Today I got the MY05 STi Brake Booster and Master Brake Cylinder installed. The extra pedal firmness (some 13%) feels amazing compared to the stock setup and as a result, my brakes are now even touchier than they were before!
Click on the image for full size!What is interesting to note is that the tyres are squealing a bit more than before under ABS-driven heavy braking, suggesting that the stock BB and MBC really weren't working the Brembo's has hard as they could go. Makes sense given that the bore of the STi MBC is a good deal larger than the stock unit, pushing more brake fluid to the calipers.
The BB and MBC fit without any issues inside the engine bay - a perfect fit with no further modification required, however it was a slightly different story inside the cabin.
The only issue seen during installation was the length of the Brake Booster rod - it was too long. The stock unit is 136.5mm in length from the body of the brake booster to the cotter pin hole on the rod. The closest we could adjust the STi brake booster's rod length to was a hair over 137mm. Not a big deal, right? Sadly, while I'm getting 13% improvement in braking firmness, it also translates into an apparent 13% raised brake pedal and locked brakes!
Click on the image for full size!The obvious solution here is to trim/grind the rod so that we can make it shorter, but the mechanic who did the work for me simply adjusted the upper stopping point of the pedal to prevent the brakes locking up (because the pedal was effectively being lightly depressed all the time). Have done several test drives now and it's working like a charm and the extra height of the pedal doesn't take long to get used to either. Brake lights still operate as expected as well.
While they worked on that, I also set about adjusting my hand brake in the cabin as the new larger handbrake shoes from the Brembo upgrade had provided a lot of extra slack in the handbrake cable (despite re-adjusting the handbrake adjuster on the rear hubs), making for a very high bite point on the handbrake lever. It now bites hard at about 4 notches instead of the previous 20 or so.
Next thing to get to complete the brakes is a Master Cylinder Brace. I didn't get around to ordering one before today's install, so I'll do that later. Needless to say, the firewall flex is very noticable from looking in the engine bay while someone else pushes the pedal, so definitely need the brace to eliminate that.
I was going to procrastinate, but I put it off...