[Rory166]

Having just ordered a used axle to refurbish I was intrigued by the design. Apparently it is the cheapest solution saving $100 dollars over the cost of independent suspension. One of the weaknesses of the design is that the side cornering load is taken by the bushes end on which is not their intended purpose. It is possible to add a watt linkage to take the side load for an additional $20 but the manufacturer is too mean. They came up with a wheeze of angling the bushes slightly so that the side load is slightly taken by the bushings in the designed direction. Clearly in order to deflect the suspension either the bushes will have to deflect or the torsion tube bend. At least any bend in the torsion tube will tend to counter the unwanted cornering camber change inherent in the design.
Trying to source oem style bushes proved tricky so I have ordered poly bushes. These are probably stiffer than rubber but hopefully they will be OK.
It is rather galling that a car selling for such a high price should have such cheap design. The reviews described the ride as fidgeting. Presumably the sprigs have to be stiff to cope with the battery weight, this may explain the poor quality ride.

 

[freddym]

Having just ordered a used axle to refurbish I was intrigued by the design. Apparently it is the cheapest solution saving $100 dollars over the cost of independent suspension. One of the weaknesses of the design is that the side cornering load is taken by the bushes end on which is not their intended purpose. It is possible to add a watt linkage to take the side load for an additional $20 but the manufacturer is too mean. They came up with a wheeze of angling the bushes slightly so that the side load is slightly taken by the bushings in the designed direction. Clearly in order to deflect the suspension either the bushes will have to deflect or the torsion tube bend. At least any bend in the torsion tube will tend to counter the unwanted cornering camber change inherent in the design.
Trying to source oem style bushes proved tricky so I have ordered poly bushes. These are probably stiffer than rubber but hopefully they will be OK.
It is rather galling that a car selling for such a high price should have such cheap design. The reviews described the ride as fidgeting. Presumably the sprigs have to be stiff to cope with the battery weight, this may explain the poor quality ride.

Watts Linkage with a torsion beam suspension??????. Not sure that any car on the market has such an arrangement. Watts Linkage with a Beam Axle, yes, very common.

 

[dk6780]

A Watts link would only support one of the trailing arms, and two would effectively be the cost of a full multilink suspension.
So many EVs and cars like the Ampera have compromised cost elsewhere in the design to offset the high costs of the battery or dual drivetrain.

 

[Rory166]

A Watts link would only support one of the trailing arms, and two would effectively be the cost of a full multilink suspension.
So many EVs and cars like the Ampera have compromised cost elsewhere in the design to offset the high costs of the battery or dual drivetrain.

The volt2 has the watt linkage on a crossframe in the centre line of the car with linkage to both trailing arms.

 

[freddym]

The volt2 has the watt linkage on a crossframe in the centre line of the car with linkage to both trailing arms.

But not a torsion beam

 

[dk6780]

I'd prefer to see a Mumford link rather than a Watts link but this is an interesting hybrid system.