c-towndave

I am looking to convert my ’68 Cutlass from front power drums to front power disks.Conversion kits listed have boosters with diameters from 7” up to the factory 11”.Is there any benefit of one booster diameter over another or is it just an appearance thing?
My engine is a regular non-performance 350 Olds with a mild cam and an Edelbrock intake so I would not anticipate any special vacuum considerations.
Thanks
Dave

joe_padavano

Remember math class, when people would ask "why do I need to learn this stuff?"

This is why.

The brake booster uses the pressure difference between manifold vacuum and atmospheric pressure to push on the diaphragm, providing the power in power brakes. Only two things affect how much assist you get from power brakes, the pressure difference and the area that the pressure difference acts on.

Assuming the same engine, and thus the same pressure difference, the larger booster has more area and thus more assist. An 11" booster has almost 2 1/2 times the area of a 7" booster. Especially on engines with little manifold vacuum, use the largest booster you can fit.

drop top olds

^^^ Good answer Joe. Math is our friend.

joe_padavano

The other possible answer is:

Of COURSE size matters...

c-towndave

Thanks for the response. 11" it is.


Dave