MTFCA Forum

Langs sells a 23” Modern micro-groove belt for flat pulleys on their website. If you use this type of belt, which side of the belt should come into contact with the pulleys - the flat or the micro-groove side? The description on their website seems to imply that the fiber reinforced poly groove side should, but I am not sure. I solicit your opinions. Thanks.

The groove side goes on the pulley and the marking on the outside.

BTTT .

A micro V belt is for alternators and water pumps that have a micro V pulley. For that application the V's go toward the pulley. A stock Model T does not use a micro V belt, it uses a smooth belt. I bought a smooth belt from Snyders recently.

Smooth side out. Grooves give extra surface area contact on pulley and/or water pump.

Thanks everyone. I appreciate your feedback.

Just an observation...
While I have no experience with microgroove belts, I had a 2001 Mustang that the AC compressor/pulley froze. A quick fix was to reroute a shorter belt, bypassing the compressor, where the belt reversed orientation on the tension pulley....belt grooves on the flat surface pulley, where normal would be flat side of the belt.
Ran like that for a year...but when fixed, the pulley ended up grooved from the 6 groove belt.
So....my imagination ponders to what degree a microgroove belt may....or may not...do the same thing, especially on what I imagine is way softer metal, and, whether marked vs unmarked pulleys would be a personal issue.

Modern grooved belts on a T are run flat side to the pulley. I dont know if there is something different about a "micro groove", but I suspect they are the same. Grooved belts are designed to run on grooved pulleys. Maybe asking Langs directly would be more definitive than a guess.

Flat side to the pulley. On a modern car you have pulleys that are both grooved and flat on the same motor, the flat side runs on the flat pulleys. THat's how they're designed to run, putting the grooved side to the flat pulleys reduces your belt contact, and the beltis DESIGNED to run flat to flat, groove to groove.

I ran a grooved belt for years, and had absolutely ZERO issues with it running flat side in.

I’ve run grooved belts for years. I ran them grove side in and out. Does seem to make any difference on the smooth pulleys on a T. I run them fairly loose with great success. And the width doesn’t seem to matter either. Just my experience.