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Sun Aug 29, 2010 5:32 pm

Hey people,

i was just wondering about fan belt sizes because I have two out in the garage, neither of which fit my engine (seemingly too small).

My question is, how many different size belts did aircooled vws use and what were the different applications for each size? anybody know?

thanks folks. I just want to buy the right one

Sun Aug 29, 2010 5:45 pm

905 mm was for generators and 912mm was for alternators. (if I remember correctly).

My engine with alternator uses a 905mm belt... don't ask me why, it just fits.

Sun Aug 29, 2010 5:47 pm

Glenn wrote: 905 mm was for generators and 912mm was for alternators. (if I remember correctly).

My engine with alternator uses a 905mm belt... don't ask me why, it just fits.

hmmm...thats odd. I'm going to try to measure one of the belts I have and see what size they are. I'll report back when I have the measurement. Thanks for the information Glenn!

Sun Aug 29, 2010 6:05 pm

indeed Glenn, the belts I have that don't fit are 905 mm. Its hard to believe that 7 millimeters could make that much of a difference. I reckon it does or Volkswagen wouldn't have changed it. Thanks again, Glenn.

Mon Aug 30, 2010 9:05 am

This belt size thing has been a subject of thought for me lately. The 9.5x905 for generators vs 11.3x912 for alternators. I have done a few gen. to alt. conversions and like Glenn found the 9.5x905 fit best with the 11.3x912 being too tight. To my knowledge there were no dimensional changes as far as pulley size or distance between axas. I can not seem to find any supporting evidence but have to believe that alternators used 10 adjusting shims as opposed to 8 for generators. (I would appreciate if someone could confirm this.) Seeing shim kits sold with 10 shims led me to this belief.

Another note on this subject is, I found that [email protected] recommends the 11.3x912 belt for doghouse fan OR alternator applications. He states that the wider belt slips less with the additional load and that it also spins the fan slightly faster for better cooling. I'm not sure if the additional fan speed is from the wider belt riding higher in the pulleys or the extra belt length or a combination of the two.

For some reason I prefer the v-belt design of the gen. belt over the grooved or is it called ribbed design of the alt. belt. I do however believe that John's recommendation deserves some consideration. At some point I plan to check on size availibility of the v-belt design.

Mon Aug 30, 2010 10:05 am

Glenn wrote:
My engine with alternator uses a 905mm belt... don't ask me why, it just fits.

Same here. Did a generator to alt conversion on a 1641 SP, and reused the original generator belt. It fit fine. This was with a stock crank pulley and replacement ('Bruck'-Made in Germany) alternator pulley.

Continental 9.5x905, IIRC.

Mon Aug 30, 2010 6:50 pm

905 x 9.5 and 905 x 10 both sold by Continental.

FYI: "Bruck-Made In Germany" is the name of a Chinese company, creative name :wink:

http://www.made-in-china.com/showroom/hh-autoparts...Parts.html

Mon Aug 30, 2010 6:58 pm

neil68 wrote: FYI: "Bruck-Made In Germany" is the name of a Chinese company, creative name :wink:
In the 60's a town in Japan changed it's name to Usa

"Made in USA".

The Chinese are not that creative.

Mon Aug 30, 2010 7:58 pm

I could be wrong, but I seem to remember a slightly smaller belt being used in the 6 volt engines. I think it was a 900 x 9.5.

I remember when I worked at a VW parts shop back in the '90's, we used to stock that belt.

Maybe you have one of those belts.

Perhaps you have a belt for a power pulley. That would be too small for a stock set up.

Wed Sep 01, 2010 8:41 am

Looks like the Continental/Contitech is now made in India.

Wed Sep 01, 2010 10:18 am

Glenn wrote: neil68 wrote: FYI: "Bruck-Made In Germany" is the name of a Chinese company, creative name :wink:
In the 60's a town in Japan changed it's name to Usa

"Made in USA".

The Chinese are not that creative.
"Made in USA" LOL! Now that's clever!!

Thu Sep 18, 2014 8:04 am

thefladge wrote: I could be wrong, but I seem to remember a slightly smaller belt being used in the 6 volt engines. I think it was a 900 x 9.5.

I remember when I worked at a VW parts shop back in the '90's, we used to stock that belt.

Maybe you have one of those belts.

Perhaps you have a belt for a power pulley. That would be too small for a stock set up. I installed a cb santana pulley and the 905 belt seems to big . waiting for cb to get back to me. i still havent shimmed it alt with stock german top pulley . this size seems to be correct 900x9.5 that extra 5mm.. we ll see ill updat this soon