While mocking up my T roadster project I used 35/6 rear radius rods locating a 9”hung on a T spring. I made my brackets tacked them on the rear end so the front of the rods met where I needed them on the frame. I then heat and bent the spring perch so they are square with the rear end. When all that was done I ended up with a measurement of 47-5/8”(I did research and the ideal measurement is 48”) I continued mocking up with just the main leaf in place. So now I have broke the frame off my frame table/bench put the spring back together with six leafs and stuck it under the car. my problem now is the spring has so much tension that the front of the radius rods are not even close to my brackets. So is this normal or should I have over compensated the brackets on the rear end to offset the spring tension.
Sounds like there's movement in the brackets between the bones and the axle tubes. In the pics they're only tacked: are they fully welded now? If not then i imagine the brackets will have moved on the tack and will need to be moved back. If fully welded, is the bracket material stout enough? I don't think you can get support gussets into the brackets, can you? There's a lot of strain from the spring as you realise, which will find the weakest point to exploit if allowed. I don't think compensation misalignment is desirable. Plating/ filling the web on the bones might be necessary, I dunno. The bones between the axle and the chassis mounts shouldn't have any stresses on them when just sitting there. Chris
I suppose things could have tweaked a small amount but being that things are tacked I’ve had parts break the mig tack instead of bending.
Make a pie cut on the inside just in front of the forged spring mount,and heat,and bend the outer side of the rod until the front end comes in where you need them. Weld up the inside,and fish plate it for strength.If thats a open drive line rear end you really want to add a top torque arm to control torque twist. Those 35 radius rods werent designed to resist torque.That was the torque tubes job.
Model A springs are notorious for having a lot of tension. Just comes with the large curve in the shape. It's very common to assemble just be main leaf to the perches first, then addd the rest of the leaves to the assembly. Which makes me wonder how many leaves you are using. There's no way the complete car will need as many leaves as a stock A does. Also, you know that any spring will settle over the first hundred miles, so any fine tuning based on the actual height you get from the mockup today will not be accurate. I don't know any good way to estimate, just by experience or measuring the installed spring height in a similar weight car. All boils down to you getting the perches really close to what the stock A uses, and then guessing how many leaves you need for final weight and height.
Well I stated I’m using a T spring not an A .I know they do the same thing but have heard many times how different a T and A spring act. As of now I have 6 leaves in it and I am aware of settling, it is tough figuring out how much it will settle for sure.
There is probably enough give in the axle mounts to let the spring tension pull some; hook the front of the bones to the brackets and then mount the spring.
That’s what I was thinking. I’ll have to dig out the spring spreader and go at it a different way. It just doesn’t seem there should be that much pressure on the bones.
Gotta think that even a little give where they are bolted to the axle mount would translate to a lot of movement at the front end of the wishbones.
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