OK ... where did this broken spring come from?!

[BTB 500]

Found this broken spring on the drive this evening, at the back of the Vito



Looks like a broken suspension spring, but it's too small to be off either our Vito or C Class estate! The spring itself is 10cm diameter, and the rod is 10mm diameter.

I can't think of anywhere else on either vehicle that would have a fairly sizeable coil spring like this?

My suspicion (and hope!) is that it's a bit of suspension spring off a smaller car that came home hooked up somewhere under the Vito and just fell off on the drive. What do you think?

 

[dozypillock]

It could still be off yours. Springs are not always uniform, as the top or bottom may sit in a cup. try measuring the gap from top of wheel to arch on each side.

Neil

 

[BTB 500]

Wheel to arch gaps look good all round on both vehicles. I've had a look underneath and the springs on both the Vito and C Class are a fair bit chunkier.

 

[SLKNick]

Do a quick google search for images of mercedes vito springs and you will see that they have a reduced diameter at the ends, so might still be one of yours.

 

[grober]

Rear spring of your S203 would be my guess -- the rear springs are considereably smaller than the fronts if you are judging by those???
Here's a video of how to change one which gives a clue at the start?
[YOUTUBE]M6jZQRtR_Lg[/YOUTUBE]

 

[BTB 500]

Do a quick google search for images of mercedes vito springs and you will see that they have a reduced diameter at the ends, so might still be one of yours.

You're absolutely right - it's the bottom of the Vito's OSR spring

It didn't occur to me that the diameter of the spring material itself would be smaller at the ends.

There's only 1cm difference in ride height (ground to top of arch) - bizarrely it's that side which is higher ... 75 cm vs 74

Funnily enough it's already going in to the dealer on Monday morning for a B service. Presumably it'll be OK to drive (carefully) in the meantime?

 

[SLKNick]

A broken spring is an MOT failure so technically your vehicle isn't roadworthy.

The reduced diameter at the ends is important for the correct location of the spring in the chassis. As one of these ends has obviously broken off I would be concerned that the remaining part of the spring could pop out.

Should be OK to limp a few miles to the repairer but be particularly careful going over speed bumps or other humps in the road and keep the speed down.

 

[BTB 500]

I've now worked out that the spring went overnight on Thursday night while it was parked on the drive (I know from other posts this is - bizarrely - a common way for them to go). So I was driving it with the broken spring on Friday ... including going over speed humps etc.!

I don't think there's any chance of the spring coming off but the bottom end could potentially move around a bit. It's almost impossible to spot visually, I had to feel around inside the spring seat to identify that the narrow coil at the bottom had gone. The 'main' spring rests on the seat, which is why the ride height was unaffected. So if I hadn't found the broken piece I would never have known, and I'm not 100% sure it would have been spotted on an MOT.

But it will certainly be getting a new pair of rear springs on Monday! If I get a chance tomorrow I'll have a close look at the front ones to make sure they're OK. Many thanks for the advice/comments.

 

[stwat]

It looks like it's been broken for some time as the break is rusty.

 

[Rory]

When one of my front's broke the mechanic said it had ben broken for some time.

I find it weird that that there's no indicaton in either the feel of the car or the ride height. The previous day I'd done a long trip in very stormy (trees blown down / roads closed type of stuff) and the car hadn't given me a moment's concern.

I seem to recall seeing discussion that a broken spring isn't an automatic MOT fail now. Testers are advised not to to check them by touch due to risk of injury and on some cars the bottom ends are impossible to see.

 

[BTB 500]

Yup this part of the spring can't be seen while it's fitted; as mentioned the main part (which is visible and actually takes the weight) is in good condition.

Where it broke the black plastic coating has come away and there's a lot of surface rust. The break itself is dirty/rusty at the top and clean & shiny at the bottom ... so I think it had been cracked for a while and finally let go on Thursday night.

There's another place where the plastic coating has cracked and the metal underneath is rusty - top right corner in the picture I posted.

 

[dozypillock]

Yup this part of the spring can't be seen while it's fitted; as mentioned the main part (which is visible and actually takes the weight) is in good condition.

Where it broke the black plastic coating has come away and there's a lot of surface rust. The break itself is dirty/rusty at the top and clean & shiny at the bottom ... so I think it had been cracked for a while and finally let go on Thursday night.

There's another place where the plastic coating has cracked and the metal underneath is rusty - top right corner in the picture I posted.

I was advised, when I put mine into Ollie at PCS due to thinking suspension was "not quite right" that it is a common problem, and hard to spot, hence my comment in post 2.

As it turned out, mine were fine. He checked whole car for me, and identified my slight wobble as the rear trunnions. He showed me how to check the base of the springs using what I can only describe as a dentists mirror, on a small stick.

I booked it in for the trunnions, as the price quoted was extremely reasonable, and car felt so much safer on the 40 mile return trip.

Probably should have left them worn, as it felt so much better I was confident enough to press the right hand pedal a lot more than normal coming back down the A27.

6 days later, I had a nice letter from Sussex police.

Neil

 

[grober]

Its to do with how the springs are made. They are cold wound which leaves residual stress inside the metal. In other words there's stress inside the spring whether its loaded or not. At this point the new naked spring should have this stress relieved by controlled heating in an oven and the surface hardened by shot peening followed by powder coating/painting.------------ ITS NOT. When eventually this paint/powder coating is broken by road debris damage the metal surface develops small cracks. These cracks act as a focus for the residual stress in the spring widening and deepening till eventually failure occurs. That's why they often "let go" when sitting in the drive- its that internal stress that dates back to their manufacture that administers the " coupe de grace"! Spring life could be extended considerably by modifying how they are made and would cost very little. The only people to do this routinely used to be car manufacturers in Japan.

 

[wongl]

I would have thought that a broken Spring would be a MOT failure, but in my experience, the springs on a MB tend to break off cleanly at the bottom end (like the one shown by the thread starter), requiring someone with considerable experience to identify this.

Every main dealership mechanic and some good indies look for this during a regular service and will notify the owner of the broken springs. This is how I have been informed of the 6 broken springs on my Mercedes cars over the last 21 years - on every occasion it was the mechanic from the dealership, and on most occasion the MOT station having missed it.

 

[BTB 500]

When eventually this paint/powder coating is broken by road debris damage the metal surface develops small cracks.

The surface coating on this spring looks like an epoxy paint ... where it's failed this is definitely not down to road debris though as it's completely hidden inside the cup it sits in.

Here's the other place where the coating has broken ... the surface of the spring is rusted and pitted underneath:



And the point where it broke - you can see the surface rusting, and that the crack extended down into the metal (from the top) for some time before it went completely:

 

[grober]

What I mean by road debris is in the main the small stuff= grit/grinding paste - stuff small enough to migrate into the small spaces between the spring and its surrounding cup. Factor in spring movement and you have a nice little "abrasive situation" to remove a protective coating. The cup may also function as a little "water bath" to retain a small puddle of moisture- conditions just right for the corrosion process.

 

[dozypillock]

What I mean by road debris is in the main the small stuff= grit/grinding paste - stuff small enough to migrate into the small spaces between the spring and its surrounding cup. Factor in spring movement and you have a nice little "abrasive situation" to remove a protective coating. The cup may also function as a little "water bath" to retain a small puddle of moisture- conditions just right for the corrosion process.

That would appear to be true. It does always seem to be the last ring that breaks, as I guess it is the only bit being worn by the cup. It is also generally smaller.

It is probably not exactly easy to use preventative maintenance for this problem, apart from better made spring ends.

Neil