Promaster, Ducato, Relay, Boxer roof mounting studs/mushroom bolt positions
Accurate Roof Mounting Stud Positions for Promaster, Ducato, Relay, and Boxer Vans
When installing a roof rack on your van, precise placement of the mounting studs—often referred to as mushroom bolts—is crucial for ensuring a secure and stable fit. Recently, I came across various documents claiming to provide these measurements for popular van models like the Fiat Ducato, Citroën Relay, Peugeot Boxer, and Ram ProMaster. However, I discovered that many of these figures are inaccurate, which can potentially lead to improper installation or damage.
The Challenge of Finding Reliable Official Data
One common issue among van enthusiasts and professionals alike is the scarcity of official specifications or detailed manuals specifying the exact positions of roof mounting points. Despite extensive searching for factory-approved measurements, concrete data remains elusive. This has led to reliance on user-generated information, which varies significantly in accuracy.
Initial Measurements and Corrections for L3H3 Variants
Based on practical experience and careful measurement on a Fiat Ducato L3H3 model, I’ve determined the most accurate spacing for the roof mounting studs—often called mushroom bolts—when installing a roof rack. These measurements are specific to the L3H3 configuration, which includes the extended wheelbase and higher roof profile.
Recommended Measurements:
- Position 4: approximately 1620 mm from a reference point (such as the front of the van or a designated anchor point)
- Position 3: approximately 520 mm from the reference point
- Position 2: approximately 910 mm from the reference point
Note: These figures are based on my own measurements, and actual positions may vary slightly depending on the specific vehicle and manufacturing tolerances.
Seeking Verified Data
Despite my measured figures, the lack of official documentation means that these should be verified before drilling or installing any roof rack components. If anyone has access to manufacturer manuals, official technical specifications, or can provide precise measurements for an L3 vehicle, I would greatly appreciate your contribution.
Conclusion
Accurate placement of roof mounting studs is essential for safe and effective rack installation. In the absence of official data, careful measurement and peer verification are the best strategies. Sharing industry knowledge and verified measurements benefits the entire community, ensuring safer upgrades and modifications for all van owners.
Disclaimer: Always exercise caution and consult professional technicians or official manuals when modifying or installing vehicle components.
