1997-2000 brake master cly question - 986 Forum - The Community for Porsche Boxster & Cayman Owners

can you run a 1997-2000 brake system with out the power boost? why you may ask? I have a alfa romeo spider 1984, and just imported a new 2015 jts motor,, have a slight problem.. tight space.. org master cly might fit, don't know right now.. all my brakes have been updater/upgraded to 12.19 vented disk all 4 corners, from the oem disk( 10.5 front soild and 10.2 read soild disks ) all the caliper are off a 1998 boxster.. 4 pot monoblock brembos( took those pesky Porsche stickers off the caliper, cleaned , new seals and ALFA ROMEO decals on the calipers now) if I do not have any room for my master cly. plan to use the boxster master cly , as it is smaller...I removed the brake booster on my car to get this new motor to fit, so this question I will be making a new mount to fit the master cly... reason would state that if you should loose vac. asst. on the boxster the brakes should work just fine,, just a little more pressure to use.. I have been running my new brake system without boost, and it woks just fine..any help here?

oh yes my hp jumps from 120 at 5500.. to 205 ish at 6600 and tq rises from 120 at 4400 to 178 at 3800 and best of all always above 135 from 1000 to 6300 rpm.. my car weighs in at 2350 so far..

if you lose boost your power brakes will work exactly one time, and then it will take all the force you can muster to even slow the car down. Just drive any modern day car down an empty road and turn off the key (just one notch please). Apply brakes once, let them off and push again. Hope no crippled kids jump into the road while doing this test. It's quite dramatic and one of the things I've taught my kids before they go for a drive test.

I removed my power asst.on my spider,I did not kill any crippled children,as compared to my other friends Alfa spiders,take just a little more pressure to stop the car.

Hello ALFAROMEO1, the problem is the ABS / ESP (which Porsche called PSM) system. Your 1984 Alfa won't have ABS. The ABS also distributes the brake power between front and rear axles. If you don't have a brake booster, the ABS wont work and breaking will be extremely dangerous because of the lack of brake power distribution. Too much break power (blocking) on the rear and you loose the car immediately. Regards, Markus

Thank you,small block,I installed a adjustable brake bias into my rear line,a few years,when I up rated my brakes from stock to 12.10 vented disk all 4 corners,and 997 brembo calipers,to balance the system.

Hello, if you don't have ABS and you have an adjustable brake bias, i think that should work without an additional brake booster on your 1984 Alfa. But be prepared it might need a lot of force on the brake pedal to brake. It also depends on your master cylinder and the brake pedal ratio. I would say just try and learn. Over here in Germany we have VW beetles (the old ones) with adapted Porsche brakes. But they use a brake booster in general, because it's a lot easier and better to brake. Regards, Markus

My car is only 2350 pounds, and I have been running the 997 brembos on all 4 corners using a stock Alfa Romeo master cly without any issues,and no vacuum boost and the pedal feels ok to me although my friends think it's hard to stop.and I like the feel without the power booster.I can modulate the brakes better.again,thank you again small block,for your help

You "might" need a change in master cylinder bore to get a higher pressure in the system without the assist. Seems like you know what you are doing pretty much with brakes, just make sure you can achieve full lockup and then you will know if the pedal force is too high for normal driving. I had an '86 spider for years and love it but decided to cut down to just 1 Alfa, so I only have my '72 GTV now. Same chassis, different body. Loverly cars!!!!! Nothing like the sound of the Alfa motor at full song. I also run big brakes; Alfaholics big brake kits. Alfaholics 4-Pot Brake Kit

My former daily driver is a Milano Verde, that I use when the 987CS is down for maintenance, I also have in storage a '79 Alfetta GT that I am trying to get back on the road. The transaxle Alfa's are awesome cars, oh, and the sound of the engine is pure Italian porn