Customer Question: My Harness Bar Is Right At The Back, Do I Need Longer Straps?
From a call this week
A customer rang this week, part way through turning his BMW into a track car. He has a harness bar fitted well behind the seats, back towards the boot, and he wanted to know whether he needs to buy long shoulder straps to reach it.
He almost certainly does not, and the reason is worth knowing before you spend anything. Unless a belt says otherwise on the listing, it is built saloon length, and saloon length means long tails made to reach back to a cage bar or the back seat area.
- Unless a listing says otherwise, an FIA or road belt is saloon length
- Saloon shoulder straps run about 150cm from the adjuster to the fixing point
- The short ones name their car. Caterham is 50cm at the same point, a third of it
- Seat height sets your shoulder line, so settle the seat before you set the harness
Saloon length is what you already have
Harnesses are sold by application, and you can see it on our listings as an attribute. Most of ours say Saloon. The rest name a car, and they name it because something about that car is unusual.
Saloon is the long one. It assumes the shoulder straps have to travel back over a seat and reach a cage bar or a mounting point somewhere around the back seat area, so the tails are cut with that journey in mind. It is why a belt out of the box usually looks like it has far too much webbing on it.
Put a number on it and it stops being vague. Our own TRS Caterham road belt is sewn to 50cm from adjuster to fixing point, and that listing says plainly a standard saloon harness is around 150cm at the same point. Three times the length, for the car where the hoop is practically against your back.
The short ones tell you they are short
Every belt we sell with cut down straps says so on the page, because it exists for one particular car. The TRS Magnum Westfield has shoulder straps cut shorter than a standard saloon harness to suit that close hoop position. The Clubman Westfield is cut for the hoop instead of being adapted from a universal saloon belt. TRS build MX-5 versions of the Magnum the same way, shortened to suit the gap between the seat and the bar so nothing is left loose.
Notice what those three have in common. Small cars, bar close behind you. Nobody makes a long version for a bar that is far away, because the standard belt already is the long version.
For a BMW with the bar back near the boot, an off the shelf saloon belt is the right starting point, and any excess goes back through the adjusters the way it is meant to.
What to check instead
The thing worth your attention is the angle the strap runs at. Our Sparco listings put it in a line: the shoulder straps want to run level or slightly downward from your shoulders to the bar, never upward, and how high the seat sits decides it.
A bar a long way back is often a bar a long way down as well, and that is where a far rear mount catches people out. Extra webbing lets a steep strap reach, which is a different thing from the strap being right.
Cameron went through the angles properly, with the Motorsport UK and FIA sources against each figure, so we will not repeat them here: How To Fit A Motorsport Harness: Angles, Anchor Points And The Mistakes To Avoid. Worth ten minutes before you drill.
Wrapping the bar, or clipping to it
Two ways to land on a bar. Wrap around, where the strap loops the bar and feeds back through its own adjuster, or a snap hook onto an eyebolt. Wrapping is the tidier job in a caged car and most of the Sparco competition belts are set up for it.
Going the eyebolt route, the length of the bolt matters more than people expect, which is why TRS list a long one next to the standard. Get the thread right for whatever you are bolting into and check it before you commit.
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And the small bits that do the actual mounting, which are the cheapest part of the job and the easiest to get wrong.
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If you are raising the seat as well
This is the part our caller had not joined up. Raising the seat lifts your shoulders, and lifting your shoulders steepens the run down to a low rear bar. If the seat height and the harness mounting are both still up for grabs, settle the seat first and set the harness to it.
We covered the mounts that put a bucket seat back up in a BMW here: Sitting Too Low In A BMW E46? The Mounts That Put You Back Up. Different parts across the range, same principle.
Common questions
How long are standard harness shoulder straps?
A saloon belt runs around 150cm from the adjuster to the fixing point, which is our own published figure. For comparison, the Caterham specific belt is sewn to 50cm at the same point.
My bar is back near the boot. Do I need a special belt?
Almost certainly not. Saloon length is the default and it is cut to reach back to a cage bar or the rear seat area. Check the angle instead of the length, and ring us if you want a second opinion on your setup.
How do I know if a belt is saloon length?
Look at the application on the listing. Ours say Saloon unless the belt is built for a particular car, and the ones naming a car are the shortened ones, Caterham, Westfield and the MX-5 versions.
What do I do with the spare webbing?
It runs back through the adjuster. Excess is normal on a saloon belt in a car where the bar is close, which is exactly why TRS make shortened versions for the small cars.
Can I bolt the harness to the seat or the subframe?
No. That is covered properly in our harness fitting guide, along with where it does anchor. It is the thing we correct most often on the phone.
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Building a track carTell us where the bar is
Give us the car, where the bar sits and how high you are running the seat. Ring Garreth and Cameron on 0115 9893488 and we will tell you what belt suits it.
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