What is this spring doing on the brake hubs?

[Grizz1963]

Previously ignored them, but my front hubs (possibly the rears too) have these springs wound around them.

Any idea why they are there, and can I remove them without expecting a blow up?

I want to remove them as they seem to serve no purpose, so that I can clean up and paint the hubs.



Thanks again as always for your help.

[71swb4x4]

Most believe that they prevent a humming/ringing noise. Others say they help dissipate heat. Maybe they do both things. I have heard they are a real bugger to get put back on.

[luvbowties]

Anti-chatter/squeal/vibration? A humming/ringing noise as 71swb suggested could drive you nuts when braking! Rubber straps wrapped around them when turning a drum are for anti-chatter--makes a heck of a difference in smoothness of the turned surface when finished.
If you can do your painting w/o removing, I'd suggest keeping them.

Also, measure how much "meat" you have left before max. diam. will be reached--could be time for new. No use for pretty if not safe.
Sam

[luvbowties]

My curiosity made me Google this myself. Here's a good discussion on another forum. Do note the "harmonics" section(s):

>> http://www.chevytalk.org/fusionbb/sh...hp?tid/311468/ <<

Sam

[indymachinist]

As my screen name suggests, I am a machinist. Let me tell you, it is AMAZING the difference something like a rubber strap or even a basic rubber band can make to break harmonics when you are turning a part. I would have to agree that is exactly what that spring is there for. GM must have realized there was a resonance in the drum and added the springs to get rid of it.

Edit: Just read a bit of that thread posted above me. The spring is absolutely not there to keep the drum concentric. I am highly skeptical it aids in any noticeable fashion to heat transfer either.

[Grizz1963]

Originally Posted by luvbowties

Anti-chatter/squeal/vibration? A humming/ringing noise as 71swb suggested could drive you nuts when braking! Rubber straps wrapped around them when turning a drum are for anti-chatter--makes a heck of a difference in smoothness of the turned surface when finished.
If you can do your painting w/o removing, I'd suggest keeping them.

Also, measure how much "meat" you have left before max. diam. will be reached--could be time for new. No use for pretty if not safe.
Sam

Thank you for your reply and other replies.

Keeping in mind that the biggest engineering skill I possess is making a cuppa tea......

We noticed yesterday that the drums that came off my truck, were noticeably lighter than those spare ones I got from Ian. As was their design as well.

My drums are smooth, no ringing, and used to work real well.

I guess someone who knows, will just pick them up and say..... "End of the line" but how do I check?

[luvbowties]

Originally Posted by Grizz1963

Thank you for your reply and other replies.

Keeping in mind that the biggest engineering skill I possess is making a cuppa tea......

We noticed yesterday that the drums that came off my truck, were noticeably lighter than those spare ones I got from Ian. As was their design as well.

My drums are smooth, no ringing, and used to work real well.

I guess someone who knows, will just pick them up and say..... "End of the line" but how do I check?

Take them to a reputable business(O'Reilly's, Advance A/P, NAPA, etc.)and have them measure the diameter of them and compare to the max diameter allowed--either in a book OR usually stamped on the drum in some conspicuous place.
Sam

[61K10]

55-56 chevy cars came with springs like those. early tk's probably had them also--maybe the design of later drums are different?

[Keith Seymore]

My screen name doesn't suggest it but my signature does: I was a brake development engineer for GM Light Duty truck at the Desert Proving Ground, specializing in Noise and Vibration work. The text below is from a previous thread -

Originally Posted by Keith Seymore

The springs are a "damper" to snuff out any noise response of the drum.

In order to perceive any disturbance you have to have three things: a source, a noise transmission path, and an responder. In the example of the interior boom: the source might be an imbalanced driveshaft, the noise transmission path is the air in side the vehicle, and the responder is the vehicle body. In view of this there are three ways to attack the problem: deal with the source (ie, properly balance the driveline), eliminate the transmission path (take all the air out of the vehicle), or change the vehicle body in some way (ie, change the interior volume, brace the interior sides, or provide additional damping on the body).

Let’s try another: a bell. Input: banging on the bell. Noise transmission path: air. Responder: the structure of the bell. Once again the potential solutions could be: eliminate the input – stop banging on the bell. Eliminate the noise transmission path – get rid of the air. Deal with the responder: change the structure of the bell (dramatically stiffer, or dramatically softer – or add damping).

I think you can see that some solutions are constrained by practicality. We wouldn’t want to elminate the air inside a vehicle (or between us and a bell); similary we might be bounded by performance constraints that limit how much you could change the stiffness of a component.

These examples may look trite, but consider how readily they translate into real life: let’s say you have a pickup truck rear brake moan. Using the same thought process: Input: stick/slip brake shoe behavior against the inside of the drum. Transmission path: air. Responder: brake drum ringing like a bell. Since we already determined we don’t want to eliminate the air around us (!) we could attack either responder or the input. In this case adding damping or changing the structure of the drum would be either increased piece cost or a new design to the drum (redesign of validated and proven brake components is typically frowned upon) we chose to go right to the source and address the input. In this case the stick/slip phenomenon was caused by improperly radiused brake shoes which were engaging the drum on the heel and toe of the shoe. Radiusing the virgin shoes so that the initial contact patch was focused in the center (and migrated outward as burnished in) eliminated the problem and cost no additional money.

So in this particular case the program team decided it made more sense to attack the response of the drum, by adding the spring "damper", than to attack the source of the problem (stick/slip phenomenon as a result of non-arc'd shoes, or whatever).

The spring is absolutely positively not an aide in heat transfer or to keep the drum concentric.

K

[Grizz1963]

Keith !!! You hero.

Thank you for the reply.

[Micmac]

You learn something new every day! Very interesting discussion.