Technical R4 AC compressor vibration..

I've been chasing this R4 vibration FOREVER. It used to do it only around 800rpm idle, so I upped my idle to 1000..but now its back with a vengeance, worse than ever at my 1000 rpm idle. Its seems to be a harmonic. I really do NOT wanna start a huge discussion about how crappy the R4s are. I do read a lot of threads with people chasing vibrations with R4s. So lets get to it.

QUESTION: If I adapt in a Sanden compressor, do I stand a reasonable chance of solving this issue?

 

I chased a York compressor vibration on a 289 once. New compressor, the factory clutch wrapped out after a year so we put a new Murray assy on it. It was different than OEM in appearance but lined up nice. The original had a pretty heavy damper ring behind the belt groove. This would vibrate like crazy at idle, worse off idle. I could not find a correct clutch anywhere. I ended up putting a Sanden on it.... best thing I could have done! Dead smooth, took less effort from the motor to turn, it would freeze you out!

 

This is the second R4 doing the same thing.. I am done with R4s, if for no other reason than to try something, HELL, anything different.

 

Believe it or not, a lot of science/engineering goes into compressor mounting bracket design to ensure they don’t resonate with the natural frequencies of the compressor. Not saying this is the cause of your issue, but something to consider. A modern swash plate design compressor will outperform the tech in the R4 and will be quieter and more efficient. We only used Sanden compressors in all of our construction, and forestry equipment.

 

Swash plate design? New one on me…. Google, here I come.

 

Yea, no pistons technically. They are much quieter and smoother.

 

What is the high side pressure at this idling?

 

All readings for high and low sides look to be within the range for the ambient temperature.

 

True. I admit I had to delete a support brace or two when I swapped out the factory intake due to no place to bolt to. I also read a link saying GM retrofitted some cars with additional bracing for R4 vibration issues.

 

When I worked for WH Thomas in Waco in the 70's we replaced a couple of R 4 compressors a week with the older A 6 style units. I went to college in the mornings and got to Tommy's at about 12 and swapped a lot of them out and put the vacuum pump on them.

I'd have to agree with changing to a Sanden compressor these days though.