I just had the brake booster go out on the 91 Dodge Spirit. I was driving home from work on Thursday and when I hit the brakes at an intersection, the car went about 10-15 feet more than usual. Fortunately there was no accident. The brake light did not come on and the pedal seemed to feel normal (i.e. did not drop any further than usual). I took it easy going home and for low speed stops, everything seemed normal.
After experimenting at different speeds, I found that the problem only occurred at higher speeds/quicker stops. My first thought was that the pad material was completely gone and I wasn't getting any friction on the rotors. Friday I inspected the brakes and the pads/shoes, and they looked good. There were no leaks of brake fluid and the master cylinder fluid looked OK. I put everything back together and got ready to go for a test drive. As I was backing down the driveway, I felt the reduction in braking power and then began to hear a "rushing" or "whooshing" sound from under the dash. It was pretty obvious that the brake booster was leaking, but I checked all vacuum lines to be sure. Everything checked out fine.
For a couple of years now, I've thought of just junking out the vehicle and I thought this might be the time to do it. Instead, I checked on prices for a remanufactured booster and found out that they cost just a little more than a full tank of gas. I checked Rock Auto, Advance Auto, NAPA, and AutoZone. Even with the on-line 30% coupon for Advance, AutotZone came in the cheapest with a 20% coupon that I found on-line. Rock Auto was not competitive when the $9.95 shipping was added, even with the 5% discount code. One local AutoZone store 16 miles away had the unit in stock and after the core return, the final cost came out to be about $58. All the stores only carried a unit made (rebuilt) by Cardone (including NAPA), so store part quality was not an issue here.
I did the replacement job late Saturday and early this morning. It was not a fun job because of the very tight working area under the dash. I have previously replaced one of these on an old Toyota Celica and that one was a piece of cake. For my Spirit, the upper right nut under the dash was extremely difficult to access. I ended up removing the brake light switch, removing the lower dash panel, and lowering the steering column. I had to take frequent breaks to give my neck a break and not risk injuring myself. I got the new unit mounted and secured, installed the master cylinder, brake lines, and cruise control unit late yesterday and decided to quit. I was soaked in sweat from the heat and humidity. This morning I attached the brake pedal to the booster, re-installed the brake switch, the steering column, and lower dash trim.
It appears that the remanufactured unit has resolved the brake issue, I have preety good solid braking and no "whooshing" sound under the dash. The brake pedal travel is slightly more than previous, so I need to bleed the lines and possibly lengthen the booster rod slightly. The instructions that came with the reman unit mention that the rod may need some slight adjustment. I have no brake light showing up, so any air in the hydraulic lines is likely a very small amount.
This is actually the first time I have had (or even heard of) a brake booster failure on an EEK car. I suspect it is a rather rare occurrence. All I can say is that it is a nuisance repair because of accessibility. I guess now I have to continue driving it it for another year or so.