Real Race Seats 40 Litre Poly-Bead Resin Seat Insert Kit Real Race Seats 90 Litre Poly-Bead Resin Seat Insert Kit £369.07 Incl. VAT£307.56 Excl. VAT
Real Race Single Cell Inflatable Lumbar Support Real Race Seats Single Cell Inflatable Lumbar Pad £36.77 Incl. VAT£30.64 Excl. VAT

Real Race Seats 3 Cell Inflatable Lumbar Pad

£44.40 Incl. VAT

Three stacked inflatable cells behind the backrest cushion of a fixed back seat. Support across the whole lower back, adjusted on the move with a hand bulb.

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SKU: 13-003 Categories: ,
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  • Free UK delivery over £100Calculated at checkout on smaller orders.
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  • Fitting advice since 2003Ask before you buy if you are unsure.
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The moulded shell that makes a racing seat safe does not bend to fit you. Once you are an hour into a motorway run or a long stint at the circuit, the shape that felt fine at the start can leave your lower back with nothing to push against, and no amount of shifting in the harness changes that.

Real Race part 13-003 is a three-cell inflatable lumbar pad. Three separate bladders are stacked vertically behind a single hand bulb. Inflate and the pad presses support across the whole of the lower back from the base of the lumbar upward, which is the practical difference from the single-cell version. That one concentrates its curve at one height, low down. If you can put a finger on the exact spot that aches after a long run, start there and spend a few pounds less. If the ache spreads across the full lower back, this is the one that addresses the whole span.

The hand bulb is within reach while belted in. You can dial pressure out on a quiet motorway section and pump it back up when the road gets interesting. Adjustment is continuous and takes a few seconds.

Fitting needs no tools and leaves the seat unchanged. On most moulded shells the backrest cushion is velcro-held. Peel it off, lay the pad on the bare shell, press the cushion back over it, and route the hose out at the side clear of the harness slots. Nothing is drilled and nothing is cut.

Two things to check before ordering. Measure the flat area behind your backrest cushion, because the 3-cell is the taller of the two pads and we need that measurement to confirm it fits your seat. Also check whether the trim is velcro-held or bonded to the shell; some seats have it bonded or stapled, which leaves no pocket to work with.

If the car competes under a regulation that specifies the seat, ask your club or scrutineer before fitting anything between you and the homologated shell. For road and track day use it is a cushion change and not a concern. Lead time on Real Race lumbar pads is typically 3 to 5 working days from order. Browse the full Real Race seat insert range. Related: Real Race Single Cell Inflatable Lumbar Pad, Real Race Spacer Fabric Covering.

Additional information

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Seat insert kit and cushion guide

These are the two ways to change how a seat fits after you have bought it. A cushion changes your height in the shell. An insert kit moulds the shell to your body. They solve different problems.

Which one do you need

If the seat fits but you sit too low or too high, you want a cushion. If the seat is the right size but you move around in it, or it is a size too big and you want it to hold you properly, you want an insert kit.

Seat cushions

Sold as low, medium and high, and the name is the cushion thickness rather than anything about the seat. It is the cheapest way to fix a driving position that is nearly right.

Type What it does Who it suits
Low cushion Drops you as far into the shell as it goes Tall drivers, and anyone short of helmet clearance
Medium cushion The standard Most drivers, most cars
High cushion Lifts you up in the shell Shorter drivers, and better vision over the bonnet
Check headroom before you go upA high cushion lifts you toward the roof, and in a car with a cage and a helmet that is exactly where you have least room. If you are close, measure before you order. Going the other way, a low cushion is the first thing to try if your helmet is touching.

Most of our cushions are made for a specific seat, currently the Mirco Classic, GT, RS1, RS2, RS7, RTS-2 and RTX-7. Check the compatibility on the product, because a cushion cut for a different shell will not sit right.

Seat insert kits

An insert kit is expanding foam and a bag. You sit in the seat, the foam expands around you, and it sets to the shape of your body. It is what single seater and rally teams use to make one shell fit one driver properly, and it is the answer when a seat is a size too big.

Sold for Litre size What it suits
Small drivers 30 to 40 litre A slim driver in a standard shell, or filling a small gap
Medium and small drivers 40 to 50 litre The usual starting point
Large and medium drivers 50 to 70 litre More material, for a bigger gap or a deeper shell

The litre figure is the volume of foam in the kit, not a measurement of you or of the seat. More litres fills a bigger gap. If you are between two, the larger kit gives you room to get it right, and you can trim the result.

You get one attemptThe foam sets once. Read the instructions properly, have someone to help you, and be dressed exactly as you will drive, in your suit, with your helmet and your head restraint on and the harness done up. Any layer you leave off is a gap you will feel every time you get in afterwards.

FIA 3795:1992

Six of our insert kits carry FIA 3795:1992, which is the standard for the foam itself. If you are running in a championship that requires an approved insert, check for it on the product. The rest are for road, track day and club use where no approval is required.

A note on sizing up and padding out

If you are between two seat sizes, our advice on the bucket seat guide is to take the wider one. An insert kit is what makes that advice work. A seat that grips your hips cannot be made bigger, but a seat that is slightly loose can be made to fit you exactly, and it will be more comfortable than either the smaller seat or the loose one.

Not sure which fixes your problem?Tell us the seat, what is wrong with how it fits, and your height. Sitting too low, sliding about and being pinched at the hips all have different answers and it is worth getting the right one. Call 0115 989 3488 or email Sales@GSMPerformance.co.uk.

All figures read from our own product data across the insert kit and cushion categories, checked 2 August 2026.

Availability

We stock a wide range of the Real Race lumbar support pump up cushions in various sizes. These can be made available for dispatch within 24 hours. 

Specicalist components: Various materials and specialist components are directly sourced from the manufacturer to order. This direct delivery method means that most in stock parts are delivered within an estimated 7-10 days. 

Need them fast?  Please contact us in advance to check our stock and product availability. we may be able to dispatch them within a shorter lead time. Speak to us in advance to find out how we can assist.

Real Race Seats 40 Litre Poly-Bead Resin Seat Insert Kit

Have you written anything related to this?
Yes: A Complete Guide to Lumbar Support Pads for Bucket Seats and Real Race Seat Insert Kits Arrive In-Store For 2026 are worth a read before you order.

Will I fit in this seat?
Send us your height and waist size and we will confirm the fit. The paper dimensions only tell half the story, and our showroom team sit in these seats every day, so you get the honest answer rather than a guess from a chart.

How do I know it will feel right, not just fit on paper?
Fair question, because makers publish widths and weights, never feel, and two seats with identical numbers can feel nothing alike in the car. We keep the ranges on display in the Nottingham showroom, you are welcome to come and sit in them, and if you cannot get to us, call and describe your build, as the team sit in these seats every day. Our head support measurements guide shows the kind of real-world data we collect.

In-store displays:

We have a premium range of over 125 seats from brands including: Bimarco, Cobra, Corbeau, Sparco, OMP, Recaro, GP-Race, and Bride to name just a few brands we work with.  

Alongside this, we also stock and display HANS devices, harnesses, race-wear, race-suits, FIA helmets and various other safety equipment. If you are looking to visit us to see and try any particular seat or product, please contact us in advance and we’ll be happy to help.

In-Store appointments:

Book now!

Due to the specialist nature of our services, we do ask that you please contact us in advance to book an appointment. We have multiple slots available each day including selected availability at the weekend.

Working by appointment allows us to dedicate our time with you and provide a personal and professional service. We’ll always ensure you leave with the right equipment for your needs.

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Use the purchase power check in the Klarna box for a quick, no-obligation look at what you could be approved for before you order.

How it works at GSM SportSeats4U

  1. 1Add the product to your basket and go to checkout as normal.
  2. 2Select Klarna as your payment method and choose your plan. Klarna gives you a decision in seconds.
  3. 3We dispatch straight away. You pay Klarna on the schedule you chose, and any refund goes back through Klarna.

Your questions, answered by Klarna

Klarna is available to UK residents aged 18 and over. Subject to status. Terms and conditions and late fees apply. Klarna Financial Services UK Limited is authorised and regulated by the Financial Conduct Authority. Full details at klarna.com/uk. Every way you can pay with us is on our payment and finance page, or call 0115 989 3488 and we will talk it through.

Fast delivery lead times:

If you require fast delivery, please contact us in advance of ordering and we’ll happily check stock allocation and availability for you. We carry a large amount of stock at our showroom and across multiple distribution hubs. This allows us to provide immediate dispatch across a huge number of brands from Corbeau and Cobra through to Sparco and OMP. (Does not apply to all items)

Due to the niche market we work in, some products are custom hand made to order, or special order from manufacturers like PCI Racing and Planted Technology. If you want to know how fast a product will be dispatched. Simply drop us a message through our Contact us form.

ParcelForce

Addtional lead time notes:

Quick dispatch: Stocked products are dispatched within 24-48 hours with Parcel Force.
Sparco roll cages: We can only deliver these to a registered (LTD) company address.
In-store collection: Please contact us in advance to book an in-store collection appointment.

Guides and advice

GuideA Complete Guide to Lumbar Support Pads for Bucket Seats
GuideReal Race Seat Insert Kits Arrive In-Store For 2026
GuideHow Deep Are Bucket Seat Head Supports? Cameron Measured Every Shell In The Showroom
GuideBase Mount Or Side Mount? The Bucket Seat Fitting Stack Explained

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