"Mercedes Streeter" (smart)
02/11/2019 at 11:15 • Filed to: wrenching, Smart
7
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"Mercedes Streeter" (smart)
02/11/2019 at 11:15 • Filed to: wrenching, Smart | 7
| 13 |
In Mercedes-Benz’s infinite wisdom, they decided to make a critical safety component out of bare metal and left it exposed to the elements.
Well it took 155k miles but my 2012 finally succumbed to the infamous reluctor ring corrosion. I actually found a 21st century way to check smart rings, but more on that later.
For the past couple months I’ve been getting a light metallic thumping noise and tactile feedback in the brake pedal when moving at slow speeds. Kinda figured that it was just the car getting worn out rotors and wear indicators of the pads making little love taps. Similar happened before to me when pads were nearing the end of their lives, so I thought business as usual. But then, beginning about two weeks ago I’ve been getting the ABS occasionally activating while lightly braking on absolutely dry roads. It seemed to get worse the faster I went, too. I started thinking that maybe the sensors had icing on them from the crazy cold we’ve been having, causing bad readings (inspection reveals pads have maybe 30% life left, but rotors look rough). However, last night the car finally gave me a clue. It threw an ABS failure while I was going 70mph down the Interstate. Suddenly, the low speed thumps were gone, too. Hmmm...
When the ABS system fails you lose all active safety features. You don’t have traction control, stability control, ABS, hill start assist, or the transmission creep mode. While the more “raw” driving experience is fun and I adore the death of creep mode, it’s frankly irresponsible to leave the car in this condition when I drive it like I do, so off to figuring out what exactly happened!
Evilution (an encyclopaedia on smart repair) recommends putting the car into Neutral, putting it up on stands/jacks, then rotating the rear wheels while you stick your head into the wheel arch to look at the rings. While this does work, it’s a very sketchy task to do in the winter and without ample tools to save the car from crushing you. An easier and safer way to check your rings is to take a smartphone with a LED flash, open your camera app, switch it to video, turn on the LED, then stick it into the wheel wells right above the tyres. Granted, you may not find the crack this way, but you will be able to see just how corroded your rings are. If you have a second person on hand you can have them slowly move the car while you film the rings? Anyway, my rings don’t look so hot.
- Left Ring:
- Right Ring:
Mmm, crusty..
They’re heavily corroded, somehow there appears to be some scoring, and spacing between each tooth doesn’t appear to be equal. This alone is enough to piss off ABS, but there’s also likely a crack somewhere, too. I actually got lucky considering that a lot of reluctor ring failures have been known to happen long before even 50k miles, let alone 155k.
How do you replace the rings? Happy you asked! Remove the rear axles then tug on the rings, depending on how corroded they are they’ll just crumble and fall to the ground. Then you take a new ring (preferably not an OEM one, but one of the galvanized and painted aftermarket ones), wire brush away the surface rust on the axle, then slide on the new ring. Button up the axles and enjoy a working ABS that should now last the rest of the life of the car.
*Sigh* Who even signed off on this? It was a rampant issue in the first gens so they just decided to change absolutely nothing in the second gens? At least the aftermarket did what MB failed to do.
RamblinRover Luxury-Yacht
> Mercedes Streeter
02/11/2019 at 11:26 |
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It’s almost like the designs that tuck the reluctor rings away into a spindle or bearing housing are onto something.
Shitty mild steel reluctors can’t corrode if you keep them away from what makes corrosion and in close to a source of heat.
shop-teacher
> Mercedes Streeter
02/11/2019 at 11:27 |
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Why would they fix it, when they can do nothing and still overcharge for those tiny piles of stylish dung? ;)
Spamfeller Loves Nazi Clicks
> RamblinRover Luxury-Yacht
02/11/2019 at 11:31 |
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You mean like this?
(Yes, you have to replace the entire hub and it’s non-rebuildable
. It’s the same deal
out back as well.)
Dr. Zoidberg - RIP Oppo
> Mercedes Streeter
02/11/2019 at 11:31 |
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Nice read. Nonetheless, I still used google because I am not handy:
A reluctor ring is a notched circle used in the anti-lock brake system ( ABS ) and the ignition system of cars. The anti-lock brake reluctor rings are located on each wheel. The distributor-less ignition, or direct-ignition, reluctor ring is mounted on the crankshaft that triggers the magnetic sensor.
Well, that sure doesn’t sound like something you don’t want exposed to the elements!
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Mercedes Streeter
> RamblinRover Luxury-Yacht
02/11/2019 at 11:37 |
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The crazy part is that the front wheel reluctor rings are sealed in the spindles up front and are generally expected to never fail.
The only reason I can think they didn’t do it in the rear is because the rear uses a different type of bearing and drum brakes...but even then it seems the least they could have done was not use such awful metal.
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Mercedes Streeter
> shop-teacher
02/11/2019 at 11:43 |
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Exactly! ...I guess? :O
The dealership says you can’t replace the reluctor rings and you have to replace the whole axle and related components. IIRC, the axles are like $700 each and the MB shop rate is very “ affordable ” .
In reality, t he rings themselves only cost $50 for an aftermarket pair that won’t rust and you can install them with not a whole lot of effort. It’s more time consuming than it is difficult.
MB also says you can’t replace the front wheel bearings and you have to buy a whole hub and $ pindle a$$ embly when the bearings go. And surprise, the reality is that you can get new bearings for $60 then have a shop press them into the existing spindles.
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RamblinRover Luxury-Yacht
> Spamfeller Loves Nazi Clicks
02/11/2019 at 11:53 |
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Yes, I did mean like that. Kind of a shame it’s not rebuildable, but that format is ubiquitous because it
works
. There are also truck hubs and others
(that are rebuildable) that have the reluctor rings essentially tucked into the front spindle. Because it’s not dumb.
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RamblinRover Luxury-Yacht
> Mercedes Streeter
02/11/2019 at 11:57 |
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I get that putting reluctor rings on CVs is a neat and effective way to get it done, but usually that happens on a FWD where the ring isn’t as exposed. And,
since sealed hubs of the kind The Actual RootWyrm posted are so commonplace for mating to CVs (and not that expensive)
, it’s a special kind of perversity to engineer something worse.
Cé hé sin
> Mercedes Streeter
02/11/2019 at 12:09 |
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I started getting the ABS and ESP light thing randomly a few months ago, but my Smart specialist diagnosed and fitted a brake light switch (following which I fitted it again myself but properly this time). I still occasionally get both lights on though, always after going at a steady speed for some time. I just stop and start the car again and it’s good for another random interval.
It’s almost
as notorious as crank position sensor failure.
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Mercedes Streeter
> Cé hé sin
02/11/2019 at 12:23 |
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Oof! Thankfully my brake switch is still alive and well (so far as I can tell).
Funny you mention the constant speed thing, that’s exactly when my ABS/ESP fails. It’ll go through the self-check and work up until I stay at a steady speed for like 10 minutes or so. I wonder if your reluctors are as crusty as mine?
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Mercedes Streeter
> RamblinRover Luxury-Yacht
02/11/2019 at 12:27 |
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And,since sealed hubs of the kind The Actual RootWyrm posted are so commonplace for mating to CVs (and not that expensive),
it’s a special kind of perversity to engineer something worse.
Sounds par for the course for smart! The 600cc engines in the early first gens needed rebuilds every 40k miles, these stupid reluctor rings that somehow survived through two generations (maybe three, I haven’t checked if my 453 has them), computers that will wear themselves out until they catch on fire , and a bunch of other dumb decisions.
And I get called disrespectful for speaking ill of the poor engineering that went into a lot of the fine details of the car. lol
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Cé hé sin
> Mercedes Streeter
02/11/2019 at 12:53 |
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I did mention it to the specialist, but he still said brake light switch. That obviously wasn’t the whole story though. What happens is that the car will eventually and gradually lose power as the traction control system thinks it doesn’t have traction.
On a related matter, I’m just back from Paris. When I’ve been there before , 450s were everywhere Now, they’ve vanished. You see a few 451s but very few 453s. They seem to
have stopped sel
ling.
AMGtech - now with more recalls!
> Spamfeller Loves Nazi Clicks
02/11/2019 at 15:41 |
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because those NEVER fail!