Hey HAMBers, could use a little help. I have a steel, full fendered 1934 Ford 3W coupe with a chassis engineering parallel leaf kit suspending my 9" Ford. It rides stiff as hell, not pleasant at all to go across a bridge expansion joint on the highway or a speed bump at 3-5 mph. I think my shocks are installed a little too vertically. Any ideas for troubleshooting this problem? I read that others really like their C-E parallel leafs. Considering going to a triangulated 4-bar with cook overs or some other set up if I can't make this ride nicely. Sent from my iPhone using The H.A.M.B. mobile app
No, but I can take some. I'm running the original red tube shocks that came from the kit. Will post pics soon. Sent from my iPhone using The H.A.M.B. mobile app
it should ride ok...but everyone has a different opinion of what ok is better post some pictures so we can see what is going on
Found some old pics from the build. They are not great, but kind of show the rear end. I'm running BC Goodrich Radial T/A with about 30 psig. Sent from my iPhone using The H.A.M.B. mobile app
Same recommendation as usual....disconnect the shocks, bounce the car, if it bounces nice, the springs are OK and tells you the shocks may be too stiff. If it bounces stiff without shocks, the springs may be too hard - maybe time to take a leaf out and test again. Apart from disconnecting the shocks, I'd also try the tyres at a lower psi. Start at 22 and see how that goes. Between psi, shocks and springs, it should be tuneable...if the install etc. is good.
Looking at shocks, they are cantered over as they should be. Optimum angle is 20 degrees however if they are installed as pet kit and instructions I would follow the above advice as to identifying the cause. I presume the car is complete with fenders, hood etc and trimmed, the gas tank is full and suspension loaded. It could be that they are new and haven't settled and may require a few miles to bed suspension in?
I had to take a leaf out on my 48 chevy delivery. if it's the same spring pack that may be your solution Sent from my SM-G920R4 using The H.A.M.B. mobile app
Another thought,,,the frame at the rear is flexing,,never having been intended for that sort of loading. As a result, the springs don't work properly, and probably too stiff also. Air pressure also a factor.
First issue with any leafspring is that you have to go beyond the friction between the leafs for them to start moving at all. If they are regular type (non parabel or with some kind of friction material between leafs) you need them to be well lubricated to work good.
second picture from the top,it looks like the shackle is already angled too far-once it moves past a certain point you have a solid spring[no suspension]even more weight on the car when finished will just make it worse
I agree with oldtom69. I have this exact system in my 34 3W and it rides quite well. The angle on the shackles completely loaded with body, etc. should be similar to what I see in the outside in the snow chassis shot. Maybe the spring has flattened out too much under the load if the dimensions are correct from spring eye to eye.
I see the problem as "one size fits all spring" that most of the aftermarket company's provide. That same spring is also spec'd for a '48 Ford 4 door sedan as well. Obviously there is a great variation in weights between the two cars. I would remove two short leaves & see what works & adjust from there.
Great feedback guys. I saw the diagram below and this helps me understand what you guys are seeing about the perch angle. Thanks! I'll try these ideas and let you know how it goes. It will be a while, Daddy doesn't get a lot of garage time these days. Sent from my iPhone using The H.A.M.B. mobile app
You really don´t want the shackle angle much over 90 since you get a jacking effect when loading unloading the spring so figure B is a bad choice. And the starting force shouldn´t be affected real bad by a few degres of shackle angle. I would take a few leafs out and make sure the leafs aren´t stuck to each other before thinking about moving the framemount.
I'm trying to make sense of the physics in this diagram, and failing. As the suspension compresses, the spring gets longer. It makes sense that at a perfect 90 degree shackle angle, the spring has the most leverage on the shackle, as well as no lift (jacking) from pivoting the shackle. Also the spring needs to move in both directions to account for body roll. With shackle angle A, spring movement under compression is compromised. The greater A is from 90, the sooner you'd run out of travel and start trying to compress the spring itself. So greater A results in less spring travel, and a harsher ride. It's angle B that I don't get. Under suspension compression, the spring is trying to get longer. Because the shackle pivots, it is going to be trying to raise the car. Shouldn't that also result in a harsher ride? Is the increasing effective length of the shackle as it pivots increasing the leverage on the shackle more important than the jacking effect? Sent from my iPad using The H.A.M.B. mobile app
The real problem with version B is when you unload the spring and loose traction to the road from jacking effect.
This old thread had interesting info, maybe you already seen it. http://www.jalopyjournal.com/forum/threads/leaf-spring-shackle-angle.682051/ I go for this when loaded.
Yes, I read that one, and several others. Most shackle angle and length threads are for the 4x4 crowd, though. You're slightly in to the A setup angle. I'm assuming that close to the 90 degree ideal is good. Just trying to find out if leverage at the shackle is more important to ride harshness than the jacking effect of B. It would seem that would have to be the case for B to give a softer ride. I guess with a relatively short shackle there must not be much jacking effect. A longer shackle, like the 4x4 guys use, would have more effect. Haven't tried to work out the geometry of that yet though. Sent from my iPad using The H.A.M.B. mobile app
By looking at this picture, seems your out of shackle movement when fully loaded. That would be spring bind=harsh ride. Should want close to 90 deg. unloaded.
I want to add something: if you have oil shocks, spend some money for gas filled. You can buy them from several sources and they will make a substantial difference. Short leaf springs are known for a choppy ride.
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