Bushings Inc. DF-100 Dual-Flex Marine Engine Mount | 850 lb Capacity
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Bushings Inc. DF-100 Dual-Flex Marine Engine Mount
Part Number: DF-100 (also shown as DF100 / BUIDF100 / BUHDF100)
The Bushings Inc. DF-100 is a low-profile, adjustable vibration-isolating engine mount for marine inboard engine and transmission installations. Its Dual-Flex design combines a heavy-duty cast aluminum alloy base with an oil- and fuel-resistant elastomer element to isolate engine vibration in longitudinal, lateral, and vertical directions. It is rated for a total installed engine and transmission weight of up to 850 lb (386 kg) when used in the recommended four-point mounting configuration. Steel components are corrosion-resistant plated. Leveling and locking nuts are included.
Specifications
- Series: Dual-Flex
- Maximum engine/transmission weight: 850 lb (386 kg) — four-point mounting
- Stud: 5/8”-18 (adjustable, with leveling and locking nuts)
- Mounting bolt size: 3/8 in. (9.5 mm)
- Mounting-hole centers: 4 in. (101.6 mm)
- Overall length: 5 in. (127 mm)
- Overall width: approx. 2.75 in. (69.9 mm)
- Overall height: approx. 4 in. (101.6 mm)
- Minimum mounting clearance: 1.875 in. (47.6 mm)
- Base material: Heavy-duty cast aluminum alloy
- Elastomer: Oil- and fuel-resistant rubber
Compatible Applications
- Marine inboard gasoline and light-duty diesel engine installations using four-point mounting
- Applications where total installed weight (engine + transmission + accessories) does not exceed 850 lb (386 kg)
- Installations requiring a 5/8”-18 adjustable stud, 4-inch bolt centers, and a minimum mounting height of 1.875 in.
Fitment Notice
Engine mounts must be matched to the installation, not just the engine model. Before ordering, confirm:
- Total installed weight — engine, transmission, and all attached accessories combined
- Number of mounting points in the engine-bed configuration
- Mounting-hole bolt size and spacing (3/8 in. fasteners, 4 in. centers)
- Required stud diameter and thread (5/8”-18)
- Available vertical clearance under the engine (minimum 1.875 in.)
- Required engine-alignment adjustment range
When calculating load per mount, include the full installed weight — engine, transmission, flywheel, and any engine-mounted equipment. Undersizing mounts based on engine weight alone without accounting for attached components is a common cause of premature mount failure.
Cross-Reference Part Numbers
- DF-100
- DF100
- BUIDF100
- BUHDF100
When to Replace Engine Mounts
- Elastomer is cracked, split, hardened, or visibly deteriorated
- Engine movement under load has increased noticeably
- Vibration transmitted into the hull has increased
- Mounting hardware is corroded, bent, or damaged
- Mount height has collapsed or sagged
- Shaft or coupling alignment is difficult to maintain
- Mounts were disturbed or damaged during engine or transmission service
Worn mounts allow engine position to shift under load, which increases drivetrain vibration and can place additional stress on couplings, shaft seals, and exhaust connections.
Installation Notes
- Mount to a sound, solid engine bed using appropriately sized marine-grade fasteners
- Use the 5/8”-18 threaded stud for vertical adjustment during engine height and alignment setting
- Set the engine to the correct height using the leveling nut, complete shaft or coupling alignment, then secure the locking nut
- Recheck alignment after launching — mounts will settle slightly once the hull is in the water and the engine weight is fully loaded
- Inspect mounting hardware torque after the first several hours of operation
Parts Desk Insights
The DF-100 is a solid all-round choice for compact inboard gasoline engine installations where the four-mount combined weight stays under 850 lb and the 4-inch bolt centers and 5/8”-18 stud match the existing engine bed. It is commonly used during engine replacements, repower projects, and mount-replacement jobs on older inboard installations where the mounts have deteriorated from age, fuel exposure, or heat cycling.
The most common mistake when ordering engine mounts is selecting by engine model alone without confirming the mounting dimensions and load rating. Weight capacity, stud size, bolt-hole spacing, and minimum mounting height all need to match the existing installation — a physically similar mount with the wrong height or stud thread will cause alignment problems that are time-consuming to diagnose after the engine is back in the boat. Also note that the DF-100 is rated for 850 lb on a four-point mounting setup; per-mount load capacity drops if fewer mounting points are used.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.