Front to Rear conversion

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Gravel Spray
Makes sense the watts link has inherent issues for long travel.

I think it was on SS that Mike Hurst(old NASCAR guy) explained the 3 link as being the most ideal for a rally car, in his opinion.

That RX car runs in Europe and from what I understand their tracks are smoother, no jumps so the watts and it's adjustability makes sense.

Pete, in the old days of nearly everything rwd, EVERYBODY---in classes which allowed it (ie Gp4 which was more or less like GpB but 400 cars min) had some sort of 4 link + panhard set up. Indeed most looked pretty similar too Ford set up.

Nobody had a 3 link.
Naturally some guy from the mid-west is much clever-er-er than the dumbshit Engineers, builders, drivers, everybody at Ford, Opel, Fiat, Vauxhaul, Toyota, Nissan Mitsubishi and even Saab who had 4 link+ panhard in the 99/900.

I say we don't have the test data to prove that the "normal Gp4 style" 5 link thing is bad, or the decades of results proving 3 link "most ideal", only a claim.

So while I say keep your politics Progressive, on "trick" ideas supported only by a claim, I say take the conservative approach and go with what we know works in the conditions we are driving..

(I mean for fucks sake clearance between diff and car floor, if any, ought to be used for MORE TRAVEL. Placing some mounts and a link on top of the diff means more floor mods or limiting travel just to make room for the mount/arm etc..
Give me a fawkin break.)

We're on the same page here John no doubt. It's always been my pholosophy to stick with the proven and not to experiment with fundamental items. I was just curious if there was some benefit to the 3 link or the watts percieved or real, over what has been standard practice.

Clearance between the diff and floor or floor and the upper link might be it, come to think of it; just remembering how far up above the diff things sit on the roadrace car. No arguing that 4-linking's the way people have done it in rally in the past, and no arguing either that it works. I dunno, just never been comfortable with conservative as a first reaction. Probably I should make an exception here.



Edited 1 time(s). Last edit at 04/28/2011 12:49PM by mekilljoydammit.

watts link will hold perfect centerline wile the pan hard can shift
about .5 to .75 inch off center of its original position so if your in
compression and off axis there could be some rear steer. But with
how long the links are its probably so minimal.

I been watching off road trucks and there trend 7 plus years ago
they used a 3 link and the center link was laterally fixed in a
triangle mounting to the top of the axle. I always thought that
would work in a car well. But now I don't see that solid top triangle
its two septate links to the top now.

3 links need three boxes, 4 links need two. 3 links need three brackets on the diff, 4 links need two. 3 links will twist the hell out of the housing as the torque reaction is working on different sections, a 4 link mostly doesn't have this problem.

A Panhard of decent length does not move the axle centerline THAT much. It's about a quarter inch. I remember that the Panhard on the RX-7 has about the same axle side to side motion than the Watts, which is asymmetrical in three ways. And way too high.

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Pete
3 links need three boxes, 4 links need two. 3 links need three brackets on the diff, 4 links need two. 3 links will twist the hell out of the housing as the torque reaction is working on different sections, a 4 link mostly doesn't have this problem.

A Panhard of decent length does not move the axle centerline THAT much. It's about a quarter inch. I remember that the Panhard on the RX-7 has about the same axle side to side motion than the Watts, which is asymmetrical in three ways. And way too high.

36 inch pan hard bar with 6 inch off center is about .5 inch off
center which is still nothing to make a big deal about.
the 3 link I was talking about would mount in the two box's.
It would use the upper mount like normal.

3 link one one side I have seen rock buggies break there
case but they are putting down 13000 plus foot pounds in 1st
low on the t case and 5.13.

I like the 4 link because if your clever you can make one spare link work for
any of the 5.

Andrew Havas runs a 3 link on his RX-7. Seems to work pretty good. Lots of axle articulation possible.

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Doivi Clarkinen
The trouble with this style with the two bent Vees is there are no tubes in tension and there is hardly any contact area between the upper and lower Vee. You are relying totally on the the gusset with that design and the example you show has a laughably small gusset. Not even FIA legal, really. If you take a big whack against a tree and the gusset fails those two bent Vees can swing in pretty far. An intersected X at least has one bar in tension and can prevent more intrusion than the bent Vees. I agree that an intersected X that only has gussets on the acute angles is still only the diameter of one tube at the intersection but that's why I like to use a connector from there to the sill bar (like on the BMW, see below) or a long taco gusset on the underside of the X and even on top. Also, in the example shown with the bent Vees the gusset is so small it's really no better than an intersected X. Any design with a bent Vee should have a big taco gusset made with material the same thickness as the roll bar material, IMO.

Dave gets the prize for being closest in analyzing this. The double bent Vee's is only good as long as the joint between them does not separate. Once they separate, they twist and swing in. Whenever anyone does these, I try to get them to:
1. Use very thick gusset material. The 40 mm stuff per FIA is a joke for these gussets; it will literally tear this thin material apart.
2. Weld both sides of the joint between the 2 Vee's
3. MOST importantly: Wrap a 1/8" plate over the full length over the joined tubes on the inside and weld along the top and bottom. This directly resists any tearing of the central joint.

If you keep this center joint together, then both tubes stay in tension, so that is not different that the X.

JVL, the idea of total weld length has to be taken properly. The info you got was for a single welded joint; with multiple welds, you have to look at each weld and what it does under what circumstances. Half of the welds you list are not doing anything in a side impact so this is not counted right. And yeah, I am saying all of this as a stinkin' engineer......

Grant's caught on; the single sloped bar plus sill bar are hard to beat.

And for general info, not all outwardly bent bars are bad. Keep in mind that preventing deformation is the FIRST function of any cage. So, while every one in rally seems to diss NASCAR side bars, they do that function in a fashion far superior to anything in the rally world.

OK, now on to the Watt's linkages: Bob said my first reaction to the Watt's link mount: it'll tear the diff civer opn on the first slam into a dirt bank or stump......The travel on that one is very small.

Mark B.

Here's what I ended up with... almost. They made me cut the top half of the A pillar bar off becuase it wasn't in "one plane"... I bent it out a bit to give me some clearance for teh steering wheel, but it was turned a little when installed (that's where it fit best!)... nope, not allowed, cut it out. Pissed me off royally... How the Fu<k can it be safer not there? Anyway, here's my door bars to add to the examples.

-Martin.