Hey everyone, I’m replacing the brake booster in my 1993 civic hatchback dx. The booster I bought is a lot smaller in diameter than the one installed on the car. Anyone know the difference between the 2 and if I need the bigger one or can I use the smaller one?

 

I'm assuming you bought the "new" one from a local parts store? If so, I would go exchange it for the correct one.

 

The new one was bought online. When I look up the oem part number it’s discontinued. I was mainly just seeing if anyone knew why there is 2 different boosters that are for the same car and one is larger than the other. I did put on the new one and everything matched up and it seemed to have worked but of course when I go to start the car it didn’t start so now I have to deal with that

 

I'm not a professional by any means, but a smaller booster, being connected to a vacuum line, would I believe create a pressure difference having a smaller chamber inside it.

Pressure decreases as the size of the chamber increases. So a smaller booster would have a higher pressure with the same vacuum load. Which in my mind could potentially affect the amount of air available to the engine, via the intake manifold, the booster is attached to.

Again I'm by no means a professional, or a scientist... but the basic principle with pressure vessels and vacuum, would affect the pressure within the system.