Which Harnesses For Your Mazda MX-5? The Complete Guide
The MX-5 is the car we get asked about more than any other when it comes to harnesses, and it is also the car where the usual answer is wrong. Buy a standard set of belts for a Mk1 or Mk2 and you will end up with a fistful of spare webbing behind each shoulder, because the bar you are mounting to sits far closer to the seat than it does in a saloon.
That is why TRS cut their MX-5 belts with shorter shoulder straps, and it is why we sell more of those than anything else for these cars. This page covers the lot: what you bolt a harness to in an MX-5, which belts are cut for the car, what changes when you go from road to track days to competition, and what we would actually fit.
- TRS cut four point belts specifically for the MX-5 Mk1 and Mk2
- Shorter shoulder straps, so no loose webbing behind the seat
- Road four points from £102, and FIA six points from £234.00
- Six point FIA belts now listed in the MX-5 cut as well
- The bar behind the seats matters more than the belt you choose
Start with what you are bolting to
This is the part the internet skips. A harness is only as good as what it is attached to, and an MX-5 does not come with anywhere to attach one. There is no factory mounting point behind the seat at shoulder height, because the standard belt runs off the B pillar area and does its job differently.
So the shoulder straps need a bar. In practice that is a roll bar, a harness bar or a full cage, and on an MX-5 it is usually a bolt-in bar behind the seats. The lap straps normally pick up the floor, either on the factory seat belt mounting points with the correct eye bolts or on the bar itself, depending on the design.
Get this settled before you buy belts, because the height and distance of that bar decides which harness suits and how long the shoulder straps need to be.
These are the MX-5 bars and cages we stock across the generations, from a simple street bar up to a bolt-in cage.
Why an MX-5 needs a shorter shoulder strap
In a saloon the harness bar sits a long way behind the driver, so a standard TRS shoulder strap of about 150cm from the adjuster to the end of the strap is roughly right. In an MX-5 the bar is right behind your head. Same belt, far shorter distance, and the difference has to go somewhere.
TRS cut the MX-5 shoulder straps to 105cm instead. Wrap that around the bar as you should and you are left with roughly 55cm from the adjuster to the bar, which puts the adjuster where you can reach it and leaves nothing flapping. The part numbers carry it: our MX-5 belts are MH229-0003-MX5, MH340-300-MX5 and 40M-MX5, the standard TRS patterns cut to the MX-5 length. Same webbing, same buckle, right length.
With a standard 150cm set in the same car you get a long tail of loose webbing behind each shoulder and an adjuster sitting somewhere awkward. It is not only untidy. Motorsport UK want the three bar slide as close to the bar as it will sit, and you cannot do that with half a metre of spare strap in the way.
The belts cut for the MX-5
Four TRS belts sit in the MX-5 range on this site, all four point, all for the Mk1 and Mk2. The choice between them comes down to webbing width, buckle and how they attach.
| Belt | Webbing | Buckle | Fitting | Price inc VAT |
|---|---|---|---|---|
| TRS 4 point MX-5, bolt in | 2 inch | Clip | Bolt in | £102.00 |
| TRS 4 point MX-5, clip in | 2 inch | Clip | Clip in | £102.00 |
| TRS 4 point MX-5, clip in, pair | 2 inch | Clip | Clip in | £204.00 |
| TRS Magnum 4 point MX-5 | 3 inch | Aircraft | Bolt in | £214.80 |
Prices include VAT and were correct on 13 August 2026. All four are road and track belts, not FIA competition belts.
The plain four point is the one most people buy, and at just over a hundred pounds a side it is honest value for a road car that sees the odd track day. The Magnum is the step up: three inch webbing, an aircraft style buckle and alloy adjusters, and it feels a different class in your hands. Both are cut short for the car.
Bolt in or clip in is about how the ends attach. Bolt in goes straight to an eye bolt or a bracket, clip in uses snap hooks so the belts come out easily. On a road car that is also a daily, plenty of people prefer clip in for that reason.
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Road, track day or competition
The three situations want different things, and the honest summary is that most MX-5s never need a six point.
Road, and the odd track day
A four point on a decent bar, in the MX-5 length. Keep the standard belt fitted and working, because a harness is not a replacement for it on the road. Two inch webbing is fine here and easier to live with.
Serious track days and sprints
Move to three inch webbing and a proper aircraft buckle, which is where the Magnum four point earns its money. If the car has a bucket seat and you are driving hard, this is the sweet spot for an MX-5.
Competition
Now you need an in date FIA belt, and the regulations for your class will tell you six point and often FHR compatible. This is where the TRS six points come in, ordered in the MX-5 length.
Road and track day belts
If your car is not a Mk1 or Mk2, or you want something the MX-5 range does not cover, the TRS Clubman family is the same webbing and buckles in standard lengths. Worth knowing that TRS also do a Clubman with a 75mm shoulder strap and a 2 inch lap, which is a good halfway house, and a three point retractable if you want a belt that behaves more like a road belt.
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Six point, for competition
A six point adds two crotch straps instead of one, which stops the lap belt riding up under load. Every one of these carries FIA 8853-2016, which is the current harness standard, and the label inside carries its own expiry.
The Magnum is the core belt and the one we sell most of. Superlite and Ultralite are not different harnesses, they are adjuster grades on the same belt: standard is steel throughout, Superlite puts aluminium adjusters on the shoulder straps, and Ultralite puts them on the shoulders and the lap straps. So you are buying weight off the car, not a different level of protection. The HANS versions are built for use with a head restraint, and TRS class those as FHR only, meaning they are not intended for road use.
Every one of these is now listed in the MX-5 cut, with the same shorter shoulder straps as the four points above. They are made to length by TRS, not pulled off a shelf, so tell us if you need one for a date and we will confirm the lead time.
| Belt | Widths | FHR | Price inc VAT |
|---|---|---|---|
| TRS Magnum 6 point FIA, MX-5 cut | 3in shoulder, 3in lap | Friendly | £234.00 |
| TRS Magnum Superlite 6 point, MX-5 cut | 3in shoulder, 3in lap | Friendly | £294.00 |
| TRS Magnum Ultralite 6 point, MX-5 cut | 3in shoulder, 3in lap | Friendly | £342.00 |
| TRS Magnum 6 point FIA HANS, MX-5 cut | 3in shoulder, 3in lap | Specific | £250.80 |
| TRS Magnum Superlite 6 point HANS, MX-5 cut | 3in shoulder, 3in lap | Specific | £306.00 |
| TRS Magnum Ultralite 6 point HANS, MX-5 cut | 3in shoulder, 3in lap | Specific | £378.00 |
All six carry FIA 8853-2016 and all six are the MX-5 short shoulder cut. HANS Friendly and HANS Specific are our own shop terms, not FIA wording; see the next section for what they mean.
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Three inch, two inch and an FHR
This trips people up, so here it is straight from the standard. FIA 8853-2016 sets a minimum shoulder strap width of 70mm, the three inch belt everyone talks about. It allows a narrower 44mm shoulder strap, the two inch, but only for use with a head restraint, and those straps carry their own FIA label saying so.
So a two inch shoulder strap is not a lighter option you can pick freely, it is a restriction. A three inch belt works either way. Lap straps are 44mm minimum whatever the shoulder is, and the crotch straps are 44mm too.
There is a third design people miss: 70mm webbing that necks down to about 50mm only where it passes the device. TRS build it into the Magnum FHR belts, and it is usually the right answer for someone who runs a head restraint but does not want a narrow strap across the chest.
Mounting it properly
- Get the shoulder angle rightMotorsport UK put the shoulder straps at no more than 45 degrees below horizontal, and the FIA recommend staying nearer 10. With a head restraint it is no more than 20 degrees below, and never angled upwards. In an MX-5 that usually means the bar wants to be level with the harness slots in the seat.
- Use proper hardwareEye bolts are 7/16in UNF or M12 8.8 as a minimum, and a new mounting point in the floor wants a spreader plate behind it. We stock the eye bolts and the plates.
- If you are wrapping the bar, wrap it properlyThree passes through the three bar slide and about 100mm of tail left over, with the slide sitting as close to the bar as it will go.
- Roll the spare webbing, never cut itLeave at least 100mm of tail past the slide, then coil anything left over from underneath and cable tie it. Cutting webbing on an FIA homologated belt modifies it, and a modified harness is no longer homologated.
- Check you can still get outSit in it, do it up, and undo it in a hurry. Then do it again wearing a helmet if the car sees track use.
One thing out of stock as this went up: the TRS three inch shoulder pads. The two inch pads are in, and the Schroth and OMP three inch pads are alternatives if you want padding on a Magnum.
What we would fit
For a road MX-5 with a bar and a pair of buckets, the TRS four point in the MX-5 cut, at £102 a side. It is the belt we sell most of for these cars and it is cut right, which is the whole point.
For a car that does proper track days, spend the extra on the Magnum four point at £214.80. Three inch webbing, aircraft buckle, alloy adjusters, and it is a noticeably better bit of kit to use every session.
For competition, the TRS Magnum six point in the MX-5 cut at £234.00 and take the HANS version if you run a head restraint or think you might. Garreth’s view on that last part is that if there is any chance of you needing an FHR, buy the belt that suits one now, because the difference in price is small against buying twice.
Whatever you land on, the bar comes first. Ring Cameron on 0115 9893488 with which MX-5 you have and what is behind the seats, and he will tell you which belt fits and how long the straps need to be. If you want a six point in the MX-5 length, that is the same phone call.
Common questions
Do I really need MX-5 specific harnesses?
If you have a Mk1 or Mk2 and a bar behind the seats, yes, it is worth it. A standard length belt physically works but leaves a long tail of spare webbing behind each shoulder and puts the adjuster somewhere awkward. The MX-5 cut costs the same and solves it.
What do I mount the shoulder straps to?
A roll bar, harness bar or cage behind the seats. An MX-5 has no factory mounting point at shoulder height, so this is a part you have to buy. Check whether your bar has harness eyes welded in or whether you are wrapping the tube.
Can I get a six point cut for an MX-5?
Yes, and they are now listed. All six TRS Magnum six points are on the site in the MX-5 cut, including the Superlite and Ultralite adjuster grades and the three FHR versions. They are made to length by TRS, so ask us about lead time if you need one for a date.
Is a four point legal on the road?
Keep your factory seat belt fitted and working, and treat the harness as track equipment. We would not sell you a four point as a replacement for the standard belt on a road car.
Two inch or three inch shoulder straps?
Three inch if you have the choice. Under FIA 8853-2016 the two inch shoulder strap is homologated only for use with a head restraint, so it is a restriction rather than an upgrade. Three inch works either way.
Do the belts fit a Mk3 or Mk4?
The MX-5 cut range is listed for the Mk1 and Mk2. For a Mk3 or Mk4 we would look at the standard length Clubman and Magnum belts, or order a set cut to suit, because the bar position differs. Tell us the car and we will work it out.
How long does an FIA harness last?
Read the label. FIA 8853-2016 belts carry an expiry, and Motorsport UK allow a five year extension on top of the date shown. The older 8854-1998 belts get no extension. Do not go by what a retailer blog says, including this one, go by the label in your car.