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Cusser
Samba Member
Joined: October 02, 2006
Posts: 33019
Location: Hot Arizona
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 Posted: Tue Jun 14, 2022 9:32 pm Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| 78BusGA wrote: |
| This is my set up with fresh new pullies and the correct belt size, yet to get the upper pully and belt to work, I needed all 10 spacers between the pully halves, and it is still too far down inside the pully. |
You need LESS spacers between the pulleys to get the belt to ride up higher and thus be tighter.
78BusGA - your photo shows an alternator, different belt than when using a generator.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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daveswoodcraft
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Joined: March 04, 2019
Posts: 241
Location: KY
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| Posted: Wed Jun 15, 2022 9:29 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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Thanks again to everyone who replied
I will try to address everyone's comments,
I have ordered a new engine bay seal, that should be here tomorrow or Friday, I just got the tines back on and have the fresh air hoses to connect and plug 2 our of 3 holes and will plug the other one. Glenn, Thank you and i will rotate the generator this week. Cusser, I have the right size socket the adjustable and screw driver was in there because I went out to take pictures and my new neighbor came out and returned them to me, he had borrowed them the day before. And in the first previous pictures the nut was not tightened on the pulley, it was just on to keep all the parts together.
So using everyone's suggestions I have the belt on, it took all 10 shims on the between the two pulleys, there is a little play in the belt but it takes some pressure and I didn't think it was .5 inches so maybe I need a longer belt? I forgot to see what size it is. This is what it looks like now
This is the pulleys with the belt installed
Again Thank you all, this little endeavor would be damn near impossible with out all of your help, if any of you find yourself in the bluegrass area of KY, give me a yell and I will buy you a bourbon!
Thanks
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toxicavenger70
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Joined: July 28, 2019
Posts: 882
Location: CO
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| Posted: Wed Jun 15, 2022 9:45 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| daveswoodcraft wrote: |
| it took all 10 shims on the between the two pulleys, there is a little play in the belt but it takes some pressure and I didn't think it was .5 inches so maybe I need a longer belt? I forgot to see what size it is |
Yes it sounds like your belt is a little short. |
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ashman40
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Joined: February 16, 2007
Posts: 16547
Location: North Florida, USA
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| Posted: Wed Jun 15, 2022 11:32 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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OP, looks like you have the belt installed. Good job! 
As a reference for future readers....
This method of tensioning the fan belt using shims often requires trial-and-error. You may have to take the stack of parts apart a few times and shuffle the shims around to get the right combination of shims between the pulley halves so the belt rides at the correct height in the pulley to get the correct tension (as measured by belt deflection between the pulleys). This is how this method was designed.
The generator pulley on the T1 engine allows the space between the pulley halves to be varied. This changes the shape/dimensions of the pulley. For the same width fan belt, this changes how far in/out it will ride in the pulley.
Like all other fan belt pulleys.... the sides of the pulley do not "pinch" the belt. The belt applies friction to the angled insides of the pulley. By changing the number of shim in between the pulley haves you are changing the shape of the pulley, moving the angled insides further apart/together, and forcing the belt to ride further in (more shims between the pulley halves) or further out (fewer shims between the pulley halves). But the pulley halves will always be parallel to each other and there will be no space/play between the stacked components of the pulley once the outer nut is torqued down. When you snug down the bolt you are compressing the stack of parts to form two parallel pulley halves.... you are not trying to pinch the belt. You typically want to rotate the crank/generator pulley while tightening the nut to prevent the belt from being pinched. As you tighten the nut and the two pulley halves come closer together you want the belt to grip higher up/further out on the angled pulley surface. If you tighten the nut without also rotating the belt it may get pinched between the pulley halves and you are no longer bringing the halves closer together and there will be a gap in the shims between the pulley halves. It is possible to pinch the belt between the pulley halves so tight that the pulley cannot rotate because it won't release the belt as it rotates!
The video above has the user tightening the nut with an impact gun. You can see the belt is being pinched between the pulley halves as he does this. But then the user rotates the pulley/belt and you can see the belt slide out and come to rest at its natural position further out; tightening the belt tension. This is fine, but I wonder if as the belt slid out the tension on the nut changed and is no longer to spec? But you can see that you need to rotate the pulley/belt as you install it to allow the belt to slide outward along the pulley as you tighten the nut.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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daveswoodcraft
Samba Member
Joined: March 04, 2019
Posts: 241
Location: KY
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| Posted: Wed Jun 15, 2022 4:23 pm Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| ashman40 wrote: |
OP, looks like you have the belt installed. Good job!
As a reference for future readers....
This method of tensioning the fan belt using shims often requires trial-and-error. You may have to take the stack of parts apart a few times and shuffle the shims around to get the right combination of shims between the pulley halves so the belt rides at the correct height in the pulley to get the correct tension (as measured by belt deflection between the pulleys). This is how this method was designed.
The generator pulley on the T1 engine allows the space between the pulley halves to be varied. This changes the shape/dimensions of the pulley. For the same width fan belt, this changes how far in/out it will ride in the pulley.
Like all other fan belt pulleys.... the sides of the pulley do not "pinch" the belt. The belt applies friction to the angled insides of the pulley. By changing the number of shim in between the pulley haves you are changing the shape of the pulley, moving the angled insides further apart/together, and forcing the belt to ride further in (more shims between the pulley halves) or further out (fewer shims between the pulley halves). But the pulley halves will always be parallel to each other and there will be no space/play between the stacked components of the pulley once the outer nut is torqued down. When you snug down the bolt you are compressing the stack of parts to form two parallel pulley halves.... you are not trying to pinch the belt. You typically want to rotate the crank/generator pulley while tightening the nut to prevent the belt from being pinched. As you tighten the nut and the two pulley halves come closer together you want the belt to grip higher up/further out on the angled pulley surface. If you tighten the nut without also rotating the belt it may get pinched between the pulley halves and you are no longer bringing the halves closer together and there will be a gap in the shims between the pulley halves. It is possible to pinch the belt between the pulley halves so tight that the pulley cannot rotate because it won't release the belt as it rotates!
The video above has the user tightening the nut with an impact gun. You can see the belt is being pinched between the pulley halves as he does this. But then the user rotates the pulley/belt and you can see the belt slide out and come to rest at its natural position further out; tightening the belt tension. This is fine, but I wonder if as the belt slid out the tension on the nut changed and is no longer to spec? But you can see that you need to rotate the pulley/belt as you install it to allow the belt to slide outward along the pulley as you tighten the nut. |
Thank you Sir!
I appreciate all your help
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 16547
Location: North Florida, USA
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| Posted: Mon Jun 20, 2022 1:04 pm Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| daveswoodcraft wrote: |
| So using everyone's suggestions I have the belt on, it took all 10 shims on the between the two pulleys, there is a little play in the belt but it takes some pressure and I didn't think it was .5 inches so maybe I need a longer belt? I forgot to see what size it is. This is what it looks like now |
Just checking, when you say "play" do you mean side-to-side between the angled sides of the pulley? The last sentence in mukluk's pic above reminds you the fan belt should not be riding at the bottom of the pulley which is the OD of the shims between the pulley halves. The two angled sides of the v-belt needs to rest against the angled insides of the pulley. This provides the max surface area to transfer power between the crank pulley and the fan pulley. If the belt is applying pressure only on the OD of the shims you have much less surface area to transfer power. The fan pulley will slip. If this is the case, you need a longer fan belt. Take the belt to the FLAPS and they can measure the diameter and find you the next larger size (diameter) belt of the same (stock) width.
One illustration to highlight a point:
In the above pic you can see many shims placed below the cone washer outside the pulley halves. Note that the nut at the end of the shaft has been tightened and a couple threads of the shaft are extending past the end of the nut. Assuming the above installation pictured has a total of 10 shims in the stack (some may be between the pulley halves)... the amount of exposed threads will ALWAYS be the same. Moving shims between the inside and outside of the pulley halves does not change the overall thickness of the total stack so the nut should always tighten to the same point on the shaft.
If an excessive amount of thread is extending beyond the end of the nut, you have to question if you are using enough shims. Also, if you are using 10 shims and in the past the threads looked like the above but after installing a new fan belt the nut cannot be threaded as far onto the shaft... your are pinching the belt and the stack is not fully compressed. Again, as long as the same number of parts are used in the stack the nut should tighten to the same point on the shaft when everything is compressed and torqued to spec.
If the end of the shaft is recessed inside the nut it means you are not getting the maximum retention possible with that nut, but you don't want a nut that is thicker than the entire threaded area of the shaft.
Be careful of thicker replacement nuts as they will change how many threads are exposed from the end. Also, aftermarket chromed capped nuts that don't let you see how many threads are exposed could bottom out without you knowing it. Since they are enclosed they could bottom out in the nut itself rather than on the shaft threads. These look nice but you need to be extra cautious making sure the nut doesn't bottom out. You may even want to count the number of turns it takes to bottom out and make sure when installing you never get close to this number.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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JeffL
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Joined: September 04, 2004
Posts: 1433
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| Posted: Thu Jun 26, 2025 10:08 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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This thread seemed to be the best to cover alternator pulleys.
My alternator had a new power pulley set but I want to go back to standard pulleys.
When I mounted them I could see the top pulley center sits far out from the cr crank pulley. When checking the power pulley set, it did offset too but the crank pulley was set out 2 mm more so it was only half.
I am going to order an alternator pulley with a fan. Maybe it is designed to sit back to align with the crank pulley. The alternator shaft must sit out about 5 mm more than a generator.
Anyone else experience this?
Pictures are back of stock pulley without fan, stock pulley with fan, stock pulley without fan mounted
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 16547
Location: North Florida, USA
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| Posted: Thu Jun 26, 2025 7:19 pm Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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If I understand your situation....
You replaced the crank pulley and alternator pulley.
They no longer line up well. Have you laid a straight edge in both pulleys to see how badly they line up?
The crank pulley extends further to the rear than the alternator pulley.
Have you tried loosening the fan shroud screws that attaches it to the cylinder head tin and the strap that holds the alternator to the alternator stand. This allows a small amount of movement fore-aft to get the pulleys to line up.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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JeffL
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Joined: September 04, 2004
Posts: 1433
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| Posted: Fri Jun 27, 2025 6:20 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| ashman40 wrote: |
If I understand your situation....
You replaced the crank pulley and alternator pulley.
They no longer line up well. Have you laid a straight edge in both pulleys to see how badly they line up?
The crank pulley extends further to the rear than the alternator pulley.
Have you tried loosening the fan shroud screws that attaches it to the cylinder head tin and the strap that holds the alternator to the alternator stand. This allows a small amount of movement fore-aft to get the pulleys to line up. |
Thanks. It’s the other way around. The alternator pulley sits out further to the rear of the bus by about 5mm (1/2 belt width) with “stock” steel pulleys. I would have to shim out the crank pulley to get the belt into alignment (which I have read some crank pulley sand seal setups do this with a longer bolt)
It had the aluminum set on when I got the Bus and I wanted to return to stock pulleys to get more/stock air flow for Florida. The aluminum alternator pulley was/is also offset towards the rear of the bus just not as much because the aluminum crank pulley extends out 2mm more than the stock steel one I had.
Out of 50 VWs this is my first alternator motor. I ordered the pulley with a fan which looks more like an “alternator” pulley.
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ashman40
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Joined: February 16, 2007
Posts: 16547
Location: North Florida, USA
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| Posted: Fri Jun 27, 2025 7:41 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| JeffL wrote: |
| It’s the other way around. The alternator pulley sits out further to the rear of the bus by about 5mm (1/2 belt width) with “stock” steel pulleys. I would have to shim out the crank pulley to get the belt into alignment (which I have read some crank pulley sand seal setups do this with a longer bolt). |
Sounds like you need this shim kit…
https://www.cbperformance.com/product-p/1915.htm
I’ve not used one but it seems to address a common problem. As you pointed out, make sure you have a good number of threads going into the end of the crank or you may need to get a longer crank pulley bolt.
Read the product description and see if there is anything you can adjust. In a way, it sounds like you could make it fit if you could grind 5mm off the alternator stand. You did replace the generator stand with a newer alternator one, correct? The alternator stands have a cutaway to make room for the larger “belt” in the body of the alternator. Though, that’s probably not your problem because there would be more than a 5mm misalignment if you were still using a generator stand.
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AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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JeffL
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Joined: September 04, 2004
Posts: 1433
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| Posted: Fri Jun 27, 2025 8:12 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| ashman40 wrote: |
| JeffL wrote: |
| It’s the other way around. The alternator pulley sits out further to the rear of the bus by about 5mm (1/2 belt width) with “stock” steel pulleys. I would have to shim out the crank pulley to get the belt into alignment (which I have read some crank pulley sand seal setups do this with a longer bolt). |
Sounds like you need this shim kit…
https://www.cbperformance.com/product-p/1915.htm
I’ve not used one but it seems to address a common problem. As you pointed out, make sure you have a good number of threads going into the end of the crank or you may need to get a longer crank pulley bolt.
Read the product description and see if there is anything you can adjust. In a way, it sounds like you could make it fit if you could grind 5mm off the alternator stand. You did replace the generator stand with a newer alternator one, correct? The alternator stands have a cutaway to make room for the larger “belt” in the body of the alternator. Though, that’s probably not your problem because there would be more than a 5mm misalignment if you were still using a generator stand. |
Again thanks. I tightened down everything with the steel pulleys and a belt. I then pulled the crank back until the belt was in alignment. The crank pulley had to be out 2mm. If the fan pulley does not cure the issue the shim kit and maybe a longer bolt is the fix.
This bus came with a rebuilt motor and new alternator so there could be lots of “stacked tolerences” causing this. I’ll update with final results.
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bsairhead
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Joined: October 08, 2008
Posts: 4463
Location: viroqua wi.
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| Posted: Fri Jun 27, 2025 8:43 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| Loosen up the stand nuts and the alternator strap and see if you can move both the direction you need and retighten. |
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JeffL
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Joined: September 04, 2004
Posts: 1433
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| Posted: Fri Jun 27, 2025 10:41 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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| bsairhead wrote: |
| Loosen up the stand nuts and the alternator strap and see if you can move both the direction you need and retighten. |
Thanks. I did get most of what I needed from the strap adjustment!
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JeffL
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ashman40
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Posts: 16547
Location: North Florida, USA
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| Posted: Thu Jul 03, 2025 11:47 am Post subject: Re: My stupid question of the day, Alternator/ Fan Belt |
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Found these pics from an old thread showing how the alternator stand must be cutaway to allow room for the larger diameter "belt" on the alternator body.
Any chance you have something stuck between the stand and the alternator preventing you from seating it all the way forward (towards the front of the car)? That would prevent proper pulley alignment. Some casting slag on the stand or even a bit of junk on the alternator body.
Honestly, it might be cheaper/easier to shave 2mm from the lip of the stand just so you can seat the alternator slightly more forward. You probably won't be able to see the hack job as it sits underneath and out of sight.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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