heres update #1 -> http://www.jalopyjournal.com/forum/showthread.php?t=198599 Well, i guess its about time i get an update on here. What i thought would take a week or so has turned into 5 weeks. We had a little bout with someone in the hospital and that just really set the car on the back burner for a few weeks. Everything is good now so im back on track. To start with, the front axle i ordered didnt suite me. Apparently i lost my mind for a few minutes and thought i would be happy with a m*** produced dropped axle. Unfortunately i was wrong, but in the end it seems to have worked out. The axle i bought just looked too narrow to me. Placing the front wheels closer together which inturn i thought would reek havoc on my wider track nose. So I opted out on that and went with a stock undropped 32 axle. I still have a possible thought of making a chromolly tube axle but it will be a copy of a 32, so i can always do that later. having the non dropped axle i was able to align the axle with the front cross bar on the frame to block the least amount of air possible from the front to help keep this car cool with the track nose. I then decided to make the front spring perch from 2 pieces of tubing to again allow as much air past as possible to the radiator. Using the stock 32 axle turned out to be another blessing in disguise. With a slight bending of the stock 32 spindles i was able to get the tie rod above the frame which will allow me to have the nose blend right into the belly pan with nothing hanging down below to catch on debris. The car currently is just tacked together so that i could put the suspension under it. The spring perches will get vertical support plates once i establish the correct angle to match the springs. The wishbones will be replaced with chromolly hairpins of some sort and will be anchored to the frame once i get the nose width figured out. The other big step here is that i set the motor in. It took alot of thinking and rethinking to go forth with the puny little motor and trans mounts, but i think it will be sufficiently strong. The trans mount will get 2 more legs on it to triangulate down to the lower rail of the frame and help for the for/aft forces from the rear end. So heres a few pictures of the rolling ch***is as of today.
So the other big step was that i took the axe to this new brookville body. Alot of slicing and dicing has it sitting on the frame pretty much where it belongs. I'll be making some fixed body mounts soon and once thats in place I plan to get rolling on the nose and belly pan. I'm pretty anxious to get the nose on there so it looks like a whole car. Heres some pictures from today with the body in place. (dont worry that upper firewall isnt staying!)
Something is missing out back. How are you locating the rearend? I can see the links from the housing to the spring, but what actually locates it?
Theres not wishbones on there yet, the torque tube is plenty strong for just rolling it around. I havent decided exactly where i want the wishbones in order to leave room for other stuff. So they're down the road. Zach
Dude, that looks really nice!! I like your style man.. Jimmy White P.s. I cant wait to see the belly pan and nose.
Looking good, but I do have one question. Would there be a weak point in the ch***is where the main tube is crossed over by the thinner one just before the Z? Excuse my ignorance but it just seems odd? I have to agree with X38 photography is killer.
Doc, That was brought up in the first post... I had alot of thinking and rethinking before i did that... I decided that the frame really didnt even need the thinner tubing...it was so terribly stiff before i added that on. Since the smaller tube is actually piercing the larger one i think it is A-O-K.... i thought it looked cool....but i defonitely did alot of questioning everyone i knew before i went through with it the main tubes are 2.25 O.D. .120 wall and its all 4130-N chromolly so i think its good to go...... thanks for the nice comments everyone trying to think outside of the box on this car but still stick to the period 1949 build Zach
Everything looks *****in except for this part. Just looks like a leverage problem. Anyway to put the pad beneath the spring and make those uprights stronger? I just like to go fast on rough stuff thats all. cool job though. TP
i might just have to quit build ing cars... but seriously i'm glad to se someone not afeared to try something twards the outer edges of whats gone before and to cut up a new body for it
thanks guys, Zibo, its .095 wall 4130 and my thinking is that the forces on the perch are vertical. I'm planning to add vertical support plates to aid in the strength of the plate. This is another one of those areas where i had concern also but after alot of thinking and rethinking i decided to go for it.... My plan is to really run this thing before i get to painting it to test out all of these areas. But I'm really leaning towards them still being stronger then they need to be.... I'm usually the king of overkill so im trying to get away from that by using stronger materials strategically placed. thanks for the concern though...its defonitely something i am going to be keeping my eye on and by the way....i dont baby it on the rough stuff either Zach
Looks great Zach. There is going to be a ****load of torsion in the front crossmember between the perch and the corner. Remember to account for impact and fatigue stresses.
thanks guys, nosurf....do you think my design is any different then any other tube crossmember with a perch hanging off of it? im thinking that the wishbones will absorb most of the impact force and also the spring take out alot of the shock....but yes i do think theres going to be torsional forces on the tube....im just hoping it can handle it? dave, probably a 59AB with a 39 ******. the one in there now was just to get the mounts made and the sideloader case makes it easier to get the body on and off for now im shooting for a smaller bore and 3-3/4 stroke with a lighter flywheel so that it revs more then a big bore/stroke motor...its a 3.78 rearend so i figure that the motor should sound really good running around in 2nd gear on the back roads with open pipes out the back
Zach, may I respectfully suggest that you add a tube from the rear of your lower strainer bar to the back of the main rail. As the ch***is is set up now any bending moment in the main rail will try to bend the angled tube below the main rail. Triangulating that area will obviate that possibility. As for the tubing diameter and wall thickness the old single rail Kurtis midgets had a main rail that was 3" in diameter (with no strainer) and they bowed all the time after a bunch of laps. In a similar vein I would suggest a plate gusset on each of the front spring perch tubes, wrapping over the top to support the perch itself. That will not put anything else in the path to the radiator but will beef the mount immensely. If you do not run some sort of panhard bar for lateral location of the axle I would also worry about the side loading on the spring perch. A traditional flat plate type perch has a lot of inherrent strength by design and the fact that 1/4" plate is the most common material used. With your design any big side impact has a chance of laying the perch over. On the radiator shrouding I think that you will find that the airflow around the spring etc is so turbulent that even plating between the tubes on your deal will not have a significant effect on cooling. Roo ps *****in' car
Thanks for the great thread,I'll be watching with keen interest, the design process being especially valuable to those of us watching from the wings in hopes of starting our own builds in the near future. Have always liked the tube framed cars, each purpose built. Do you have a target weight?
I would have to run the numbers for that section at work on Monday if I have time. With the high perch I just worry about the moment capacity. I am sure it's fine- but I just like to check sometimes. Also alot of bending in the spring perch plate between the spring and the top of those tubes. Maybe put some gussets on top? (The quote above my desk: "Structural Engineering is the art of modelling materials we do not wholly understand, into shapes we cannot precisely ****yse so as to withstand forces we cannot properly ***ess, in such a way that the public has no reason to suspect the extent of our ignorance." ) Did I mention it looks great?!!
nosurf....there will be plates on top of both spring perches....vertical plates tieing into the tube crossmember on back and the upright tubes infront rooman, sent you a p-m unclee, no target weight really...just....as light as possible without hindering strength thanks Zach
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