Most side mount problems arrive after the seat has already been bought. The shell is sat in the footwell, the subframe is bolted in, and the driver has worked out that they are either looking through the top of the windscreen or cannot get far enough back to straighten an arm. The seat is fine. The brackets between the seat and the floor are doing the wrong job.
Side mounts are the cheapest part of the whole assembly and the part that decides where you actually end up sitting. Get them right and a 6ft 4in driver fits a car that looks like it should not take one. Get them wrong and you buy a second set.
This is the bit that catches people out, and it costs the most in returns.
The bracket spans further front to back, so the seat can sit further forward or back before you run out of holes. It does not lift you.
The bracket holds the seat higher off the floor. OMP use it properly on one pair, the 380mm high model against the 350mm low model.
On a Sabelt bracket this means it is cut to fit Sabelt’s XL size seats. It is neither longer nor taller.
I have had that conversation more times than I would like. Three words that all sound like “bigger”, and only one of them does what the customer wants.
OMP’s universal brackets are the ones worth understanding first, because the range covers both materials and every length, and because the naming on the longer ones has nothing to do with height.
| Part | Material | Length | Mounting positions |
|---|---|---|---|
| Low model | 3mm steel | 350mm | Multi-hole |
| High model | 3mm steel | 380mm | Multi-hole |
| HC0-0922 | 3mm steel | 400mm | Minimum 16 |
| HC0-0923 | 3mm steel | 495mm | Minimum 36 |
| HC0-0924 | 6mm alloy | 400mm | Minimum 16 |
| HC0-0925 | 6mm alloy | 495mm | Minimum 36 |
The 350mm and 380mm pair are the ones where high and low genuinely mean height. Everything from 400mm up is sold on length and hole count instead. More positions means finer adjustment, both in where the seat sits and in how far you can tip it back.
Steel or alloy is a straight trade. The 6mm alloy saves weight over the 3mm steel at the same length and costs more for it.
Until recently the honest answer here was to buy the taller bracket and hope. OMP make a spacer that does the job properly, and we now stock it.
It is a pair of spacers that bolt between the vehicle specific adaptor and the side mount. Drilled for three heights, so one kit raises the seat by 50mm, 62mm or 75mm without changing your brackets.
It also lets you take 2.5 or 5 degrees out of the seat angle, which matters more than people expect. Half the drivers who tell me they want to sit higher actually want the front of the cushion lifted so their thighs are supported.
Length in the bracket buys you a wider mounting window, but it is a fixed choice. Once it is bolted up it stays there. Adjustment you can use while sat in the car comes from runners.
The millimetres in a runner listing are where people go wrong. Every runner in the range gives the same travel and the same front to back movement. That figure is the handle width, and you pick it to match the width of the seat you are fitting. Corbeau list theirs at 291mm, 345mm and 405mm, all three at the same price, because it is one runner design with a different handle version on each. Our own attribute on those listings reads “291mm wide handle type” for exactly that reason.
Base mounted seats have their own runner kits from Sparco, OMP and Endurance Motorsport, sized to the seat rather than to a handle. If your seat bolts through its base rather than its sides, those are the ones you want.
Beyond OMP’s own alloy pair, three others are worth knowing about, and one of them is the answer for genuinely tall drivers.
495mm long, bent at 90 degrees, and cut in three heights at 425mm, 475mm and 490mm depending on the seat. The pair weighs 552g. The one I point tall drivers at.
CNC machined and black anodised in standard length, with the XL version cut for their XL seats. Their 3mm steel bracket is the cheaper way into the same fitment.
4mm and multi drilled, tensile tested on every production batch, and approved against Cobra’s own seat homologation.
Sparco’s alloy sits at the top of their range and their steel long bracket is 460mm overall with 290mm side hole spacing, which is the spacing most side mounted seats use, so it fits far more than just Sparco shells. If you want the cheapest FIA compliant way to hang a seat off a subframe, QMS do a 3mm steel multi-hole bracket from £26.50 and it does the job.
Working out which combination gets a particular driver into a particular car is most of what I do here, so if the maths is not obvious, drop us a message with the car and the seat and I will work it out for you. I am Cameron, by the way.
The full range is in motorsport seat side mounts and sport seat sliding runners. OMP publish the dimensions for their universal brackets on their own site, which is where every figure in the table above came from.
No. Length gives you a wider mounting window front to back, so you can move the seat further forward or further back on the subframe. Height comes from a high model bracket or from a spacer.
It means the bracket is cut to fit Sabelt’s XL size seats. It is not longer and it is not taller. A tall driver ordering the XL version because it sounds bigger will get a bracket sized for a wider seat.
The OMP spacer kit bolts between the vehicle specific adaptor and the side mount, and it is drilled for three heights, so one kit raises the seat by 50mm, 62mm or 75mm. It also lets you take 2.5 or 5 degrees out of the seat angle.
Runners, not the side mount. A side mount bolts the seat in one position, and a runner lets you move it while you are sat in the car. Runners sit between the subframe and the side mount, so they raise the seat slightly as well.
Handle width, not travel. Every runner gives the same front to back movement, and those figures tell you how wide the handle is so you can match it to your seat. Corbeau price all three the same because it is one runner with a different handle version on each. Measure across the base of your seat and order the one that matches.
Usually, because most side mounted seats share the 290mm side hole spacing. Measure your seat before ordering rather than assuming, since that spacing is what decides it.
How finely you can place the seat. The 400mm brackets carry a minimum of 16 positions and the 495mm carry a minimum of 36, which gives more choice over where the seat sits and how far you can tip it back.
For most people in most cars, the 400mm steel bracket. It is the length that suits the widest range of subframes, 16 positions is plenty of adjustment, and steel at 3mm is strong enough for anything short of a weight-limited build.
If you are tall, go to the 495mm. The extra length and the jump to 36 positions is what buys you the seating position, and it is a smaller step than buying the wrong bracket twice.
If the problem is height rather than reach, buy the spacer and keep the brackets you have.
The brackets are the cheapest part of a seat installation and they decide more about how the car fits you than the seat does. People spend weeks choosing a shell and then order whatever bracket comes up first.
Measure the hole spacing, work out whether you need length or height, and buy for that. If you are between two options, send us the car, the seat and your inside leg and we will tell you which one to run.
Cameron
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