I mentioned a few weeks ago that I was working on cading the increasingly popular option of book front/tiger back. I thought I give you all a quick look at work in progress. The transmittion tunnel isn't finished, but the back isn't far from completion. The rear uprights are my own design which are designed to take the old mounts from the sierra to get away from the potentially rather difficult task of making them. So, take a quick look in my photo archive and say what you think. Only one pic at the moment, but if you want to see any more, I can grab a few.

Kingr

uprights look familiar....how are you going to adjust toe?

First impressions: Why choose such a heavy top wishbone design? A single bush/Rosejoint at the upright end would suffice.
If you are going to use that double bushed configuration, I hope you'll fit a crush tube within the upright bracket.

Why you are at it, have you thought of designing in any anti squat geometry?

How have you worked out the position of the wisbone pivot points? Have you matched the front and rear roll centres? My disertation at uni was to design and build an IRS for the F27, i have managed to find a copy of it if you are interested in reading it?

I've decided to do much the same as you but as my CAD skills arn't up to much I tend to rely on 'fag packet' jottings. I have kept the bulkhead angle and the rear panel area as per Ron's book and have adjusted the wishbone mounting tubes to suit. I will be interested in your progress with the uprights, (I'm half way through removing the adaptors from the DeDion tube). See my website (February) for photos.

OK, thanks for the replys, I answer your questions in order :

viper, great minds think alike eh? I don't think I'd even seen your pics before I sketched my first design, but your whole rear end is very nice indeed (ooh err). One question for you - have you thought about how the springs are going act? Where are the bottom of them connected to? The bottom wishbone or the upright?

Rorty - Yes a smaller lighter top wishbone would be more desirable, but I don't have access to a tube bender and to put a threaded section in would mean getting a new tap and it might be tricky to get all the tubes to marry up nicely and.... (you get the impression, the good thing is that with this design, I can easily put a couple of new top wishbones in at any time without having to change much else.... Apart from cutting out the crush tube section in the centre of the upright top bracket (I'd planned on doing that I just hadn't bothered putting it in the model yet). It looked to me that the bracket at the top of the upright shown in the book would bend in when pressure was put on the crush tubes though the bushes, not good, thanks for the heads up though.

MK9R - No toe in, because tiger didn't bother to design any, although with my modified uprights, there's more scope for adding it at a later date, probably at the same time as changing the top wishbone to a centre spherical bearing design, which would also lend itself to toe in adjustment. I haven't even considered roll centres or anti squat, I know next to nothing about either of them, so any info you could give me would be gratefully recieved. I plan to read a few books on suspension and chassis design at some point, but at the moment I'm plough every last (very limited) penny into the car so no real space for shelling out on books. I'm already starting to think (to be honest I was thinking it from the start) that I'll build another car, possibly instead of changing the current one to bike engine power, so I'd probably want to do a bit more redesigning before I built that. Who knows though, I've got lots of projects that I'd love to do given the time, money and know how, so it'll probably never happen.

Mix - I've been keeping an eye on your site with interest, I like the new design, much more profesional looking, so congratulations to your son.

Kingr

King R,

Are you going to stafford? If so i could bring you a copy of my report, which explains about all these things and the conclusions, calculations and designs i made.

Unfortunately not, I worked out it would be 2 1/2 hours each way, and apparently there's road works on the way too, I wasn't desperately impressed by Exeter, so don't really want to spend ages driving and a load of money on petrol.

Kingr

the shock is mounted on the bottom wishbone, what do you mean how the springs are going to act??

kingr:

quote:

---

I haven't even considered roll centres or anti squat,

---

Viper - Sorry, I'd only looked at your pictures briefly and thought you'd done something different, forget it, I'm talking crap!!

Kingr

Just been looking around for info on the web about roll centres and anti-dive. Haven't found lots about roll centres yet, but anti dive I found more info about. If I can just confirm that anti dive/squat is produced by altering the angle of the top wishbone, therefore producing a change in castor when the suspension is compressed. If I understand correctly, anti squat is confined to altering the rear upper wishbones, and anti dive is confined to altering the front upper wishbones. Neither appear to be evident in either RC's or Tiger's design, or there be any provision for altering it.

What I'm really interested in hearing about, is the interactions between front and rear suspension, what they are, how they work and how I can control them. Just to make things clear, the rear suspension isn't a completely new design, the geometry is exactly the same as tigers, all that I have changed is the size of the wishbone bush tubes to allow me to use the ones supplied by lolocost without any change in pivot centres.

Thanks for all your comments,

Kingr

P.s. MK9r, I didn't realise how long away Stafford is (May isn't it?) so I might well be tempted to drive up, I'll decide nearer the time, but if I do, I'd be very interested to see your work.

kingr:

quote:

---

Just to make things clear, the rear suspension isn't a completely new design, the geometry is exactly the same as tigers

---

ont he locost mirror is a file calculating the wheel movement, haven't realy checked it out yet. But seems to give some results (track width change, RC height ) on max bump and drop me I would prefer to see the changes in wheel angles trackwidth through the movement and not just on the maximum movements. so that is what I 've been tinkering with for some time, not perfect yet, still have to incorporate bodyroll in it.
The effect of moving pivot points does effect changes in camber more then expected at first. That is why I'm not keen on just replacing the cortina-uprights with the sierra parts and cutting down the top wishbone.

Kingr what CAD program did you use to draw the chassis please.

thanks