DIY Underground Car Lift: The Secret Build - Part 1
Key Takeaways
- •Colin Furze is building a full-scale DIY hydraulic car lift capable of raising a vehicle 3.4 meters from an underground garage to street level — and rotating it once it gets there.
- •In 'SECRET Garage Car Lift Part 1,' Furze walks through the entire engineering process, from early CAD modeling in Onshape to load-testing a single leg prototype with 800 kg of sand.
- •The design solves real problems: imperfect box section steel, inaccessible hydraulic cylinders, and the nightmare of four hydraulic legs that don't rise at the same rate.
DIY Hydraulic Car Lift Design Fundamentals
The core challenge with any DIY hydraulic car lift design at this scale is that a single telescoping post tall enough to span 3.4 meters becomes dangerously unstable under load — so Furze splits the job across two separate systems. He documents the full engineering process in SECRET Garage Car Lift Part 1 on the Colin Furze channel.
Outer Static Legs vs. Inner Lift Platform Architecture
Four outer legs handle the structural elevation to ground level, while an inner lift platform carries the car itself, with a turntable sitting at the base of the whole assembly for rotation.
Each leg is essentially two box sections sliding inside one another, driven by a hydraulic cylinder tucked inside — straightforward in concept, genuinely fiddly in practice.
Material Selection and Tolerancing Challenges in Lift Construction
Off-the-shelf box section steel is not, it turns out, reliably square — which matters a lot when you're expecting two sections to slide cleanly inside each other under a car's worth of load.
Box Section Steel Quality Issues and Solutions
Furze borrowed the fix from telehandler design: instead of full-length sliding pads running the whole contact surface, shorter pads sit at the ends of the sections only, with adjustable shims and grub screws to dial out any play.
It's a system that tolerates real-world steel's imperfect geometry rather than fighting it — practical engineering over theoretical precision.
Hydraulic Cylinder Integration and Maintenance Access
Once a hydraulic cylinder is sealed inside a fully assembled leg, replacing it means dismantling the whole thing — unless you plan for that problem before you weld anything shut.
Slotted Inner Box Section Design for Component Removal
The inner box section is slotted lengthways, so the cylinder can slide in and out horizontally rather than being dropped in vertically, which stops being an option the moment the leg weighs 460 kg.
That slot was added after Furze realized the hard way that vertical cylinder removal was simply not happening without a redesign.
Guide Rail System Design and Stress Testing
A guide column fixed to the wall keeps each leg tracking straight during travel, with bearings on the leg riding along it — but the first iteration didn't survive the stress testing intact.
Eccentric Cam Adjustment Mechanisms
Initial 10mm plate brackets with slotted adjusters bent under load and made bearing adjustment awkward, so Furze upgraded to 15mm steel and swapped the slotted holes for eccentric cams.
Eccentric cams let you rotate a single bolt to shift the bearing position precisely, which is considerably less miserable than nudging a plate through a slot and hoping it stays put when you tighten the fastener.
Load Testing Results and Safety Requirements
The completed single-leg prototype lifted 800 kg without complaint — and since the car's weight distributes across all four legs, that margin is substantial.
Synchronization Systems for Multi-Cylinder Hydraulic Lifts
Four independent hydraulic cylinders won't naturally rise at the same rate, so Furze is adding a cable synchronization system to keep all four legs level during travel, plus a cable-actuated brake rated to hold 7 tons per leg to prevent any uncontrolled descent.
Those two systems address the two things most likely to go wrong with a multi-cylinder setup: drift and drop.
CAD Modeling Best Practices for Complex Lift Engineering
Furze used Onshape throughout the design phase — a cloud-based CAD platform that stores everything online and lets collaborators access the same live file rather than passing around conflicting versions.
For a project this iterative, where the guide rail design alone went through multiple physical revisions, having the model accessible and up to date from any machine matters more than it might seem.
Our Analysis: Colin gets the hard part right — he tested before he committed, and the eccentric cam adjustment is exactly the kind of detail that separates a build that lasts from one that wobbles itself apart in six months.
The slotted leg design for cylinder access is smart maintenance thinking most DIYers skip entirely until they're lying on a cold floor regretting it.
This fits a growing trend of serious home fabricators treating their garages as real engineering spaces, not just workshops. Cable-synced hydraulic legs is the part to watch — if he nails that, the whole system becomes a legitimate blueprint others can follow.
Source: Based on a video by Colin Furze — Watch original video
This article was created by NoTime2Watch's editorial team using AI-assisted research. All content includes substantial original analysis and is reviewed for accuracy before publication.
