrubline requirements is tucked inside the rails. You can't tell by the pics I posted but the car has a gorgeous side profile and I sit well into the body, not on it. I also have great legroom and really nice footroom which is my biggest ***** about a lot of buckets, you just can't access the pedals especially in a hurry. . This whole discussion would be a no brainer if I was able to use 4 bars tucked inside the frame rails but with the torque tube it's not happening. I may revisit the Ford radius rods under the frame structure but that will need to wait as the frame table is spoken for until after the first of the year. No Wildwood this year...
The only change I could see that 'may' be beneficial would be if the braces you added had a vertical plane instead of a horizontal plane. That would counter both lateral and rotational forces of the axle housing acting on the torque tube. I completely agree with your ****ysis of the weight differences involved and so stated in my post above. Carry on! Ray
The '42-'48 radius rods are indeed significantly shorter, but take note of where they terminate: just aft of the center bearing (you can see the grease zerk sticking out on the right side in the pic above). The shaft is adequately supported with bearings from the center bearing to the transmission. Additionally, with the exception of Model A, the early Ford radius rods locate the rear axle to the torque tube by bolting both underneath the axle housing and underneath the torque tube. If you were to draw a line through the radius rods to where they intersect with the torque tube axis, their projection is much further ahead their actual termination point. This helps resist the moments the axle/torque tube/radius rod ***embly will see in acceleration and deceleration much better than if they were, say, located axially along the axle housing and axially along the torque tube as he has done. To take this a bit further, look where the gussets terminate in relation to the picture of the driveshaft coupling: it looks as though the driveshaft itself is unsupported from the transmission coupling to the axle coupling. Lastly, as mentioned by others, the 90* relationship between the axle and the torque tube will be far more difficult to maintain with the small gussets when compared to the as-wide-as-possible radius rod arrangement. Look how much leverage the tires have, potentially in opposite directions, due to the distance between contact patch and locating gusset - almost the entire length of the axle shafts. I know I stated this previously, but you're asking each component of this ***embly to do something it was not designed to do - yes, hot rodding in a nutshell I suppose. I also know your situation is unique due to the significant weight reduction and packaging constraints, but as mentioned by someone in the comments, you're an excellent ch***is builder and you can do better (not saying I don't appreciate the design and creativity)! As the self proclaimed builder of the ho-hum "belly ****on", I know it is difficult to be different. You'll come up with something. Keep us posted!
I'm with the crowd that doesn't think this will work. It would be no different than moving your front bones together so they're 12" apart on the front axle.
It is a LOT different.......the front end doesn’t have a 4” longitudinal tube secured to the axle....and the front axle cross section (small I beam) resistance to bending is nowhere close to the strength of the relative large diameter tube rear axle housing in that respect. Ray
In my opinion, the banjo rear axle housings are more than up to the task without any triangulation as can be seen when Ford went to the parallel leafs in the open drive pickup rears from I believe '41 to the early fifties. The driveshaft is about 29" long which is shorter than the unsupported length of a stock '46-'48 rear. Because it is so short I am not using an intermediate bearing, just the front stock Ford bearing. The weak link here is the flange between the torque tube and the rear. Even if I hit something really hard with one wheel I can't imagine breaking one of those gussets. More than likely I would tear a section out of the torque tube. The axle bells are a bit over 3/16" thick and aren't goiint to deform their If anything I might consider banding the torque tube with some .250 to stop that problem. I'm not worried at all about rotational forces, either way, as I will break an axle key way before any of the fabbed work would let go. Forty style breaks are not like locking up some Wilwood discs on a 9". I plotted out where the radius rods would set if I put them under the ch***is on some legs hanging down and they would be pretty much useless. I could put them on just as a backup but it would limit suspension travel to less than 2 1/2" which is too damn close for comfort and still meet scrubline. In short, taking all the above information into consideration, I'm going to band the torque tube, cut and weld an additional set of gussets off the axle bells so I have gussets on both sides, (where the bolts are), and give it a go. It should be pretty easy to tell after the first few miles how stiff the rear is and if it doesn't work I'll get on here and come up with a plan "B", (which I can't think of right now). I'll post some pics shortly after this work is done. Thanks for the help guys!
^^^^^^^^probably 'overkill', but when attacking a potential threat...better than 'underkill', I suppose... I admire the tone of your responses to your critics......... Ray
Since your holes holding the big gussets to the axle housings are reamed for a tight fit, should you have the banjo and housings at their final gasket clearances before you do the welding?
I would worry more about the rear spring being able to flex fore and aft with that short of a torque tube length/arc..OP could add a "artistic" back brace to the rear of axle housing, from backing plate flange to center banjo to backing plate flange; should quill any flex..Oh and if one really knows how a differential works there is not one wheel drive!! There are MANY g***ers running ladder bars maybe 18" or so out from the center and there doesn't seem to be a worry of axle tube flex with slicks, high HP, 3000 lbs weight and brute force from high rpm drag strip launches...
I'am interested to see how this works in practice. I don't think you'll run into significant issues as is, and realize you've formulated a game plan, but how would wider gussets work? It looks to me like your current gussets are about 18" apart? What if that was increased to 24"? 36"? Since your torque tube is significantly shorter than it used to be, you likely don't have to go forward, but increasing the span that the gussets strengthen would serve very well to minimize some of the concerns stated above. My 2 cents. Carry on. Mike
alchemy, The rear is already done, 3.78. So I don't need to worry about the bolts lining up. Suspension travel on this is not going to be substantial and adding a back brace, as suggested by seb Fontana, and as is typically done on a 9" and the like does nothing on a banjo which has that covered by virtue of the tapered axle tubes. Henry really thought these things through but that doesn't mean you can't play a little. The braces are as wide as I can get them at 22" without intruding on interior space. At full suspension arc I have 1/4" clearance to ch***is center section. When this was on the table and the geometry was being worked out it was damn near set with a feeler gauge. Everything on this car is close but it all works just fine. I'm comfy with this setup with the two minor upgrades listed in my last post. I'll keep everyone posted as to how well it works over the next few weeks and by next year I'll either have a lot of s**** metal or 20 other guys will be building a rear like this one.
Wanted to throw an update here...... I've been really busy in the shop this year so I only get to work on mine an hour at a time here and there. It is further along than it looks and if I get Sunday this week I should have the ch***is ready to blow apart for paint. A few things have changed in that I've decided to use 15" wheels in place of the 16"ers. Also I'm running a 283 as the car is built to take both the flatty and the SBC. This is a concession to time and funds as I already have a workable engine and won't need to go through the flatty. This is the 195 hp version as I'm sure I can grenade that drivetrain with half of that. Tire size is 6.40-15 and 8.20-15 Firestone blackwalls. The car is supported on ride height in the pics so there are no scrubline problems at all. Most of the tough stuff is done so it's only body and panel work, the biggest part being the louvered partial belly pan. I've also acquired some early "A" roadster hinges to make both doors operable even though the drivers side will be pretty much useless. The shifter needs to be rebent due to a screwup on my behalf. Hopefully I can save the new chrome. Way too high! It will still be black on black with blackwall Firestones and Moon screw on discs on all four corners. If I can work it out I will open the centers on an extra pair for the inside of the front wheels. Just love that old racer look. Trying to get it ready for the Fall Wildwood run as usual. I at least have a fighting chance this year.
My muse for the color scheme...... No idea of whos' car this is or where I got the pic. Really nice though. Bill Hirsh Auto has the top material just a tad darker, (which I want), and I have a very nice Packard back window that will work perfectly. As the seating position in my car is so low my top will be very close if not slightly lower than this one.
I sold the T to a good client of mine and picked up the Vicky I'm building now. The rear went under a different T and as of last week is performing nicely. It has this Spring and maybe 2000 mi. on it now and the last I looked at it, no problems at all. I might add, this T drives and handles very nicely. The white T is coming in next month for completion. It will have the same rear setup. If you're interested my Vick build thread is here- https://www.jalopyjournal.com/forum/threads/working-on-the-vicky-body.1197541/ . I loved the T but my wife had some difficulty getting in and out, (we're both 70 something), so when the Vick became available I reluctantly made the move. She does like an open car and as such, I may possibly make one of my aluminum lift off tops for the Vick.
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