MyE28.com

Most parts suppliers list the AC belt on an e28 as a 13.0 x 800, but I've been having trouble working with that belt. Even with the adjustment all the way in, the belt is a PITA to get on and when it's on it's way too tight. The ETK lists a 12.5 x 800. Anybody have a clue what's going on here?

Unfortunately, they're all like that.

Shawn D. wrote:Unfortunately, they're all like that.

Yup, the AC belt sucks to install.

So get a Conti 13.0 x 810, 823 or 850 belt.

http://autoparts.cardomain.com/auto-par ... t?bq=conti

Steve H. can also get what you need.

you won't find a 12.5 any more (usually) so get a 13. The listing is wrong- do not try to use an 800. Even an 810 is a tight fit, so I normally use up to an 825.

I just used a screwdriver and some muscle, it wan't that bad.

mooseheadm5 wrote:you won't find a 12.5 any more (usually) so get a 13. The listing is wrong- do not try to use an 800. Even an 810 is a tight fit, so I normally use up to an 825.

Will do. Having the belt as tight as it is destroyed the last belt prematurely and is not good for the compressor.

On the M20 , the belt is a tight squeeze. But once it is on the pulleys you have to take up the slack, That being the case, you aren't stressing anything except maybe your fingers. Just start it on and bump over the engine.

Seems like 810 is the size I use, I know I went thru a couple of my spares when I lost all my belts last year and it was a pretty narrow range that would fit. That said, a screwdriver and a ratchet on the crank bolt make it less dramatic than many seem to feel it is.

Mike W. wrote:Seems like 810 is the size I use, I know I went thru a couple of my spares when I lost all my belts last year and it was a pretty narrow range that would fit. That said, a screwdriver and a ratchet on the crank bolt make it less dramatic than many seem to feel it is.

I know, i've gotten it on before, but there's no reason why the belt should be overly tight with the eccentric all the way out

My guess is manufacturing tolerance.

Mike W has it right - use a screw driver and turn the crank. It slips right on. Unfortunately I've done it enough to learn that trick too. "Necessity" is a mother....oh yeah, "the" mother of invention.

On some cars that this belt is spec'd for, it will not go on even that way, or it will go on and be banjo string tight. I never bothered to find out why, just went to using 810s instead and never had a problem.

I used Mike W's method with the 810 belt I put on in Feb.

How are belt sizes categorized?

Patrick McHugh wrote:How are belt sizes categorized?

By width and total length. A belt of the same total length will seem "larger" if the width is narrower because it rides further down in the grooves.

Cool, so 12.5 would be the width and 800 the length?

Patrick McHugh wrote:Cool, so 12.5 would be the width and 800 the length?

Yep. 12.5mm x 100mm, or 1/2" x 31-1/2".