I am doing some welding work on a Model A. The owner wants to have split bones in the rear to match the split bones in the front. I have made up brackets and tacked them to the frame and it looks good. However, he brought over the running board brackets and a splash apron to go on it too. After putting the brackets on the frame the wishbones hit on the rounded corner of them. I can move the brackets outboard a bit and will solve the immediate problem, but am not sure how it will be when the rear suspension is completely unloaded ( big dip, or jacking it up). Has anyone done this o a full fendered car, and are there any pictures of it? Thanks,
So the car is running an original style rear with a torque tube and he wanted to split the bones purely for aesthetic reasons? You should always try to keep the front of the bones as close together as possible (in a triangle).
Not smart, assuming you still have the torque tube. Something will break. All the rear bones were designed to do was keep the axle square to the torque tube. In this scenario the break will most likely not be a disaster. If you have an open drive line and mount original rear bones to the frame rails something will eventually break. And at speed it will not be pretty.
i don't see in your post if you stated you have the torque tube or not by your description i'm not really sure how your rear is set up....you should post some pictures so we all can see what you are trying to do
I'll try and get a couple of shots of it in the next day or so. No torque tube, it is being converted to open drive line.
The Model A rear wishbones are not suitable for use as suspension members!! They are just braces for the TT, and are downright flimsy.
That got hashed over big time when 5WBomber lost the rear end out of his coupe about the time I joined the HAMB http://www.jalopyjournal.com/forum/showthread.php?t=224871&highlight=rear+wishbones+breaking <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
These are not model A bones, they are later model. I know of the arguments against them. I may consider using them as the bottom link in a 4 link setup but that doesn't address the problem of using them with running boards.
Heres a picture of it. You can see the wishbone hits on the crook of the running board bracket. I have 3 1/2" between the top of the rear axle and the bottom of the z in the frame right now. If I move the wishbone bracket to the outboard side of the frame it will give me about 1 1/2" clearance between the bottom of the wishbone and the top of the bracket.
Tell your customer, "NO". This is not going to work, it's a dumb idea for many, many reasons. Split rear bones should be used only on fenderless cars. there is no reason to do it otherwise. Too many problems inherent in the application. I used split bones in the rear of my T roadster. All was fine for a while, until I broke the banjo rear end. Then I replaced it with a 9". Then the brackets that bolt on to the backing plates started to crack as I had no 'torque arm' built into the suspension. Bad design on my part, I admit. Ended up building a pseudo-ladder bar out of the bones. All is well, now that the design flaw has been corrected. You customer needs to understand the whole concept of the car. If he's running fenders and running boards and then split the rear bones, he's complicating things unnecessarily. r
If this setup is what your customer really wants, the best I could recomend would be to go to later wishbones ('42-'48) that are quite a bit shorter. I would also move the mounts to the inside of the frame to get them into a bit better triangulation, which will also help reduce stress on the wishbones. I have used the '42-'48 rear 'bones as a sole axle control on a couple of cars in the past, but be careful. These were never meant to be a locating medium, and are a bit light in construction. Using them as lower bars in a four bar is not a bad idea, but you could make up a torque arm to help out as well.
You are a welder/fabricator. That set up will come back to haunt you. Move the tie rod ends into center to form a 3 point triangle and do it safe.
According to some of the local old dirt trackers i know it will improve handeling, one guy i know even has 'em split on his 47 coupe stocker that he's had for 30+ years
Is he running an open rear or closed? An open rear needs a way for the torque to transfer to the frame. With out it, it will break something. I know this all too well. The torque tube acts as a torque arm, if you will. r
Okay, you are right there, misread ya, i had a neighbor put a flattie powered T on the road with the setup as mentioned, started bending right away Brace it, run a second set of rods from the top of the trans inboard of the frame rails to the same pivot point and it should work fine, it'll act as a hairpin, instead of a 'bone, OR brace the bone with a piece of tubing going from it to the top of the axle, turning it into a hairpin. I've seen both done on old rods and both can be made so they are unnoticable
Thanks for all your help. I got the axle changed to a four link, using the wishbones on the bottom. It worked out pretty well. Here is a link to the new thread. http://www.jalopyjournal.com/forum/showthread.php?p=4523622&posted=1#post4523622
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