E28 alternator upgrade project pics
Posted: Sun Sep 01, 2013 10:53 pm
I finished this project back in the spring, but it took a while to organize and upload the pics. The pictures capture several electrical system upgrades: upgrading from 55A 530i alternator to 80A E28 alternator, installation of new 12V cabling from the battery positive terminal, and installation of an adjustable voltage regulator.
http://www.flickr.com/photos/robertbond ... 228456477/
Swapping the alternator itself is a fairly easy job once the aluminum E28 bracket and tensioner HW is in hand. The by-product "hard" part is what to do about your E12 P/S pump. I see about 3 solutions to this:
1. Use your E12 pump and modified E12 P/S brackets. This results in a few residual spacing issues to get the pulley in the expected plane. In the old archives, most people just threw in a bunch of washers for a quick fix. I think some cuts were also made to the E12 brackets.
2. Convert to the E28 P/S pump. I'm sure this is fine, except the interface problem now moves into the P/S hoses and fittings which aren't identical to the E12.
3. Use E28 bracket design with E12 pump. This is the route I took.
Pics show both E12 and E28 bracket systems on a work bench. After studying the E28 design, I decided it was superior. The E28 has a pivot point that the E12 design lacks. The pivot point helps ensure that the pulley plane doesn't change during belt tensioning, while the E12 design leaves it up to the mechanic's prying skill to ensure that the front and back of the pump move equally while the bolts are sliding through those slots. E28 belt tensioning also uses a rack-and-pinion approach that allows you to tension with a ratchet or wrench - NO CAVEMAN PRYING!
The hard part is the front E28 bracket. It could be used directly if the bolt hole pattern matched the E12 pump, but it doesn't. I fabricated my own hybrid E12/E28 front P/S bracket by machining a 3/8" thick piece
of aluminum 6061 on a router table w/ aluminum router bit. I expect the 3/8" thickness is overdesign; I don't race my car, so I'm erroring on the side of strength. I also had my used brackets plated and assembled everything with stainless steel HW.
The solution in the pics has about 4500 miles on it from summer trips to 5erWest and Four Corners, so it appears reliable.
This would make a good FAQ write-up, although FAQ activity seems to have died years ago and the webmaster isn't easy to reach these days.
Robert
http://www.flickr.com/photos/robertbond ... 228456477/
Swapping the alternator itself is a fairly easy job once the aluminum E28 bracket and tensioner HW is in hand. The by-product "hard" part is what to do about your E12 P/S pump. I see about 3 solutions to this:
1. Use your E12 pump and modified E12 P/S brackets. This results in a few residual spacing issues to get the pulley in the expected plane. In the old archives, most people just threw in a bunch of washers for a quick fix. I think some cuts were also made to the E12 brackets.
2. Convert to the E28 P/S pump. I'm sure this is fine, except the interface problem now moves into the P/S hoses and fittings which aren't identical to the E12.
3. Use E28 bracket design with E12 pump. This is the route I took.
Pics show both E12 and E28 bracket systems on a work bench. After studying the E28 design, I decided it was superior. The E28 has a pivot point that the E12 design lacks. The pivot point helps ensure that the pulley plane doesn't change during belt tensioning, while the E12 design leaves it up to the mechanic's prying skill to ensure that the front and back of the pump move equally while the bolts are sliding through those slots. E28 belt tensioning also uses a rack-and-pinion approach that allows you to tension with a ratchet or wrench - NO CAVEMAN PRYING!
The hard part is the front E28 bracket. It could be used directly if the bolt hole pattern matched the E12 pump, but it doesn't. I fabricated my own hybrid E12/E28 front P/S bracket by machining a 3/8" thick piece
of aluminum 6061 on a router table w/ aluminum router bit. I expect the 3/8" thickness is overdesign; I don't race my car, so I'm erroring on the side of strength. I also had my used brackets plated and assembled everything with stainless steel HW.
The solution in the pics has about 4500 miles on it from summer trips to 5erWest and Four Corners, so it appears reliable.
This would make a good FAQ write-up, although FAQ activity seems to have died years ago and the webmaster isn't easy to reach these days.
Robert
