Hey - I have a 2.88 off XJS that I intended to install in my SII. Not going to use it.
New seals, bearings on the hubs. Otherwise original.
Im in San Francisco. Can ship!?
Dave 415 559 1832
I guess technically the choice is between âswing axle independentâ and âfully independentâ in the nomenclature I am familiar with. Having broken a swing axel on my racing Spitfire and totalled the carâŚperhaps I am a little sensitive to the difference.
i thought the hot set up for Vees was the zero roll rear
Zero roll resistance: there is no anti-toll bar on them.
The suspension actually freely teeter totters!
Bill, whether you like the suspension or not, and indeed whether the suspension is technically a good or a terrible design has nothing to do with its âdescription.â I believe most define an independent suspension as one where one wheel can move independently of the other. Although no wheel is totally independent of every other wheel, a swing axle does meet the required description. Yes, the tire does move up and down in an arc. But then so does an E-type, just not near as much of an arc. But that is not part of the definition or IRS.
Tom
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Actually, I think what you may be talking about is called a Z-bar. Its function is exactly the opposite of an anti-roll bar. When one wheel goes up, it pushes the other one down. If the springs have any inherent anti-roll stiffness, a Z-bar counteracts it. Itâs called that because it is literally Z-shaped.
The issue with a swing axle is the direction in which the contact patch of the tire moves. In the typical double-jointed IRS, the contact patch moves straight up and down near the mid-laden point; it starts moving toward the centerline of the car at more extreme travel. But with a swingarm, the contact patch moves downward and inward at the mid-laden point. Basically the contact patch is moving in an arc around the inboard pivot joint, which is well above the road surface. As a result, when sideways loads are applied â cornering hard â the outboard wheel tries to tuck under the car. The more you can get the car to squat, the better it will handle.
Modern Vees did away with the Z bar, decades ago.
The hot set-up is zero roll resistance. A Z bar doesnât impart any roll resistance: its purpose was to prevent axle âtuck under,â which on zero roll setups, is taken care of by a limiter link, across the upright rockers, between which is the single spring and shock.
Kirbert, my comment is that both a single jointed swing axle and a double jointed system such as the E type are both independent suspensions. An independent suspension is not defined by the size of the arc that the tire may or may not follow when moving.
Tom
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That is correctâŚ
And, while we are at it, not all double jointed rear suspensions are classified as independent suspensions, such as de Dion.
Tom
True: like my Rover. DeDion is considered semi-independent. Good thing is essentially zero toe change throughout the range of bounce and droop.
Could be, but I thought it was not considered independent at all, as the wheels are tied together just like a standard live axle. The advantage being the differential was mounted to the chasiss, not the axle to reduce unsprung weight.
Tom
Nope: they are tied together, but can articulate a bit, up and down, independent of each other, due to Roverâs unique design of the tube.
Thanks to YouTube, you can see it work: that rubber boot you see is where the two halves of the tube pivot, wrt each side.
However, in that motion, due to the DeDion tube, they impart camber changes across the carâs midline.
The diff mounted to the chassis is the key, but not to reduce unsprung weight. Itâs to maintain traction on both rear wheels. When you drop the clutch at WOT in low gear, something like 800 ft-lb of torque is applied through the drive shaft to the diff. With the diff mounted to the chassis, this results in a twisting of the chassis; the engine/transmission is trying to twist one way while the diff is trying to twist the other. Itâs a simple matter to design the chassis to handle this twisting load without noticeable effects.
If the diff is mounted in a live axle, though, things get far more messy. The torque applied through the drive shaft tries to twist the axle, meaning it tries to lift one tire off the pavement while pushing down harder on the other tire. The tire that is trying to lift will obviously lose traction first, so it starts spinning. The fact that one tire spins has led a couple of generations to mistakenly believe that one tire is the only one getting power to it. Both wheels are getting the same torque, itâs just that one has far more traction than the other.
Detroitâs idea for a fix is a locking differential which applies more torque to the wheel that has more traction. Car goes faster, for sure, but it also tries to turn sideways because one rear wheel is pushing harder than the other.
DeDion is one fix. Another is to mount the differential gears in the transmission and run two counterrotating drive shafts to the live axle, one to drive each rear wheel. Thatâs been done but not often. Itâs just so much simpler and more popular to install an IRS of some sort.