Replacing a Differential Car Part

A differential car part

A differential car part

When you are looking to buy a differential to replace your old one it is important to match up the part numbers and the gear ratio to be sure it’s the correct one for your car. Get it right the first time – You do not want to purchase the wrong one and then go though the process of finding the correct one all over again.

At Your Car Spares Ltd  – What we test and look for!!!!

When deciding whether to keep a differential or not we look at the mileage and the history of the car. If the mileage is high and it hasn’t previously been replaced then the chances are it may not last much longer thus posing a risk for a customer if they were to use this part. Once we have the car started we listen out for any unusual noises coming from the differential. We aren’t able to diagnose problems based off the noise it’s making but it will give us an insight into where problems could be , some noises are easily treatable so before deciding to replace your differential because it is making a noise do some research or take it to a mechanic because it may be an easy fix like lubricating the mechanism.

Where to find the Part Number

Depending on the make of your car will depend on where the part number can be found. The part number is usually stamped on the back but in some cases it could be on a sticker on the top. As well as matching the part number you also need to match the gear ratio , which can also be found stamped on the differential or on a sticker. Below we will show you examples of the locations of the part numbers and gear ratios on a differential.

Differential parts number

Where to find the parts number on a differential part

Differential serial number

Close up of a differential

Other view on the parts number

Different view of where to find the parts number on a differential

Made in Germany

Another close up of the serial number

How does a Differential work?

The differential is responsible for sending power to the wheels as well as distributing more power to a wheel to make it rotate more so you to make a turn. When making a turn your outside wheel will rotate more than the inside wheel as it has further to travel , and this is the doing of the differential. Power from the drive shaft is sent through a pinion into a ring gear which is then connected to a spider gear. The speed at which the drive shaft rotates will depend on the make and model of the car and this speed is wrote as a ratio , for example 3.27:1 which means that the drive shaft will rotate 3.27 times in comparison to one full rotation turn from the wheel, and it’s often referred to as a gear ratio or a rack and pinion ratio.

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The spider gear is an integral and unique part of the differential because it can spin on its own axis and it can rotate with the pinion gear. The spider wheel is engaged to two side gears and because the 3 of them are bevel gears it allows for the power to be transitioned fluidly between them and the drive shaft. When driving in a straight line the spider gear will rotate with the ring gear and it will make both side gears turn which makes the spider gear and the two side gears one solid unit. In a left turn the spider gear rotates with the ring gear and on its own axis to spin the side gears. The right side gear will be moving to the sum of the rotational and spinning speeds , but as the left sided gear is on the opposite side it moves at the difference between the speeds. Simply this means that the right side will rotate more than the left side and this will be replicated on the wheels.


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