Any one use of know somebody that has used the Posies Ellipta front suspension? Wondering how the handeling and stiffness is?
In your profile,, working on putting together a 32 roadster setup for Land Speed Racing. I think I would use a traditional suspension for a land speed car. My thoughts are the suspension that Posies offers may transfer too much bouncing but them again I am not an expert. HRP
It was just a general question because i havent seen that setup before. Thanks for the reply, I have a different style of suspension for the 32 Im wanting to build for LSR. It does look like it might bounce too much, and i wouldnt feel comfortable using those mounting brackets from the springs to the front axle at high speeds.
I've been looking at those spring for a new project. I plan to use them in the rear only. I don't understand your reference to "bounce" as that is what shocks are designed absorb. That is ***uming you have the correct spring rate and rebound rate in the shocks. I agree, the mounts they provide for the axle scare me too. They look like a disaster waiting to happen.
Nerver2old, My terminology isnt always the best, it just doesnt seem to be very stable even with the correct spring rate and rebound. It must be those mounting brackets..ha!..
My 32 runs half leaves on the rear. I've had the car 4 years. They work fine, but it does hit a little hard sometimes.
By design we build our cars very low which translates to short travel. A stiff spring rate is necessary to prevent bottoming out too often. I don't have an opinion on the strength of the brackets shown, but Posie products have a pretty good reputation. I did notice that they are available in two spring rates.
I would think that the roll stiffness would suffer. The spring ends would probably be mounted further inboard than a transverse spring. If the ends were theoretically moved all the way to the center,there would be no roll stiffness. The other concern would be a possible harmonic frequency problem .The spring would be mounted some distance from the wheel and so has less control on the wheel. You might find that at some speed the wheel gets into a natural bounce. I would stay with the cross spring as they are known to work just fine.
I don't know about the posies product but quarter elips have been used for decades even on the salt ( although back thenm 125 was fast ). Set up properly a quarter elip is as good a suspension as the other stuff that we use. Probably won't compete with a new Lambo though. If it were me I would build my own if I wanted to run one, but I am not too big on the check book thing.
what are you guys talking about ???? roll stiffness?? too much bounce ? i have used 1/4 eliptic setups before and my experience is handling is much better , they react much like a parallel leaf setup and you can also set height and the spring rate a little with the screw jack...that is what that little bolt is on top of the bracket, in case you were wondering
I'm running quarter eliptical front and rear on a 27 roadster on a 32 "style" frame. Handles better than any parrallel leaf spring front end i've ever drove. Rides extremely nice. I had a local spring shop make my spring packs and i made the rest. Cost was about half that of the posies kit. I dont run the adjuster bolt...seems like too much load for threads to really hold up long term in my mind.
If I were going to run jacks on a set I would want to run ACME threads. I don't have any actualy scientific proof but from what I understand the idea behind quarter elips is that the suspension articulates better then with a buggy spring or parallel leafs. Like I said I have no scientific proof just what I have heard over the years.
The Jalopy Journal
