How to Work Out a Diff Ratio
Three easy ways to find your diff ratio: count the gear teeth, count the turns, or read the tag. No special tools needed.
George Bull, owner 1 min read
Your diff ratio is simply the number of times the pinion turns for each turn of the crownwheel. There are three ways to find it, and you can do two of them in the driveway.
Count the turns
Jack up both rear wheels, mark the driveshaft and one tyre, and turn the wheel one full revolution with the other wheel held still. Count the driveshaft turns. On an open diff, that number is your ratio.
Count the teeth or read the tag
If the cover is off, divide crownwheel teeth by pinion teeth. Otherwise look for a tag on a cover bolt or a stamping on the housing. Our online ratio calculator will do the sums for you from the tooth counts.
Think your diff is making noise? Around 120 rebuilt exchange diffs on the shelf for 30 plus makes and models. Fitted here in Sydenham, or shipped anywhere in NZ with free freight both ways.
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