Monte Carlo Z34 brake master cylinder options/ ABS delete?

[carkhz316]

As the title states, I'm looking for any/ all info in regards to the proper master cylinder needed for ABS deletion. I'm only wanting/ needing to do it in order to fit turbocharger piping in the engine bay, and not because of some naive safety circumvention. I am already running a smaller first gen brake booster found on the manual transmission cars if this matters. While searching RockAuto, there seems to be a lot of overlap between the 1st gen W-bodies through 1.5, with and without disc brakes, etc. So, I figured I'd ask the experts since I've seen brake systems discussed here in the past. Thanks!

[Bake82]

Do you have drums still in the back?   

 

[carkhz316]

Disc all around.

[55trucker]

Being an ABS VI you will have to either re-bend the existing lines at the current ABS module to fit into the 4 ports of the non ABS master or add extensions onto what's there.

What's not known is if what is there right now will have the same 4 different line nut fittings that the non ABS master makes use of. Each line nut that goes into the appropriate master port has a different thread pitch & diameter  so they could not be mixed up.

 

[carkhz316]

Flaring and making lines in no issue. I have benders and a hydraulic flaring tool which makes making lines a breeze. If I have enough line, I'd just bend and reattach, but I may make some unions otherwise. I know GM likes to make oddball thread and line sizes at the MC, so no surprise there.

[Bake82]

Since you're already disks, and using the 1st gen booster, I'd grab a 1st gen master cylinder and re-do the lines as needed.  

 

Only thing I'm not entirely sure has been ever discussed has been the bore size of the master.  I see there is 7/8 and a 15/16 size bore.  I'd ensure you're getting the biggest bore for the disks. 

 

Otherwise - not sure on tuning or flashing the BCM to de-activate the ABS so you don't have a light on at all times.  

[carkhz316]

The Monte is pretty simple and old school. All the warning lights are just regular 194 light bulbs. So I was just planning on removing the ABS light bulb and the EBCM.

I was curious about the MC bore sizes, since bigger would typically be better unless I'm overlooking something.

 

Edited November 17, 2025 by carkhz316

[Schurkey]

"Bigger" master cylinder bore = less hydraulic advantage.

If you have low-drag front calipers, you NEED the OEM three-chamber, step-bore, Quick Take-Up master cylinder.  But I don't know if you have low-drag calipers.

[carkhz316]

I honestly don't know if they're low drag or not. I've never seen anything referencing that in SI or anywhere. I did find in the meantime, a thread by Miko K where he uses a 2nd/ 3rd gen MC with a 1" bore and installed it in his Cutlass. The biggest difference being two line outputs instead of 4, but he T'd them on the car to split the 2 channels to feed the 4 corners.