Is one 'better' than the other, or do something the other doesn't?

Cheers!!!

go fancy and do a watts linkage

quote:

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Originally posted by blakep82
go fancy and do a watts linkage

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Amongst other things it will affect your roll centre. I think 7's dont use the A frame due to packaging really, the seats are where the mounts would have to be.

well, panhard rod will give a slight sideways arc when the axle goes up and down. a frame wouldn't, can't think of any down side to an a frame set up, except the space it takes up maybe, and if one wheel is pushed up, maybe some sort of twisting, but that depends on whether the bars are all independant and have rose joints etc?

watts linkage, i don't think is any more difficult to fabricate than a panhard rod, except you need 2 axle brackets, and 2 shorter rods, and a bracket in the centre of the chassis. (most have 2 brackets on the chassis, and 1 on the axle, but not mine )
give a much straighter up and down travel, slight arc on the extremes of the travel.

here's mine


photo should work...

quote:

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Originally posted by JoelP
Amongst other things it will affect your roll centre. I think 7's dont use the A frame due to packaging really, the seats are where the mounts would have to be.

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What's the horizontal bar on the lower left of your axle Blake?

How many links we talking

If a 3 link A frame v a 5 link Panhard then the 3 A frame link imparts torque loads into the axle meaning an axle needing a big heavy reinforcing plate stuck to it. - See Caterham live axle.

A frame is simple and gives a nice low roll centre at the base of the axle casing.

Panhard to get the same RC is rather exposed + not quite symetrical loads in LH and RH roll

Watts - OK but to get a low RC one link is scraping the tarmac.

Andrew

thats half of (or rather 1 of) the watt link bars the other is on the top right, with a swiveling thing in the middle.

the axle can't move side to side because of the bars, both pushing and pulling on the swivel at the same time, yet when the axle moves up and down, the bars can either both push or both pull at the same time to stop the axle moving in an arc, its an awesome design works better than the panhard rod too

I'm being a biff (nothing new there), but I'm struggling to make sense of that photo.

It looks like the watts-links are attached to the axle only and not to the chassis at any point???

PS - Cheers Andy!

ah, right, yeah... the swivel in the middle is black, so its hidden by the inside of the diff case slightly

silver chassis tubes come down in a V, and the swivel is between that and the axle, and powder coated black to help hide it even more

a bit more close up

Chassis connection is to that big Vee shaped member centre photo. - easy to miss

Andrew

ETA - not quick enough

[Edited on 22/12/11 by Andy S]

I can't get my head round that (told you I was a biff!) as every watts-linkage I've seen before connects to the chassis at the end of each link like this...

The A frame on the caterham goes up and down it does not twist at all, there is a sperical joint in the housing that allow the axle to twist

Blakep82

Is the watts linkage geometry the same with this style of mounting as opposed to the more usual method of mounting?

Cheers
David

yeah.... i know... not sure why that is, i think mine is better anyway.
mines easier to put together i think. diff covers aren't particularly strong, unless you get a special watts link one, which aren't cheap.

don't think it works any different to the ones in your picture though

quote:

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Originally posted by Minicooper
The A frame on the caterham goes up and down it does not twist at all, there is a sperical joint in the housing that allow the axle to twist

Blakep82

Is the watts linkage geometry the same with this style of mounting as opposed to the more usual method of mounting?

Cheers
David

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Ah... got it!

I was thinking that yours bolted right through and onto the diff cover too!

ha ha that would break pretty quick
it all works quite nicely, so this would be my recommendation if you can make it

If going for a nice chassis pick up bracket like that I would go for a Mumford

Andrew

Are the handling characteristics between any of the aforementioned radically superior to the others?

Scootz

Have you looked at the Dax Rush rear setup?

De Dion/A frame setup which has always struck me as rather well packaged. By all accounts it handles OK too.

Will check it out. Ta!

Just to point out guys an A frame and two fore-aft links is actually 4 bar link system, although it is welded into a single assembly the "A" frame is in spatial location terms 2 links.

The minimum number of links needed to locate an axle is 4.

well at least you know where to go to find dax's round here

..and I've got that scimitar too (watts linkage as standard)

I thought the 1960' Lotus 7 S2? , had an A frame and they were famous for breaking the diff mount.

What about a Mumford or Woblink?

http://www.lescanfield.info/rear_geometry.htm

If a panhard rod is 95% perfect the other systems are 97-8% perfect nothing is 100%....on a road car you wont notice any real improvement (nor is there any real advantage converting to fully independent rear axle on a "7" style road car)....track cars are a different matter, if they are solely track cars and they are built for that purpose with no compromise. (in which case they are usually lousy for normal road use)
There is a lot of hassle and complication in fitting alternative systems and they have very little advantage over a properly located panhard rod. Make it as wide as possible and as as low on the car as possible.