i want to fit a race harness but which is best and how are the fitted , ive just fitted a corbeau forza seat what a pain that was
Harnesses do not fit in the same way as seat belts. You can use the lower belt point, the one that is at the base of the B pillar, but there are no other built in points. While in earlier cars, the buckle part will have a transmission tunnel mounting, on latter cars you would have to drill and fit spreader plates, however, there is no suitable mounting point on the rear parcel shelf, for shoulder straps, these would normally fit to a propper roll bar or cage or harness bar. If you have one, fitting is pretty obvious, if you don’t have this stuff, basically you can’t fit harnesses.
It doesn’t matter which brand you pick, as long as its either ECE approved (approved for road use) or FIA approved (3" webbing, approved for track use). Don’t go anywhere near unbranded harnesses. There are also counterfeit harnesses about; copies of the Japanese Takata harness.
http://www.takataracingproducts.com/landing.php
The fakes are scarily bad; think about that if you buy from Ebay;
Use of a harness on the road is positively dangerous, as it restricts your movement if used correctly. If used correctly, you’d barely be able to adjust the heater.
For hillclimbs/sprints I used a TRS Magnum 6-point harness with aircraft-style quick release. Most harnesses have lap belt adjustment my pulling down on the straps; you have to sinch yourself in everytime you use the harness. Pulldown lap belts are very difficult to adjust in a fully trimmed MX5 cabin. Willans do a Caterham specific harness with a pull up lap adjustment. They can produce a custom harness that will combine the Caterham lapbelt with longer shoulder straps (Caterham straps are too short). Harnesses can be ordered with different length shoulder straps; saloon car straps will be too long, but you can tape up the excess.
Fitting a harness to a car without rollover protection is a terrible idea. If you just need to be held a bit tighter for Autotests, a CG lock can be added to the standard seatbelt.
Most rollbars can be specified with a harness bar, which usually includes UNF tapped points to fit the shoulder straps. Some people wrap the straps around the bar to attach, but I prefer using the tapped points so the straps can’t move outward. Do not use the 1.8 factory cockpit brace as a harness bar; its not strong enough. If your rollbar doesn’t have a harness bar, the correct place to attach the shoulder straps is by drilling points at the rear of the shelf behind the seats, and fitting strengthening plates. This point is specified by the JAF for Eunos Roadster racing (they frown on bolt in harness bars), but is suitable only for the drivers side. Scrutineers had no issue with my chosen mounting point in hillclimbs/sprints. This also gives the correct 10 degree deflection from the driver’s shoulder. When I’ve used harness bars, the loading from the shoulder straps can be pretty painful.
When you buy a harness, you can specify bolt in or clip in. ECE harnesses, which aren’t worth buying, are always bolt in. The lap belt you attach to your existing seatbelt points. With a clip in belt, you replace the existing bolts with strong eyelet bolts. This enables you to retain the existing seatbelt, as the harness won’t affect the normal movement of the seatbelt. With a bolt in belt, mixing the harness with the seatbelt can work, though really you need some longer bolts and work out some extra spacers. If fitting a 5-P or 6-P belt (better than a 4-P belt, as these stop the lap belt riding up, and causing internal injuries in a sharp stop) attach the crotch/ anti-sub strap to the floor, by drilling. I used a clip in belt and found that with a plastic window top, the eyelets on the shelf did not interfere with the top. This won’t be the case if you have a glass rear window.
I’ve had two sets of harnesses in my car.
The first was a bolt-in 3-point, using a bolt-hole that was on the rollbar (and a bolted-in mount point as Nick described). The seconds was a clip-in 4-point, with the shoulder straps wrapped around the rollbar.
My advice: don’t get 3-point. The logical mount point (rollbar or a harness bar) is to close to the seats for 3-points. The shoulder straps just didn’t sit right.
The clip-ins are much easier to remove if I need to take the seats out.
This is a bad way of attaching shoulder straps in a MX5; seen it too often in this country;
This Japanese owner did what I did, basically;
The yellow hatched area is the part you can’t use.
Strengthening plates (you can fit bigger)
This harness I used; this harness is no longer legit.
Having seen many a crashed Mx-5, I wouldn’t attach shoulder straps to the rear parcel shelf for love nor money.I don’t care who says what about the strength, a substantial rear end impact and the shoulder will be loose.
A substantial rear end crash will also compromise a bolt in rollbar. A substantial side collision will also cause failure of the seatbelt tower in 89-93 cars. In a properly run trackday, it is unlikely that one car will run into another. If that happened, the organiser will likely be facing HSE investigation and criminal proceedings. A car will not run into the back of another during a sprint or hillclimb.
An Australian CAMs approved solution; the harness integrity is no longer dependant on the integrity of the half cage
And in what way what so ever does a statement like that make a pikey modification of drilling through your parcel shelf to fit harnesses mitigate doing the job properly?
Of course no one has ever parked backwards in a hill climb, track day and never ever on the road. Do it right or go home!
That’s the most stupid thing I’ve seen all week.
Every other decent rollbar bolts down to the chassis, not onto some weak metal. You can rip through that material quire easily. I had to cut a load of that out to fit a Hard Dog bar (which is held in by 3 much larger bolts per side).
well thanks all thats answered that question , im having major agro with this seat its side mounted as i wanted to get lower me being tall. it has four bolts which hold the mounts to the floor and four alen bolts which hold the mounts to the seat . if you fit the mount to the seat you cant get to the bolts under the seat and if you fit the mounts to the floor first you cant get the alen keys , has anyone had similar trouble