Rear rotor fitment issues, 2002 e320 4matic WAGON
 

Hi folks,

Been a long time.

I capitalized "wagon" in the subject line as that seems to be the issue.

I have now been through three sets of aftermarket rotors for my '02 e320 4matic wagon. They fit when placed on the hub, but the issue is that once tightened down the wheel won't turn.

What I have found is that while front rotors are still available for these cars, all the aftermarket companies seem to be selling sedan rear rotors as a "substitute" fitment as the correct parts are no longer available.

I have now ordered the dealer rotors. But even Mercedes only had three rotors in stock in all of Canada when I called, and after those are gone they are listed as "backorder" with no delivery date.

Is this a known issue on the w210 wagons?

It was always harder to find wagon rotors. But Centric still lists 12135044, the sedan shows as 12135034. Raybestos shows the wagon as 980111R, the sedan as 96762R. Bendix shows the wagon as PRT5436, the sedan as PRT5277. I can't believe that all of those manufacturers are selling fake parts. All the above numbers are available from R*ckauto.

You can always have the old ones resurfaced if they aren't too bad.

Also note, Centric parts on RA generally show dimensions.

Let me clarify. Everyone LISTS the wagon part in their catalogue. If you try to order, no one actually has them but they all show the sedan rotors as direct interchange. So they send them. Been there and done this three times.

At least this is the situation here in Canada. Maybe stocks are higher in the U.S.

Unfortunately as I am in Canada, mail order isn't really an option due to shipping costs.

I ordered from the dealer, who told me once mine ship from the Toronto warehouse, there will be one wagon rotor left in national stock. After that they are listed as backorder with no delivery date.

One more thing. The fitment issue is that once the rotor is installed - and it slips on perfectly - when you tighten the lockscrew the hub won't turn.

The difference between the wagon and sedan rotor is that the parking brake is wider on the wagon. So when you tighten it up, the unmachined section of the drum surface impinges on the brake shoe. If you absolutely can't find a set of rotors, a machine shop can turn a sedan rotor into a wagon rotor by removing a little bit of material from the inside of the rotor.

Cab sedan park brake shoes be used in a wagon?

Sixto
98 E320s sedan and wagon

I suspect the answer is yes, but there would be a reduction in swept area, so less braking power.

Thank you for that info, Mxfrank.

You need to measure your original rotor and compare that to the published specs of the rotors you're buying. Rock auto lists that information for most of the rotors they sell. This includes, diameter, thickness and hat height.

Here's something I put together for the w124 all based on rock auto data.
https://i.imgur.com/CVzJf98.jpg

Probably only noticeable when parking a fully loaded wagon on a steep incline. But yes it's a valid point. MB saw fit to equip the wagon with beefier parking brake shoes for a reason.

You always have the transmission pawl as a backup when you park. I think the wide shoe would be important if you needed to use it as an emergency brake.

Modern cars have dual diagonal hydraulic circuits for the brakes. A sudden catastrophic failure of the braking system is nearly impossible, so I would not view the parking brake as an emergency brake - some new cars that have an electronic parking brake will not even allow you engage it while the vehicle is in motion, so it does not function as an emergency brake at all on those cars. Those two little drums are not going to slow the car from highway speed anyways, in an effective way. Additionally the parking pawl has been known to break off, and using it exclusively puts undue stress on transmission internals.

The correct way to park an automatic vehicle is to put the transmission into neutral, set the parking brake, remove your foot entirely from the brake pedal allowing the weight of the car to rest against the parking brake, and then lastly shift the transmission from neutral to park. This eliminates the stress from the parking pawl, and uses the parking brake as intended. The shoes performing as intended are therefore a rather important part of the system.

This isn't funny now.

Ordered rear rotors from dealer. Tried to install. Same issue. Once rotor retaining screw is tightened, wheel won't turn. Confirmed this with both sides.

Also removed the parking brake shoes entirely. Made no difference.

Interference is not with the parking brake shoes, its with the backing plate. All the rotors have a pronounced lip around the perimeter of the inside rim of the hat. That isn't fitting properly into the groove around the inside of the backing plate. That's all we can see.

Rotors Mercedes sold me are 210 423 05 12 64. I have looked online and with the exception of the 64 tacked on the end, that seems to be the correct number.

My mechanic used to own this car. He did the brakes once while he had it, with Zimmerman. He then sold it to a customer about four or five years ago. That guy did the brakes 18 months ago with cheapo white box parts. Never was there any fitment issue, either time.

I have now tried Zimmerman, white box and dealer rotors. While we confirmed with the supplier that the Zimm rotors she was sent were a 'crossover' part number, my mechanic's partner measured then against the Mercedes ones and says they are absolutely identical in every dimension except that the hat on the dealer ones is a hair larger diameter.

The old rotors, in other words the ones that fit, are a hair shallower if you measure their height. Luckily they are still functional, just warped.

Why does the issue occur after tightening the set screw? Is it because the rotor then presses against the backing plate?

Also, when I go to r o c k a u t o, I see that both Bendix and Centrix offer part numbers for the wagon (290mm dia vs 289.7 for the sedan). Are you saying even the aftermarket guys aren’t supplying those anymore?