Pilot bearing and bushings
From Crankshaft Coalition Wiki
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===Pilot Bushing=== | ===Pilot Bushing=== | ||
| − | <blockquote> "In most cases, this is a porous bronze, pre- | + | <blockquote> "In most cases, this is a porous bronze, pre-flexplate bushing rather than an actual bearing, as it is often called. A few applications still use an actual bearing and others use a needle roller type bearing, but by far, the most common type is bronze. You cannot use a roller bearing on a transmission shaft originally designed for a bronze bushing due to different type of heat treatment on the shafts.</blockquote> |
<blockquote> "For a list of several versions of pilot bushings offered by Novak, [http://www.novak-adapt.com/catalog/pilot_bushings.htm jump here].</blockquote> | <blockquote> "For a list of several versions of pilot bushings offered by Novak, [http://www.novak-adapt.com/catalog/pilot_bushings.htm jump here].</blockquote> | ||
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<blockquote> "The pilot bushing is seldom thought of as a part of the clutch system but it is one of the most vital parts of the system. It pilots the end of the transmission input gear in the crankshaft. If it is worn or not running "true", it can cause serious clutch problems or transmission failure. Pilot bushing bore runout should always be checked with a dial indicator and should be within 0.002" total. The bronze bushing type should be a press fit in the crankshaft bore. It must be installed carefully. It should have between 0.002" and 0.003" clearance on the transmission shaft when installed. The pilot bushing is only functional when the clutch is disengaged but it is a factor in input gear alignment at ALL times.</blockquote> | <blockquote> "The pilot bushing is seldom thought of as a part of the clutch system but it is one of the most vital parts of the system. It pilots the end of the transmission input gear in the crankshaft. If it is worn or not running "true", it can cause serious clutch problems or transmission failure. Pilot bushing bore runout should always be checked with a dial indicator and should be within 0.002" total. The bronze bushing type should be a press fit in the crankshaft bore. It must be installed carefully. It should have between 0.002" and 0.003" clearance on the transmission shaft when installed. The pilot bushing is only functional when the clutch is disengaged but it is a factor in input gear alignment at ALL times.</blockquote> | ||
| − | <blockquote> "Most people have no idea what an important part the pilot bushing plays in the life of the transmission and clutch. The job of the pilot bushing is to support the end of the transmission input (main drive) gear in the crankshaft and it only acts as a bushing when the | + | <blockquote> "Most people have no idea what an important part the pilot bushing plays in the life of the transmission and clutch. The job of the pilot bushing is to support the end of the transmission input (main drive) gear in the crankshaft and it only acts as a bushing when the flexplate is depressed. This pilot bushing should be a light drive fit into the crank bore. Care should be taken when installing any pilot bushing as they are soft and easily damaged by crude installation techniques. A damaged pilot bushing can bind on the input gear giving symptoms of clutch drag. Transmission damage and early failure can be caused by a pilot bushing or crankshaft bore that "runs out" in relation to the transmission locating bore in the bellhousing. It is advisable to check the bore of the crank with a dial indicator before installing the pilot bushing. If the bore runs out more than 0.003" total, the crank should be set up in a lathe and the bore trued up OR a special pilot bushing should be made that runs out the same amount as the crank bore. The run out in the bore of a pilot bushing is put 180 degrees off from the crank bore run out and the pilot bushing installed. If properly done, this can put the bore of the pilot bushing well within the 0.003" required. We have used this method to save engine disassembly many times. A disadvantage of this method shows up at pilot bushing replacement time as a special pilot bushing will have to be reproduced."</blockquote> |
==Types of pilot bushings/bearings== | ==Types of pilot bushings/bearings== | ||
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====Fluted bushings==== | ====Fluted bushings==== | ||
[[File:GM pn 10125896 pilot bushing.jpg|thumb|200px|]] | [[File:GM pn 10125896 pilot bushing.jpg|thumb|200px|]] | ||
| − | The flutes reduce the load bearing capacity- even though there's not a terrific amount of load on the pilot bushing- provided the bellhousing is indexed correctly. They also present a way for contaminants to get into the bushing. <br style="clear:both"/> | + | The flutes reduce the load bearing capacity- even though there's not a terrific amount of load on the pilot bushing- provided the bellhousing is indexed correctly. They also present a way for contaminants to get into the bushing. <br style="clear:both"/> The reason for a fluted bushing is to stop the input shaft from glazing over. Contaminants can be had in either style of bushing due to clearance that is within both. |
==Damage caused by a pilot bushing containing iron == | ==Damage caused by a pilot bushing containing iron == | ||
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*[http://www.crankshaftcoalition.com/wiki/Health_and_safety_in_the_shop_or_garage Health and safety in the shop or garage] | *[http://www.crankshaftcoalition.com/wiki/Health_and_safety_in_the_shop_or_garage Health and safety in the shop or garage] | ||
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[[Category:Transmission]] | [[Category:Transmission]] | ||
[[Category:Good articles]] | [[Category:Good articles]] | ||
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