Seeing this sure turns your head around. Some of what I see appears to push the limits on whether the wall thickness of the wishbone material is up to the job, and the shear forces that are placed on the spring perch device, be it a pin, or fabricated, as well as the wisdom of that, and having a tie rod end at the end of a wishbone (lever) with loading and unloading forces on it --- a ball would be better, at least to me. But, yes, it is a novel solution to an old problem, and is nice to see old parts used in novel and practical ways to lower mass. I also like the fact that lever action shocks are being re-purposed, as well. And, as to 'with horns', or not, as gentleman of the iron, I hope we can all agree to disagree without acrimony. Both can look bitchin'. I have studied this and found it interesting. Carl
fortynut, taking your comment into consideration and applying it to the front suspension set up that laidout53 just posted really brings the matter to the fore. laidout53's spring shackles are almost sitting at a 90 degree angle. At that point there is no allowable lateral movement in the shackle, effectively making it a solid mount. In suspension design there is a little idea called the "moment of infinite stiffness", and once that is reached, the moving suspension compenent in question will act as a solid and the load will be transferred somewhere else, usually this results in breakage and the operator learns why that suspension set up is called a "suicide front end"...basically, the spring or shackle or mount shears and the whole mess drops onto the road.
So since my is in question, my shackles need more angle (down)? Meaning the spring needs to be longer, correct? I was wondering this myself. I used the posie spring the rolling bones use but I have a 41 front axle, I will change it out for a longer one if the front end is not going to work correctly or could break. Anymore info would be appreciated. thanks Justin
Justin, yep, you nailed it. With your current set up the spring has a limited ability to flex or act like a spring, it is almost in effect a solid bar, the "suspension" is actually going to be a combination of your tires flexing and the chassis twisting. Don't know if Racefab is still on here, but he is one of the best chassis design build guys I have seen. The above diagram is great to work from. Since you have the current set up installed, grab your protractor, find the 45 degree down angle from the center of the spring perch, and add the distance to the current spring eye to intersect that line to find the "optimal" width. One thing to take into consideration is that the new spring will be wider and the eyes will like be lower. Easy test, as the car is currently set up, stand on the front cross member and jump up and down, does it move say 2 to 3"? Another test if you are so inclined, would be (with the car level) to place a jack under 1 front wheel and brace under that other, and start to jack the one wheel up, how far does the wheel move before the frame starts to twist. Think about a car going down the road at 75 and hitting a pot hole, how far is the axle going to travel before the whole chassis twists and the steering locks and something sheers. This is a great book to read on chassis set up: http://www.amazon.com/Race-Rally-Car-Source-Book/dp/0857333488/ref=sr_1_1?ie=UTF8&qid=1401289760&sr=8-1&keywords=Race and Rally Car Source Book: The Guide to Building or Modifying a Competition Car Good luck and have fun!
So I just re- measured my spring perch centers and there 35 1/2" so would a 31" spring work . I think 31" would put the shackles just a touch under 45 degrees? I have stock shackles to put back on with the proper length spring.
Seems like "spring arch" should be mentioned here as well. Eg: perhaps your perfect spring length is...34"...well a flat spring with a 34" spread is going to behave a lot different than a spring with normal arch and a spread of 34". Just another thing that needs consideration....
for sake of simplicity, going to make an assumption, that the posies diagram would take into account the spring arch. but you know what they say about assumptions...they make and ass out of u and an ass out of me.
Wouldn't it be simpler to stick an A axle in there? It's narrower at the perches, so you could use your current spring and the correct shackles, and will also give you more room for turning radius. Or a '33-36 axle if you don't mind grinding for clearance on the wishbone perch area.
Not hijacking the the thread , but I wonder , with those cool low hung headlights I was wondering if night time visibility is an issue ??? Thinking of doing the same on a 24 dodge roadster . You guys who have driven this set up , what do you think ?
built my headlight bar like rolling bones,no issues @ all.If you are interested in where the rolling bones got many of there chassis ideas checkout doane spencers roadster.Ken and Keith have a great eye for design and create some amazing hot rods.
Thanks, but I got the two inch longer spring (posie 1002L) and the shackle angles are about 50ish degrees.
how does it feel when you jump up and down on the front cross member now? i bet before it was hard has a rock. now you can have even more fun building a panhard rod. let me know if you would like me to post the math to calc it out.
Great thread, hoping for more pictures. What wheelbase would be correct for a similar setup on a 27 T roadster? I see you guys throwing out 106 to 109" for these 32s. I'm thinking that would be too long for a 26-27 T.
What ever this is, darn near perfect...for a tub...and not 26/27...but still perfect. Off the top of my head, T wb is 99", if you move the axle forward to clear the stock front crossmemeber, that is 103-104". Depending on wheel choices, I would not go much beyond 106" which happens to be the WB of a '32.
Yes that would be awesome. The suspension does move better now. Im also wondering if I need a sway bar?
way over kill...you are building a traditional rod...panhard bars have been around since the turn of the last century, therefore are traditional . the panhard bar will help control the inheirent side to side motion associated with a transverse leaf suspension (also with a normal parrellel leaf suspension). Most guys build panhard bars for the front, this helps keep the front end "located" under cornering loads (stand near the side of the chassis towards the front and give it a nice heavy shove with your foot. watch the front spring, the whole front end should shift side to side. the panhard bar is going to "elimate" that. mind you that the tires are going to tuck under just as much if not more anyways. ) if you want to have some fun with suspension tuning, once you have driven the car for a while, get double sided friction tape and wrap it around the springs. the tape will provide dampening/control the ability of the springs to slide on themselves. start with one wrap then go to 2. feel how the car reacts. suspension 101: loads will be transferred and the weakest link will give. but before you do ANYTHING, step number 1 is learning how to calculate roll center and center of gravity and for that, nothing beats the HAMB: http://www.jalopyjournal.com/forum/threads/vintage-ford-axle-roll-center.220819/
CAN ANYONE TELL WHAT ISSUE THE WALDEN COUPE WITH THE JITTNEY BUILT FRAM IS IN OF THE JR?? I WOULD LIKE TO LOOK AT IT. Thanks
Here's a link to some info and pics on the Walden Coupe. Not exactly what you asked for but might help. http://www.streetrodderweb.com/tech/1302sr_aftermarket_frames_and_suspension/
Walden makes their own bat wings. They are cut so the spring can hang down and flex through the the plane of the bat wing under compression. The perch cups and "C" bracket look like they might be from Hortons. I have the first set of the Jitney bat wings sold to a customer without a chassis attached. They custom made mine to accommodate the taller perch bosses on my narrowed Lincoln axle (2.30").
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