AST 5100 Monotube Coilover Struts and Shocks BMW E36 M3

Introduction

The 5000 Series damper stands as AST's full race setup. It is available in one, two and three way adjustments. 5000 Series coilovers are fully streetable but utilize the full race components like inverted struts, teflon flat bearings and spherical bearing mounts. 5000 Series coilovers are great for competitors with points based rules or rule-free damper requirements. The 5100 gives the customer the ability to have the highest end components without running reservoirs. 5200 models use remote reservoirs or "piggyback" reservoirs to control low speed compression. 5300 models use remote reservoirs or "piggyback" reservoirs to control low and high speed compression.

Key Features

• Monotube shocks and struts that use 44.5mm shafts for struts and 14mm shafts for shocks
• Nitrogen charged to 265 psi for all models
• Utilizes AST's Load Bearing Piston (LBP) for all strut designs (AST is the only coilover in this price range to use this feature)
• Steel bodied struts use European KTL coating which is stronger and more weather resistant than powder coat or wet paint found on most shocks
• All shock models use high grade aircraft aluminum for bodies
• All shock models (where applicable) use spherical bearing mounting points. Pin style spherical top mounts are available for purchase separately
• Available as Rebound-only adjustable (5100) or Rebound/Compression adjustable (5200), Rebound/Low Speed Compression/High Speed Compression (5300)
• Fully rebuildable and revalvable
• Shortened appropriately for lowered race cars
• All kits include hardware for installation
• The 5000 series have been tested at events including the 24 Hours of Nurburgring, SCCA Nationals, NASA Nationals, 25 Hours of Thunderhill and Grand Am races
• Wins in Redline Time Attack, SCCA Nationals, and NASA Nationals
• Valved for an aggressive street ride that performs great at the track

Modularity

One key feature on the 5000 series shocks is modularity, which makes them easily upgradeable. This provides an upgrade path for customers on a tight budget that want an adjustable, high performance, race-ready shock but can't quite afford the double adjustable 5200 or triple adjustable 5300. Simply purchase 5100s, and when you're ready, send your ASTs to an authorized rebuild center to upgrade them to 5200s or 5300s with remote reservoirs. Rest easy knowing that your shock absorber investment will perform today and in the future, as your budget and needs grow.

Parts Included in the basic AST 5000 kit:

• 2 AST 5100 Single Adjustable (12 adj, Rebound only) Monotube Front Inverted Struts (no reservoirs) with alloy steel strut bodies
• 2 AST 5100 Single Adjustable (12 adj, Rebound only) Monotube Rear Shocks (no reservoirs) with threaded aluminum shock bodies and spherical lower shock mount
• AST upper spring perches for 60mm springs, for use on the front struts and your OEM upper strut top mounts (we do not recommend using the 5100 dampers without the camber plates)
• AST Tool Kit
• Springs must be purchased separately, we can help with spring choice for your application

Also note: the rear shock in this kit is made to work with a spring in the OEM location ("true coilover" rear shock conversion kits are available for BMWs on all 5000 series rear shocks, which come with externally threaded aluminum rear shock bodies). Please call for more details.

The Design 

AST coilovers are monotube, high pressure nitrogen shock absorbers. Why do you care? Most other products on the market are twin tube designs and are not pressurized, or only have 1-2 atmospheres of Nitrogen in a little bag inside. Monotube shocks offer the biggest pistons for more control. High Nitrogen gas pressurization in Monotubes (8-12 atmospheres) means the oil will never cavitate around the piston. This is particularly important in environments where the vehicle makes rapid changes in direction such as autocross and road racing. Monotubes also allow for a wider damping range and can more easily provide a better ride with stiffer spring rates - we usually start with 3X the stock rates and often go to 6-7X the stock spring rates, even on street driven cars. This is the same technology used on $7,000-10,000 shocks packaged here in a competitively priced kit.

Tuning Assistance and Installation

At Lang Racing Development we race all of our cars on AST suspension, that includes our BMW race cars, our Porsche rally cars, and our daily driven/weekend track vehicles. That means we know how to install your suspension right and how to suggest any other changes you might want to consider at the same time, get the most out of your AST suspension by having us professionally install it and get the initial settings configured.

We can also help you dial in your suspension with the easy to adjust AST dampers. We can also provide you with spring recommendations based on your car and particular application. As as Swift and Hyperoil spring distributor we can get your car set up with the perfect spring to match your AST dampers. Whether you are road racing, rally racing, or have a dual duty track day/daily driver, we can help you get the perfect setup. To get started tuning your AST suspension we suggest reading through the AST Tuning Guide.

Custom Valving

AST-USA is setup to offer custom valving services to its customers, including dyno services on their Roehrig 2VS shock dyno; they can even rate your old springs if you are curious (fees apply). There's no need to find a third party company to get your custom valving applied - Just send them back to us and we will work with AST to get your shocks revalved to your exact specifications.

REAR SHOCK MOUNTS : Optional Rear Shock Mounts include AST-USA Spherical design or Heavy Duty rubber E46 M3 style. We recommend the spherical RSMs for most users that see any competition use, such as autocross or track events. If the car is a daily driven vehicle only and/or the user is worried about bad roads and any additional NVH transmitted through a rear spherical mount, then choose the HD rubber style instead. Our HD rubber RSMs will be machined to fit the 12mm rear pins on the current 4100s and the 4150s at no additional charge. The advantage to spherical RSMs is their ability to transmit reactions to shock forces instantly and direct - something that shows up on a shock dyno plot.

RSM REINFORCEMENT KIT : Many BMW models are prone to cracks near the rear, upper shock mount bolt holes from both street/track use with higher cornering loads (and higher damper forces) as well as normal street use over extended time periods. Bolt these steel reinforcement plates on top of the rear shock tower sheet metal to strengthen this known weak area and prevent these cracks. Can be used with OEM style rubber RSMs or spherical RSMs. Can be bolted or welded in place. To install just place above the shock tower, underneath the RSM top nuts, as shown below - takes mere minutes to install.

SPRING RATES: While AST-USA provides you with the shocks only, Lang Racing Develoment offers the unique option for racers to pick their own front and rear spring rates at a reduced cost. These options will included new Hypercoil or Swift springs depending on the rates you request, AST rear ride height adjusters, and nylon rear spring alignment platforms. We know that every application is different so we let you tell us what rates you need, or just select "custom" and we can discuss with you your specific spring needs and find the best solution for you.

HELPER SPRINGS : We have found that certain applications benefit greatly from helper springs. When lowering the rear of an E36 the shock travel is usually longer than the short spring required in the stock location which can sometimes make the spring fall out when jacking up the car. A nightmare when the car needs to be serviced or even when changing a tire. To solve this we use a helper spring which keeps the spring in location when uncompressed but acts as a flat spacer when compressed, allowing the linear spring to do all the work. This can also be beneficial on a coil over shock that has a lot of travel like in rally applications.

• 2 Front 60mm Coilover Springs, 180mm (7") Long
• 2 Rear 60mm Coilover Springs, 140mm (5.5") Long
• Optional helper springs for front, rear, or both.
• AST Rear Ride Height Adjusters
• 2 Rear Spring Alignment Platforms