Sprinter Hymer AL-KO SLC Chassis Rear Semi-Air Suspension Kit — AKS3300AD
The AL-KO SLC (Super Light Chassis) is a specialist platform supplied exclusively to Hymer, used on the Mercedes Sprinter-based B-MC T and B-MC 550 / B-MC 690 ranges. Its low-frame design is what gives these Hymer motorhomes their lower floor and larger living space. That same low frame also means there's less rear clearance to give away in the first place — so when the rear settles under a full payload of water, gear and passengers, ramps, ferry decks and steep site entrances become a real problem sooner than they would on a standard chassis.
This rear semi-air suspension kit is the aftermarket answer for the AL-KO SLC chassis. Air springs work alongside the existing SLC torsion-beam suspension — nothing is removed, and the original setup is fully retained. You add rear height control and load support without changing the vehicle's kerb weight or GVW.
How the AL-KO SLC air suspension kit works
The air springs sit between the chassis and axle and take up load as payload increases, holding the rear at the height you set rather than letting it settle. Add air to raise the rear when you need extra clearance for a ferry ramp or a steep driveway; release it to return to normal ride height. The springs also add roll stiffness at the rear axle, which resists body roll under lateral load such as crosswinds or the draught from passing high-sided vehicles.
As supplied, the kit is inflated manually. Cab-controlled and fully automatic options are covered below.
Running heavier, or thinking about up-plating?
Many owners of 3,500 kg motorhomes look at up-plating to unlock more legal payload — a separate re-rating carried out by a specialist, not something a suspension kit does. This kit doesn't change your kerb weight, payload or GVW. What it does do is manage ride height at whatever weight you're plated to. The closer a motorhome runs to its maximum, the more the rear settles under load — so whether you've up-plated or simply travel fully loaded, the air springs hold the rear at the height you set rather than letting it sag. If you're weighing up an up-plate, [Motorhome Up-Plating Explained] covers whether you need one and how it works.
Kit contents
The bracket assembly is supplied by MAD, designed specifically for the Hymer AL-KO SLC platform. SABO air springs and On Air Suspension fittings complete the kit.
- MAD bracket assembly — designed for the Hymer AL-KO SLC chassis
- SABO air springs × 2
- On Air Suspension fittings and air line
- Fitting instructions
Fits these Hymer AL-KO SLC models
- Hymer B-MC T
- Hymer B-MC 550 / B-MC 690
- Any Mercedes Sprinter-based Hymer on the AL-KO SLC (Super Light Chassis)
Not sure whether your Hymer is on the SLC chassis? Contact Us and we'll confirm before you order.
Manual, cab-controlled or fully automatic
The kit works three ways, so you can match convenience to how you use the motorhome:
- As supplied — manual. Inflate at either air spring with a standard tyre inflator or workshop compressor. No electrics, nothing to fit inside.
- Add a compressor and gauge control. Adjust rear height from the cab or a control panel instead of at the wheel — useful if you change load or want to raise for clearance regularly.
- Add On Air Active. For owners who'd rather not think about it, On Air Active levels the rear automatically as load changes, hands-off. Suited to higher-value motorhomes where set-and-forget matters more than the extra outlay.
Compressor, gauge and On Air Active options can be added alongside the kit — [Sprinter / Crafter Dual Digital Compressor Kit — PCP9022Z].
Related reading
Frequently asked questions
Does this kit change my Hymer's weight or GVW?
No. The air springs assist the existing suspension; kerb weight, payload and GVW are unchanged. The original AL-KO SLC suspension stays in place — nothing is removed.
Will it fit my Hymer?
It fits Mercedes Sprinter-based Hymer motorhomes on the AL-KO SLC (Super Light Chassis) — B-MC T and B-MC 550 / 690. If you're unsure which chassis you have, call 01277 552030 and we'll confirm from your details.
Do I need a compressor, or can I inflate it manually?
As supplied, the kit inflates manually with a tyre inflator or workshop compressor. A compressor and gauge control can be added to adjust height from the cab, and On Air Active can be added for automatic levelling.
Does it level the motorhome side-to-side on a pitch?
No. This is a rear kit that holds ride height under load — it works front-to-rear, not side-to-side. Site levelling is a separate job.
Can I still tow with it fitted?
Yes. The kit supports rear load, which includes the nose weight a towed load or a rear rack places on the rear axle.
Does fitting affect my warranty or the original suspension?
Nothing is removed and the original SLC setup is retained, so it can be reverted. For vehicle-warranty specifics, check with your dealer.