McCloskey J35: The Magnet Mistake That Cost $28,750 (and the Pre-Buy Checklist That Prevents It)

If you’re specifying a McCloskey J35 right now, the most important decision isn’t jaw size, transport width, or engine power. It’s whether the machine is configured to handle the actual feed material you’ll put into it. For us, that meant a cross-belt magnet. I skipped it to save $16,000 and hit a mobilization date. It ended up costing $28,750 and nearly three weeks of headaches.

Bottom line: on any concrete-recycling job, spec the magnet. Budget for it. Wait for it. Don’t let anyone tell you “you can add it later” — because later will be after your belt is torn and your crusher is down.

According to McCloskey International’s product page (accessed January 2025), the J35 is designed for small-to-medium crushing applications, and the overband magnet is listed as an optional accessory. That last part is where the trap lives.

Why I’m Qualified to Say This

I’ve been handling equipment orders and fleet procurement for crushing contractors for 11 years. That’s not a brag; it’s a confession. I’ve personally made and documented four significant mistakes, totaling roughly $72,000 in wasted budget. The J35 mistake below is the one that hurt the most, because the warning signs were on the spec sheet and I ignored them.

I’m not a crusher design engineer, so I can’t speak to wear-part metallurgy or jaw-plate geometry. What I can tell you from a procurement and commissioning perspective is how to avoid the configuration trap.

The Mistake: What Actually Happened

In September 2022, we won a small demolition-concrete job. The feed was broken concrete with rebar, wire mesh, and the odd chair tie. The spec called for a compact track-mounted jaw crusher. I went back and forth between the J35 and a larger J40 for two weeks. The J35 offered transport ease; the J40 offered more throughput. On paper, the J35’s numbers made sense. But my gut said we’d be throughput-limited. I ignored the gut because the J40 needed a permit and an escort on the haul route, and the J35 didn’t.

The optional cross-belt magnet added $16,000 and four weeks to the lead time. The project couldn’t wait. I convinced myself we could manage the rebar with a handheld wand and careful sorting. Rose, our operations lead, asked me twice: “Are you sure?” I said yes. I was wrong.

Day one was fine. Day two, a 3-foot piece of #5 rebar slipped past the pre-screen and wrapped around the tail pulley. It tore the discharge belt and scored the pulley face. We shut down at 9:15 AM. Rose found belt debris and a chunk of rubber the size of a phone.

The repair added up fast: $8,500 for a new belt, $2,250 for labor, and $2,000 in lost production on the rental-equipment cost. Then we had to retrofit the magnet anyway — $16,000 and a two-week wait. Total: $28,750 and nearly three weeks of headaches. The original four-week delay I was so afraid of? We basically traded it for a three-week mess, a torn belt, a rushed retrofit, and a very unhappy project manager.

“The option that looks like a delay is often the fastest path to production.”

Here’s something vendors won’t tell you: the “standard” J35 configuration on many quotes doesn’t include the magnet. It’s an optional extra. Salespeople aren’t hiding it maliciously — they assume you know. But if you’re new to crushing, it’s easy to miss. On our first quote, the magnet wasn’t even in the summary; it was on page 4 of the proposal. (Which I didn’t read. Ugh.)

What I Check Now

After that mistake, I built a simple pre-purchase checklist. We’ve caught 17 potential configuration errors in the last 18 months. Here’s the relevant part for a J35:

• Feed material audit — List every material that might go through the crusher over the life of the lease or purchase: clean concrete, rebar concrete, asphalt, natural stone. Each changes magnet and pre-screen needs.
• Magnet spec — If rebar content is at least 5% by volume (like most demolition concrete), the cross-belt magnet is not optional. Period.
• Lead time reality check — Ask the dealer: “What is the lead time difference with magnet vs without?” If it’s less than two weeks, wait. If it’s more, ask whether the machine frame is pre-threaded for a retrofit. Ours was, but we still lost a week because the magnet kit shipped from a different warehouse.
• Pre-screen or grizzly — For dirty feed, a pre-screen is worth more than a bigger engine. The J35 can run with one; verify it’s on your quote.
• Dealer installation — Don’t let a third-party hydraulics shop do the first retrofit. Have the dealer or their certified tech install it, or at least review the hydraulic schematic.
• Transport check — Confirm transport width, height, and weight with the specific options. A magnet adds weight. If you’re hauling by road, this can change permits.

The Cost of Waiting vs. The Cost of Ignoring

Based on dealer quotes we received in March 2023, a cross-belt magnet retrofit for a J35 ran $15,000 to $22,000 depending on installation. The option at order time was $16,000. Skipping it didn’t save us money; it added $12,750 in damage and delay on top of the same $16,000 package. What was best practice in 2018 — “skip the magnet and sort by hand” — is obsolete on modern concrete feeds. The fundamentals haven’t changed, but the execution has.

When This Rule Doesn’t Apply

I’m a big believer in checklists, but I’m not going to tell you the magnet is always the right answer. If you’re crushing clean, screened natural rock with zero ferrous content, a magnet is a wasted $16,000. If you’re using a dedicated excavator magnet to remove steel before it enters the hopper, that can work — but only if you have an operator who is disciplined and a feed size that doesn’t hide rebar in the middle of a slab. In our case, we had neither.

Also, the J35 isn’t the only machine that fits this story. The same mistake applies to other compact jaw crushers, including McCloskey’s J40, J45, and the larger J50. The specifics change, but the lesson remains.

This is where I hit my professional boundary: I’m not a safety consultant or a regulatory expert, so I can’t speak to OSHA requirements for magnetic separators or lockout procedures. If you’re setting up a crushing circuit, check current regulations at osha.gov and consult your equipment dealer. What I can tell you is that the financial case alone is enough to justify the option.

Final Thought

If you’re evaluating a McCloskey J35, start the conversation with your dealer by asking: “Show me the machine configured for my actual feed material.” Not the brochure configuration. Not the price-leader configuration. Your configuration. That one question would have saved me $28,750 and a very bad Tuesday.

Not What You’re Looking For?

This article is about McCloskey International’s J35 track-mounted jaw crusher. If you searched for “Mark McCloskey accident,” “First Congress,” “rose,” or “how to get hair,” you’re probably not looking for crushing equipment — and I don’t have any special insight into those topics. But if your search was actually about a McCloskey crusher, the checklist above is the part I’d read twice.