i own a 1992 miata and i experience very tough braking. the guy at the workshop told me i had problems with the hydrovac but he couldnt fix it. im looking for information about fixing it or purchasing a new one :S
I beleave it is the brake booster,, It's what your master cylender mounts to on the drivers side of the fire wall. most of the time when they go bad, the brake padle gets stiff, ID just get a good used one from a junk yard , these things rarely go bad,
He is right when he says he can not fix the one that is on there. But before you go and spring for a complete booster check to make sure that all the vacuum lines are connected and not cracked or split. I own 2 90 Miata's and I still have not had this problem (less then 150K on each).
Simply put, its the brake booster. It provides hydraulic assist to your braking to make your brakes operate better. I don't understand why he was saying he can't fix it. You can replace the system no problem. While you're at it, replace the stock brake lines with braided steel - they'll reduce the loss of hydraulic pressure on braking - you'll have a more firm, positive feel, and if you have to go that far to replace the hydraulic assist, you'll have to bleed your whole system anyway - why not take this opportunity to upgrade?
