Hundreds Of Products Ready Today. Dispatch/Collection Jass Performance
If you are tall and you drive an MX-5, this is the brand that exists for you. Jass make seat lowering adapters for every generation, and the reason they work is written into the product copy: they are designed by somebody who is 197cm tall and needed to fit in an ND. Five products, £35 to £289, and every one of them buys you headroom.
Lowering adapters for the standard seats on Mk3 and Mk4, adapter rails to make a Sparco fit a Mk1 or Mk2, and a sliding lowering rail if you need the seat to still move.
Designed by somebody with the problem
Most product copy is written by a marketing department. Jass Performance listings are written in the first person by whoever designs the parts, and they are more useful for it.
The ND listing explains the 56mm drop by saying the designer is 197cm tall with a 100cm torso and needed the car to work for him. The NC listing describes the problem before the solution: the Mk3 is roomier than the others on paper and offers similar or less usable space in practice.
That is the whole brand. Somebody tall solving the MX-5 headroom problem properly, one generation at a time.
Adapter rails so a Sparco Sprint or R100 actually fits, rather than needing redrilling and still sitting high.
Two lowering options depending on whether your seats adjust for height. Up to 2.5in, with full seat travel kept.
The biggest drop in the range at 56mm, and a choice between fixed and sliding. Also fits the Fiat 124 Spider.
The NC brackets are described as computer stress calculated for real crash situations and weight optimised.
The figures, by generation
These are the numbers from our own listings rather than estimates.
| Car | Part | Drop | Keeps sliding | Price |
|---|---|---|---|---|
| Mk1 / Mk2 | Sparco adapter rails | fits a Sparco properly | yes | £35.00 |
| NC Mk3, non height adjustable seats | lowering adapters | 1in or 2.5in | yes, full travel | £53.33 |
| NC Mk3, height adjustable seats | lowering adapters | 1.5in | yes, full travel | £77.50 |
| ND Mk4 and Fiat 124 | fixed seat adapters | 2.2in / 56mm | no, 3 fixed positions | £129.16 |
| ND Mk4 and Fiat 124 | lowering slider rails | lowered | yes | £289.00 |
On the NC the listing gives a headroom figure as well as a drop: 90.3cm to 94.3cm on the 1.5in option. That is the sort of number worth measuring against your own helmet before you order.
Three questions
They narrow it down quickly.
Which generation?
Mk1 and Mk2 are the pop up and facelift cars, NC is 2005 to 2015 and ND is the current shape. The parts are not interchangeable between them. If you have a Fiat 124 Spider, the ND parts are the ones that fit.
Are you keeping the standard seats?
If yes, you want lowering adapters. If you are fitting a Sparco Sprint or R100 into a Mk1 or Mk2, you want the adapter rails at £35 instead. Those are different products for different jobs.
Do your NC seats adjust for height?
This decides which NC part you need. Non height adjustable seats take the £53.33 adapters with a 1in or 2.5in choice. Height adjustable seats take the £77.50 part which gives 1.5in and keeps the adjustment.
On an ND, do you need the seat to slide?
The fixed adapters give the most drop for the least money but the seat stops sliding, with three preset positions 25mm apart. If the car is shared, the lowering slider rails at £289 are worth the difference.
The honest version of the ND choice: £129 if you are the only person who drives it, £289 if you are not. The drop is the point either way.
Cameron, GSM PerformanceThe cheaper end of the range
The Sparco adapter rails at £35 are the cheapest thing here and they solve a specific problem: a Sprint or an R100 is not a direct fit in a Mk1 or Mk2, and without them you are redrilling. The two NC parts are picked on whether your seats adjust for height.
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From £35.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
Fixed or sliding
The ND is the smallest MX-5 inside, which is why it has the biggest lowering options. Fixed adapters at £129.16 for 56mm and three preset positions, or lowering slider rails at £289 if the seat needs to keep moving. Both fit the Fiat 124 Spider as well.
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From £129.16 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
Both do MX-5 lowering, differently
We list two MX-5 specialists and they overlap, so here is plainly which does what.
Jass is about lowering the seats you already have. Adapters and rails for standard seats, plus the Sparco adapter rails for a Mk1 or Mk2.
Cybul is about fitting bucket seats and adding a rollbar. Their seat mounts take a side mounted competition shell as low as the floor, and they also do an ND stock seat lowering kit at £115 which is the one product that competes directly with Jass.
If you are keeping the standard seats, start with Jass. If you are fitting buckets, start with the Cybul guide.
The ones we get asked
What does Jass Performance make?▾
Seat lowering for the Mazda MX-5, and not much else. Adapters that drop the standard seats, and one set of adapter rails that make Sparco seats fit a Mk1 or Mk2 properly. The ND parts also fit the Fiat 124 Spider.
How much lower will I actually sit?▾
It depends on the generation. On the NC there are two options, a 1in or 2.5in drop on non height adjustable seats, or 1.5in on height adjustable ones. On the ND the fixed adapters give 2.2in, which is 56mm. Those are the figures from the listings rather than estimates.
Are these FIA approved?▾
No, they are listed Road and Track. They are lowering brackets for standard seats rather than competition parts. If you need an FIA seat installation, you want a proper subframe and side mounts instead.
What is the difference between the two NC options?▾
Whether your seats adjust for height. If they do not, you get the choice of a 1in or 2.5in drop at £53.33. If they do, there is a separate part at £77.50 that gives 1.5in and keeps the height adjustment working. Check which seats you have before ordering.
Fixed or sliding on the ND?▾
That is the real decision. The fixed adapters at £129.16 give the biggest drop, 2.2in, but the seat no longer slides, though three positions are predefined 25mm apart. The lowering slider rails at £289 keep the seat sliding. If more than one person drives the car, pay the difference.
Do I lose seat travel?▾
Not on the NC adapters. Both NC options are listed as preserving full seat travel and giving the lowest position achievable on the standard rails. On the ND fixed adapters you do lose the slide, which is the trade for the extra drop.
Will they fit a Fiat 124 Spider?▾
The ND parts will, both the fixed adapters and the lowering slider rails. The Mk1, Mk2 and NC parts are MX-5 only.
What are the Sparco adapter rails for?▾
Fitting a Sparco Sprint or R100 into a Mk1 or Mk2. Those seats are not a direct fit in an MX-5, and without adapting them you end up redrilling and still sitting too high. The rails are £35 and they bolt on.
Tall, and not sure which to buy?
Tell us your height and which MX-5 you have. That is genuinely all we need to point you at the right part.
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