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Wheel Cylinder Replacement

TRW was recently asked if a vehicle with a leaking wheel cylinder on the offside should have the nearside cylinder replaced as well. The answer is ‘yes’ and it is recommended that parts such as wheel cylinders should always be changed in axle sets.

However, the age of the vehicle should also be taken into account. This was not mentioned in the original query, so it is assumed that the car is of an age where natural wear and tear have played their part.

Remember, if one cylinder has started leaking, the likelihood of the other following suit very shortly is quite significant. Also, the brake force balance can be affected if one side of the vehicle has a new wheel cylinder and the other has a worn one.

You should also look at the condition of the shoes, particularly on the side with the leaking cylinder, as this may have lead to contamination of the friction lining. If this is the case then the brake shoes must be replaced, and again the same rule applies – replace both sides.

The Good News

TRW offers a range of Drum Brake Superkits containing all the parts needed to replace the wheel cylinders and shoes. But it gets better still, the shoes come pre-assembled with a new self adjuster and springs, pre-spaced to fit the application, and include new screws, clips and anti-judder pins. Not only does a Superkit save you valuable workshop time (and therefore money) but you are able to inform your customer that their rear brakes are now fully restored to original factory condition and good for many miles of worry free motoring.

Just think of the possible aggravation you could receive from the customer if, after only changing the offside wheel cylinder, they were back at your workshop in two months complaining of poor braking again and you have to repeat the process all over again! Not only is it more time consuming for you, but the customer may think they were short changed in the first instance.

Useful Tips

Once you have removed all the old components and before you fit the wheel cylinder, ensure the backplate is cleaned thoroughly with a reputable brake cleaner.

To help reduce wear and noise always apply grease on the backplate, but ensure it does not come into contact with the shoe friction face or the auto adjuster mechanism as this can lead to collection of dirt and incorrect operation.

You can now fit the pre-assembled shoes and connect the hydraulic system, but before connecting the handbrake cable, actuate the foot brake to activate the auto-adjust mechanism so that the shoes are in the correct position. Only then should you re-connect the handbrake cable. If the cable is adjusted too much it will affect the correct operation of the auto-adjustment and could lead to long pedal travel.

And finally, ever more relevant now, with an increasing number of small vehicles having drum brakes on the rear and with all the variations of handbrake mechanisms in the market place, a logical but often overlooked tip is to just work on one side at once, that way you have a reference to how everything is fitted.

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Published on: May 1, 2020

Filled Under: Technical Articles

Web site: https://www.trw.com

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