How To Fit The Cobra Le Mans Into Your BMW E21
Seat fitting guide
The BMW E21, built from 1975 to 1983, was the first 3 Series and is now a favourite classic for fast road use, sprints and track days. The standard seats give very little side support, which is usually what starts the search for something better.
The Cobra Le Mans is a reclining sport seat with a retro shape that suits the E21's era. This guide covers the two E21 frames we list, what to have ready, and how the job goes, so you can plan it before you order.
- Two E21 frames: Planted Technology SB128 and Corbeau BMWE21
- Both pick up the E21's factory floor mounting points, no drilling
- The Planted bracket is handed, so order two for a pair
- The Le Mans is a steel framed recliner, 820mm tall and 540mm wide
- It is Road and Track approved, with routing for a 4 point harness
What is on this page
Why the Le Mans suits an E21
The Le Mans is the touring end of the Cobra range. Its orthopaedic style backrest supports the length of your back, it has proper side bolsters, and it reclines. The recline matters in an E21: the cabin is compact, and a fixed back shell can push a tall driver’s head towards the headlining.
It is also a seat you can live with on the road. It is Road and Track approved, not FIA homologated, so it is the right choice for a fast road car or a track day car, not for a championship that asks for an FIA seat. Cobra hand trim it in the UK in vinyl, leather or spacer fabric.
Measure before you buy. The Le Mans is 820mm tall, 540mm wide and 620mm deep, and it weighs 13.4kg on its steel reclining frame. It suits all heights and waists from 32 to 38 inches.
Compare the width with the gap between the E21's transmission tunnel and the sill, and remember the headroom check at the end of this guide. Garreth's advice is to sit in one in the showroom if you can, because the seat's shape is the whole point of it.
Which frame: Planted Technology or Corbeau
We list two frames made for the E21, and both pick up the car’s factory floor mounting points, so the original seats come out whole and nothing is drilled. Keep the original seats somewhere dry, because E21 interior parts are very hard to find now.
The Planted Technology bracket, part SB128, is the one we pair with the Le Mans. It is handed, so you need to order two for a pair of seats. The Corbeau E21 sub-frames, part BMWE21, are well made, but they use a Corbeau seat bolt pattern, so ask us to confirm the mounting stack for a Le Mans before you order that option.
Before either goes in, lift the carpet and check the floor. E21s rust in the floors and sills, and a frame can only pass the seat’s load into sound metal.
Fitting the seat, step by step
Have ready a socket set with an extension bar, a torque wrench and thread lock, and check everything is in the frame’s box before you start.
1. Remove the original seat. The E21 seat runs on two floor rails fixed at four points. Slide it fully forward, take out the rear bolts, slide it back, take out the front bolts and lift it clear. If it has any wiring underneath, unplug it first.
2. Fit the frame. Line it up with the factory floor bolt positions and start every bolt by hand before tightening any of them. Tighten in a cross pattern, with thread lock, to the figure given in the frame’s instructions.
3. Attach the seat. Start all the seat bolts before fully tightening one, so the base does not bind on one corner, then tighten them evenly.
4. Check the headroom. Sit in the seat in your normal driving position, with the backrest where you will use it, and check the gap to the headlining. A replacement seat can sit a little higher than the original, so do this before you call the job done.
Adding a harness
The Le Mans has routing for a 4 point harness, which makes a road and track 4 point belt the natural partner for an E21 used on the road and at track days. Route the straps through the seat before the final tightening, while there is still a little play to get them lined up.
The anchor points matter as much as the harness, so plan them before you order. Our guide to 4 point or 6 point harnesses explains the choice, and if the car is getting a cage too, our classic BMW roll cage guide covers the E21.
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![Planted Technology BMW 3 Series [E21 Chassis] (1975-1983) Seat Bracket](https://www.sportseats4u.co.uk/wp-content/uploads/sites/2/2026/08/SB128PA-2-300x300.jpg)
![Planted Technology BMW 3 Series [E21 Chassis] (1975-1983) Seat Bracket image 2](https://www.sportseats4u.co.uk/wp-content/uploads/sites/2/2026/08/SB128DR-2-300x300.jpg)
What frame fits a Cobra Le Mans in a BMW E21?
We pair the Le Mans with the Planted Technology E21 bracket, part SB128, which picks up the factory floor mounting points.
Do the E21 seat frames need drilling?
No. Both the Planted Technology and Corbeau E21 frames use the car’s original floor mounting points.
Is the Cobra Le Mans FIA approved?
No. It is Road and Track approved, so it is for road and track day use, not for competition that requires an FIA seat.
Can I fit a harness to the Le Mans?
Yes. It has routing for a 4 point harness, and the anchor points need planning for your car.
Do I need one Planted bracket or two?
Two for a pair of seats. The bracket is handed, driver’s side or passenger’s side.
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Our E21 pairingLe Mans on Planted SB128
A reclining classic seat on a no drill E21 bracket.
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