w126 Bigger Brakes on W123
 

There's a few good threads that state its a direct bolt-on. I replaced my W123 frt brakes with the ATE Calipers, backing plate & rotors from a 420SE. Bolts up just fine until I went to put my stock 14" Bundt's on. The Caliper rides on the rim. My combination seems to match what other people have already used with no problem. Any advice? Is there certain 420SE years where Calipers don't work?

Up to 1986 the W126 & W123's used 14" wheels. The 1986 W126's went to 15" wheels due to the larger front brake discs that were used.

If you want the larger brakes you need the larger wheels.

I don't know if it's related, but is there a reason that some of the cars have sliding front calipers, while others in the same time have fixed (two piston) calipers instead?

My SD has the fixed calipers, while the SEC has sliding calipers. I've been eying the SD style ones as a possible conversion, but am not sure why there was a difference.

That is not the reason, I don't think. I think the floating calipers offer better performance or lower weight so are fitted to the sec. which has some parts in common with the SLs of the same era, such as the gorgeous aluminum a arms in the rear.

Tom W

Only the early Gen I SEC's have floating calipers. As of 86 here in the states they went to 2 piston calipers/larger rotors.
Personally, I like the piston on each side method.. I know AMG used 560SL 4 piston calipers as part of it's brake kit back in the day.

Jonathan

I prefer the non floaters too. Are the sec calipers four piston? I would have thought two.

Tom W

The Gen II SEC calipers are two piston...the SL calipers are the 4 pot.

My Hammer has the AMG brake package which at first look is running the SL calipers. Haven't pulled a disc to see if they are different...

Jonathan

If you have 15" and up diameter wheels later w126 calipers and discs should not be an issue?

I don't know from experience but I would guess yes.

Tom W

My only concern on this car would be wondering what the ABS computer would do with the different braking potential.
I'm not sure just how to express this, but if you improve the brake efficiency for the given pressure applied at the pedal, I would think that the automatic brake application/release that the ABS was calibrated for could be wildly out of spec with the new brakes.

All that being said, I'm more then willing to listen if there is info about this that I'm missing, or if there is a different rear brake configuration that can be fitted along with the improved front brakes, to enhance them to match!

I don't think that would be a problem..all it's looking for is a wheel that is moving a certain % less then the others and that's how it 'reads' a locking wheel..it will then pulse the pressure until that % comes down.

Front and rears are the same on all of these cars..MB used the same rear disc for Ages:)

Jonathan

jhodg5ck is correct. the transducers on the wheels only care about the speed in which the wheel is traveling in relation to the other wheels. They have no idea what kind of binders you have. They just tell the ABS unit to apply them!