Body Mount Chop (BMC) Kit for 5th Gen 4Runner
Metal Tech BMC Kit – Step by Step overview on Cutting Body Mounts for the 5th Gen 4Runner
When you make the move to larger tires, you are likely going to need a body mount chop (BMC). There are other areas you need to trim as well, but your body mounts are one of the most important.
Making the jump to 33″ – 34″ tires, or even larger, will mean rubbing throughout your wheel well. After you have trimmed fender liners (also push back), rocker panel caps (valance caps), splash guards, and your actual body, you will need to take your 4Runner in for a body mount chop or do it yourself.
You have a few options for chopping your body mounts. You can do it yourself or take it a shop. You can also use a model-specific kit or use scrap metal to connect your mounts after you chop the ends off. I would recommend using a kit that is specific to your 4Runner, unless you can cut and design your own plate.
The body mounts are awkward to cut so having the right tools for the job will make a big difference. Using a 5″ angle grinder will work, but be prepared to make quite a few cuts before you get a decent amount of the body mount cut off. A plasma cutter might be a better option as you have a little more flexibility in the angle of cut.
Not everyone has a plasma torch sitting around so just know, a grinder will work. I used a 5″ cutting wheel with a battery-powered Milwaukee grinder and was able to cut the mount off just fine.
What Are Body Mounts?
Body mounts are exactly as they sound; they mount the body to the frame. You often hear the term “body on frame” construction. Our 4Runner has a body and a frame.
The body sits on top of the frame and is mounted in place using these “body mounts”. Inside the body mount is a rubber bushing that helps dampen vibrations which makes the ride for you and your passengers more comfortable.
Body mounts protrude into the wheel well often causing problems for larger tires. Cutting off the tip of the body mount and welding on a new plate is not going to comprise the strength of your frame.
Where to Purchase:
Parts in the Kit
- 1 Left Body Mount chop plate
- 1 Right Body Mount chop plate
- Plasma Cutter
- Grinder with 5″ cutting disk
- Grinder with flap disk for blending and sanding
- Bucket of water and towels
- Light-colored paint pen or red sharpie
- Basic hand tools
DIY Body Mount Chop Vs. 4×4 Shop
If you do not weld, use a plasma cutter, or have general experience with a grinder, I would strongly recommend taking your 4Runner to a shop. We have cut off our body mounts, and it’s not difficult. Like everything, it just takes time. Just make sure you are taking the necessary safety precautions; glasses, gloves, facemask, ear protection, etc. After we cut off our mounts, we usually head straight into our local shop and have them weld on new plates. If you cut off your mounts, weld on a new plate as soon as possible. The front body mounts handle the most weight of the 4Runner so you want to make sure you restrengthen the body mounts by welding on a new plate.
Only perform the steps below if you are an experienced fabricator/welder or have enough experience with the tools to accomplish this task. At your local off-road shop or fabrication shop, they will have all the tools you need to get this job done right. The cost for a shop to do a BMC is relatively inexpensive ($100-$250).
Looking for a good shop?
Stellar Built is a very reputable 4×4 fabrication shop in Greater Sacramento. If you are looking for a good off-road shop, give Stellar Built a call. They are much more of a Toyota shop as opposed to a Jeep shop. Stellar Built has now become our go-to fabrication shop in Sacramento. You can find them on Yelp and Instagram.
Step 1: Jack up Truck & Locate Body Mounts
Initial Steps Recommended by Metal Tech 4×4:
- Remove battery ground cable from the battery
- Remove the front wheels
- Remove any installed sliders or aftermarket parts that may be in your way. Allow yourself as much room as possible to work with.
Start by cleaning off your body mounts and then let dry. Lay your body mount chop pieces out and notice the radius corners on the plates. These plates are specific to the driver and passenger side. The side with the radius corner is the top. The flat edge of the plate is the bottom.
Step 2: Remove Rubber Bushing from Mount Housing
Remove your body mount nut, washer, and bushing. This is to prevent the bushing from catching on fire when you are cutting or welding your body mounts.
Step 3: Mark Cut Lines on Body Mount
Using a light paint pen or sharpie, hold up your BMC kit plates and mark your cut lines.
Step 4: Using Plasma Cutter, make initial Cuts
Using your plasma cutter or tool of choice, make your initial cuts on the body mount.
Step 5: Using Angle Grinder, Grind Ends on Body Mounts
Using your paint pen or sharpie again, mark your locations to grind down to. Using your angle grinder or tool of choice, grind down your body mounts so you have a flat edge.
Step 6: Weld Plates to 4Runner Mounts
Weld the driver/ passenger-specific plates to your body mounts. Make sure your radius corners are facing up and the flat edge is facing towards the ground.
Step 7: Flat Black Spray your Body Mounts
You can use flat black spray paint to paint your body mounts. This will give the end result a cleaner, more factory appearance.
Body Mount – Driver
Body Mount – Passenger
If you are looking for more clearance around your tires, this a great kit that is specifically made for our 4Runner. To sum up the install, it is fairly straight-forward. Metal Tech 4×4 provides a detailed step by step installation sheet that you can refer to if you have any questions.
Your options here are simple, do it yourself or grab a kit and have someone else do it. It may sound crazy to pay someone else to cut metal off your truck, but if you don’t know what you’re doing, you can make mistakes.
After owning three 5th gens, I have cut the body mounts off and paid to have it done as well. Sometimes I think its easier to just pay someone to do it but it depends on your skill level, time and budget.
I personally recommend having a professional get it done but to each their own.
Questions or Comments? Leave them below!