Outer Limits 4x4 Board

in a post to Ruff re his TTC 110 trayback, i asked him why he was changing the rear link from a watts linkage to a 4 link. he informed me that the factory rear set up was not a "Watts". i could have sworn i read somewhere that the rear on rovers is a watts(note to self:never trust memory) i know its an A frame set up with ball joint. i'm not totally dull. but thought this was a watts. So the questions are; what is a watts linkage? Ruff mentioned braking ball joints. what are they made from and can they be made better? I think Tony Cordell metioned a ford transtit ball replacement that allowed more degree of rotation? i have recently seen a balljoint that was made 35mm longer to put more seperation in the rear links to offset the effects of portal boxes.
cheers, Serg

I believe the following is a watts linkage.


edit* this is from a racing landrover (www.bowler-offroad.com). Seems to be used a bit in offroad racing 4wds.

The Disco2 has that setup. Mind you that pic also looks like a Disco2 axle.

as far as i know, the bowlers do use disco s11 axles. i believe outback-import supplied some full maxdrive set up axles for one of there dakar vehilces. from what i have read this setup is good for high speed stability, taking into acount that they don't need huge amount of travel for this type of racing compered to rockcrawling etc. great rigs IMO
serg

A Watts link is an equivalent (only better) to the good ol' Panhard rod.

Live axle coil sprung Ford Falcons and Rover SD1's used them.

The best thing about them is that they locate the differential without prescibing an arc during travel. Ever seen a lowered Commodore going over a bump? Bloody things look like they're about to jump sideways....

Slunnie wrote:The Disco2 has that setup. Mind you that pic also looks like a Disco2 axle.

Did they stop the A-frame setup with the d2 or is it watts on the front?

The D2 is Panhard on the front and watts linkage on the rear, with radius arms front and rear.

uninformed wrote:So the questions are; what is a watts linkage?

A Watts linkage is system to prevent sideways movement of the axle housing.
It's an improvement on the panhard rod that allows the housing to move in an arc.

The Watts linkage has a lever pivot in the middle of the axle, and from memory the arms are horizontal in a neutral postion.
As the axle moves up and down, the pivot lever rotates, but the axle does not move sideways.

All the V8 Supercars are using them (as has Ford since the XE), however the V8 Supercar guys adjust the height of the pivot to change the Roll Centre.

Watts Links on racing cars use Heim joints and give very precise lateral control. However on a road vehicle such as Falcons, Disco 2's etc there are 5 compliant rubber bushings compared to a Panhard rods 2, so lateral location of the axle when cornering may not be as good, although they don't have the ''jacking'' effect of a panhard when cornering to the right.
I have heard of ''A'' frame balljoints breaking on earlier Rangeys, but I always reckoned it was due to the nut working loose and being left that way. The later ball joints had substantially larger threads. Are people really still breaking these?
Bill.

AFAIK, and my experience, it wasn't the ball joint that broke, but the bracket used to rip out of the top of the axle. Later brackets were much stronger design. My 77 did it twice. admittedly, I had it rewelded on car the first time and it turned out he didnt get good penetration all round.
reagrds Philip A

daddylonglegs wrote:I have heard of ''A'' frame balljoints breaking on earlier Rangeys, but I always reckoned it was due to the nut working loose and being left that way. The later ball joints had substantially larger threads. Are people really still breaking these?
Bill.

Maybe not in the average rangie but yes we have broken both in a buggy. And the first time we thought the not had come loose because it stripped the thread off it but the last time it snapped the balljoint clean and the nut was still attached with the split pin still intact.

RUFF wrote:

daddylonglegs wrote:I have heard of ''A'' frame balljoints breaking on earlier Rangeys, but I always reckoned it was due to the nut working loose and being left that way. The later ball joints had substantially larger threads. Are people really still breaking these?
Bill.

Maybe not in the average rangie but yes we have broken both in a buggy. And the first time we thought the not had come loose because it stripped the thread off it but the last time it snapped the balljoint clean and the nut was still attached with the split pin still intact.

RUFF, are you breaking stock ball joints or the Maxi-Drive strengthened, adjustable one?

Ruff, were the balljoints still braking at the threads or above the taper ?
If at the thread it sounds like the taper isn't biting hard enough. Just like a steering balljoint if the taper is doing its job their should be no shear load on the thread, only the tensile load from tightening it up.

On the earlier Rangey axles the designers did underestimate the forces acting on the balljoint mounting bracket. ie in low range 1st gear of 48 :1 if the engine was delivering 100 ft lb of torque (very conservative) there is the potential to transmit 4800 ft lb of reactive force to the axle housing. The balljoint mount is around 4 1/2 inches from the axle centre so potentially there could be over 12000 pounds of force trying to tear that bracket off the housing. Of course traction, axles or differentials usually fail before the loads reach those levels, but you can see why the brackets,balljoint threads and sometimes the axle housings crack after a while.



Bill.