Different clutches use different pressure plates and disc configurations. These configurations will effect how your throwout bearing performs, or doesn’t perform in some cases. Al from auto parts experts, ZZPerformance, explains how to measure the air gap in your clutch assembly and properly install a throwout bearing spacer to avoid issues in your clutch assembly.
‘Air gap’ is a term used to determine how far your throwout bearing is from being bottomed out when your clutch assembly is in its resting state. Varying air gap distances are a result of which clutch your using and with which pressure plate — it’s not a one-size-fits all situation. This is a common area of the installation and adjustment process that comes up a lot when people go to install their new clutch assembly. Improper air gap is such a common problem with clutch assemblies that ZZPerformance made their own throwout spacer bearing, that’s a 1/4” thick.
If the air gap is too long, what will end up happening is that the throwout bearing will extend too far, and the seal at the end will blow out. However, there are applications that don’t need the spacer, so if you install it, the throwout bearing will bottom out on the pressure plate fingers, preventing the clutch from fully disengaging.
The first thing you’ll need to measure for the air gap is a straight edge of some form. Rest the straight edge on the clutch fingers, without pushing down on them, and measure the distance from the edge down to the block with the bell housing space on the block. Check both sides, and mark your measurement down. With the throwout bearing installed, go to the transmission, have someone push the throwout bearing until its all the way bottomed out, and measure the gap between the transmission mating surface and where the bearing is at while bottomed out, note this measurement. Subtract the first measurement from the second, and you’ll want the air gap to fall around 3/8”, give or take a few thousandths of an inch.
The setup in this video is a good example of when you would not want to use a spacer because it would cause the bearing to bottom out. If it was more on the 1/2” side, you would need to use a spacer to keep it from overextending. The concept is pretty simple, so don’t overthink it. Make sure to double check your measurements, and check again if you don’t get the same outcome twice.
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