180K on my 1996 C1500, 4WD. I had the brake booster replaced at ~150K and I changed out the master cylinder a couple months ago. Before replacing the master cylinder, the pedal would travel to the floor with multiple pedals pushes and the pedal effort was normal. There were no signs of brake fluid loss either from the resevoir or at the wheels.

I replaced the master cylinder but now the pedal is very difficult to depress. Hopefully, the booster didn't fail already. But, when purchasing the master cylinder, the parts shop said to look at the Service Parts ID sticker to determine JB6 or JB7. I found the sticker, but I didn't find where it identified JB6 or 7. Comparing the two visually with the one that was removed from the vehicle, there was virtually no difference.

If I put the incorrect one on, could this result in increased resistance for the brake pedal? Also, how can I use the VIN to validate if it's a JB6 or 7?

 

I have same problem - what to do?
180K on my 1996 C1500, 4WD. I had the brake booster replaced at ~150K and I changed out the master cylinder a couple months ago. Before replacing the master cylinder, the pedal would travel to the floor with multiple pedals pushes and the pedal effort was normal. There were no signs of brake fluid loss either from the resevoir or at the wheels.

I replaced the master cylinder but now the pedal is very difficult to depress. Hopefully, the booster didn't fail already. But, when purchasing the master cylinder, the parts shop said to look at the Service Parts ID sticker to determine JB6 or JB7. I found the sticker, but I didn't find where it identified JB6 or 7. Comparing the two visually with the one that was removed from the vehicle, there was virtually no difference.

If I put the incorrect one on, could this result in increased resistance for the brake pedal? Also, how can I use the VIN to validate if it's a JB6 or 7?

 

this thread is EXTREMELY old.. from 2008.. you might want to start a new thread and post your problem