Thoughts on decoupled suspension. 1

[TMcRally]

I'm headed into retirement and want to plan a toy to build for fun, for me. It won't necessarily make sense to others but it will to me.

I have been around Subaru Impreza Tarmac Rally cars a lot and have a shed full of parts so I'll make use of those.

I'd like to design a space frame for the AWD bits and pieces with double wishbone independent suspension front and back if it will fit.

I like the idea of decoupled suspension because I like to see good, new? (at least the road less traveled), ideas put into practice and have some benefit, but mostly because I love to see the cause and effect of R&D but not so much if it's a total failure.

As a side note: I am a huge fan of the Porsche PDCC system where they power a hydraulic motor in line with the sway bars to control/override roll. Not a gimmick at all but a fantastic thing to drive on a twisty mountain road. So I imagine I could incorporate this to the hydraulic decoupled system by adding a pump, some measures and some software.​

This will end up a club circuit racer/show car.

Does anyone have experience or contribution to this discussion, either electric dampers or hydraulic.

Looking forward to hearing your comments.
Dave

 

[GregLocock]

Yes I was part of the rather small team that designed Lotus' SID which had any sort of suspension interlinks you want. Sadly it fell into a black hole when it was nearing completion but eventually got finished and used.


First of all define whet you mean by decoupled - zero warp and fully interconnected?

Check out UWA's FSAE-A car which had a suspiciously professional setup reminiscent of Perth's Kinetik suspension, later used in various Toyotas.

The advent of Fox type shocks with remote reservoirs has vastly simplified the hydraulic side, none of that MOOG stuff needed.

 

[TMcRally]

Thanks Greg.

This is a learning curve for me. I enjoy the R&D learning and inventing the most so I'll follow up your leads and see where it goes.

That must have been a great project, it must have been really frustrating when they hit the pause button.

Regards
Dave

 

[GregLocock]

Situation normal with research projects. https://www.vehicledynamicsinternat...-a-significant-active-dynamics-programme.html Richard occasionally posts on motorsports/dynamics related forums, John died a few years back. The other two are after my time there.

My particular interest in SID was "SI". That is we had the spine and the subframes at each end, and the suspension arms, and the body itself, . Alll the bushes for those were of identical size, and then a French elastomer company knocked up all sorts of bushes that would fit. So the idea was we could investigate whether isolated subframes (pah) gave better secondary ride than putting the isolation in the suspension, or whether we should have a rigid gokart with the body isolated from it (and so on and so forth). Sadly I left in the hiatus, and I think they ended up just running the original config.

This investigation was sparked by many experiences with the GM large rear wheel drive chassis (Opel Omega etc). I would routinely knock out the subframe bushes and fit nylon or aluminium pucks instead, for a vast improvement in secondary ride.

Fast forward 12 years or so and we launched a RWD car with a rigidly mounted rear suspension 'subframe', and it was just as excellent as I had expected, and my NVH partner in crime Mr Sherry had modelled. Bolts straight to the frame, vertically, not bushes. As you can see the drag link has a nice big soft bush for NVH, and it makes no odds for handling.


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