When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
idea for 85-87 ac compressor extra brace location, thoughts?
need slightly longer head bolt possibly longer ac bolt. get tube stock and crush ends flat and drill holes through. ive had two broken ac compressor brackets.
In addition to the rear that goes to the exhaust manifold, yes that might work.
I never cracked my 86's mounting, only the 88s, the real fix though is the whole bracket being made out of something besides the cheap pot metal they used.
i figured it was aluminum. was going to grind a v out and mig weld aluminium then grind down on one of my broken ones. if its pot metal that may not be effective
there is a single brace that connects to the forward most RH exhaust manifold mounting hex-stud. the other end of the brace connects to the outer-right bracket/compressor mounting bolt (#6). if properly installed, no additional bracing is needed.
and , they are aluminum. one thing I might add - I modified my bracket so the one bolt (#7 in the diagram) that comes in from the rear is now reversed. it will make any future compressor removal a bit easier --
edit - let me add this when I say "properly installed." i'm thinking it's all about the sequence of events. I've spend some time trying to visualize how the AC mounting bracket and compressor was installed at the bowling green assembly line. the best I figure, the compressor was first set in the bracket with two bolts, #6 and #7, along with the exhaust manifold brace, and installed in finger snug. since bolt #7 comes in from the rear, I doubt the assembly line removed the RH valve cover on an already completed engine assembly to install that bolt, so the bracket and compressor had to be mated prior to installation on the engine. the bracket/compressor was fitted to the engine with the two nuts to the water pump studs, along with the lower compressor mounting bolt (that funny hex bolt with the torx recess). the exhaust manifold brace, fitted with bolt #6, was now fitted to the exhaust manifold stud - finger snug. with everything properly positioned, the lower mounting bolt and the two water pump nuts were now evenly torqued to spec. this should minimize any stress on the bracket. next, the #6 and #7 bolts were now torqued, and finally, the exhaust manifold nut was tightened and torqued. tightening the water pump nuts and the lower mounting bolt first should minimize any external stresses on the AC bracket. the final tightening on the exhaust manifold nut should stabilize the assembly without adding any additional stress to the bracket assembly. finally, the belt tensioner was installed.
Joe i saw an earlier lost where you modded that bolt. great idea.
Now, ive had two of these crack ac brackets break where the secret bolt is, and both of those air compressors had a vibration when operational.
so im not sure about the " ot needed if factory braces" comment. n
have you guys had trouble free ac brackets? its possible that mine broke from impacts or fender benders on my cars. i hadnt considered that really. i thought it was a weak inherent design.
thnx for feedback guys, im going to install factory bracing now and if i have time later ill fab ine up using that metal conduit and a vise and grinder.
No it is aluminum, but its cheap **** metal and a bad design for all l98 cars if you ask me. They wouldn't have needed to add so much bracing later on if it was a good design, and the design actually got much worse in 88. It should've been steel from the start with how its designed.
Joe i saw an earlier lost where you modded that bolt. great idea.
Now, ive had two of these crack ac brackets break where the secret bolt is, and both of those air compressors had a vibration when operational.
so im not sure about the " ot needed if factory braces" comment. n
have you guys had trouble free ac brackets? its possible that mine broke from impacts or fender benders on my cars. i hadnt considered that really. i thought it was a weak inherent design.
thnx for feedback guys, im going to install factory bracing now and if i have time later ill fab ine up using that metal conduit and a vise and grinder.
running my 85's original compressor mounting bracket (33 years/163K miles). no cracks to date. IMO, an adequate design. if anybody is having bracket failure due to compression vibration, it's not the bracket's so called poor design, that's the issue, but something with the compressor that needs addressed -
ac compressor related vibrations dissapeared after doing this?
NO FLAMES -- adding a brace is not going to hurt anything, but have you looked into what's causing the compressor vibration? if anyone is having vibration issues bad enough to cause mounting bracket failure, personally, i'd look into what's causing the vibration, and not adding a "band-aid" to fix the problem. if you've had two bracket failures, IMO, somethings not right....
hey Joe, not sure what you mean about the flames. I get what you're saying about checking for the source of the vibration. Thing is, I thought The source of the vibration was a lack of racing. Some kind of isolation or something from lack of support. The two braces I have had broken arm from two separate cars both of which had functioning AC but a vibration.
hey Joe, not sure what you mean about the flames. I get what you're saying about checking for the source of the vibration. Thing is, I thought The source of the vibration was a lack of bracing. Some kind of isolation or something from lack of support. The two braces I have had broken arm from two separate cars both of which had functioning AC but a vibration.
sometimes my comments are taken the wrong way -
vibration issues are most always caused by something being out of balance. not a lot in or within the compressor that could cause "abnormal" vibration unless it's a bearing or clutch issue - ??? does the vibration change when the compressor clutch engages or disengages, or is it all the time?
Last edited by Joe C; 06-16-2018 at 07:58 AM.
Reason: added "abnormal" to my post
Compressors produce a vibration from the valves opening and closing in sequence as the compressor rotates. Just like the engine creates torsional vibration on the crankshaft as the cyls fire. The higher the RPM, the higher the frequency. Occasionally, the compressor "buzzes" from the refrigerant flowing through the cycling valves.
you're right, but let me throw this into the mix. I don't think the vibration caused by normal operation of the AC compressor, is enough to cause bracket failure. you may have frequency, but you would not have the force dynamics. if there is sufficient compressor vibration causing the bracket to fail, there's some other underlying factor at work here. I've google "car ac compressor vibration" -- seems there is a host of issues or problems that cause excessive vibration. so, back to my original statement -- if it is indeed the compressor causing the bracket failure, i'd look into what's causing the "abnormal" vibration, and not by adding a band-aid fix.
@ Joe C: I thought about this a little bit. I discovered a crack in mine (way down low, by the tensioner mounting location) in 2006 after I got it out of 12 years of storage and began to prep it for the NCRS campaign. I welded the crack, and put it back together. No biggie. 12 years and 15,000 miles I haven't looked at it recently, maybe it cracked again. During the above discussion I attributed the crack to "normal" vibration from the compressor.
My original compressor was noisy when engaged. And it leaked. During it's NCRS campaign I would charge it up, go to the meet and pass Operations, then upon my return recover the R-12 and put the car away until the next event. For my Performance Verification I installed a new Service Replacement compressor. Then took it off and reinstalled the original for the next two events where originality was necessary. Then in 2009 I installed the Service Replacement again, and it has been on there for most of those 15,000 miles since I welded the bracket.
So yes, the compressor may have been "vibrating" because it was noisy, and cracked the bracket.
Sorry for the TLDR. But your thought makes sense.
if i'm understanding this post and others, your failure seems to be in the same place as vikingtrad3r's - (i'm thinking VT3 indicated) the area around the belt tensioner. we may be chasing the wrong rabbit here - ??? it just may be the belt tensioner is the culprit. now that I think about it, that might make more sense. it would be interesting to catalog the bracket failure location(s).
VT3 - where were the locations the cracking on your two AC brackets? same place?
06-14-2018, 02:46 PM
idea for 85-87 ac compressor extra brace location, thoughts?
, they are aluminum. one thing I might add - I modified my bracket so the one bolt (#7 in the diagram) that comes in from the rear is now reversed. it will make any future compressor removal a bit easier -- 
. looking at you pic, shows the throttle body linkage on the RH or compressor side - 
