So after trolling the parts yards and disasembling far to many vehicles i have some questions. All the big brakes threads i see reference the 420 4 piston ATE calipers whats the difference between those and the 4 pots one the post facelift 320 sportline cars?

The big brake threads I've seen reference 1st and 2nd generation W126 front brakes.

What are the donor and recipient cars in your query?

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

Ive already done the upgrade. My questions stem from the fact everything i have read says these will not fit under 15" rims yet there they are. So Im wondering if the 94 320 calipers are slightly smaller then the 420 calipers. I dont have a 420 to measure. I do know this was worth it, all told it cost $75 for two calipers $8 for rotors and I'll need new brake lines at $12-$20 ea. The stopping power is awesome. In other words I wanted to know if the 320/420 have the same caliper and also to share that this is a great upgrade for a fairly low price. [IMG][/IMG]

The early big brakes (400e and 1993 300e) have 295mm x 22mm rotors.
The later big brakes (E320 and E420) are 294mm x 25mm rotors.
There is no diff between sportline and non sportline brakes for any given model year.
The early skinny rotor 4 pots have a bad habit of warping. I have the skinny brakes on my 87 (previously installed on my old 190e) and I warped one set of rotors in 30k miles which isn't terrible but not great either. When you order rotors makes sure they are for the correct model year and model. There is some overlap in 1993 and and some cars were dealer upgraded from the early to later rotors. best bet is to just measure the thickness of the rotor.

Lots more info here. Scroll down.
http://www.w124performance.com/docs/mb/W124/124_brakes.pdf

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CENSORED due to not family friendly words

Excellent! Ill pop a wheel off and mic the calipers later if it ever stops raining.