924s AC Delete Belt Size

[curtisr]

Sorry everyone but my searching has left me more puzzled than before...

I have an '87 924s and plan to delete the AC and, of course, move the alternator to the bottom.

When I search for the correct belt size there are lots of listing for AC delete but it assumes that your car did not have AC to begin with. Is this the same thing? Regardless, my question is what size of belt do I need to make this happen?

Thanks in advance.

Roger

[v2rocket_aka944]

ac delete belt is the same as if your car never had it in the first place.

for your 924S the "interchange part number" for a belt to get at your local parts store should be 6K720

[curtisr]

Got it and thank you, v2!

[rbuswell]

Originally Posted by curtisr

Sorry everyone but my searching has left me more puzzled than before...

I have an '87 924s and plan to delete the AC and, of course, move the alternator to the bottom.

When I search for the correct belt size there are lots of listing for AC delete but it assumes that your car did not have AC to begin with. Is this the same thing? Regardless, my question is what size of belt do I need to make this happen?

Thanks in advance.

Roger

Originally Posted by v2rocket_aka944

ac delete belt is the same as if your car never had it in the first place.

for your 924S the "interchange part number" for a belt to get at your local parts store should be 6K720

I need to run the car without the A/C compressor for a while and would like to use the aforementioned belt (which I've bought) on the alternator. I can't really tell how to configure it to work. Moving the alternator down makes sense but dumb ol' me can't see how it's done. The brace for the compressor applies the tension but what applies the tension if the compressor is gone? Thanks for the help.

[9FF]

Originally Posted by rbuswell

I need to run the car without the A/C compressor for a while and would like to use the aforementioned belt (which I've bought) on the alternator. I can't really tell how to configure it to work. Moving the alternator down makes sense but dumb ol' me can't see how it's done. The brace for the compressor applies the tension but what applies the tension if the compressor is gone? Thanks for the help.

To do it “factory” you need to buy an AC delete bracket which replaces the bracket that’s on there which currently supports both the AC compressor and the alternator. You can buy the AC delete bracket from Porsche or a number of aftermarket vendors make a substitute. I recall the 944 Cup racers had a workaround to buying the bracket, maybe one of them will chirp in and advise you, otherwise this may help:

[v2rocket_aka944]

PN for belt and procedure in this thread.
no tensioner required, just ease the belt on like an old V belt...
https://rennlist.com/forums/924-931-944-951-968-forum/420972-bargain-early-ac-delete.html#post5395126

[rbuswell]

Thank you guys. I'm only taking the compressor off line until I can rebuild it for R134A and get the hoses rebuilt. The hoses that go into the cabin are a real bear and I haven't found an actual tutorial for that yet. It looks like you dismantle everything inside of the cabin so that you can twist and turn the steel pipes in the right direction to pull through the firewall. A really big deal. Porsche proved, yet again, that they really don't want to sell us anything other than race cars for the street. The car is black and I live where it gets pretty hot so A/C delete isn't an option for my new daily driver.

If I'm understanding V2's post, the belt will hold tension after sliding it over the pulleys. I suspect it holds long enough to get this project done.


BTW, 9FF, I've contemplated building a 924S race car someday so sharing the Excellence article is a big plus. I don't think my Excellence collection goes back that far.

[911tracker85]

I have a LR AC delete bracket I removed from my 86 951 now that I am rebuilding the AC.

with the engine out for full rebuild, decided to fix the AC. got to looking and realized I needed to remove the brake booster to get my hard lines out for rebuild. they were the original cause of AC not working and having me install the delete bracket.

I thought removing my AC lines were a pain until I happened to look at the lines in my friend's 84 944 we are working on and saw they did not disconnect at the firewall.....

got my lines rebuilt and back in the car. now finish up reinstalling the MC and booster and then putting the engine back in.

good luck.

[rbuswell]

Originally Posted by 911tracker85

I have a LR AC delete bracket I removed from my 86 951 now that I am rebuilding the AC.

with the engine out for full rebuild, decided to fix the AC. got to looking and realized I needed to remove the brake booster to get my hard lines out for rebuild. they were the original cause of AC not working and having me install the delete bracket.

I thought removing my AC lines were a pain until I happened to look at the lines in my friend's 84 944 we are working on and saw they did not disconnect at the firewall.....

got my lines rebuilt and back in the car. now finish up reinstalling the MC and booster and then putting the engine back in.

good luck.

Mine is a '87 924S. The hoses/lines that go into the cabin on my car are steel (or whatever the hard metal they are made of) and have some bends. Since they are hard, they would need to be twisted and turned to make it through the firewall. That's why I think I have to take out all the A/C and heater gear under the dash to provide relief for them to twist. There are two brackets that hold them to the firewall which don't appear to be the hangup but I may be wrong on that since I haven't tried to extract them from the cabin yet. My lines seem to go in a more diagonal direction than yours to a bracket about 1/2 of the way down the left fender. It doesn't look the the MC or power booster would get in the way. I'd post pictures but I have yet to figure out how to do that on Pelican so I gave up trying years ago.

I'm not an expert on A/C but one thing I've wondered is whether I could abandon the steel throughout and have new barrier hoses made of rubber all the way. Then I could just cut all the old stuff as needed and us pliable hoses going back in.

[rbuswell]

Originally Posted by v2rocket_aka944

PN for belt and procedure in this thread.
no tensioner required, just ease the belt on like an old V belt...
https://rennlist.com/forums/924-931-944-951-968-forum/420972-bargain-early-ac-delete.html#post5395126

The idea looks like it will work fine but I compared the picture in the thread to my configuration and they look different. Is there a way to measure my actual belt length accurately?

Also, doing it this way doesn't put too much pressure on the alternator bearings, does it?

[v2rocket_aka944]

wrap a string around the alt/crank pulleys and find the closest belt to that length?

[rbuswell]

Originally Posted by v2rocket_aka944

wrap a string around the alt/crank pulleys and find the closest belt to that length?

Took my wife's measuring tape for sewing. Put it around the center (at the grooves) of the two pulleys and it came back 33.25 inches which is 844.55 mm. I assume that is a 845 mm belt. Uncle Maz was saying 855 mm on Rennlist so it is a little different. That came back as a 6PK845 belt. Sound about right?

Also, any concerns about the alternator bearings?

Update: Did some additional research and the part number represents the outer circumference of the belt. To get to the inner circumference of 845 mm, the 6PK850 appears to be the correct size given the thickness of the belt.

[rbuswell]

Originally Posted by rbuswell

Took my wife's measuring tape for sewing. Put it around the center (at the grooves) of the two pulleys and it came back 33.25 inches which is 844.55 mm. I assume that is a 845 mm belt. Uncle Maz was saying 855 mm on Rennlist so it is a little different. That came back as a 6PK845 belt. Sound about right?

Also, any concerns about the alternator bearings?

Update: Did some additional research and the part number represents the outer circumference of the belt. To get to the inner circumference of 845 mm, the 6PK850 appears to be the correct size given the thickness of the belt.

The 6PK850 was also too big. Given how much slack there was I thought the 6PK845 would be too big too. As it turns out the 6PK845 is mostly used for a snowmobile and a couple other specialty uses so it was pretty pricey. Going to the 6PK840 meant an inexpensive Bando on Amazon. It turned out to be the perfect fit ... for my 924S engine anyway. It had a nearly perfect amount of deflection (until it gets stretched a little over time, I assume). I'm sure it will work just fine until I get all my A/C problems sorted out.

When I installed it, I put the entire belt on the alternator pulley and worked the main pulley while turning the crank. The main pulley went on pretty well but then the alternator pulley started to work itself back off. I decided to just keep turning it and firmly work the alternator end back on. Nothing is a sure thing but it looked like it wanted to stay on both pulleys even when revving the engine to a pretty good RPM.

[v2rocket_aka944]

i dont get on Pelican much but I wouldn't worry too much about the alternator bearings.
they're pretty beefy for the job they have to do.
i think if the belt put up more of a fight and really needed to be forced on then that might be an issue of overtension but it sounds like you didn't have too much trouble once you saw what was going on.

[rbuswell]

Originally Posted by v2rocket_aka944

i dont get on Pelican much but I wouldn't worry too much about the alternator bearings.
they're pretty beefy for the job they have to do.
i think if the belt put up more of a fight and really needed to be forced on then that might be an issue of overtension but it sounds like you didn't have too much trouble once you saw what was going on.

I don't really know enough about the differences in the alternator mounting points for 924 and 944 cars to say the 6PK840 will be the right belt for everyone. Through trial and error I found it to be the right one for my car. Once I got the belt pulley on the alternator end to cooperate, the belt seemed perfect for the job.

I don't think the belt is stressing the bearings. I had the alternator rebuilt by a reputable firm and I'm confident the bearings were inspected and replaced with good parts if needed. The only other thing I would suggest is to keep a close eye on the belt since it should stretch over time. Replacing a $12 belt from time to time is a small price to pay for those who want to do an A/C delete. Thanks again for your insights.