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Jonathan Joseph
Expert
Date registered: Oct 2006
Location: Charleston, South Carolina
Vehicle(s): 2004 G55
Posts: 1538
| 460 brake rotors
I'm about to replace my front brake pads but the rotors are pretty badly pitted. Yes, pitted like they have been under salt water for some time. No grooves like you might expect after alot of abuse. They measure just a hair under 16 MM now which I believe is what they are supposed to be new. 13MM supposedly is the minimum. Has anyone had experience cutting these rotors and to what minimum thickness? I think removing 3MM will clean them up pretty well. I've had experience with machined rotors warping in the past but I am hoping that MB designed in a little extra meat just for this reason?
I'm willing to take the chance that they warp as it's cheap to machine them and not a big deal to change them out if it doesn't work.
Jonathan |
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Inkblotz
Expert
Date registered: Apr 2006
Location: Georgia
Vehicle(s): 90 300GD "Thundering Turtle II", w/ 603A turbo
Posts: 3186
| RE: 460 brake rotors
Jonathan
As long as it is within MB spec go for it. If at some time in the future they warp (you'll feel it) replace them then.
Mark |
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Jonathan Joseph
Expert
Date registered: Oct 2006
Location: Charleston, South Carolina
Vehicle(s): 2004 G55
Posts: 1538
| RE: 460 brake rotors
Thanks Mark, that's the plan.
Jonathan |
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Adoni
Expert
Date registered: Apr 2006
Location: Sacramento, CA
Vehicle(s): '00 G500, '15 C300 4Matic, '06 L322 G4
Posts: 1283
| Re: 460 brake rotors
Mine were blued when I replaced them, I think it corresponded perfectly with my speed crazed reckless driver brother driving a 5k lb. G-Wagen down the grade from Lake Tahoe... |
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Brent
Expert
Date registered: Apr 2006
Location: SW Colorado USA
Vehicle(s): '13 Wolfsburg GTI
Posts: 1754
| RE: 460 brake rotors
Personally I would just replace them now. The rotor is a heat sink, removing mass reduces the rotors ability to absorb and dissapate heat. They will certainly warp sooner than later if you take them down anywhere near the minimum spec.
My opinion is that the brakes on G's the prior to the G320 are seriously marginal to begin with. New rotors are not that expensive. Replacing them now saves the hassle of doing it again next week  The other issue is that many shops have very antiquated equipment for machining rotors and many times they do not come out true. I just don't bother anymore and simply pony up for new ones. |
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Jonathan Joseph
Expert
Date registered: Oct 2006
Location: Charleston, South Carolina
Vehicle(s): 2004 G55
Posts: 1538
| RE: 460 brake rotors
Brent,
Thanks, thats the kinda experience I was wondering about. but since the rotors are off and its a fraction of the cost to turn them and it looks like it's the first time, I'm gonna give it a shot. We'll see. Like I said before I'm hoping like so much on the G, Mercedes designed it for repairability, and that removing .075-.100 inch will be within acceptable tolerances. ( At least they say it is.) I'll let you know how it works out. |
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pistonhead
Member
Date registered: Apr 2007
Location: Loughborough, ENGLAND, UK
Vehicle(s): Nissan QX.
Posts: 22
| RE: 460 brake rotors
Jonathan Joseph - 4/6/2007 4:52 AM
I'm about to replace my front brake pads but the rotors are pretty badly pitted. Yes, pitted like they have been under salt water for some time. No grooves like you might expect after alot of abuse. They measure just a hair under 16 MM now which I believe is what they are supposed to be new. 13MM supposedly is the minimum. Has anyone had experience cutting these rotors and to what minimum thickness? I think removing 3MM will clean them up pretty well. I've had experience with machined rotors warping in the past but I am hoping that MB designed in a little extra meat just for this reason?
I'm willing to take the chance that they warp as it's cheap to machine them and not a big deal to change them out if it doesn't work.
Jonathan
Hello Jonathan,
You should have no problems machining your brake discs, I have been doing this for a number of years. Obviuosly, care must be taken not not cut below the minimum thickness, and cut only what is necessary to remove the pitting. I usually gave my discs to a machince shop to skimm them, and they made sure they did not cut below the minimum. If more has to be cut, then rest assured, the disc is in need of renewal. Relatively, these are not too dear, for what they do.
Regards,
Rakesh K Anand |
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Brent
Expert
Date registered: Apr 2006
Location: SW Colorado USA
Vehicle(s): '13 Wolfsburg GTI
Posts: 1754
| RE: 460 brake rotors
I guess everybody has had different experience with machining brakes. I guess ones expectations are to be considered, as well as the use. Sure it can be done, sure it works (sometimes). The question I pose is.....do you want to do the brakes on the cheap? The brakes are seriously marginal to begin with, a solid, non-vented disc on a 5000lb machine  My little Subaru has much bigger brakes and I can smoke those coming down the mountain. To each his own but it seriously disturbs me when peoples best evidence that it is a good practice is that they have done it for years? Really, on G-wagens? For as cheap as the rotors are, it is a no-brainer in my book, especially on these trucks. To each his own  |
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dai
Expert
Date registered: Apr 2006
Location: Oregon USA
Vehicle(s): 300GD 300TD BMW R100RS Landini 80F
Posts: 2110
| Re: 460 brake rotors
I would take the opportunity to try the rotors that AMZ found in South Africa. The rotors coupled with the matching pads sound like a big improvement and any improvement on these stoppers would be worth a try. They are very reasonably priced. I think turned rotors will be more likely to warp than full thickness new ones. I never consider turning rotors on our 123 chassis. They are also solid non vented rotors like the G and turning those isn't worth it in my opinion. I try to change out the pads at 50% to avoid having the pistons travel too far out of the calipers. They push back in smoothly and I find I have fewer caliper seizures and the associated cost of buying a pair of those rather expensive parts. Rotors are pretty inexpensive for what they do and pads are a bargan. It is a really heavy truck.
-Dai |
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Jonathan Joseph
Expert
Date registered: Oct 2006
Location: Charleston, South Carolina
Vehicle(s): 2004 G55
Posts: 1538
| RE: 460 brake rotors
I was a car mechanic until 1993 or so. We rarely replaced rotors that could be machined within specs. This was standard practice among all of the garages I was familiar with them, so much so that alot of shops had their own brake lathes on site. We sent ours out to a machinist but it cost only about $10-15 USD per rotor( or drum) Rare was the car that came back with warped rotors anytime soon. (We had a very loyal client base and tried to provide the best service not rape them and take their money, probably why that shop no longer exists!)
I should say that many rotors that I have seen needed resurfacing almost at every pad change interval. This would be a costly maintenance regime if one were to replace rotors and pads every time.
My style of driving the G (seven days a week, probably about 15 thousand miles in the last 15 months, sometimes towing as much as 6000lbs) has so far caused me no alarm, even with the current condition of the brakes(Not great) I don't drive in the mountains, and I don't try to get up to 60mph between every red light. ( Not that that is possible in a 300GD!) I think factory spec is good enough for me right now. And if MB says there is a 3mm range in rotor thickness, doesn't this indicate they intended that the rotors could be machined?
Dai, one thing I think I've seen alot more of than warped rotors is seized or sticky calipers. I don't hesitate to rebuild them if they even look too dirty to me.
Talk about cheap insurance, new seals and dust boots and the assurance that you know what the inside of your caliper looks like, and that all the actions of the caliper are moving smoothly( Grease those sliders!)
Jonathan |
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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| RE: 460 brake rotors
I had my rotors cut down to 13,5 mm, and have had 5,000+ trouble free miles since.
Let me qualify it, though, because my truck use is solely around town "stop and go" driving, and we have absolutely flat terrain. |
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roughneck
Expert
Date registered: Apr 2006
Location: UK, Germany & USA
Vehicle(s): 270 cdi.300 GD 300 GE.lwb 300 GE.swb. Disco 2
Posts: 4398
| RE: 460 brake rotors
When it comes to brakes, I prefer to know I,m going to stop than wonder wether I will. |
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Jonathan Joseph
Expert
Date registered: Oct 2006
Location: Charleston, South Carolina
Vehicle(s): 2004 G55
Posts: 1538
| RE: 460 brake rotors
Roughneck I was going to direct a question to you since you seem to piece together so many G's . You don't machine rotors? Just replace them?
Jonathan |
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