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Timken Tech Tips: Proper preload prevents... you name it

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The amount of end play, or preload, existing in a mounted pair of bearings is vital to a vehicle’s performance. Too tight or too loose of a preload can result in a damaged bearing or alignment problems.

Seals, brake components and tire operation may also be affected, according to the experts at The Timken Co. In addition, improper bearing setting can negatively impact factory settings of camber and toe.

To help technicians safely maintain tapered, the company has developed the following guide for both passenger car non-driven wheels and independent suspension rear axles.

Setting for passenger car non-driven wheel

There are several mounting methods for tapered single roller bearings. Some are more common than others. One of the most popular methods is mounting and adjusting the bearing setting with a bottle cap stamping, hexagonal nut, cotter pin and threaded shaft. This approach is typically used on passenger car front wheels in combination with a hardened tongue washer between the outboard bearing’s inner ring and the adjusting nut.

To adjust the setting of this bearing:

1. Tighten the nut while turning the hub. When there is a slight bind on the bearing, the parts are seated correctly.

2. Back off the nut one-sixth to one-fourth of a turn, or sufficiently to allow .001-inch to .007-inch of end play. Failure to back off adjusting the nut could cause the bearing to run hot and become damaged. The wheel could also lock or separate.

3. Place the bottle-cap-type stamping over the nut and insert the cotter pin to prevent the nut from backing off.

Setting for independent suspension rear axles

Hardened surface nuts, tongue washers and outer jam nuts or lock nuts are commonly used for wheels with full floating rear axles and some front-wheel applications. To adjust the setting of this bearing:

1. Tighten the nut while turning the hub. When there is a slight bind on the bearing, the parts are seated correctly.

2. Back off the nut one-sixth to one-fourth of a turn or sufficiently to allow .001-inch to .007-inch of end play. Failure to back off adjusting the nut could cause the bearing to run hot and become damaged. The wheel could also lock or separate.

3. Tighten the jam nut to remove thread clearance and to prevent the nut from backing off.

For more information about Timken's automotive aftermarket products, visit www.timken.com/aftermarket.

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