Continuing Strut Problems.

[C-Kwik]

Can't make a comparison of struts and springs. They serve different purposes that are combined to achieve a desired response. Tat is, a spring is designed to hold the weight of the vehicle while providing compliance so that the tires can follow the road as well as allowing some level of comfort to the occupants. A strut is basically a shock absorber that. A shock absorber's job is to damp the motions of the vehicle. Without the damper, the car would just bounce along the road everytime you hit a bump. Ask anyone who's driven a car with shocks that were completely blown about this one. A shock differs from a strut in that a shock is only loaded along the axis of the shock (the compressive forces). A strut is a geometrically locating member of the suspension, and will be subjected to lateral loads. Easy way to tell, is if you remove a shock, the suspension will still be able to move along the intended path. If you remove a strut, the wheel and tire will essentially fall out only being held onto the car with the lower ball joint.

That said, I'd suspect in general cases,. shocks outlast struts. The lateral loads put a side load on the piston which may wear one side out more prematurely. But more specifically, its impossible to say for sure as there are many variances in engineering design and quality between different struts or different shocks. So a well engineered strut can easily outlast a poorly engineered shock.

[jbfalaska]

New model, always happens, and with no in stock parts, a real time killer if something does go wrong. Hang in there - my story goes for 30 days in the shop, all tied to the "battery enhancement" recall. Now, I have the car the company designed -working fine. The nice thing about buying a General (GM), is they will stand behind the product. And you own a flagship car - it'll be fixed, even with the learning curve going.

[Fulgerite]

whats better (and last longer) struts? or springs?

Struts are not springs... They are dampers. (Like shock absorbers.) The Volt has coil springs and struts. Generally speaking struts provide higher performance and better handling. Struts can outlast shock absorbers if they are properly designed for the car.

[C-Kwik]

Generally speaking struts provide higher performance and better handling.

Shocks can be used with at least 2 general types of suspensions. Live Axle and Double Wishbone or Multi-Link. In general, a live axle will not perform as well as a strut. But a DW/ML design can outperform a strut. Depends on how well its designed, but the DW/ML designs are much more flexible in geometrical parameters such that an engineer can optimize dynamic wheel alignment much better than a strut or live axle. Struts are used because they are cheaper and take up less space. That's not to say they can't be tuned to handle very well (i.e. Porsche and BMW) but its not the most ideal set-up to work with in terms of performance.

Struts can outlast shock absorbers if they are properly designed for the car.

While its plausible that a well engineered strut can out last a poorly engineered shock, if all components were equal, shocks would last longer simply because a shock only experiences a uniaxial load. Struts experience a moment where it attaches to the hub and therefore there will be three load points that exist along the piston assembly. 2 of these points are subjected to sliding friction. While the wear caused by this effect can be minimized, it is something shocks simply do not have to contend with.

[mtndrew1]

All,

There's TWO issues here common to 2012 models. I've had both issues:

1. Struts make a noise at low speeds, even over relatively smooth pavement. Issue is not that they are loose, but rather experience stiction in the strut seals. Sounds EXACTLY like something is loose. Unaffected by braking. Mine went noisy 2 weeks after purchase. Dealer replaced both struts. Good for another week, then the noise returned. Next set, with blessing from GM Engineering, were the right ones. New supplier brought on board; took a while to ramp up. Might still be some old design struts in the supply chain.

2. Front calipers / pads will rattle over sharp bumps. How to diagnose? Put car in neutral when it makes the noise, and LIGHTLY apply the brakes. Neutral forces switchover to 100% conventional brakes (no regen), and applying the brakes tightens up the pads and calipers. A new set of pads and hardware did the trick on mine. No more rattles.


Just to be clear: Both issues now known and understood, at least by GM and Volt advisors. Take it back to your dealer, or find another dealer more up to date on current events!

Thank you!!! I'm going to try this tonight.

My first Volt had issue #1 and it was the most maddening noise in the world! Dealer fixed it by replacing the rear shocks. Front struts started to do the same thing just before buyback.

My new Volt has an obnoxious banging/rattling sound on rough pavement so I've suspected it could be the caliper issue but have had no way to get the damned calipers to cinch up short of a full-on panic stop given the regen priority. Fingers crossed that your suggestion will be a good litmus test and I can go for repair with an immediately-reproducible symptom and solution.

I know dealers hate chasing noises as much as I hate having them so I always try to have it instantly reproducible in the vicinity of the service department (any car, any make).

-Drew

[vrunner]

Hmmm I have rattles at low speeds and over ruff pavement. May have to try the neutral method to narrow down the noise.