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1999 500SL, 1988 SEC
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Well, with nothing else to do today I saw a set of Brembo front calipers off a 2003 SL 500 on Ebay so snagged them. THey are 4 piston type. What I do know know is if the total area of all 4 pistons is greater than what I have. That is step 1. Cost was $70 which included shipping which is livable. Once I get these for the heck of it I will see what it would take to make a bracket to make them fit. Seems like Roadhouse has already done most of work. I will see what the rotors cost and then see about putting those on the lathe. I have a friend with a lathe and a vertical mill and I am sure he will help, so just maybe I can come up with a cheap upgrade. I know, probably only 3-5 people willing to do this but might as well do something instead of sitting here. Thoughts on the material for the bracket? I am sure original is cast steel but the other sites with new brakes look like aluminum. Would you guys trust aluminum to hold the calipers in place? If so what type. I am skeptical here. I also have to look and see how the antilock brake sensor is mounted. If anyone has ideas, chime in. It might be funds wasted but heck I can't drink in a bar, or go out to eat so.... If it works I will copy the dimensions of the bracket for all.
 

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87 Euro500HVSEC. 88 Euro 560HVSEC. 89 Euro 560HVSEL
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Yes the later 560SL has the same issue with rims re clearance to the centre spokes rather than diameter clearance
The bigger brake aftermarket options is usually more about rim diameter clearance requiring either 17" or 18" rim as a minimum
I know with my gen2 500 & 560 it required the ATE calipers to be skimmed (more rounded) on the outer and upper/lower edges to fit 16" AMG Gen1 Penta's on the front - otherwise they interfere with the spokes.

That CEIKA big brake option on the front with 6 pot option would require 18" as a minimum, but i would say 4 pot option would take a 17" rim
 

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This is not my first time fitting bigger brakes to various cars and usually along the lines of what Roadhouse has done.
Radial mount callipers are easier, due to the simplicity of the bracket in the event there is an offset. The W204 rotor offset will be 3.7mm greater outboard
I just designed a bracket another application with an outboard offset like the attached drawing - note how to accommodate an offset on axial mount ears
Material is 6061 T-6 aluminium
I now 3D print the bracket to confirm fitment, before carving it out of billet

I just bought some 322 x 32 front rotors from a W204/W212 that look like the only mod will be opening up the register bore to the W126, 80mm size as Roadhouse has done
So far cheap and cheerful
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At 185.00 USD for a pair of new, loaded, Brembo 4 x 42 axial callipers from a Caddy, was too good to pass up. Acura TL are the same.
On Fleabay now - eBay item number 164108784527
2625173

It looks like Caddy rotors are 30mm?? so if the calliper does not fit the 32mm MB rotor, and there are no pad shims to remove, I will have to grind the pads/rotor.
Worst case I will have to use my 996 radial mount callipers

Note that the Caddy has 4 large 32mm pistons, so the rear callipers will have to be sized accordingly - how large depends on the lever arm length provided by the rotor
Then the MC becomes an issue...............................

The next problem is how to incorporate a parking brake.
Is there a 5 on 112mm rotor solution for the rear that will fit the stock shoes and mechanism? I would rather avoid a separate mechanical calliper(s)

Much more fun than simply buying an off the shelf big brake kit, and what the hobby is all about for me
 

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Lots of time, confined to home....................
Where does the e-brake shoe ride in the rear rotor?
Width of the shoe?

Stock W126 - 500/560 rear rotor:
2625178


the closest 5 x 112mm rotor, that I can find with integral parking brake:
300 x 22mm
Note that the drum ID section is larger than stock
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my preference is this 320 x 24mm one:
2625180
 

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1999 500SL, 1988 SEC
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Well are you in the process of doing this on a W126? If so I am going to put myself on hold since you are farther ahead of me. No sense of two of us inventing the wheel and you are much better at the drawings than I would be. I am not so sure you need to upgrade the years. 60 % of the work is done by the fronts and the rears are going to be complicated due to the e brake. We also have to watch the MC size and I think we can get away with leaving the original with just the front upgrade. The cadillac calipers look good but will have to see how the rotor size thing works out. Keep us posted please. All my intent is simply to get a cheap, easy to install upgrade for those that might want to try. Maybe Hoghead would be willing to sell brackets at a price to us (hint). Again lets see where this goes
 

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Well are you in the process of doing this on a W126? If so I am going to put myself on hold since you are farther ahead of me. No sense of two of us inventing the wheel and you are much better at the drawings than I would be. I am not so sure you need to upgrade the years. 60 % of the work is done by the fronts and the rears are going to be complicated due to the e brake. We also have to watch the MC size and I think we can get away with leaving the original with just the front upgrade. The cadillac calipers look good but will have to see how the rotor size thing works out. Keep us posted please. All my intent is simply to get a cheap, easy to install upgrade for those that might want to try. Maybe Hoghead would be willing to sell brackets at a price to us (hint). Again lets see where this goes
Yes on a 500 SEC

These 322 x 32 rotors give a lot longer lever arm than the Gen II 300mm rotors, and depending on the size of the front callipers you will have to pay attention to the bias if intending to use stock rotors. In for a penny............so I have decided to do both F and R in order to get the correct bias, use a proportioning valve for good measure, and run 18 " wheels

These 322mm rotors and Caddy callipers were too good to pass up. The 322mm rotors + Caddy 4 x 42mm callipers will be far too much front biased when using the stock rears.
If the Gen II mod will not suffice for you, an acceptable Gen II + solution would be 300mm x 28 Gen II rotors, stock OD rear rotors, both on appropriately sized "bigger" callipers. Radial mount front callipers makes the mount easy, but the skinny rear rotor will dictate an axial mount. I would use thicker rears to simplify the issue, but have not looked into a suitable rotor. Wheels would need to be 15" or more depending on calliper choice.

E-brake is an issue as you point out. Wilwood make a mechanical calliper I have used before but only for a 20.5 mm rotor which limits rotor choices
Hot rod applications use these on the drive shaft as well, which simplifies the rotor calliper mount
Probably too much work for "the look" of radial mounts F&R

I am thinking about modifying the Brembo 09.B745.01 to use the stock e-brake shoes and would appreciate if anyone could confirm the width of the stock shoe.
Likley more work than it is worth for a street car, but has "the look"

Failing that, a calliper with integral handbrake on the Brembo 09.B745.01 rear is easy, effective, and cheaper given machine shop rates. Probably the best bang for the buck on the street. There are lots of other large single piston, US car brand sliding callipers c/w handbrake that could be used. The drawing I posted is for a Lincoln 52mm single pot sliding calliper with integral handbrake on another of my cars.
Not very sexy looking however, unless you glued on a tacky, fake Brembo/MB cover!! I am leaning toward a mid grade budget mod as this is a street car - the same 322 x 32mm on the front and 300 x 20mm or 320 x 24mm on the rears.
Big radial or axial mount 4 pots on the front and a US brand single piston slider on the rear with integral handbrake
Cheap, cheerful, and easy. This is likely the way to go, if you can accept the look of the slider on the rear.
It is not be difficult to get the bias right using a Wilwood proportioning valve, and I have done this before.

Once I figure it out, I could make a few extra brackets if there is interest
No warranty, no liability, for racing use only, not for use in CA, may cause cancer, do not tell your wife you have been modifying the brakes, blah, blah, blah.........

The MC is the next problem
 

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1999 500SL, 1988 SEC
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How about we do this for starters. Does anybody have a set of genIi calipers off? If so let us know the piston sizes and the area of the brake shoes. I also think we need to zero in on a set of rotors about the 330 mm size that the center can be machined to fit the centers on our cars. Ideally a certain distance from the center of the spindle so making the bracket will be easy. 2003 SL 500 rotors look promising. Btw, I have a gen II car with the larger brakes. Adequate but not optimal.

When the SL 500 brembo 4 piston calipers get here I will measure the pistons and brake pads.
 

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Can't see the forest for my old school hot rod rooted trees.
Another solution to the e-brake would be an electric one. Not the complicated in hub method that MB uses, nor a servo + cable system, but a simple piggyback electric motor on the back of the calliper. Not very sexy looking however.
Figure out the mount, and job done!

2625318
 

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2003 SL 500 rotors look promising.
The SL500 fronts have a lot less offset than stock at 71.6mm:
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The W211+ fronts are a lot closer offset to stock, larger OD, thicker, and sexy drilled vents stock. Both will need the centre register bored to 80mm
PN# 204 421 1012 204 421 1012 39 000 421 1112 000 421 3012 000 421 3012 07 000 421 1112 07

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03-500 SL Rears are a bit wimpy by modern standards at 278 x 9mm and issues with the e-brake
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Well the calipers came today and they were fully loaded, in that they have new ceramic pads on them which was great. If this does not work out I am sure I can sell them for what I paid so no loss there. Here is the data from those:
Area of the brake pads 2.25" x 4.5" x 2 pads= 20.25" square inches of brake surface. I did not go to all the trouble to decide on the arc, I mainly assumed a square so surface area = L x W if memory serves me right. You have to multiply by two since there are two pads.

The caliper pistons measured approximately 8 mm bore. If you look one is a slightly different size than the other and I will have to give that some thought as to why they did that but for this it does not matter. So Area = Pi x R squared which would give us 39.44 for each piston, and the total would be 157.76 sq mm of piston area since there are 4. If someone has a stock 88 or newer front caliper off, send the measurement please of those pistons so we can compare. ( I don't want to disassemble my car for this right now). While area alone is not going to give us total clamping force, it is one of the largest factors and we can start there.

Hoghead, thanks for the info on the rotors. While I am not committed to using the calipers I have (the cadillac ones look good) I simply had these coming to see what I could do with them. Again it does not makes sense for any of us going different routes so I am anxious to what transpires with you. We do have to take into account the brake pad wear sensor and the antilock brake one too. That is why I was leaning towards Mercedes.

As to rotors, the 03 SL front rotor size is 330mm but the spacing is wrong and the 1999 Sl is 334 mm with that not being ideal either. Not sure if the 211 is big enough. The ones you were looking at were in the 330 range which is ideal. Its just finding the right one I guess. The less machining the better but it looks like the very least we would have to increase the center bore size. I suppose if we have a rotor on the lathe we can reduce the size too which doing the center bore but no matter what its going to be an issue when you want to change brakes!

Also, if someone has a toasted car with a front spindle, along with the front hub can you send me a pm? I don't want a good one just a mock up.

I was not thinking of back brakes at this time since I really did not want to fool with the bias. Its one of the reasons I was leaning towards the slightly smaller Mercedes ones too.

I will also try to do some research on Master cylinders on a 98 SL and a 99 to see if there is a size difference since between the years MB went to the bigger 4 piston Brembos.

Thanks and anyone that wants to chime in, go ahead but Hoghead seems to be in better design studio.
 

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Area of the brake pads 2.25" x 4.5" x 2 pads= 20.25" square inches of brake surface. I did not go to all the trouble to decide on the arc, I mainly assumed a square so surface area = L x W if memory serves me right. You have to multiply by two since there are two pads.

The caliper pistons measured approximately 8 mm bore. If you look one is a slightly different size than the other and I will have to give that some thought as to why they did that but for this it does not matter. So Area = Pi x R squared which would give us 39.44 for each piston, and the total would be 157.76 sq mm of piston area since there are 4. While area alone is not going to give us total clamping force, it is one of the largest factors and we can start there.

I was not thinking of back brakes at this time since I really did not want to fool with the bias.
Use only 2 of the 4 pistons in calculating clamping force. You will need to measure piston size in order to do that, and know the MC bore

If a differential bore, lead with the smaller piston in direction of rotation

With hopefully more clamping force, and more friction area, you have increased the bias.........................
 
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