JunoJim

I have a '97 SL 320 - the pads look thin, and rotors look like they may need turning - is this a job for an MB specialist, or can the average shop handle the turning ??? Also, what are those "dustless" pads I heard about ???

steve s

rotor turning is usually the last thing u do. is something wrong with ur rotors?

scorchie

Most shops do not have rotor lathes that can turn the rotors to the specifications MB requires. Therefore, rotor replacement is the preferred avenue. Since rotors for your car are not terribly expensive, I would recommend doing that rather than turning. My SL500 rotors were about $80 a piece a long time ago for Ate Powerdiscs, and stock replacements should be much cheaper now. So considering that turning may cost you $50, rotor replacement is almost always a better choice. If you find you need to not eat lunch a few days to justify the extra cost of new rotors, I suggest you not eat lunch for a few days, and also consider a different vehicle because when you have a major problem with your SL, the repair bill will shock you!

-s-

JunoJim

Geez - I thought rotors were a lot more expensive than that !!!

My rotors don't look too bad - they're just scored a little...

To tell you the truth, I never turned the rotors on my RX7, even tho they were scored - just put on new pads - they worked fine...

Hopefully I won't have a major problem... but with the complexity of that cars various systems, I'm probably dreaming...

scorchie

If your rotors aren't near the minimum thickness imprinted on the rotor hat or edge, you should be OK with just replacing pads!

-s-

SLCPUNK

I have read somewhere that you cannot turn Mercedes rotors. I had my 190e 2.6 a couple of years ago. I pulled the pads and the rotors were grooved pretty bad. I was in auto tech school at the time (brake class no less) and there was a brake spec book. I found that Mercedes did have spec that I could turn to. Once I measured it and then looked at the spec I realized it would be too thin after I turned it anyway! So I bought new rotors and did it all at once. If you were able to turn it I couldn't imagine it being any different than any other rotor on a lathe.

scorchie

In general, you CAN turn Mercedes rotors... there are a few applications that you should NOT though. Check the technical specs for the car in question.

Many of the cars have a specification to turn the rotors. This are specifications in excess of just a minimum thickness, they are specifications that apply to a rotor lathe. If you look at rotor lathe marketing materials, you will see that they have various specs. When comparing these specs to the requirements that Mercedes-Benz sets out, you will see that it takes a VERY EXPENSIVE lathe to meet the minimum requirements. Most places will not shell out this kind of cash for a lathe when rotor replacement is relatively cheap compared to the amount a service center must charge to recoup the labor and cost of tools.

I am not sure which school you went to, but when I was in auto tech school our lathes were DEFINITELY not up to Mercedes specs... last time I checked (about a year ago) there were only two lathes sold in the US that even met the requirements.

So yes, the Mercedes rotors are a bit different than most other cars' rotors when on a lathe!

-s-

SLCPUNK

That makes sense, thanks for the info.

Edit: "I am not sure which school you went to, but when I was in auto tech school our lathes were DEFINITELY not up to Mercedes specs... last time I checked (about a year ago) there were only two lathes sold in the US that even met the requirements. "

I don't think I meant to imply that the school lathes were up to Mercedes specs. What I said was that I had heard that they should not be turned (from techs on and off the internet) and when I was in class I had a raybestos spec book that listed a spec to turn Mercedes rotors to. I was suprised to see this since I always read/heard they should not be turned.

I assumed turning a Mercedes rotor couldn't be much more difficult than turning any other rotor and stated this as such. I did not mean to state it as a fact, rather, just as an opinion.

JunoJim

My mechanic says the rotors are harder material than most other, and there's also somrthing about the surfaces are not finished parallel...

Anyway, if I buy new rotors & pads, I guess I need new bearings too, and then there are the sensors - do they come with the pads ??? Are they proximity sensors, or something like that ???

Most of all, where can I get these parts, at a reasonable price, and are they more difficult than other disks to replace ???

scorchie

Actually, Mercedes rotors tend to be made of SOFTER material than, say, American car rotors. This is because they are considered sacrificial, and give better braking performance (in Mercedes' eyes) that way.

Sensors sometimes come with pads, usually do not, and can be reused from your old pads if you did not wait for them to be activated.

Wheel bearings are completely separate, and do not need to be touched. The hub and rotor are two different parts on Mercedes, as this fits in with the belief that rotors are sacrificial, they should be easy to replace.

There are a number of places you can get OEM parts inexpensively, such as bimmerzone.com and thepartsbin.com ... hope that helps.

Places you can get upgrades (such as crossdrilled, etc.) include evosport.com and autowerksdirect.com.

-s-

rob_fed

I would tend to agree that Mercedes rotors are softer than others. It would seem that BMW rotors are very similiar. Both on my '94 540 and my '99 E320, the rotors wear with a ridge on the circumference. It is very noticible and I have seen others just like mine.

From my post on the W210 forum, my front rotors were stuck on the hub, after some penetrating oil and a few good whacks with a small 5lbs. sledge hammer (hit near the mounting holes), they poped right off.

I went for the simple brake job:

* Stock Pagid pads
* Rotors turned - Pep Boys $8 each From their computer database, they have all makes/models rotor thickness specs.
* Unbolted everything with a $20, 12V electric impact wrench

As for the expensive lathe, Pep Boys does not have one. I have replaced pads with and without turning the rotors, for everyday use, probably does not matter. For you more "performance" oriented ones, probably does and probably should upgrade all components.

My 2 cents,

Rob Lee