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need some help - 1985 AC compressor mounting modification
there are 3 mounting bolts holding the AC compressor to the mounting bracket. I want to modify or flip the direction of the far inboard or LH bolt. I need to know if there would be any interference with the head of the bolt if it comes in from the front side? I have everything apart, and I can't totally visualize this...
could someone take a quick look to see if there would be be any interference with the serpentine belt, or any other hardware with this mod?
In the stock configuration, it's a royal PITA to R&R the AC compressor, because, with the bolt coming in from the rear, the bracket/compressor sub-assembly has to be jockeyed forward to clear the valve cover, and install the bolt. there are all kinds of issues with fuel lines, and smog plumbing because those lines come in within the bracket itself. there is no install problem with the bottom and RH mounting bolts. here's a pic of what I want to do -
my thought is to insert a heli-coil on the aft side of the bracket. it would make things a lot easier if with the bolt came in from the front side.
I'm somewhat amazed that you're even considering this.
I don't have an '85 to compare but your snapshot "hints" interference. Can't you route a belt and "visualize" maybe better yourself?
Slip a "thread to head" bolt or maybe threaded rod(s) with nuts through the front threads on both of the mounting points and just "hang" the compressor for comparisons.
One M10 threaded rod and done, first hand relying on no one.
I'm somewhat amazed that you're even considering this.
I don't have an '85 to compare but your snapshot "hints" interference. Can't you route a belt and "visualize" maybe better yourself?
Slip a "thread to head" bolt or maybe threaded rod(s) with nuts through the front threads on both of the mounting points and just "hang" the compressor for comparisons.
One M10 threaded rod and done, first hand relying on no one.
- sort of, and not sure what you mean about being, somewhat amazed that i'm even considering this - ???
just went through a trial fit - used a straight edge for the belt routing between the compressor and the crank pulley. in stock configuration, there is interference with the head of the bolt and the belt. I did however come up with a solution - shave approximately .125 from the head of the (flange) bolt (thus making it a low-profile bolt), and a step cut on the bracket flange by .125 - that recesses the bolt head by .250 and then clears the belt. structurally, there shouldn't be an issue with the bracket. as of right now, i'm thinking on proceeding. my good friend has a small machine shop, and i'm going to talk with him later today about doing the step cut. there doesn't seem to be any problem with the heli-coil end of it. right now, i'm thinking this will work. this will definitely make reassembly a piece of cake! - .
You're only modifying the upper of the M10 mounting - correct? The lower requires I think the rear entry to anchor the lower rear brace that I believe is there.
I'd think you need to be sure the OD of the "step" is sufficient for the socket you intend to use for assembly and NOT just sufficient for the "flange head" of the bolt.
A splined nut-sert might do very well for the modification on the rear, an effective M10 "heli-coil" I believe requires more depth for a quality install than the bracket allows.
I understand the plan
*** Since your friend has a machine shop perhaps ideally at the rear might be to have your friend machine an M10 long/tall nut so that it could be inserted into the bracket so that you could use a box-end wrench on it to secure the compressor, bolt and nut. Long/tall is generally marketed as a coupling nut but tall/long would likely have maybe higher properties classification.
Best advice put it back as is remove valve cover to solve clearance issues, changing AC compressor is something not to be rushed anyway, what's an extra 20 minutes to make things right??
Also with comp in position bolt not able to slide thru for the pulley clutch assembly!!
You're only modifying the upper of the M10 mounting - correct? The lower requires I think the rear entry to anchor the lower rear brace that I believe is there.
I'd think you need to be sure the OD of the "step" is sufficient for the socket you intend to use for assembly and NOT just sufficient for the "flange head" of the bolt.
A splined nut-sert might do very well for the modification on the rear, an effective M10 "heli-coil" I believe requires more depth for a quality install than the bracket allows.
I understand the plan
*** Since your friend has a machine shop perhaps ideally at the rear might be to have your friend machine an M10 long/tall nut so that it could be inserted into the bracket so that you could use a box-end wrench on it to secure the compressor, bolt and nut. Long/tall is generally marketed as a coupling nut but tall/long would likely have maybe higher properties classification.
correct - only modifying the LH mounting. I did look into the flange diameter, 15mm socket diameter, and the step radius. the flange diameter of the M10 bolt is approximately 21.5 mm, the socket is slightly smaller at 20.7, therefore, i'll need a minimum of radius of 11mm (22mm diameter) on the step cut. I hope my friend can finalize the cut dimension. it might depend on some tolerance requirements and stack up, but i'm thinking i'm in the ballpark. for the heli-coil, the rear flange is .530 (13.5mm), and the M10 heli-coil depth requirement is .420 (11mm). seems there is enough meat on the flange to insert a heli-coil.
not sure I understand this though, but i'll pass it along to the shop -
machine an M10 long/tall nut so that it could be inserted into the bracket so that you could use a box-end wrench on it to secure the compressor
i'm also looking into a M10 low profile, allen head cap screw, but I need to look at some dimensional data. that might solve any socket/wrench issues -
Best advice put it back as is remove valve cover to solve clearance issues, changing AC compressor is something not to be rushed anyway, what's an extra 20 minutes to make things right??
I can somewhat understand this, but, at this point, i'm not willing to undo a bunch of stuff. I could get the bolt in as is, but it would be a major PITA.
now this, I have no idea what you're saying -
Also with comp in position bolt not able to slide thru for the pulley clutch assembly
Take a long/coupling nut and turn the depth of the rear bore to a diameter somewhat larger than the M10+ bore that is there, insert that turned diameter into that bore leaving a hex extended that you can put a box/open-end on to tighten.
You would be fabricating your own "barrel bolt" in some terminologies. Here's a link to a 5/16 similar but less the hex that you would be salvaging.
Take a long/coupling nut and turn the depth of the rear bore to a diameter somewhat larger than the M10+ bore that is there, insert that turned diameter into that bore leaving a hex extended that you can put a box/open-end on to tighten.
You would be fabricating your own "barrel bolt" in some terminologies. Here's a link to a 5/16 similar but less the hex that you would be salvaging.
- now I understand. actually, I like that idea over a heli-coil. i'll see if I can find one local. on-line shopping for small items is cost prohibitive because of S&H. if not, the shop may be able to cut me a long/tall nut.
talk with my (shop) friend and we're a go on the mod. learned something new yesterday - I was referring to the mod as a "step cut," where actually, it's a "spot face." i'm finalizing the dimensional data today - seems I have 5/32" between the flange face and the rear side of the pulley. I have plenty of room, so my spot face cut will only be about .125 deep, and about .125 off the bolt head. I need to check the flange diameter for interference with the pulley for the install - I may have to cut a flat on the bolt flange for assembly - similar the the bottom mounting bolt. so far, nothing seems to be a show stopper.
- now I understand. actually, I like that idea over a heli-coil. i'll see if I can find one local. on-line shopping for small items is cost prohibitive because of S&H. if not, the shop may be able to cut me a long/tall nut.
My first suggestion was a "splined nut-sert" for the rear and I really think it's maybe the go to solution. The under-head dimension (depending on brand) is 17mm or less and would certainly suffice I'd think.
This is a UK link but a better image of what I meant. Others have a more generic image and actually don't display a "low profile".
I have some that match the spec listed but these were intended to be used with a pneumatic installer to relocate a sway bar mount. I haven't done it yet so I don't know that I have extras. The 13.5 hole size would mean very little material removal on the rear. Under-head on mine is the 16.67 mentioned or very close.
What I was saying is once the compressor is set in position to pas bolts thru the pulley will not allow the bolt to pass thru from the front! I constipated the same change to mine when engine was rebuilt but just to much hassle! How often will the AC compressor be off the car anyway? But if you find easy solution I am interested!
Some pics of the two tone mine is exact same as yours 85 z51 silver over graphit 4+3...
What I was saying is once the compressor is set in position to pas bolts thru the pulley will not allow the bolt to pass thru from the front! I constipated the same change to mine when engine was rebuilt but just to much hassle! How often will the AC compressor be off the car anyway? But if you find easy solution I am interested!
Some pics of the two tone mine is exact same as yours 85 z51 silver over graphit 4+3...
what I want to do with the upper/inboard bolt is basically the same as the bottom bolt, which comes in from the front. since the bottom bolt clears the pulley, my modified upper mount shouldn't be any different. my face cut on the upper portion of bracket should mimic the face cut/recess, on the bottom mount. the radial dimension from the center of the compressor pulley to all three mounting points or bolts is the same. not sure why you think there is an issue - ???
it's not so much that i'll be removing the compressor too often, in fact, my hope is never to remove it again. my mod is to make installation a lot easier, even if it's only one time. I tend to look for the easy way out, i have plenty of time to do this mod, and the cost involved is minimal. now, speaking of time, spent most of the day sorting thru new GM replacement hoses that are not quite the same fit as the originals, and my new compressor - ordered a AC Delco #15-20227 (correct for an 85 corvette) - what came in was a 15-20225 - that seems to be correct for a 87 buick regal - WTF? anyway, i'm in the middle of the exchange process. one step forward, two steps back - -
Interesting thread and I have also thought about putting all the bolts in from the front. ON the stock bolt heads there is one flat shorter than the others that allows it to pass under the pulley. And I also dont plan on taking the compressor off, but it sure will be a lot easier to pull the bolts from the front than to remove the valve cover. I just didn't have the guts to drill out the threads in the bracket. Thanks for the discussion.
Interesting thread and I have also thought about putting all the bolts in from the front. ON the stock bolt head there is one flat shorter than the others that allows it to pass under the pulley. And I also dont plan on taking the compressor off, but it sure will be a lot easier to pull the bolts from the front than to remove the valve cover. I just didn't have the guts to drill out the threads in the bracket. Thanks for the discussion.
besides the OE modified flange bolt, there are two notches cut into the pulley/clutch assembly, 180 apart. these notches plus the modified flange bolt allows sufficient bolt/pulley clearance for assembly. the same should hold true for the upper inboard bolt with this mod -
UPDATE - getting ready to install the AC compressor mounting bracket with the mounting mod. basically, drilled out the 10mm threads at the front of the bracket to clear the bolt, and added a 1.0" spot face, around .150 deep to front surface. i used another flange bolt, the same as the bottom, outboard, mounting bolt - it has a smaller flange diameter/hex dimension, and is about 8-10mm longer to accept a fastener. i cut approximately .08" from the head of the bolt, making it slightly more low profile to clear the pulley and belt. on the back side, i evaluated several threaded inserts - helicoils, E-Z serts, keensert, timesert, etc, - all had their advantages/dis-advantages. i chose the most simple solution - a flat washer and M10-1.5, low profile jamb nut. the length of the bolt allowed for the washer, nut, and a couple threads showing. the jamb nut should be more than sufficient for a 25-30 lb.ft torque requirement. for a little insurance, i'll use blue threadlocker. the only issue - it's wrenches only - not quite enough clearance for a socket on either end. a thin wall might work on the flange side, but i don't have a thin-wall, metric set. small price to pay for the convenience.
the mod took some time and effort, but still, an easy mod. the cost was almost nothing. hopefully, tomorrow, i can install the bracket, connect the fuel lines to the fuel rail, route the emission tubing, etc.. it should just be a matter of dropping the compressor in place and installing the three bolts. installation at this point "should be" a snap, and making any future maintenance and RH valve cover removal a bit easier.
final - the AC compressor installed without issues - quite easy for that fact. it would have been better to have a threaded insert in place of the jamb nut - it was a bit tricky getting the washer and nut in place and getting a 17mm wrench on the nut - tight quarters, but overall, not an impossible task.
final - the AC compressor installed without issues - quite easy for that fact. it would have been better to have a threaded insert in place of the jamb nut - it was a bit tricky getting the washer and nut in place and getting a 17mm wrench on the nut - tight quarters, but overall, not an impossible task.
DONE
There's always second thoughts regarding "What I could've or should've done OR might've worked maybe better/easier".
need some help - 1985 AC compressor mounting modification
- sort of, and not sure what you mean about being, somewhat amazed that i'm even considering this - ???
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