Reman vs New Brake Master Cylinder?
 

I was looking a replacing my brake master cylinder some time here and saw some reman masters..they're like 50% cheaper than the new ones...

Anyone have any feelings towards reman/new?

This would be for my 201 190E, it'll be a 0044307501 master (500E, v8 126s, etc)

The fact Mercedes doesn't include these in its own rebuilt parts catalog might be of some significance. (It would influence me to purchase new)

http://www.startekinfo.com/StarTek/outside/11039/?requestedDocId=11039

I'll throw this out - not because I necessarily believe it - just making it available for view.

Back in the earlier days of the internet - there was the Ritter-Easley MB list.

Stu Ritter was an MB tech - owned an independent dealership in Colorado - worked on MBs for 30 years. He started his career in a San Franscisco MB dealership.

He was adamantly against the use of rebuilt brake calipers - safety issue.

The new/dealer provided MB calipers were top flight in his view; anything else was liking skating on thin ice.

Believe what you want.

Well, we're talking master cylinders here, and we're also talking a stable of well-worn mules. Basically the wear items on MC's are the piston seals. If it ain't a-leakin' it's a-workin'. If your brake pedal isn't caving in as you maintain pressure, the seals are good.
The next question would be are rebuild seals as durable as OEM? No idea, but how long do they need to hold, another 18 years? Also, on my '85 W201 I remember replacing the master cylinder in 1997, so who's to say that OEM is better quality anyway?
I'm sure the re-man has a warranty, so I'd have no qualms using it, but would just make sure it worked to my satisfaction within the warranty.

Hirnbeiss,

My pedal is fairly soft, up until the final 1/4 worth of travel where it mostly engages the brakes. The first 3/4 really dont stop the car. Slow it down a little yes..The pedal kind of sinks thru the first 3/4 with ease..

With the size of the calipers on my car I feel it should really be stopping it by no more than 1/2 pedal travel. if that.

Refurbished hydraulics - on cars - hmmm that can be a tricky one. On aircraft (particularly military aircraft) there is a wonderful thing called scheduled maintenance where things get taken off - checked and repaired. Having been part of this - I can say that that is where components get saved before something gets to a non-repairable stage or corrosion sets in.

From my experience of hydraulic components on cars I would say that if the part is corroded near or on the sealing surfaces you may as well chuck it. I have recently, for example, spent a lot of time trying to reseal the calipers on my W123 but they were too far gone.

But that doesn't necessarily mean that your MC is dead - if you can do the work yourself you could rebuild and test it. Failing that if you know of someone else who can why not get their professional opinion?

EDIT ah ha seeing what you've just written I'd say bleed it first!

Ah I knew someone would say bleed them first.

They've been bled numerous times. I went through several tins of ATE TYP 200 fluid bleeding them. I swapped master cylinders from another 500E unit I had sitting on my shelf (for about a year) then had them professionally bled..was nice for a few months..but now its as I described above.

I think I've decide on getting a new ATE master, its like $155, a reman one is like $100+core, $55 isnt much for a new unit.

I hope it fixes the problem - but remember there are more parts to the system than just the MC...

I've not bought it yet but, yes you are correct.

I'm also going to replace all the soft lines with new ones. I hope at the point it solves the problem. Not sure what the next step would be. Not the booster...as if that was bad the pedal would be hard to apply, which is not the case. I guess that leaves calipers?

It would indeed mean calipers - but if as you say the MC is good for a few months I feel obliged to point out that flexible lines are cheaper than a MC...

Good point, I should probably just pickup a set of flexible lines, install them, bleed, and see if theres any difference. Then, if none, either master or calipers. Good point sir.

for safety reasons I would always buy a new m/c. Don't have to have it in a mb box- ATE or whom ever supplies it to benz.

If you wanted to skimp and use a rebuilt caliper- that would be different.

Aerospace quality should be higher than any car stuff- but there again failure rate of new versus rebuilt, I think new will always win.

Michael

Why would that be different?

Mercedes wants ~$470 for a new caliper. Rebuilts are $92.

I've decided I wont buy a rebuilt master cylinder, the $50 is a lot different than $300+x2.
They sell a rebuilding kit, but its as most than a new ATE mc...

First order of business is the hoses though. I dont detect the brake pedal sinking. I detect it just taking full range of motion to fully apply. My 420SEL's brake feel 10x better.

i replaced the MC on my 108 due to the sinking pedal ,turned out one of the front pipes was swelling up under pressure and causing the sinkage.firm pedal now
On 126 replacing the MC has not done the trick as has pressure bleeding the system.it is indeed soft in the first half .braking works well .
mak

mak, when you say front pipes..you mean the soft rubber lines or the hard metal ones?

I'm not sure if master cylinders are "paired" to certain types of calipers. Since you've upgraded yours, it might be possible that the upgraded calipers require a beefier type of MC and would (might) prematurely wear yours out.

Just tossing this idea out there.

master cylinder should be about 190.00 retail, that's for a genuine ATE brand master. might get it for less but just make sure it's ATE brand and it will be exactly the same as the one from the dealer.

Sponginess alone is usually not caused by a bad master cylinder. If you don't have visible leakage caused by deteriorating grommets or corroded fittings, the other failure mode would be leaking piston seals due to wear or corrosion. This will cause fluid to leak back into the reservoir, and you will notice that your pedal continues to sink to the floor to compensate.
Sponginess = gas in the fluid or elasticity in the brake lines
Sinkiness (yes, approved King Julien word) = fluid leakage around internal seals or out of fittings.

LOL King Julien.

I've got a replacement set of brake lines coming and a liter of typ 200. I'll replace them and bleed the system.

We'll see what that does, if I still have sinkiness, perhaps some replacement calipers are in order.

Alright. I replaced the lines, no real differences.

I replaced the master cylinder, bled the system with a power bleeder, I opened each bleeder for like 30 seconds to get all the air out...still feels soft. Like I dont get any REAL breaking power until I hit 3/4 pedal travel..

When I got the old master out, I squeezed the piston on it and fluid shot out of the side port, but nothing from the top port...is that a return? or does that indicate that its bad?

Whats next on this list? Could the calipers be bad?

On my W123 I often need to bleed a bit longer than 30 seconds to get the air out... it isn't really a time thing - it is more of a stubborn bubbles still coming out thing.

If I were you I'd give the system another bleed - if you still see bubbles - keep going!

Another trick - just in case you are still busy welding - is to wedge the brake pedal down for a night or two or three! I read this tip on this forum but I've forgotten who posted it originally - so credit goes to ???? - still if this makes even a slight difference then you know it is air in the system.

As for the calipers you can check them out by pushing the pistons back in - catch fluid that pops back out of the MC with rags (it has to go somewhere) - and then get someone else to apply the brakes whilst you watch the piston travel. They should be fairly smooth. Sometimes it is difficult to see this on a car - you can test this with the calipers removed from the car but you need stop the pistons from popping out with an appropriate sized block of wood (for example).

You did bleed the MC thoroughly first?

I didn't do anything special to the MC. I had searched on here and the general consensus seemed that I could power bleed it after it was installed and be OK.

I did notice the follow:
-On long highway cruises, stopping at the off ramp, the pedal felt pretty good on the first press
-Leaving this morning after setting up Army's leave-the-pedal-engaged overnight trick seemed to improve the pedal for the first few pumps.

I have no external leaks. It could be an internal seal issue on the calipers, I'm not sure how their internals are laid out and what could "go bad"...

I'll give it another bleed in a few days.