How to Measure and Adjust Conveyor Belt Drift with Flexco 20378 Fasteners: A 5-Step Quality Checklist

Who This Checklist Is For

If you're dealing with a conveyor belt that consistently tracks to one side—and you're using or considering Flexco 20378 fasteners—this is for you. I've reviewed over 200 belt maintenance jobs annually for the past four years. Belt drift is the single most common cause of fastener failure I see. Not the fastener itself. The installation.

Here's the thing: drift isn't always a mechanical problem. Sometimes it's an installation problem. And in our Q1 2024 audit, we traced 34% of premature fastener replacements to improper alignment during lacing. Not belt tension. Not pulley misalignment. Installation.

This checklist covers five steps. Step 4 is the one most people skip.

Step 1: Verify the Splice Is Square

Before you even think about pulley alignment, check the splice itself. With Flexco 20378 fasteners, the splice should be perpendicular to the belt centerline within 1/16 inch over the full belt width.

How to check:

• Mark the belt centerline at both ends of the splice area.
• Measure from the centerline to the leading edge of the fastener strip at 12-inch intervals.
• Any deviation over 1/16 inch means the splice is pulling unevenly.

What most people don't realize is that a slightly crooked splice can create a corrective steering force that worsens with belt speed. The numbers said the splice was 'close enough'—within 1/8 inch. My gut said test it. I insisted on redoing it. The redo cost us about 45 minutes of labor. The alternative was a $1,200 belt replacement eight weeks later.

Step 2: Check Fastener Gaps for Uniformity

Flexco 20378 fasteners rely on consistent gap spacing to distribute load evenly. Uneven gaps create localized stress points, which can cause the belt to cup at the splice—and that cupping translates into drift.

Use a gap gauge:

• Target gap: 0.015–0.025 inches between fastener segments.
• Measure at both ends of the belt and at the center.
• Variation exceeding 0.010 inches indicates uneven installation.

We rejected a batch of pre-laced belts in 2023 because gaps varied by 0.018 inches. The vendor claimed it was 'within industry standard.' Normal tolerance is 0.010 inches max variation. We sent them back. The replacement run? Perfect tracking from day one.

Step 3: Measure Tension at the Splice Point

Belt tension directly affects how the splice interacts with the pulley. Too loose, and the fasteners can slip or rock. Too tight, and the belt stretches unevenly across the width.

Do this:

• Use a belt tension gauge at the center of the belt, 3 feet from the splice on both sides.
• Record the reading.
• If tension varies by more than 15% between sides, adjust the take-up or snub pulley.

The question everyone asks is 'what's the right tension?' The question they should ask is 'is the tension uniform across the belt width?' Uniformity matters more than the absolute number for drift control.

Step 4: Evaluate the Crown—This Is the One Most People Skip

Here's something vendors won't tell you: the pulley crown might be wrong for your belt and fastener combination. Flexco 20378 fasteners are designed for belts with moderate crown (typically 1/8 to 1/4 inch over the pulley face). If the crown is too aggressive, the belt will self-steer into the high point, amplifying any splice imperfection.

What to look for:

• Measure pulley crown height with a straight edge and feeler gauge.
• Compare to your belt's recommended crown range (check the belt manufacturer's spec).
• If the crown is outside spec, consider a pulley replacement or crown modification.

We had a case where a customer blamed Flexco fasteners for persistent drift. Turns out the pulley crown was 3/8 inch on a belt rated for 1/8 inch max. The fastener was doing its job. The pulley was the problem. I'm not 100% sure, but that one swap probably saved them a full system overhaul.

Step 5: Perform a Loaded Run Observation

Unloaded tracking means nothing. Belt behavior changes dramatically under load—material weight shifts the center of gravity, and the splice reacts differently.

Protocol:

• Run the belt empty for 10 minutes. Mark any drift points.
• Load to 50% capacity. Run 10 minutes. Recheck.
• Load to 100% for 15 minutes. Record final tracking position.

If drift appears only under load, the issue is likely material loading distribution or belt sag between idlers—not the splice.

Looking back, I should have insisted on this test earlier. At the time, the unloaded run looked perfect, so we signed off. The first loaded shift produced a 2-inch drift. Cost us a weekend redo.

Common Mistakes and What to Watch For

Mistake 1: Assuming 'Good Enough' Alignment

Don't hold me to this as a hard rule, but in my experience, anything over 1/16 inch splice angle error will eventually show up as drift under load. Take the time to get it square. Use a laser alignment tool if available.

Mistake 2: Ignoring Fastener Segment Orientation

Flexco 20378 fasteners have a directional indicator. Install them backward and you'll get uneven wear that mimics drift. That sounds obvious, but I've caught it three times in the last year.

Mistake 3: Skipping the Crown Check

As I said in Step 4—this is the big one. Most maintenance teams focus on belt tension and pulley alignment. The crown is the silent contributor to drift. Check it. Measure it. Fix it if needed.

(Should mention: Flexco 20378 fasteners are rated for belts up to 600 PIW. If your belt is exceeding that, the fastener may not be the right choice. Verify your belt spec against Flexco's published ratings.)