Leaf spring vs coils and 3/4 link
Leaf spring vs coils and 3/4 link
(OP)
Hello all, I am building a leaf spring model Falcon for track days. The rear suspension is my big problem. Can I make the leaf spring rear into something acceptable with a watts or mumford link, or am I best off changing to the later 4 link coil spring rear end with the watts link. If I can use the lower control arms from the coil spring setup for my lower links and build a long 3rd link similar to the RRS conversions it would be a great setup I think, but am hoping for simpler answer to the problem. There is not enough room for diagonal top links attached to the diff. Would simply adding a mumford link give me a large gain in handling, close to what I would achieve with coils, or are leaf springs a lost cause?





RE: Leaf spring vs coils and 3/4 link
Some (all?) chrysler minivans use leaf springs with a panhard rod. Maybe it's not a stunning example, but it shows that it can work.
It will never work as well as a properly engineered link type suspension with coil-overs; for one thing, it won't solve axle wrap-up, but the compromises necessary in fitting something like this into a chassis that was never meant for it might make that option not much better unless you feel like cutting up the whole rear end of the chassis, which it sounds like you don't.
RE: Leaf spring vs coils and 3/4 link
I'd build either something similar to the RRS kit (which is actually a torque arm much like GM's 3rd and 4th generation Camaro/Firebird) or a real 3-link (like the current Mustang). An upper 3rd link need not encroach extensively into the passenger compartment, though its additional attachment structure needs to be thought through carefully to avoid fatigue issues. The kinematics and the stress analysis of a torque arm differs from that for a third link, so in spite of what the advertising copy says it's best not to consider a "torque arm" and a "3-link" to be the same thing.
Should you retain the leaf springs and add any other sort of lateral locating device, avoid replacing the spring eye bushings with stiffer stuff, as that will increase whatever roll binding results. I'd investigate all three (so far) additional lateral locating devices for their roll center migration over the anticipated range of suspension movement and choose the one that can be kept closest to the RC determined by the leaves.
Norm
RE: Leaf spring vs coils and 3/4 link
Compared with the coil sprung setup, well, it might be OK but you'll never really sort the shocks out, and the weight is not going to be your friend.
ED and EL live axle setup was pretty good, if you've got less than 300 hp. If you've got more that you might want to copy the Supercars setup and go to a long parallel UCA rather than short inward pointing ones.
I have no opinion about 3 link setups for a Falcon, the floor is designed around 4 links.
Cheers
Greg Locock
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RE: Leaf spring vs coils and 3/4 link
RE: Leaf spring vs coils and 3/4 link
To prevent spring wind up, use a hefty link that is parallel to and equal length the front half of the spring leaves.
Regards
Pat
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RE: Leaf spring vs coils and 3/4 link
Mike Halloran
Pembroke Pines, FL, USA
RE: Leaf spring vs coils and 3/4 link
If you look at the back of an RTV you'll see the arms Pat is talking about. You might want to think about lifting them a bit, if you don't need all the wheel travel.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Leaf spring vs coils and 3/4 link