Q: What size tire can I run with a 2.5" lift system from James Duff?

Tire size can vary depending on wheel offset, wheel width, and tire tread design. These sizes are based on a 15x8 wheel with 3.5" backspace. These tire sizes are a general guideline because a wider tire or offset rim can cause interference with the sheet metal. A large lugged mud tire will also require more clearance or a shorter overall height in order to clear compared to an All-Terrain tread style.

*For Uncut rear wheel openings, you may have to roll the inner fender lip depending on what tire and wheel combination you go with.

**For 2.5" of lift with 1" of body lift, we recommend 33 - 35" tires. Minimal cutting to the body inside the fender opening is likely required for maximum turning and articulation w/o rubbing.

Q: Do these systems Require Welding?
A: In some cases yes. If your system includes different shock mounts such as our classic shock mounts. Then the shock mounts will need to be welded on. If your system comes with a shock mount that welds on the c-cap, it will require welding too.

Q: What is a Hellwig Swaybar?

Q: What are Long suspension systems and why aren't they on the 2.5"?

Q: I have a 1966 Bronco is there anything I should know before purchasing a system?
A: For the first year of production, Ford used a stud/eye shock in the rear in early 66 production models only. Our suspension systems require an eye/eye style shock at the rear axle. Our suspension systems do not come with an additional set of our classic shock mounts to convert to an eye/eye shock in the rear. This is because very few Broncos require them. You can purchase an additional set of mounts here or you can purchase an additional set of stud/eye shocks here if you want to retain the factory shocks. If you’re not sure if you need the additional mounts, check the pictures here where we showcase the difference.

Q: Leaf Springs... Medium Duty or Heavy Duty, What's the deal?
A: Before you choose your spring, you need to understand the difference between Medium duty and Heavy duty. First off the difference has nothing to do with ride quality. Our Heavy Duty spring will not give your Bronco a stiffer ride. This is simply to make sure your Bronco will sit level or at the very least not squat in the back when your Bronco is complete.

Medium-Duty springs are for 66-77 Broncos that have very few add-ons or accessories in the rear. For example, if you have a stock half cab or roadster you would choose medium duty. If you have a resto-mod wagon with a soft top, stock rear bumper, no spare tire, and stock fuel tank, with or without a back seat but not typically using it, then you also would choose medium duty springs. We do NOT recommend medium duty for trailer towing.

Heavy-Duty springs are for 66-77 Broncos that are geared more towards a well-equipped resto-mod for on and off-road use. If you have or plan on upgrading to a 20+ gallon rear fuel tank, tire carrier + tire, steel plate rear bumper, and/or want to run a hardtop, the heavy-duty leaf spring is also a great choice for your build. These are also the best option if you plan on ever towing anything with the Bronco. If you like going off-road and hitting the trails, the heavy-duty leaf springs are typically the best option for you as well.

For some of you, there will be some combination of parts that accessorize your Bronco in between a soft, medium, heavy, and extra heavy-duty setup. This is why we offer lifted spring perches, 1/2" and 1" lift blocks as well as pinion shims for driveshaft angle corrections to get your ride height and driveability spot on. Our new 1/2" lift block will also offer the option to move the axle back for that perfect amount of tire to fender clearance for the uncut lifted 66-77 Broncos.

Installation Note: The Double spring Wrap aka Military wrap is to be installed towards the front of the vehicle.

You can also add on great upgrades when purchasing these springs like Leaf spring and shackle mounting hardware, Shackle bushings, the Duff HD spring plates, U bolts or HD U- bolts (both that come standard with new HD hardware), HD shackles, pinion shims, lift blocks and new Duff HD weld on spring perches offered in factory and 1" built-in lift.

Q: Will 8 shocks make my Bronco ride rough?
A: The only time we have seen 8 of our classic 70/30 shocks create a rough ride on a Bronco is when the Bronco had very few accessories on it or was a stock roadster(U13) or a half cab(U14). Even then it was not across the board rough for every Bronco since several other factors create a rough ride like overinflated tires, stock or worn-out seats, poorly installed suspension, other company's suspension combined with Duff shocks, and sometimes it just comes down to personal preference.

The biggest misconception in the industry is that all off-the-shelf twin and monotube off-road shocks have the same 50/50 valving. At James Duff that couldn't be farther from the truth! We developed a shock over 30 years ago that lets our springs do their job and spend more time controlling the rebound. This is a large reason why you can run 8 Duff classic 70/30 shocks on your Bronco and experience a smooth ride. 8 shocks also help control body roll. Especially when lifting your Bronco over 3 inches.

Read more of our FAQ's here.