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AutoTalent · 06-10-2018, 08:36 PM

ACL Bearings

ACL Race Bearing Catalog: http://www.aclraceseries.com/images/catalog.pdf
Wiki: Full Technical Specifications
Photo Blog: About 100 full resolution photos

ACL Bearings has a long history in the automotive and racing bearing market. They are the latest company to throw their hat in the ring of S65 aftermarket bearings. ACL markets these bearings as extra clearance. The measurements below will show them to have a little extra clearance over stock bearings.

Appearance:

At first glance, the ACL bearings look worn and/or damaged. To the untrained eye, they might look like they just came out of an engine showing excessive bearing wear. Don't let the looks deceive you. This is normal appearance for ACL race bearings. ACL addresses this issue in their catalog with a lengthy description of their appearance. (See "Picture Description" below for a direct citation from the ACL bearing manual.)

Tools and Calibration

All measurements are performed on new "virgin" connecting rods and "virgin" connecting rod bolts. These rods and bolts have never been used in any engine. Using virgin rods and bolts is an essential step for obtaining reliable and calibrated results. After use, every connecting rod big-end is deformed with extra diameter. Using virgin rods and bolts ensures that the measurements obtained will be the same reference as a new factory engine. It's the only way we know to ensure repeatable and reliable results.

The image above shows the tools used for this job:

* Two virgin connecting rods (P/N: 11247838623)
* Snapon electronic torque wrench (P/N: ATECH3FR250B)
* Mitutoyo data-logging drop indicator (accurate to 0.00002 inch) (P/N: 543-562ACAL)
* SPI bore gauge (accurate to 0.00005 inch)
* 2-inch calibration ring
* SPI gage blocks

The Mitutoyo drop indicator is used to measure each bearing thickness. It's a very pricey tool that is accurate to 0.00002 inch. It features the ability to data log to computer, categorize the results with go/no-go screen colors, and it's the same tool used by BE Bearings to measure each and every bearing shell thickness.

Before beginning to measure thickness, the instrument must be calibrated. The SPI gage blocks are used to set the proper instrument calibration.

The bore gauge used to measure the bearing clearance and eccentricity must be calibrated as well. The 2-inch bore gage shown in the picture is accurate to 0.00004 inch.

Production and Composition

Manufacturer: ACL

Composition: Trimetal steel/lead/copper

Coating: None

Part Number: 8B1580H (STD, +0.25 mm), 8B1580HX (+0.025 mm)

Target Market: OEM replacement market; Minimal increase in clearance over OEM rod bearings

ACL Bearings are a full custom rod bearing designed and manufactured by ACL. ACL manufactures the bearings to their own custom specifications.The composition is a standard lead/copper bearing. The bearing does not contain a low-friction coating.

Set Numbering
ACL RACE Series bearing sets are identified by the ‘H’ after the set number e.g. 8B663H-Std. Most ACL RACE Series bearings are also produced in a ‘HX’ version e.g. 8B663HX-Std. The ‘X’ signifies the set will give an extra .001” (.025mm) oil clearance on a standard size shaft when compared to the H-STD set. The wall size of these HX-STD bearings is .0005” (.013mm) thinner than the H-STD Bearings, in all other respects the HX set is identical to the H-STD set. There are selected con rod bearing sets that are manufactured with a dowel hole in the lower shell, to suit a dowel location in the con rod cap. These are designated with a ‘D’ in the set numbering e.g. 8B663HD-Std or 8B663HXD-Std etc.

Lead/Copper, Tri-Metal design
Tri-Metal, lead/copper are considered the world's best bearings. The steel backing is coated with copper, then topped with a soft lead. The lead is embeddable, meaning small particles can embed themselves in the lead without causing any damage to the crankshaft. Look in the best automotive engines, and you're likely to find a Tri-Metal bearing design.

Oil Clearances
Oil clearances are most accurately measured using micrometres and bore gauges. Bearing wall thickness measurements are taken at 90 degrees to the parting line (i.e. at the crown of the bearing) using a micrometre with a ball anvil, for use on the curved ID of the bearing.

Vertical oil clearance is best measured by assembling the bearing in its housing, with bolts torqued to specification, then using a bore gauge measure the assembled ID of the bearings at 90 degrees to the parting faces. The mating crankshaft journal size is measured, and subtracting this measurement from the bearing ID bore size, gives the assembled oil clearance.

ACL RACE bearings can be assembled with .00075-.001” per 1” of journal diameter (0.020-0.025mm per 25mm of journal diameter) plus .0005” (0.013mm).

As an example for a 2.000” (50mm) journal diameter, 2.000 x .001= .002 + .0005 = .0025” (50/25 x 0.025= 0.050 + .013 = 0.063 mm) Bearings should not be polished with abrasive pads or paper, on the bearing surface, to change the oil clearance.

Picture Description

Questions about the appearance of the RACE Series bearings are quite common, as this series of trimetal copper lead bearings have a very different appearance to regular aftermarket “ACL Duraglide” trimetal bearings, which have a light silver /grey appearance.

The RACE Series performance bearings as manufactured have an appearance that is a dark tarnished colouration, which can vary from dark black/brown/blue colours. This colour comes from the electroplating which is the last manufacturing process. The electroplated overlay has copper as one part of its composition, which tarnishes to the dark colours described above. This tarnish colouration has negligible thickness, so once installed in the engine, the crankshaft journal contacting the bearing, will polish the bearing surface, removing the surface colour and leaving the bearings with a polished silver appearance.

Performance bearings do not start out with the silver grey appearance of regular aftermarket bearings, as there is no final silvery tin flash applied to these bearings. Not applying a silvery tin flash to these high performance bearings is a specific design feature. A silvery tin flash for appearance and long term corrosion protection, as applied to the regular aftermarket bearings, can under high loading and heat, move, with the plate migrating and causing high spots on the back of the shells, and distorting the bearing. For this reason the ACL RACE Series performance bearings do not have a cosmetic silvery tin flash applied, so there is no risk of any overlay plate movement on the backs of the shells, giving better bearing to housing contact and better bearing performance and function.

Standard (STD)

+0.250 MM, +0.010 INCH

Dimensions

Standard (STD)

+0.025 MM, +0.001 INCH

+0.250 MM, +0.010 INCH

Bearing Clearance Specifications

Clearance Measurements

Eccentricity Measurements

Bearing Eccentricity: ACL-H, ACL-HX Bearings vs. stock 702/703 rod bearings

Supporting photos

06-10-2018, 08:36 PM	#1
AutoTalent Lieutenant General 2324 Rep 12,654 Posts Drives: e92 M3 6mt \| e60 M5 6mt Join Date: Jul 2007 Location: Los Angeles iTrader: (11)	Official ACL Rod Bearing Measurements ACL Bearings ACL Race Bearing Catalog: http://www.aclraceseries.com/images/catalog.pdf Wiki: Full Technical Specifications Photo Blog: About 100 full resolution photos ACL Bearings has a long history in the automotive and racing bearing market. They are the latest company to throw their hat in the ring of S65 aftermarket bearings. ACL markets these bearings as extra clearance. The measurements below will show them to have a little extra clearance over stock bearings. Appearance: At first glance, the ACL bearings look worn and/or damaged. To the untrained eye, they might look like they just came out of an engine showing excessive bearing wear. Don't let the looks deceive you. This is normal appearance for ACL race bearings. ACL addresses this issue in their catalog with a lengthy description of their appearance. (See "Picture Description" below for a direct citation from the ACL bearing manual.) Tools and Calibration All measurements are performed on new "virgin" connecting rods and "virgin" connecting rod bolts. These rods and bolts have never been used in any engine. Using virgin rods and bolts is an essential step for obtaining reliable and calibrated results. After use, every connecting rod big-end is deformed with extra diameter. Using virgin rods and bolts ensures that the measurements obtained will be the same reference as a new factory engine. It's the only way we know to ensure repeatable and reliable results. The image above shows the tools used for this job: * Two virgin connecting rods (P/N: 11247838623) * Snapon electronic torque wrench (P/N: ATECH3FR250B) * Mitutoyo data-logging drop indicator (accurate to 0.00002 inch) (P/N: 543-562ACAL) * SPI bore gauge (accurate to 0.00005 inch) * 2-inch calibration ring * SPI gage blocks The Mitutoyo drop indicator is used to measure each bearing thickness. It's a very pricey tool that is accurate to 0.00002 inch. It features the ability to data log to computer, categorize the results with go/no-go screen colors, and it's the same tool used by BE Bearings to measure each and every bearing shell thickness. Before beginning to measure thickness, the instrument must be calibrated. The SPI gage blocks are used to set the proper instrument calibration. The bore gauge used to measure the bearing clearance and eccentricity must be calibrated as well. The 2-inch bore gage shown in the picture is accurate to 0.00004 inch. Production and Composition Manufacturer: ACL Composition: Trimetal steel/lead/copper Coating: None Part Number: 8B1580H (STD, +0.25 mm), 8B1580HX (+0.025 mm) Target Market: OEM replacement market; Minimal increase in clearance over OEM rod bearings ACL Bearings are a full custom rod bearing designed and manufactured by ACL. ACL manufactures the bearings to their own custom specifications.The composition is a standard lead/copper bearing. The bearing does not contain a low-friction coating. Set Numbering ACL RACE Series bearing sets are identified by the ‘H’ after the set number e.g. 8B663H-Std. Most ACL RACE Series bearings are also produced in a ‘HX’ version e.g. 8B663HX-Std. The ‘X’ signifies the set will give an extra .001” (.025mm) oil clearance on a standard size shaft when compared to the H-STD set. The wall size of these HX-STD bearings is .0005” (.013mm) thinner than the H-STD Bearings, in all other respects the HX set is identical to the H-STD set. There are selected con rod bearing sets that are manufactured with a dowel hole in the lower shell, to suit a dowel location in the con rod cap. These are designated with a ‘D’ in the set numbering e.g. 8B663HD-Std or 8B663HXD-Std etc. Lead/Copper, Tri-Metal design Tri-Metal, lead/copper are considered the world's best bearings. The steel backing is coated with copper, then topped with a soft lead. The lead is embeddable, meaning small particles can embed themselves in the lead without causing any damage to the crankshaft. Look in the best automotive engines, and you're likely to find a Tri-Metal bearing design. Oil Clearances Oil clearances are most accurately measured using micrometres and bore gauges. Bearing wall thickness measurements are taken at 90 degrees to the parting line (i.e. at the crown of the bearing) using a micrometre with a ball anvil, for use on the curved ID of the bearing. Vertical oil clearance is best measured by assembling the bearing in its housing, with bolts torqued to specification, then using a bore gauge measure the assembled ID of the bearings at 90 degrees to the parting faces. The mating crankshaft journal size is measured, and subtracting this measurement from the bearing ID bore size, gives the assembled oil clearance. ACL RACE bearings can be assembled with .00075-.001” per 1” of journal diameter (0.020-0.025mm per 25mm of journal diameter) plus .0005” (0.013mm). As an example for a 2.000” (50mm) journal diameter, 2.000 x .001= .002 + .0005 = .0025” (50/25 x 0.025= 0.050 + .013 = 0.063 mm) Bearings should not be polished with abrasive pads or paper, on the bearing surface, to change the oil clearance. Picture Description Questions about the appearance of the RACE Series bearings are quite common, as this series of trimetal copper lead bearings have a very different appearance to regular aftermarket “ACL Duraglide” trimetal bearings, which have a light silver /grey appearance. The RACE Series performance bearings as manufactured have an appearance that is a dark tarnished colouration, which can vary from dark black/brown/blue colours. This colour comes from the electroplating which is the last manufacturing process. The electroplated overlay has copper as one part of its composition, which tarnishes to the dark colours described above. This tarnish colouration has negligible thickness, so once installed in the engine, the crankshaft journal contacting the bearing, will polish the bearing surface, removing the surface colour and leaving the bearings with a polished silver appearance. Performance bearings do not start out with the silver grey appearance of regular aftermarket bearings, as there is no final silvery tin flash applied to these bearings. Not applying a silvery tin flash to these high performance bearings is a specific design feature. A silvery tin flash for appearance and long term corrosion protection, as applied to the regular aftermarket bearings, can under high loading and heat, move, with the plate migrating and causing high spots on the back of the shells, and distorting the bearing. For this reason the ACL RACE Series performance bearings do not have a cosmetic silvery tin flash applied, so there is no risk of any overlay plate movement on the backs of the shells, giving better bearing to housing contact and better bearing performance and function. Standard (STD) +0.250 MM, +0.010 INCH Dimensions Standard (STD) +0.025 MM, +0.001 INCH +0.250 MM, +0.010 INCH Bearing Clearance Specifications Clearance Measurements Eccentricity Measurements Bearing Eccentricity: ACL-H, ACL-HX Bearings vs. stock 702/703 rod bearings Supporting photos Last edited by AutoTalent; 12-13-2018 at 08:32 PM..
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