Diff Pinion Seal Replacement - Classic FIAT 124 Spider

Posted by Auto Ricambi Staff on May 28th 2021

How to replace your Diff Pinion Seal - Classic FIAT 124 Spider

The technical tips listed below are intended to aid in the care of your Fiat 124 Spider and should be used accordingly. They are based on many years of experience but are in no way a replacement for factory recommendations. Seek the professional mechanical assistance for all issues beyond your abilities.

Auto Ricambi, LLC is in no way responsible from the consequences of applying these technical tips. By using (accessing) these technical tips you agree to these terms.

The 'by the book' instructions for changing the pinion seal (front differential seal) involves replacing the crush sleeve that is in the differential. To do that properly the rear ends needs to be disassembled and special tools are needed, as the rolling torque of the pinion shaft needs to be measured. These instructions can be found in the factory shop manual.

Many people have successfully changed the seal without replacing the crush sleeve by marking the exact position of the pinion nut (and the flange relative to the shaft), and then reinstalling it in the same position after replacing the seal. Be certain to mark the relationship of the nut to the shaft - not to the flange.

Of course, this may not be the 'proper' way, and there is a small risk that the pinion bearings will wear more quickly. Most are prepared to take the risk, in order to tackle the job in about an hour, instead of an all day project that needs special tools. So far there have been no cases where this procedure caused any ill effects.

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