Do You Need to Cut the Subframe When Replacing the Control Arm?

[LeWillow]

Replacing the control arm does not require cutting the subframe. Here are the precautions for replacing the control arm: Using a Jack: First, lift the car with a jack and place bricks around the vehicle for added safety to prevent jack failure, though this step is optional. Pay Attention to Direction: Remove both ends of the control arm, select two corresponding-sized bushings, and install the rubber bushings. Larger rubber bushings are marked with L (left) and R (right), while smaller ones are not directional. Apply Dish Soap: After removal, use a torch to burn out the middle bushing. Apply dish soap to the new bushing for lubrication during installation, as it does not corrode rubber. Do not use engine oil.

[Emilia]

I recently researched this issue when replacing the triangular arm on my old Sagitar. Under normal circumstances, there's absolutely no need to cut the subframe. The standard repair procedure involves removing the subframe mounting bolts. The repair manual clearly states to first loosen the rear subframe bolts, support the subframe with a jack, and then remove the steering ball joint lock pin to completely extract the triangular arm. The only exceptions would be for extremely old vehicle models or accident cars with severely deformed sheet metal. Even in those cases, repair shops would recommend attempting correction first rather than directly cutting. Last week at the repair shop, I saw an accident vehicle where the mechanic used a frame straightener to correct the deformed areas before installing the new triangular arm. They repeatedly emphasized never cutting structural body components unless absolutely necessary.

[DiTravis]

In our workshop, we replace three to four control arms every day, and we have never cut into the subframe. The standard operating procedure is to first remove the lower ball joint, loosen the connecting bolts of the subframe and the steering gear, then use a lift with a hydraulic jack to lower the entire subframe by about two fingers' width, allowing the old control arm to be completely removed. Once, we encountered a flood-damaged car with rusted bolts. The master technician still used rust remover to soak them repeatedly and then forcefully removed them with an impact socket, preferring to spend an extra half hour rather than compromise the vehicle's structure. The subframe is a critical component related to the overall rigidity of the vehicle. Cutting it carelessly would pose safety hazards, and no reputable repair shop would perform such an operation.

[SanGabriel]

When I first bought the car, I was also worried about this issue. Later, I watched the technician replace the control arm at the 4S dealership and realized there was no need for cutting. The technician lifted the car, removed the tire, loosened several chassis bolts, and used a hydraulic jack to lower the entire rear subframe by about five centimeters, which provided enough space to work. Modern vehicle designs take maintenance convenience into account, and the connection between the crossmember and the control arm is specifically designed to be detachable. However, I've heard that some modified cars forcibly lower the suspension, resulting in insufficient space that might require cutting. But such unprofessional modifications can cause permanent damage to the body's structural integrity and even fail the annual inspection.