Why the driver side front diff mount cracks on 2021 and newer Ford Bronco frames, how to check yours, what Ford's service bulletin says, and how to replace it with a heavier 3/16" steel bracket.
The Short Answer
The driver side front differential mount on the 6th gen Ford Bronco frame can crack or break off where the diff bushing bolts to the frame. The usual first sign is a loud clink or clunk from the front end. Ford recognizes the problem in TSB 25-2613 (which replaced TSB 24-2408) for 2021–2024 Broncos with the 2.3L and 2.7L engines. The FMI replacement bracket is 3/16" steel, laser cut and CNC bent in-house, and welds to the frame in place of the factory mount. It fits 2021–2026 Bronco and 2022–2026 Bronco Raptor, and it can go in before your factory mount ever cracks. We built it after two Broncos came into our shop with this exact failure.
What Breaks on the Bronco Front Diff Mount
The 6th gen Bronco's front differential (the M210 / Dana 44) is held to the frame by bushing mounts. The one that fails is the driver side frame bracket. Owners on the Bronco6G forum describe the hooked side of the bracket, where the diff bushing bolts to the frame, cracking first. Once that side lets go, the rest of the bracket is carrying the load alone, and it can keep tearing until the mount breaks completely off the frame.
It is not limited to trucks that have been beaten on. The original Bronco6G report came from an owner with a fully stock 2022 Bronco Everglades at about 31,000 miles, with no hits to the front suspension, underbody or diff. Other owners in the same thread found the same failure on their own trucks. One owner who pulled the front diff on two Broncos, one with under 300 miles, noted the mount bolts were not tight from the factory.
We Have Seen It in Our Shop
This is not just a forum problem. Two Broncos came into the Foutz Motorsports shop recently with a cracked driver side front differential mount, and that is why we designed this replacement bracket.
What Ford Says Causes It
Ford's bulletin attributes the crack to flexing of the front differential from driving in four wheel drive low (4L) for extended periods. The bulletin also tells dealers to advise owners to use 4L and Rock Crawl mode only when necessary. That is useful advice, but 4L and Rock Crawl are exactly what most Bronco owners bought the truck to use. The load on that mount is part of off-roading a Bronco, which is why a stronger mount makes sense.
Clink or Clunk Up Front
The symptom Ford lists: a loud clink or clunk noise from the front end that leads back to the cracked bracket.
Visible Crack at the Bracket
A crack on the driver side frame bracket around the diff bushing, or the bracket separating from the frame.
Lots of 4L and Rock Crawl
Ford ties the failure to long periods in 4L. If that describes how you use your Bronco, inspect the mount.
Loose Mount Bolts
One owner who pulled two front diffs found the mount bolts were not tight from the factory. Worth checking.
How to Check Your Bronco's Front Diff Mount
Get Under the Driver Side
With the Bronco safely supported, locate the front differential and the frame bracket on the driver side, above the diff. Depending on your skid plates, you may need to remove one to see it.
Use a Mirror and a Light
The cracks start where you cannot see straight on. Ford's inspection uses a mirror. Look along the bends of the bracket and around the bushing bolt.
Check the Bolts
Confirm the mount bolts are tight. A loose mount lets the diff move, and that movement works on the bracket.
Decide: Repair or Prevent
Cracked means a structural repair. Not cracked, but you wheel hard? That is the window to install a stronger mount before it fails.
Factory TSB Repair vs. a Heavy-Duty Replacement Bracket
There are two real ways to fix this mount. Here is how they compare.
| Ford TSB 25-2613 Repair | FMI Replacement Bracket | |
|---|---|---|
| Vehicles | 2021–2024 Bronco, 2.3L and 2.7L | 2021, 2022, 2023, 2024, 2025, 2026 Bronco and 2022, 2023, 2024, 2025, 2026 Bronco Raptor |
| When it applies | The bracket repair is done when inspection finds a crack. A passing truck gets the AWD module update only. | After a crack, or before one as a preventive upgrade |
| What it is | Ford frame bracket repair service kit, plus an AWD module software update | 3/16" thick steel bracket, laser cut and CNC bent in-house, that fully replaces the factory mounting structure |
| Installation | Dealer, following the service kit instructions. Ford lists about 5.5 to 6.2 hours of labor, plus extra time for camber and toe adjustment. | Welds to the frame. Installed by a qualified fabricator or professional welder. |
| Coverage | A TSB does not change warranty. Coverage depends on your warranty status. | Owner-paid upgrade |
Still Under Warranty?
If your Bronco is a 2021–2024 within its warranty and the mount is already cracked, talk to your Ford dealer first and ask about TSB 25-2613. If you are out of warranty, your truck is a 2025 or newer, you drive a Bronco Raptor, or you want a heavier mount in there before it ever cracks, the FMI bracket is built for that.
The FMI Bronco Front Differential Mount Bracket
We build this bracket as a complete replacement for the factory front differential mounting structure, not a patch over a cracked part. It repairs the mounting area without relying on the damaged factory bracket, and it is thicker and heavier-duty than what came on the truck.
- 3/16" thick steel, precision laser cut and CNC bent in-house
- Fully replaces the driver side factory front differential mount
- Repairs a cracked or broken mount, or installs as a preventive upgrade
- Fits the factory front differential mounting location
- Ford Bronco: 2021, 2022, 2023, 2024, 2025, 2026
- Ford Bronco Raptor: 2022, 2023, 2024, 2025, 2026
- Kit includes the driver side mount and installation hardware
This is a structural repair, not a bolt-on. The bracket welds to the frame. Correct bracket position, alignment and welding procedure are critical, so it must be installed by a qualified fabricator or professional welder.
View the Front Diff Mount Bracket →
Other Weak Spots Worth Reinforcing
The diff mount is not the only factory front-end mount that benefits from extra support on a Bronco that sees real trail time. The Bronco lower arm pivot gusset kit adds 4130 plate to the front lower arm mounts, and a Bronco skid plate kit protects the components underneath from rocks. Building a Bronco Raptor? See The Best Bronco Raptor Suspension Upgrades and The Best Ford Bronco Raptor Parts.
Bronco Front Diff Mount FAQ
Why does the Bronco front differential mount crack?
Ford attributes it to the front differential flexing during long periods in 4L. Owners have also reported failures on stock Broncos with no impact damage, and one found the mount bolts were not tight from the factory.
Is a cracked front diff mount a common Bronco problem?
It is common enough that Ford issued a service bulletin for it, Bronco owners have reported it on the forums, and two Broncos came into the Foutz Motorsports shop recently with this failure.
Which side of the Bronco front diff mount breaks?
The driver side frame bracket, where the front differential bushing bolts to the frame. The FMI kit replaces that driver side mount.
Is there a Ford TSB for the cracked Bronco front diff mount?
Yes. TSB 25-2613, dated January 2026, replaced TSB 24-2408. It covers 2021–2024 Broncos with the 2.3L and 2.7L engines and calls for a frame bracket repair kit plus an AWD module software update.
What does a cracked front diff mount sound like?
Ford describes a loud clink or clunk from the front end. If you hear a new front-end clunk, inspect the driver side diff mount with a mirror and a light.
Does the FMI bracket fit the Bronco Raptor?
Yes. It fits the 2022, 2023, 2024, 2025 and 2026 Ford Bronco Raptor, as well as the 2021 through 2026 Ford Bronco.
Can I install the bracket before my factory mount cracks?
Yes. It can go in as a preventive upgrade, so the mount is addressed before it fails instead of after.
Does the FMI front diff mount bracket bolt on?
No. It welds to the frame and must be installed by a qualified fabricator or professional welder. Bracket position, alignment and welding procedure are critical.
Should I stop using 4L?
Ford's bulletin advises using 4L and Rock Crawl only when necessary. Use them when the trail calls for it, and check this mount regularly if you do.
- Ford TSB 25-2613: Front Differential Mount Frame Bracket Cracked or Broken (NHTSA)
- Ford TSB 24-2408, the original bulletin (NHTSA)
- Bronco6G forum: Front Differential Mount Failure / Broken
- Bronco6G forum: TSB 24-2408 discussion
Found a crack, or not sure what you are looking at? Send us a photo or call the shop.