Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Half-shaft torsional damping

Half-shaft torsional damping

Half-shaft torsional damping

FWD cars often seem to use a clamp-on or spline-on torsional damper. Some seem to be simple masses, others have an elastomer component too.

Can anyone point me to a calculation of how these dampers work, and what their capabilities are? Google just throws up countless references to parts manuals & 'auto 101' type references.

Thanks, Ian

RE: Half-shaft torsional damping

Thanks Greg,

I can understand where the damping comes from in the elastomer versions, but not the bolt-on masses.

Maybe they are trying to create two stiffer shafts connecting an inertia?

Regards, Ian

RE: Half-shaft torsional damping

Adding inertia to suppress vibrations is the oldest trick in the book. They could be detuning some local resonance or they could be increasing the input impedance of the system so that some fixed excitation is insufficient to create a problem.

Adding inertia is an inelegant solution, but it is quick, robust and cheap.


Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: Half-shaft torsional damping

They are not typically torsional dampers (with exceptions). The usual problem is bending vibration caused by resonance with one of the engine firing frequencies. If the problematic frequency occurs near idle, a simple mass will lower the natural frequency. ωn = √(k/m). If the problem frequency is near the engine redline, stiffening the axle with a tubular bar is the most frequent solution. If the problem is in the middle of the power band, a tuned absorber is what is called for. These are metal rings molded into rubber mounts. The rubber acts as a spring, and the whole thing acts like adding a second-degree-of-freedom absorber. Look up 2 degree of freedom vibration solutions. Since the equations of motion are coupled, you can trade energy between the two. Essentially the absorber vibrates like crazy and the axle stays stationary.

The only real torsional dampers I'm aware of were in the late 80's early 90's upper end GM FWD cars had torsional dampers to lessen the clunk in the transmission while shifting into drive from reverse.

RE: Half-shaft torsional damping


Your post is very interesting. I can imagine coupled modes being a problem for auto drivetrain components when it comes to minimizing every potential source of noise or vibration in modern production vehicles. But I also can see how difficult it would be to design an elastomeric mass dampener that is effective at mitigating a low-frequency (and energetic?) bending mode in a driveshaft without creating problems at other operating conditions. The huge combination of gear ratios and engine firing frequencies possible between the engine flywheel and drive wheel would seem to make the design task extremely difficult.

RE: Half-shaft torsional damping

I had one of those on my old VW. It eventually came off the axle ...
Decouplers are much more useful.
Litens Automotive is the leader, but does not make much readily available for public study. http://www.litens.com/vibprod2.cfm


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


eBook - Simulation-Driven Design with SOLIDWORKS
Simulation-driven design can reduce the time and cost of product development. In this engineering.com eBook, we’ll explore how SOLIDWORKS users can access simulation-driven design through the SOLIDWORKS Simulation suite of analysis tools. Download Now
eBook - Integrating the Engineering Ecosystem
Aras Innovator provides multiple options for integrating data between systems, depending on the scenario. Utilizing the right approach to meet specific business requirements is vital. These needs range from authoring tools, federating data from various and dissimilar databases, and triggering processes and workflows. Download Now
Research Report - Simulation-Driven Design for SOLIDWORKS Users
In this engineering.com research report, we discuss the rising role of simulation and the paradigm shift commonly called the democratization of simulation. In particular, we focus on how SOLIDWORKS users can take advantage of simulation-driven design through two analysis tools: SOLIDWORKS Simulation and 3DEXPERIENCE WORKS. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close