No Rob you certainly haven't muddied the waters, it's a nice summing up.

Although I think you're a little harsh on the standard Bellett set up, it's part of what makes a Bellett a Bellett and I think it would be a shame to ditch the whole lot.

Lots of cars use this sort of rear end, to varying effect...I personally became aquainted with plenty of hedges and ditches in my Triumph Heralds and 'mighty ' Vitesses. BMW 2002 used it pretty well and of course the nations favourite Ford Sierra..........................it's just 'how can this be improved?'
Now, techno Chris is the brains behind our push for Goodwood, and his meat and drink is building Sports 2000 cars for wealthy customers. These cars always have their suspension travel (front and rear!) limited by the shockers alone. And consequently he favours this approach with other race cars he builds, hence our leaning towards this system, to quote 'reduce the complexety by making components do 2 jobs'

Anyway, hopefully this goes some way to explain our reasoning behind the rear end. We should be testing again next week, so more results soon.

I don't exactly know what Tom's got in the back of his GT (re leaf spring) but certainly, the wheels do not appear to drop any appreciable amount in the picture and thats a good test ! I do know (from looking under it many years ago) that he has coil over shocks in the rear, not the original type coils and shockers but an 'aftermarket' coil-over. Presumably racing types that can handle (no pun intended) this sort of thing.

glenn

Actually Tom has coil-overs in front also. Apprently the Group N? regs stated that suspension must be in same configuration as original. Coil-over units meet this description although might be seen as not in the spirit perhaps. I vaguely recall that Tom's GT rear leaf is still there, but does nothing.

glenn

Yes, a lot of this set up game depends on what rules you have to abide by. Over here we go by the FIA's Appendix K, which specifies we have to have the suspension pick up points in the same position as the original.
This can be a little limiting, but obviously that's the point since it stops people from grafting the back of, I don't know, an F3 car for eg, onto a period classic saloon!

Tom's GT still has the transverse spring, from memory is has at least 3 bars in the transverse spring, it is a works set up.
Mark you are right, some of these set ups also come down to driver style and trial, however I don't think I personally would be running without that tranverse leaf spring, BUT that is a personal choice!
Travel safe!

Possibly Tom's spring is there but modified to only act to stop suspension dropping since on a race car, lots of suspension travel is not required.

True enough MoBel, but Glen if that's the case, why not do away with all those KGs and stop the drop with the shocks?

The question about what the leaf spring does depends on it's configuration .
In a standard setup after forty odd years it doesn't seem to do much.
However the leaf spring whether standard or modified is partly for roll control.
Without the spring only basic control can be exerted by the shock absorbers and coil springs.
On a very light car it is possible to get away with very little roll control which can be handled by the shocks and coils.
I'm not sure at what point,( ie weight, centre of gravity, cornering forces) that control of the polar
moments require some from of coupling that a roll bar or in the case of a Bellett the leaf spring is required.
This maybe what everyone is experimenting with, without knowing.
Tom's car certainly looks like it has it correct, I'd love to see some pictures of cars without the leaf spring.
Pom, does you suspension guru use roll bars on the SR2000 and does he have any idea how to put a normal
roll bar on a Bellett rear?
Hope I've written this right only got mobile phone at the moment, which is hard to type with!! Fat fingers and small screen

Cheers
Rob

Ah, that rings a big bell..........my understanding is that the regs state the pickup points and configuration remain basically the same. hence the use of coil-over shocks replacing the standard shockers and separate springs, but the configration is the same. The spring has to be present, as its the normal config. Whether Tom's car has a 'dummy' spring there or if it does anything at all i do now know.

BUT, Tom's car has another item in the rear.... It's a "Z-bar". Like a normal anti roll bar but its a Z shape.

It's a long time since i saw it, but it's actually INSIDE the car. In the boot, sitting above the floor. There are holes in the floor through which the connecting rods i think with heim joints on them, drop through to the suspension. Just where they connect to exactly, i don't know. Nor do i know the 'rate' of the whlel thing. But i beilve this is the 'secret' to the rear -end handling of Tom's GT.

glenn

a nice drawing etc of the Z bar is here

http://www.shoptalkforums.com/viewtopic.php?t=122651

glenn

This is just too long ago but i think Tom's Z bar is adjustable also.

I think iwas essentially made from a straight bar, (possibly cut from a donor sway bar from another car) mounted in bushes at an angle in the boot, with the arms clamping (very securely ! ) to the ends of the bar. The length of those bars to the connecting rods down to the suspension points was adjustable also.

glenn

Interesting article, good read!

Glenn, mate that is fantastic information.
It explains much more than I could have imagined.

Cheers
Rob

When you see that bar and imagine how it works, it's quite 'simple' really. Its seems that VW type ones had them as standard. It might be worth finding one of those as they are probably cheap at wreckers, and looking how it's done and it's sizing to fit the Bellett. Plus the brackets etc might well be usable in modified form.

One might need to play with the rates, by initially fiddling with the pickup point down to the suspension.

One would imagine though that there are aftermarket ones for upping rates etc in the VW world that once you have the base one fitted, you could swap to later ones. Might take some fiddling about but eventually could find the right combination.

glenn

This suspension topic is a great read,few of you would have caught me
laying under the back end of a Bellett or two at Coona,question how many
leafs in cross spring on a GTR. As you can see when I got the Peter Lyons
GT it came with alot of parts and two cross springs,at the moment running
four leafs also have the two leaf,what would be the difference,have heard
of that Z bar on a Bellett,would need to talk to those in the know
Gerry

Now we have a expert on bellett rear ends Gerry has studied every one in aus and we may have proof of looking up rolies rear in the uk ?

I'd imagine you're not getting a lot of body roll there Gerry? Heavy duty!

Yes Matt the car rides well and hugs corners,but pushing it on a race
track,well would have to leave that to Pinky,I've seen what happens
when they hit the gaurd rail Gerry

Sorry I've missed out on the earlier discussions, but it's all very interesting and thanks for your contributions. I've taken a few pics of our set up, I'm afraid they've not come out as well I hoped, but they may still be of interest.
You might have to put your screen onto its side for this one!

And this is a photo of the Scandanavian set up

One of my reasons for not joining in on the more recent discussions is that we've suddenly come up against some problems with the engine......amongst other things, after the test we've ended up with two broken valve springs and a broken valve guide. Under the bonnet boys

And lastly, I like this one.....it's Rolie and his stablemate.....one of Techno Chris' earlier creations that ran at Goodwood last year.

Great set of photo's Mark,interesting to see your set up and others,wondered
about the strap set up,wishing you all the luck with the motor,Gerry