SagadSetup

iTrader: (38)

Hello to all.

Been browsing and I came across this:

http://www.rcmart.com/3racing-sakd33...Path=1102_1106

From what i understand, DCJs have the same kind of principle. It lets you turn without the chattering. This part also does the same thing.

Question is, What is the difference between these two parts?

*Edit - Can they be considered as an alternative to DCJs?

Regards!

funked1

iTrader: (10)

I think these will chatter, but they will let you turn further than standard CVDs. Probably only useful for drifting. I haven't heard of a TC needing more than 30 deg. for racing.

ThePanda

iTrader: (68)

The high angle ones have only one joint. They have a large radius but chatter.
dcj shafts have two joints. They may not have the same steering ability as the high angle ones, but they won't chatter.

SagadSetup

iTrader: (38)

I understand now.

Chattering means friction therefore power loss. I was thinking that the high angle DCJs could be used for racing touring car application.

(0000000000)

iTrader: (2)

These are regular cvd's, which are not bad.

The outdrive cup connecting to the U-joint will have a slightly larger inside diameter, but it is identical in anatomy to a cvd, which will allow you to maintain constant uninterrupted velocity up to a certain angle - and at 45' to 55', there will be plenty of interruption. Even at 35', a regular cvd is going to start chattering at high speed/high load. These were revolutionary to RC back in the early 90's, where dogbones were the norm, and standard universal joints were still very fragile. The large outdrive cups of CVD's provided better protection, and the ability to perform maintenance/reconstruction. And nobody needed to use 45' steering on a regular basis. This model that you quoted will alloww your car to hit that angle (so long as castor blocks and linkage allow it). But it won't be very comfortable or sound pretty at high velocity.


Enter the double cardan joint (double U-joint)

This has a different anatomy:
http://www.rcmart.com/3racing-drives...Path=1102_1106

It's essentially two universal joints (aka: cardans) on a single driveshaft. Imagine having a second wrist between your hand and elbow. A person could pick their nose at all sorts of new and creative angles. Likewise, it provides new rc cars with the potential for greater angles of uninterrupted steering (so long as the castor blocks and steering linkage allow).

Although not a necessity by any means, they do remove a lot of the "chatter" that full-tilt steering provides.

Mr P!nk

iTrader: (1)

I agree with what everyone has said.

DCJ's (double cardan joint) essentially has two joints within it and they cancel out the the opposing velocity differences. It's about as close to a true "constant velocity" as we are going to get in our hobby.

CVD stands for "constant velocity drive", even though none of the CVD's in RC (at least none that I can think of) actually have a constant velocity so it's a bit of a false statement sometimes.

Short answer is "high angle" gives you just that, a high steering angle but at the price of severe velocity differences. DCJ's have about the same steering angle as a standard touring car CVD, but they have reduced velocity differences (chatter as most call it).

I would agree that most drifters, or even rock crawler guys would prefer a high steering angle as the chatter is less of an issue for them. Whereas a touring car guy is going to prefer the smoothness of a DCJ.

A hot bodies TCX DCJ


I am generally curious if any other joints have been used in our hobby though. I feel like I remember reading a thread on this site about some joints flying under the name of lightmodz or something like that. The concept was good in theory as they were a ball type CV that's used on most 1:1 cars. But I feel like they just never pulled it off, maybe someone else can comment on that whole situation.

SagadSetup

iTrader: (38)

My thoughts were using these with a spool. Lubricate it well to minimize chatter.

Well DCJs are still the norm.

SagadSetup

iTrader: (38)

Mr P!nk hello!

Does chattering mean power loss? I'm referring to high angle cvds. Would you consider using high angle as a substitute for dcj?

Mr P!nk

iTrader: (1)

Yes, you are introducing more friction. More friction = less power being transmitted through the joint

SagadSetup

iTrader: (38)

Mr. Raman if you're reading this, would you use high angle cvds in substitute to dcjs?

(0000000000)

iTrader: (2)

When using cvd's with a spool, and operating at high angles, you'll wear out the spool outdrives as well. As a result, the "chatter" will occur in two places. For drifting (or even club racing), it's not a big deal. You're likely to have a greater loss in efficiency by using high IR batteries from hobbyking.

SagadSetup

iTrader: (38)

Next question is will DCJs reduce wear as compared to hi angles?

(0000000000)

iTrader: (2)

The outdrives of the spool will typically wear out faster when operating at high angles - dcj or cvd.

With that said, the DCJ will be more efficient than the cvd at high angles, thus provide less overall wear.

If the price difference between the two 3racing products is only $3, go with the DCJ's.

SagadSetup

iTrader: (38)

Thanks!

ThePanda

iTrader: (68)

if max steering angle is what you are after, say for drifting high ratio CS go with high angle cvds. by design the further they turn the more resistance in the joint you will incur and the more chatter.

DCJ turn very smoothly through the full range but usually can't match the range of some very high angle single joints.

DCJ shafts are better in most circumstances. especially on the front of touring cars.