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This thread is based on some recent discussion, perhaps the off-topic parts, in this thead, in which the most important thing (IMHO) was the beginnings of a potential class action or legal case against Ford. If you have/had any MIC (or soft top failures), please sign up with your information here:
https://classlawdc.com/2025/07/03/2021-2024-ford-bronco-leaking-cracked-roof-class-action-investigation/#:~:text=The law firm of Migliaccio,TSB issued for this vehicle
OK, with this introductory information out of the way, the idea here was to begin some technical discussion on what might be causing these MIC failures, which seem to be 2 categories, cracking (and other deformations) along with core "printing through" into the resin. This could support peoples additional decision calculus about upgrading, preventative measures, etc. I think this root cause list is a very solid starting list as a basis for modification and perhaps excluding items that are not possible.
Again, due to the fact that folks generally don't stop by to make a post about their top NOT failing, we should admit that for those of us actually affected and based on the many posts here, the problem seems very widespread, but due simply to the fact that a recall hasn't happened, the failure rate is likely fairly small.
Other important observations:
Potential Root Causes for MIC Top Failures
. I can update the original post here with additional Important Observations, Data or changes to this Root Cause List.
https://classlawdc.com/2025/07/03/2021-2024-ford-bronco-leaking-cracked-roof-class-action-investigation/#:~:text=The law firm of Migliaccio,TSB issued for this vehicle
OK, with this introductory information out of the way, the idea here was to begin some technical discussion on what might be causing these MIC failures, which seem to be 2 categories, cracking (and other deformations) along with core "printing through" into the resin. This could support peoples additional decision calculus about upgrading, preventative measures, etc. I think this root cause list is a very solid starting list as a basis for modification and perhaps excluding items that are not possible.
Again, due to the fact that folks generally don't stop by to make a post about their top NOT failing, we should admit that for those of us actually affected and based on the many posts here, the problem seems very widespread, but due simply to the fact that a recall hasn't happened, the failure rate is likely fairly small.
Other important observations:
- Failures have been noticed on the showroom floor and also developing many months or year(s) after being in service.
- There was a person who had his top professionally prepped and painted and it is still showing cracking.
- Some folks have been through as many as 4 or 5 MIC tops.
- AFAIK, there has been no reported failures of the newer Modular Painted Hardtops
Potential Root Causes for MIC Top Failures
- 1. Design & Fabrication Choices
- a. Outer skins too thin: Lacks stiffness; can print the core pattern during manufacturing.
- b. Missing barrier or surfacing layer: Core texture telegraphs through to resin.
- c. Irregular core surface: Without a smoothing veil, the pattern appears on the finish.
- d. Brittle resin system: Low strain tolerance increases risk of fine cracking.
- e. Improper surface prep before paint: Amplifies minor surface irregularities.
- f. Thermal expansion mismatch: Different expansion rates between core and resin cause cyclic stress cracking.
- 2. Material Related
- a. Core Material Issues
- i. Moisture absorption (not from cracks): Cardboard core swells or weakens, stressing outer skins.
- ii. Unsealed or resin-absorbing core: Resin penetrates and shrinks unevenly, imprinting the core pattern.
- b. Resin / Matrix Problems
- i. High resin shrinkage: Causes surface tension and fine cracks during cure.
- ii. Poor adhesion to core: Allows micro-movement or delamination that shows at the surface.
- iii. Incompatible resin-core chemistry: Poor wetting or bonding creates stress risers.
- a. Core Material Issues
- 3. Manufacturing Process Related
- a. Layup & Molding Problems
- i. Insufficient vacuum pressure: Core geometry imprints due to uneven compaction.
- ii. Resin pooling or starvation: Causes non-uniform stiffness and visible surface distortion.
- iii. Overheating during layup: Degrades or deforms cardboard core, imprinting its texture.
- iv. Uneven mold surface or release: Introduces stress points leading to surface cracks.
- v. Uneven fiber distribution: Stiffness variations cause localized cracking (does the resin in the MIC even use fibers, I actually think not, whereas I think the MPH does)?
- vi. Density variation or crushing: Uneven support under skins leads to local print-through.
- b. Curing Cycle Issues
- i. Rapid or uneven heating: Differential expansion induces fine cracks.
- ii. Missed post-cure: Residual stresses later manifest as cracks.
- iii. Excessive cure temperature: Chars or shrinks the cardboard core, distorting the surface.
- iv. Incomplete or uneven cure: Leads to later embrittlement and cracking under stress.
- a. Layup & Molding Problems
- 4. Environmental/In-Service
- a. Thermal and Humidity Effects
- i. Thermal cycling: Expansion mismatch between resin and core forms hairline cracks.
- ii. Moisture ingress: Swells the paper core, lifting or printing through the skin.
- b. Exposure & Aging
- i. UV degradation: Embrittles resin, revealing cracks and core outlines.
- c. Mechanical Effects
- i. Vibration or flexing: Fatigue or stress exceeding allowables leads to cracks along core features.
- ii. Handling or impact damage: Small dents initiate visible fracture lines.
- iii. Long-term stress relaxation or creep: Slowly propagates microcracks over time.
- a. Thermal and Humidity Effects
. I can update the original post here with additional Important Observations, Data or changes to this Root Cause List.Sponsored
