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Discussion Starter #1
Somebody asked me, and I don’t know:

Is the R171 braking system “brake-by-wire”?

If, as I suspect, it’s all hydraulic, what kind of brake-bleeding system is the best to use? My friend, who, like me, has been a car head all his life (we’re the same age, grew up in the same town in Upstate NY, just 40 miles from Watkins Glen, and I attended my first race there in 1961 — yeah, we’re no spring chickens) advised me:

“Get a pressure bleeder with the right adaptor for the master cylinder reservoir, unless that won’t work with brake by wire (if that is what you have). I have a Motive brand pressure bleeder.”

Is this what I need?

https://www.ebay.com/itm/Motive-Products-European-Power-Brake-Bleeder-0100-Hand-Pump-Pressure-Tank/323662376805?epid=1530558652&hash=item4b5bc7ef65:g:rFYAAOSwrMhcjdMq

Thanks for your help!

Bart
 

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No, only some S, SL, E and CLS got Mercedes brake by wire which was then discontinued due to high cost and negative publicity (it was beautiful btw).
Yes that bleeder will work, you need to provide enough pressure to open the valves on the abs/esp to bleed the system.
 

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Discussion Starter #3 (Edited)
No, only some S, SL, E and CLS got Mercedes brake by wire which was then discontinued due to high cost and negative publicity (it was beautiful btw).
Yes that bleeder will work, you need to provide enough pressure to open the valves on the abs/esp to bleed the system.
Thanks, V117!

When my friend says “Get a pressure bleeder with the right adaptor for the master cylinder reservoir,” how do I know I’m getting “the right adaptor for the master cylinder reservoir”?

NEW EDIT: the seller’s listing says “Works on most European cars, including Alfa Romeo, Audi, BMW, Fiat, Mercedes, Peugeot, Porsche, Renault, SAAB, Volkswagen, Volvo, and all other cars with 45mm threaded hydraulic fluid reservoir caps (This kit includes adapter 1100).”

I just contacted the seller with the specific question “does the 45mm threaded hydraulic fluid reservoir cap fit my 2005 R171?” Does anyone know if that’s the size and type of reservoir cap I need?

Thanks!

Bart

Bart
 

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Discussion Starter #4
Weight of R171 Brembo brakes, front and rear

Does anyone know the weight of my R171 Brembo front and rear brakes?

Thanks

Bart
 

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Super Moderator UK SLK 55 AMG 2007
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Beware of works on a list of makes.

Yes, it may work on Mercedes, but does it work on an '05 55.
If seller cannot answer, look elsewhere.
 

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brake bleeder

Or get a empty freon tank, pull a vacuum on it and attach a clear hose to the tank and one that fits over the bleeder valve on the brake bleeder, slower open tank valve and brake fluid flow from the master cylinder to the tank.


1. Step, suck out the old brake fluid from master cylinder and fill with new.


2. Connect hose to brake bleeder at the wheel. Loosen bleeder and open tank valve. First time have someone watch the master cylinder so you do not run it empty. It must stay full. Bleed the rest of the brakes. Top off fluid in master cylinder when finish. Been doing this way since the late 60s and works on Aircraft, my RV, SLK and all my other vehicles.



Have a nice day.
 

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Premium Member 2005 SLK 55; 2005 SLK 350
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The cap sizes on all R170's and R171's I've seen is a common size across many makes, models, and years. I have a motive bleeder as well and it came with this cap.


The rotors weigh 22 lbs 8 oz per the wife's kitchen scale.
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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I'm not an expert at all
but if you are just doing rotors and pads, you do not need to mess with the bleeder/brake fluid at all.
See caliper hanging?



 

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Yes that bleeder will work, please take precautions when working with particularly old or damaged reservoirs as these might fail when pressurised.
 

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Discussion Starter #11
The cap sizes on all R170's and R171's I've seen is a common size across many makes, models, and years. I have a motive bleeder as well and it came with this cap.


The rotors weigh 22 lbs 8 oz per the wife's kitchen scale.
Thanks for the kind reply. Is that 22 lbs 8 oz per rotor (please correct me if I’m wrong, but every video I’ve seen on the subject seems to claim the two-piece Brembo-style w/aluminum hats are lighter than the rears.

Bart
 

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Discussion Starter #12
Brake fluid should be replaced every two years due to moisture build up.
This prevents both brake failure under heavy use and corrosion to the brake system.
I have all the CarFax reports on this car, and most of the service notations go something like “performed x-thousand mile maintenance.”

As jbanks has noted, and I’ve seen from videos by FCP euro (35 miles down the coast from me), LegitStreetCars, and elsewhere, I’ve only seen one video where the brakes have been bled and the reservoir topped off after changing pads and rotors.

As jbanks’ post shows, in almost all the videos on the subject, once the pads are out of the calipers, the caliper is tied up out of the way with nylon cable ties or coat hanger wire, and when finished, with new rotors and pads, the calipers are simply re-bolted in place, with no bleeding.

I’m sure brake fluid has a finite life. Is there a way I can tell if the fluid is past its prime — specific gravity, color, anything? It’s always been my supposition that from the brake fluid reservoir to the calipers, it’s a closed system, into which air cannot intrude. Is that wrong?

Thanks for your post.

Bart
 

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They sell rather inexpensive testers for brake fluid, you could also go by color as MB is clear and gets darker with moisture.
Replacing brake fluid is not necessary when changing pads, the 2yr interval is independent.
Brake fluid is hygroscopic, the system is semi sealed and moisture can travel through rubber.
 

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Discussion Starter #15 (Edited)
I'm not an expert at all
but if you are just doing rotors and pads, you do not need to mess with the bleeder/brake fluid at all.
See caliper hanging?



Though this is not spam, I HAVE, to avoid repetition of other words, copied and pasted part of my reply to V117 in response to jbanks’ post.

Jeff:

Yes, I have seen many, many videos where the caliper is simply trussed up out of the way, then when the rotors and pads are installed, the caliper is un-trussed, and re-bolted in place, and no bleeding is performed. The reservoir is sometimes topped off.

Thanks for your reply.
Bart
 

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Discussion Starter #16
:laugh:g
The cap sizes on all R170's and R171's I've seen is a common size across many makes, models, and years. I have a motive bleeder as well and it came with this cap.


The rotors weigh 22 lbs 8 oz per the wife's kitchen scale.
Thanks for the response! Is that weight for one rotor, two, or four?

Regards,

Bart
 
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