Hydroboost Master Cylinder Options

ForeverDriven · Feb 9, 2024

Yo everyone.
I've been eyeballing the "cheap ass" 4-piston brembo upgrade, the ATS fronts and Taurus rears.

At this point my biggest question is the master cylinder. Pedal feel becomes a big issue, pushing all that fluid into 4 pistons. So I went to look at larger brake cylinders and just can't find anything about compatibility?

Anyone know the magic behind what can/cant bolt to a hydroboost system, or if we are stuck with the hydroboost master cylinder because its such a specific system?

If this gets too complicated, the 4 pistons likely aren't worth it. I don't want/need to order a custom bore cylinder from Willwood or anything like that.

If it turns out to be a crap setup, I've heard of swapping 05-9 calipers and Boss 302 13.94" rotors? Let me know about that too, if you got experience. Will be looking into it myself.

Thanks,
Blake

cobrajeff96 · Feb 10, 2024

Depends on what generation hydroboost you're working with. You might find one option for the 94-95 boosters out there and I think it was Hydratech maybe. But the real options come with the 99+ hydroboost unit. For instance, I had to switch from a 96-98 booster to the 99+ which allowed me to get the Baer Remaster. Bear in mind that just because you get a new m/c with a bigger bore doesn't necessarily translate to the right pedal feel or ultimately the final brake torque. My recommendation would be to contact someone at Maximum Motorsports via their email and tell them your specs, then they can recommend you what size m/c bore to get. Because for instance the Baer Remaster can be had in I think three different sizes. Turns out the one I needed was the largest at 1-1/8" due to such massive caliper volume front and rear.

ForeverDriven · Feb 10, 2024

cobrajeff96 said:
Depends on what generation hydroboost you're working with. You might find one option for the 94-95 boosters out there and I think it was Hydratech maybe. But the real options come with the 99+ hydroboost unit. For instance, I had to switch from a 96-98 booster to the 99+ which allowed me to get the Baer Remaster. Bear in mind that just because you get a new m/c with a bigger bore doesn't necessarily translate to the right pedal feel or ultimately the final brake torque. My recommendation would be to contact someone at Maximum Motorsports via their email and tell them your specs, then they can recommend you what size m/c bore to get. Because for instance the Baer Remaster can be had in I think three different sizes. Turns out the one I needed was the largest at 1-1/8" due to such massive caliper volume front and rear.

Good info! I thought the 94-95s were vacuum tho?

Either way, if Baer can shoot me a good cylinder, I'll definitely contact. Is Baer through MM?

I'll look into the different booster too. The only difference I've seen is the mount tho, how it hooks up to the pedal? Ik the firewall backet is slightly offset from the older version.

cobrajeff96 · Feb 10, 2024

Yea, that's right actually. 94/5 were vacuum.

I don't believe MM has ties to Baer but it never hurts to ask.

There's definitely big differences between booster generations. Firewall clearancing is one of them, I had to slightly curl up the 11 to 1 o'clock position of the sheet metal. Not a big deal, took all of 15 minutes. But the stroke lengths are going to be different I think, and the pedal ratio on the foot box is also different. I remember I had to get a 99+ pedal box but it's a direct bolt in, you just transfer the brake and clutch switches across. And then there's the booster-to-m/c flange orientation. The 96-98 is vertical I think, and the 99+ is kind of diagonal so they are not compatible. To run a Baer m/c you can only run a 99+ booster. And finally the power steering port orientations are completely different on the two booster generations. Most people when they go this far into the deep end is to just go full custom AN lines like I did, otherwise you have to source OEM lines and mount it all up (if a junkyard doesn't pan out, I'm sure LMR or CJ and the link now sell them, and there's Rock Auto too that I know sells at least some of them). MM is going to be your best source of info as to how you put this all together and modify what's already there to make it all work... and work safely.

ForeverDriven · Feb 10, 2024

cobrajeff96 said:
Yea, that's right actually. 94/5 were vacuum.

I don't believe MM has ties to Baer but it never hurts to ask.

There's definitely big differences between booster generations. Firewall clearancing is one of them, I had to slightly curl up the 11 to 1 o'clock position of the sheet metal. Not a big deal, took all of 15 minutes. But the stroke lengths are going to be different I think, and the pedal ratio on the foot box is also different. I remember I had to get a 99+ pedal box but it's a direct bolt in, you just transfer the brake and clutch switches across. And then there's the booster-to-m/c flange orientation. The 96-98 is vertical I think, and the 99+ is kind of diagonal so they are not compatible. To run a Baer m/c you can only run a 99+ booster. And finally the power steering port orientations are completely different on the two booster generations. Most people when they go this far into the deep end is to just go full custom AN lines like I did, otherwise you have to source OEM lines and mount it all up (if a junkyard doesn't pan out, I'm sure LMR or CJ and the link now sell them, and there's Rock Auto too that I know sells at least some of them). MM is going to be your best source of info as to how you put this all together and modify what's already there to make it all work... and work safely.

Great info. Good to know its a relatively known thing at least, if the firewall is bendable and a pedal box is easy pickings, I can look into it.

On a weird note, I wonder if I can have my current cylinder bored? I'm clueless about the intricacies but if that saved me the pedal box, new cylinder, and wack config, might be worth a look. Car doesn't have to run for a good few months.