Jb What?!

[meeker]

I am new to this forum. Actually I am new to the whole K5 mania.
I recently got a 1980 Silverado K5 with rough country four inch lift with 36 interco super swamppers.
My question pertains to breaks, in particular the break booster. My truck is very slow to come to a stop and it emits this swoosh sound while I press the break pedal. I think that I may need a new or more powerful break booster. I just don't know which one of the "JB's" (jb5,jb6, etc) is correct or better.

does any one have any ideas?

thank you.

 

[resurrected_jimmy]

your brake system should be JB-5. If you look in the glove box there should be a sticker with a bunch of codes. Those are all the options your K5 was equipped with. The swoosh sound is normal so thats not much to go on.

 

[vortec]

mine makes that "whoosh" too. no problem.

the booster could be fine, but running 36" tires on a vehicle where 235/75/r15 (or something similar) was the stock size changes the physics significantly. viewing the radius of the tire as the length of a lever, you've gone from a "lever" of less than 15" to one of approximately 18". 3" doesn't sound like a lot, but with the same amount of force applied at a tangent to the circumference of the tire, quite a bit more force will be applied to the brakes. it's like using a cheater bar on a bolt.

another simple fact is that these beasts are simply very heavy, so they'll never stop on a dime. not to turn my back on the general, but i like the new tundra's rotors. they look almost as big as my wheels.