Driveshaft characteristics

[DCM]

I know there is a difference between the two, but what difference in handling is there between a U/J type driveshaft and a CVD type please?

[Martijn]

Is this wat you are looking for?

CVD or BONES per Charlie Perez

"bones", will tend to make the rear end behave as if you are running a softer spring. Sometimes this is a good thing and yields better bump handling....sometimes it will cause you to go over the line and your rear suspension will not center-up....thus a loss in ability to accelerate straight.

Most of the guys don't try the bones except on blue groove or extremely bumpy tracks that still have pretty good traction. Then the loss in acceleration stability isn't as much as the gain in grip for the bumps.

If you put your bones on and the car won't accelerate straight on corner exit, then go back to CVDs. This case typically happens on lower grip tracks with a dusty top layer.

[mattr]

UJ has more vibration from what i can remember, and harder to balance as the shafts move around a fair bit. (both along axis and off axis)
The more you change speed and bending angle, the worse it gets

CV joint keeps everything in plane. So its (pretty much) tolerant to all variables. Until you get to silly angles of articulation.

Handling effects are pretty much limited to how much vibration you can live with.

[SlowOne]

A universal joint does not operate at a constant velocity as it goes through its arc of movement. This situation is improved if there is a UJ at each end of the shaft, but it still gives changes in angular velocity at the extremes of articulation that are required on the steered end of the car.

As the name suggests, a Constant Velocity joint is designed to give a constant velocity during angular articulation, but as MattR notes above, there are extremes when it can't continue to give that. There's a reason for that - it isn't really a CV joint! It's a clever adaption of the designs in the attached link. As you can see, a true CV joint is the one with the spherical cages trapping six balls. This would be too expensive and difficult to make in our sized cars.

http://en.wikipedia.org/wiki/Constant_velocity_joint

As for the handling impacts, it is likely that the UJ will help with traction as action of the joint will tend to drive the wheel into the track. However, as it isn't a constant velocity I would expect that it would give you problems on large jumps and bumps where the car may land with differing rear wheel velocities. The so-called CV joint most people use removes many of these issues, and should give a much more linear response in all situations.

At the front, the likelihood is that a UJ will drive the wheel at variable velocities during cornering and give some darting effect. At high speed and a bit of lock, the UJ will tend to pull the wheel straight making high-speed steering a bit of a struggle.

That's all theory, you need a top-ten driver to tell you the practice! HTH

[DCM]

The reason for asking, is I am trying to work out whether to invest in the SVR CVD driveshafts and try them on the SV2, as I know one driveshaft squares the car up on throttle and one is smoother which one is which, I can't remember, as I am trying to improve traction on throttle pick up as I am coming out of a corner.

[jimmy]

I can't say I've ever tried UJ's and CVD's back to back - as not many make the UJ's any longer, at least in 10th scale.

I've tested dogbones against CVD's when I raced at the Euros in Italy and it was surprising how much it effected the car especially at the rear - there was far less traction with the CVD's and I quickly switched back but kept them in the front because they work better than dogbones at steering angles of course.

This was in a Tamiya DB01.

[DCM]

Bugger, even more confused!!!

Someone rattle Mr Doughty's cage, see if he is awake after Austria, I know he explained it to me once, think I all the spraying has erased that knowledge though!!