Long awaited GS300 BBK

[cuttyman9]

For everyone interested in my GS300/GS400/GS430/Aristo BBK
(I believe 93-04)

You'll need:

——————CALIPERS—————
02-10 VW Toureg
03-10 Porsche Cayenne
05-15 Audi Q7

NOTE: I have found car-part.com is the cheapest place to search(60 per caliper) It’s an annoying website but yields the cheapest prices outside of local junkyards which are the cheapest (25 per caliper)

The calipers should say 17ZL and 17ZR (it’s come to my attention most parts stores show the rotor size, 330mm instead of 17z so tell them 330mm is the caliper you need lol)
PNs 20.8432.06 and 20.8432.05 (see pictures)
(use these numbers to confirm, there are many calipers that look similar but wont work)


—————-HARDWARE—————-
4x M12-1.75x30 (McmasterCarr.com PN 90128A297 - Socket cap style bolt or equivalent)

4x SCH M16-1.5x40 caliper bolts
(or reuse the hardware from Cayenne/Toureg/Q7 on the top bolt hole, the lower holes are too close to other things)
(Mcmastercarr.com PN 96144A330)

8x  Fastenal PN 0136087 or  1245L from ace hardware
 https://www.fastenal.com/products/details/0136087
 (~2.5mm thick)

30mm Roll Center Adjusters (RCA)
(available soon for $150)
 
———————-ROTORS—————-
Rotor specs should be 356x30mm- confirm that before ordering as there are many that are 334 which will not work.

1x 2013-2018 GS350 F sport rotor-121.44204 front iron brake rotor (Centric PN shown)

1x 2013-2018 GS350 F sport rotor-121.44205 front iron brake rotor (Centric PN shown)

**These are not gsf rotors. Is350 f sport do not work either.
Only gs350 F sport.**


For drilled and slotted use this link, make sure to request only fronts (courtesy of Kirk smith)
https://www.ebay.com/itm/401594122059




Stock brake lines can be used although I would recommend getting stainless braided lines as it improves feel vastly.


Make sure to take the crossover lines and bleeders off and switch sides with them (because the cayenne/q7/Touareg have the caliper on the front of the knuckle and the is300 has them on the rear of the knuckle)



NOTE: Calipers will need to be modified
See pictures in later posts.

NOTE: The Washers will go between the bracket and the caliper.





** UPDATE**
18z calipers WILL NOT WORK (without custom pads and more clearancing on the back but none for the rotor)

The OEM tie rod/ball joint fits it better.

If you purchased calipers bare the hardware to mount the pads can be had here:
https://audibbkparts.bigcartel.com/product/brembo-17z-18z-caliper-hardware-kit





Edit: for 15” rotors it’s possible to use RCF rotors with 18z calipers.
Clearancing is still required and it hasn’t been fully tested but the test fit looks promising.

[cuttyman9]

Here are a few pictures of the clearancing needed to fit these to a GS300.

Due to the unusual tie rod mounting on the same side as the caliper it takes a little bit of work to make this happen but it’s a budget friendly setup.

Do note that some of the clearancing on this specific caliper was setup for the is300(friend of mine had an IS and decided to switch to GS and the clearancing isn’t the same) the cnc machining is the IS300 and the grinder part is for the GS)

Something also different about GS vs IS is the edges near the bolt holes need to be clearanced on the lower part of the caliper to clear the knuckle.(picture of red caliper)

[cuttyman9]

Closer looks at the two spots specific to the GS.

[cuttyman9]

This shows the clearancing on the lower bolt hole of the caliper

The next picture shows the differences between calipers after clearancing has been performed.

[cuttyman9]

Here’s a couple of measurements to show about how much is removed from the radial area of the caliper.
These suckers are so thick there’s still a ton of meat there.

[cuttyman9]

This is the rough thickness of the washers.
The least amount of washers means less clearancing on the backside.

Some have used enough to center the caliper, this is how many I installed upon mockup.



The last picture shows an optional 15” RCF rotor and 18z caliper.
A test fit of an Unmodified 18z caliper shows promise, it requires clearancing like a 17z, albeit less
The rest of the parts will be the same.

[cuttyman9]

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