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Old 06-17-2013, 06:00 PM
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mach4 mach4 is offline
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Join Date: Jul 2011
Location: San Diego County, CA
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Originally Posted by BillGrissom View Post
I really appreciate your being pro-active on all these issues. This new bracket concerns me if it could crack the upper oil pan, since steel often wins against cast aluminum. I know M-B hung other things off that lip, like the high-pressure AC hose (seems silly), but it would be a major pain to deal with a crack there (must remove engine).

I haven't installed your compressor bracket yet since my son hasn't returned with the car. I may look into welding a stiffener down the front of the plate instead, or maybe adding a rubber snubber that presses against the block to damp vibrations. I would rather risk the compressor plate than my upper oil pan.
I'd like to offer up my solution to the issue of extra support for the compressor.

As I analyzed the problem, I was very concerned about the amount of the bracket that was cantilevered and the amount of stress and vibration that was present. I don't have the capability to do finite element analysis or anything other than "back-of-the-napkin" engineering, so I can't speak definitively. I also had a problem in that, I couldn't use the bottom adjusting solution because of space so I had to develop a belt adjusting strategy that could be accomplished from above. In fact I had to cut the bottom two inches of the bracket off. (My 617 is in a 107 chassis, so I have extremely limited space to work with.)

My solution is to tie the outboard ear on the Sanden to the lower P/S bolt like this: ( I apologize for the picture - it was taken during mock up with my junk compressor and temp rods for mounting )

The adjusting rod is a 1/2" tube with heim joints on either end. I used a long 1/2" bolt with sleeves to keep the lower heim joint at the proper 90 degree position relative to the compressor. I needed to use a longer bolt on the P/S pump due to the additional width of the heim joint. The adjuster nut in the middle makes adjusting a snap using a crows foot wrench. Also, using this strategy puts the adjustment components in tension rather than compression.

This provides a pretty substantial triangulation which is illustrated in the following

If I were using an unmodified GenII bracket, I'd supplement the support using this strategy. The adjustment procedure would be as follows - double-check the tension on the P/S belt; loosen the bottom adjuster on the GenII bracket; adjust the A/C belt tension with the adjuster rod; snug up the bottom adjuster as backup.

I've got over 5k miles on the setup and the only problem has been keeping the belt in adjustment. (I think this is mainly due to belt stretch due to using a cheap belt - my bad!).
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