246 replies to this topic

[cptkirk]

Hey Dawg - hows it coming along? I am working my way through Staniforths suspension book at the moment and got the Kimini book for Christmas, makes for an interesting read but is definitely just a rough guide.

Do you have any other easily attainable books on suspension you can recommend?

Mine has been real slow for the last couple of months - lets face it its been fricking cold. On a big push now to get it ready for springtime.

Looking forward to seeing your progress.

[SukiDawg]

Ai Ai Captain,

Progress has been a bit slow recently, not helped by the fact I took a hard snowboarding tumble a few days into January and fractured a vertebrae in my back (wedge compression fracture of L2). There's no nerve damage thankfully, so everything still works correctly and the quacks say I should make a full recovery - but its meant I've been flat on my back pretty much since. Thats meant - since getting out of hospital - sitting at the computer's been difficult for anything other than a few minutes - slowing down the mini project.

Towards the back end of last year, I got to the point of having a reasonable rear geometry that controls camber pretty well in bump, but to finish it off I need to get a much better idea of all up vehicle weight and distrubution - and therefore COG height, to finally set the roll centre heights and finish the suspension. I've also decided that I don't like the rear structure very much around the diff because it looks over engineered and heavy now I've been looking at it for a while. I have a revised scheme in my head that will involve raising the floor to the level of the top wishbone mounts, and mounting them to it. Than have a small subframe that bolts up to this, with the diff and lower w/bone mounts on it. Its just a rough idea yet, and I've not begun to lay it out in the tube.

As the previous chap mentioned, accounting for weight transfer in braking / accel does require a good knowledge of the all up weight, so there is defintely a good case for doing all the important bits that have not been fleshed out yet. Speaking about books, I found that "Tune to Win" by Carroll Smith is really really good, and has a section on suspension design which is pretty handy. Its not all that modern in it's approach (but you have Staniforth to also refer to, which is still old fashioned but better methodology imho). I got one out of the library here in Northampton.

All of that means that basically, the next step is to do the front end of the car - the new front subframe to carry the engine and front suspension. Its one of the weightiest bits, so when I've designed it and put the weight into my spreadsheet its a large tick in the box. Also this revised rear thing should drop some weight out too. I'll probably go as far as filling in the rad / intercooler etc, and knock up my plenum and throttle body arrangement as well to try and fill in the gaps as much as possible - plus this is more enjoyable than cocking about with suspension geometry!

In the last few days I've been a lot better and getting much less pain from the knackered back, so I have spent a bit of time in front of the CAD looking at first ideas for the front subframe and engine mounting arrangements. Here's a picture or two.....

General view



I have the engine mounted via fabricated bracket to a tube in the bottom of the frame. You can see the bracket - its green - on the left of the engine in the ic. At the top - either end of the cylinder head - are two more mounts (black round things). There will be a fabricated - or maybe machined from solid - "arms" with those black mounts in the end. I have guessed a size for the rubbers for now. Anyone know what others have used?

Front end on



The eagle eyed out there might spot that the bottom tube of the new frame extends further out on the passenger side - thats to clear the turbo. I can see this having to change yet, and have a funny bend in it to go under the turbo rather than round it. Have to see how this goes as I progress... This is very much first go at it really...

From below:



You can see the charge pipe across the front of the engine (red) and the exhaust secondary across the back (purple). I'm pleased this fits in so nicely (at the moment!).


Edited because the "p" key on laptop is playing up (I think its the Strongbow I spilt all over it recently!).

Edited by SukiDawg, 31 January 2010 - 03:38 PM.

[Rosslin Racing]

after looking at the grand turismo version you are making how is the real one coming on?

Edited by Rosslin Racing, 31 January 2010 - 05:56 PM.

[SukiDawg]

Its finished thanks.

[Rosslin Racing]

show us then

[SukiDawg]

What flavour are the windows on your bus?


Honestly - I thought we were all fluffy these days and only made useful contributions to project threads, so please play the game.

[cptkirk]

Camber Compensation & Anti Roll system

Unfortunatley it appears that you can only use under licence - boo............

[SukiDawg]

Thats pretty interesting eh? So many of these people out there with clever ideas.

Only thing with my little project though, is that I would never be able to package that at the front as the engine is int he middle of the wheels. You could have it on the back, but then potentially you'd be looking at significant changes between the fornt and rear behaviour with varying bump/droop and roll... I guess that might make the handling a bit unpredictable....

I reckon I'll just stay with what I've got - but the guy's website is an interesting read...

[SukiDawg]

[The Matt]

As SukiDawg has said, please keep project threads on topic.

Thankings.

[SukiDawg]

[R1mini]

Looks great,
A tubular frame is the only realistic way of getting the masses and clearances for turbos, exhaust, etc. Are you going to use mini hubs, steering rack, etc or will it be custom made / alternative stuff. One more thing is the whole thing going to be spaceframed or are you using the standard front subframe mounts to bolt this frame on.

I know it's a fair old hike as I live in Chandlers Ford near Southampton, but I have a protools bender which bends thin walled tubing really well, you are welcome to pop down and do the bends, each bend only takes a few minutes

Cheers
David

[SukiDawg]

Standard hubs and urights is the intention at the moment. Thats whats in the model too, although I haven't fully modelled the upright, just the main points that things hang off. Same with the rack - may go for one with a higher ratio once the car is built - but for now it will be entirely standard item. May be on the subframe though - depends what the ackerman geometry ends up looking like with it there...

As regards mounting the subframe to the body - the body is intended to remain a structural part of the car although the crash structure is welded in, and therefore also adding strength (most of the strength!). I am changing the way the subframe mounts to add room to the engine compartment - the beam on the bulkhead that the normal mounts go through is removed, and the frame connected directly to the crash structure inside the car via horizontal bolts. The bellcrank pivot runs through that area so to accomadate this and the rear engine mount I changed it.

All should become a little clearer as I progress. A lot of what was done early on with laying out a roll frame is out of date now with all the changes I've made to the concept along the way.

[Kustom]

Is bit hard to tell from the picture is that on offset rocker so you can get the pushrod up between the wishbones and package the dampers?

Edited by Kustom, 21 February 2010 - 08:24 PM.

[SukiDawg]

I am thinking pushrod off the top wishbone at present...

Those wishbone designs are just "save as" from the rear, and there to constrain the uright only for now. Final ones will be quite different I think. The rocker is offset a little backwards and I've yet to work out the proper geometry - thats next. Might be better on the bottom, should be straightforward to try either or..

I do now have a fully parametric model though where you can adjust static camber, castor and inner pickups and the wishbone dimensions update automatically... Woop (geek moment )...... Once I add in the pushrod should be able to read the spring ratio directly off the model..

Edited by SukiDawg, 21 February 2010 - 11:20 PM.