When it comes to bagging a car for the first time, or even dealing with an unusual car that isn't often bagged, a common question we get is, "What suspension is the best?" Here at Bag Riders, we say that a bolt-in kit is always going to be the best. Since the kits are specifically designed for your car, they can be installed with little-to-no modification, and will have the best travel and performance right out of the box. However, these bolt in kits are often the most expensive route to take, or they may not be available for uncommon platforms. In this post we'll give you the pros and cons of the other types of air suspension and you can make your own call on which type best suits your needs.
The first thing we look at is how the factory spring is mounted on your vehicle, as this plays a big factor in what options will work. A spring can either be mounted to the damper, or it may be totally separate which is very common in the rear of most modern vehicles. Keep in mind that the front and rear of your vehicle will often be different types and therefore need different setups.
For suspension where the spring is mounted to the damper, you have the most options:
For suspension where the spring and damper are separate units, you are limited to the following:
Bolt-In Air Suspension
Bolt-in suspension kits will always be our go-to recommendation as long as there is one for your vehicle. These kits are designed specifically for your vehicle. Because of this, they usually retain the same setup as your factory suspension and come with vehicle specific brackets/mounts that will bolt right in with little-to-no modification. Bag Riders carries bolt-in kits from Air Lift Performance, D2 Racing, TruHart Suspension, and UAS (Universal Air Suspension, but referred to as UAS to avoid confusion with universal bags). Bolt-in kits will generally give you the most usable travel, when compared to slip-on or thread-on conversions, and the kits are tested before being released to ensure a comfortable ride.
- Travel Range - Because the dampers and air springs were designed with your specific vehicle in mind, in most instances the travel range of a bolt-in kit will outperform the other options.
- Starting Fresh - Your car is starting with brand new dampers meaning longer life ahead of them. These dampers are valved to match the air spring resulting in a more comfortable ride.
- Install Guide - The top brands often have installation instructions that break down the entire process. If you are thinking of doing this project in a home garage, this can be a big factor.
- Warranty & Support - This is the only option that offers the buyer a warranty against manufacturer defects. If you convert your coilovers to hold a thread-on or slip-on bag, you will no longer be covered under that coilover manufacturer's warranty. As a Bag Riders customer, you have our expert staff to call for support, in addition to the manufacturer.
- Limited Applications - Bolt-in kits are designed with a certain car in mind and therefore manufacturers cater to popular models. Less popular cars may not have kits available.
- Development Times - When a brand new car is released or a popular model changes generations, manufacturers need time to research & develop a new kit to match the new suspension and therefore a kit may not be available right away.
- Price - Often a bolt-in method is the most expensive option when looking at the cost of parts. However, if you are paying someone to install it, that can result in a less expensive installation or easier installation if you're doing it yourself.
Slip-on conversions were quite popular when Bag Riders started in 2009. They work well in MacPherson applications, but their "donut" style manufacturing can be a pro and a con. New advancements in technology has moved the UAS Aero Sport out of the spotlight in favor of thread-on conversion bags. These bags are still the only solution for converting OEM dampers to an air setup.
- Compatibility - UAS's Aero Sport line slides over your existing damper, and since it is a sealed unit, can be mounted around a variety of existing dampers
- Price - Cheaper than a bolt in kit, but more expensive than thread-on bags, these bags require brackets to properly fix them in addition to the price of the bags.
- Keep OEM damper control - Since these can be slid over many factory dampers, you can keep any OEM damper controls while adding the ability to slam the car.
- Size - These bags require at least 6" diameter clearance. This can cause issues with double wishbone suspension as the upper arm can contact the outside of the bag. With MacPherson cars, adding camber can cause the inside of the bag to touch the wheel well, or wider and larger diameter wheels can contact the outside of the bag.
- Travel Range - although these bags have an average amount of travel, if you are using them with a factory damper, you may be limited in how low you can go. Factory dampers tend to be taller than aftermarket dampers, and therefore limit you on the lower end.
- Unique installation - The universal mounting brackets will often require welding or fabrication to fit on your car. In some cases you will need to cut and modify OEM components in order for these to fit. UAS does make threaded brackets for coilovers, but if you have the choice between a thread-on bag or these slip-on bags, we recommend the thread-on.
A newer solution to going air, thread-on bags are quite popular for customers who already have coilovers and are trying to go air on a budget. To install, you'd take your coilover apart, remove your spring & spring perch, and install the bag. The bag itself is not sealed, but is slid over the top of your coilover and the bottom of the bag is then threaded onto the damper body to seal it. The top of the bag seals to the damper rod once the the top hat is reinstalled and tightened down. Bag Riders currently carries VERA Bags for BC Racing Coilovers and in the past we carried Bags by Only Charged Dubs (Bags by OCD). These bags only work for applications where the spring is mounted to the damper.
- Straightforward Install - Remove your spring and spring perch, and thread these on in their place. No extra brackets or mounting hardware necessary.
- Price - Thread-on bags can be the most cost effective solution to bag your car, with VERA bags coming it at $225 per bag. If you don't already own compatible coilovers, we would recommend seeing if there is a direct bolt-in kit for your vehicle. The price of compatible coilovers plus thread-on bags is usually similar to a vehicle specific kit.
- Diameter Options - Have an area that a slip-on bag is too big for? A slim double bellow could work instead. Smaller diameters mean more adjustment to camber and the ability to run wider wheels without worrying about contacting the bag.
- Variety of Vehicles - Since coilover manufacturers often make quite a lot more kits than air suspension manufacturers, you now have the ability to bag more unusual cars without worrying about custom fabrication.
- Travel Range - When compared to slip-on bags used on OEM suspension, these bags tend to drop a car lower due to the fact they're being mounted on aftermarket coilovers which generally have shorter-than-OEM dampers. However; if you are using a very low coilover package (BC Extreme Low), you may not be able to lift the car as high due to the shorter damper.
- Limited Compatibility - Currently we only carry bags that match BC Racing's coilovers. If you have another brand they will NOT fit. There are a few BC Coilover kits that use different size dampers as well. Please call us before purchasing if you are unsure about compatibility.
- No Guarantees - Bag Riders can help you verify whether the bags will physically thread onto your coilovers but unless we've already dealt with a customer on the same car with the same coilover variant, we can't determine whether the coilovers have too little, or too much travel to work well and ride comfortably.
These bags have been around for as long as air ride has. It's simply a sealed bag that can be used in place of a standalone spring. These are extremely common in rear suspension setups nowadays and come in a wide variety of diameters and heights to suit almost any application. They usually require mounting brackets to be securely installed. These will not work for applications where the spring is mounted to, or around, the damper.
- Price - Universal bags are among the cheapest you can purchase as they are some of the easiest to manufacture and range in price between $50 and $165 a bag
- Diameter Options - These bags have the widest variety of heights and diameters as there are so many different kinds, and should be able to fit in most applications.
- Travel Range - Due to how many options there are, the range of travel is usually not an issue unless you are limited by the damper on the same corner of the vehicle.
- Brackets Required - Standalone springs often sit in spring pockets or sit around a nipple at their upper mount. When converting to a universal bag you may need a lower bracket that elevates the bag up out of the pocket so it doesn't rub, or an upper mount that goes over the nipple so the bag is secured and can't slide.
- No Guarantees - Bag Riders can help verify whether the bags will physically fit in the space you have to work with, but unless we've dealt with a customer who has talked to us about how they fabricated their bracket setup, we cannot provide advice on the best way to install brackets and we recommend pairing up with a shop.
In summary, if a bolt-in kit is available for your vehicle, we always suggest going with that. The research and development that the manufacturers put into their products means you'll get a kit that works well out of the box without custom fabrication or hours of dialing ride height and quality in. The other options can all be cost effective alternatives but which to choose really depends on what brand of suspension you are currently on, and the design of it as well. Often you'll end up using a mix of thread-on, slip-on, or universal bags to best suit your suspension setup. If you still are unsure about what to choose for your car, just give us a call and we're more than happy to answer any questions you may have!