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MG TD TF 1500 - 3 point seatbelt

OK, now the rollbar is complete I need to figure out how to install a 3 point seatbelt system. Has anybody done this and what would you recommend?
Geoffrey M Baker

My first thoughts on a 3 point system is that now the rollbar is in place, I have possible mount points for both the shoulder and the lap points. Currently (like a lot of TD owners, I suspect) I have a two point lap system installed directly to the plywood floor - which, as we know, is not a great idea in any circumstances.
I know Horst Schach's book has a mounting system involving welding bits to the tranny tunnel... but how about this for an idea...
My rollbar has four mounting points at the front, all level with the rear floor, which sits about six inches higher than the main floor, or about three inches above the seat level. Could I just fabricate mounts which would mount to the bolt holes on my rollbar and use those for the lap belt mounts? I'm thinking it would be a really good strong mount, but perhaps too high? I could even build a plate which curved over the edge of the rear floor and went down a couple of inches...?
I envision mounting a plate on the floor between the two center hoops, bolted to the center base hoop bolts, and this would be the mount point for the driver and passenger's inner seat belt mount. It could be as simple as a steel triangle with two holes for the 3/8 bolts and a central hole for the lap belt mounts. On the outside, the outer hoop mount could also be used by adding a plate which would extend to the far edge of the car interior (about three inches further out) and that could be the outer point for the seat belt mount.
Geoffrey M Baker

I always recommend lap belts, with the outboard anchors sharing the tub to frame bolts, and the inboard bolts at the junction of the transmission tunnel and the rear cross brace. This does require drilling two holes, one each for the inboard anchors. I have seen cars crashed with the belts in this location, and they held. In my opinion, these are the best points to attach lap belts, or the lower two anchors for a three point belt system. Any anchor on the rear shelf is just too high for mounting lap belts.
An effective three point belt would require a third mounting point slightly above shoulder level. Perhaps you could weld a 3/8 grade 8 nut to the roll bar for the anchor point? In my opinion,mounting a three point belt to an anchor point any lower than the sholder would cause crushing spine and sholder injuries.
David
D. Sander

How about a shoulder harness. You can get them that will attach to the roll bar. I have my rear mount on the floor behind my seat in my solution. No reason why ( and probably better) to mount on your roll bar. Keep the straps mounted above your shoulder level.
Dave


D Moore

Geoffery,
I have done as Dave Sander suggests for the lower two points. I use the bracket for the seat back adjustment as the third point.
Mort


Mort 50 TD

Dave, could you possibly email me those images, they are a bit low-res on this site...
Thanks!
Geoffrey M Baker

You have a roll bar for safety piece of mind. Why would you not put in 4 point or five point harnesses if you plan to do any spirited driving? Just asking

Will The Bar pass Tech inspection? I really like that you can get the top up. How tall are you? How about a pic with you seated in the car to get an idea of the overall height of the bar in relation to your relative size?

Keep us posted on your progress it's coming along nicely

Cheers

Bill Chasser Jr
TD4834
W. A. Chasser Jr

Go with a 5-point belt unless the roll-bar is simply for looks.
Gene Gillam

I´d go with a 4 (5?) point belt as well.

The left and right side can be fixed nicely outside the bench, they go right through the frame

from the top, just before the wheel acrh


Mike Fritsch

and from the bottom




Mike Fritsch

The middle point I´m not so sure about, since it goes into the middle tunnel sheet metal in my car, but you could probably fix it to your tansversal bar somehow, which would be ideal.



Mike Fritsch

Bill, I'll get someone to take a pic of me I the car in the next few days. I'm 6'2" and I think the rollbar is about an inch over my head. Having discovered that I have more headroom than I thought when raising the top, I'm thinking of increasing the rollbar height another inch, just by using inch thick plates and longer bolts...
As far as 4 or 5 point seatbelts, I'm not going to race her - and I don't want to frighten my girlfriend by suiting up in fireproof armor before getting in the car, either :)
Bottom line, when you drive your modern car around town, chances are you have a built in rollcage of sorts; if you have owned a sportscar like a Miata or a Z4 or a 350Z, you had a rollbar ... and three point seatbelts. The rollbar isn't for looks, its for safety. And a 3 point harness will increase my safety even more.
Yes, a 4 or a 5 point restraint system would increase safety even more... but hey, if we're that worried about it, driving on the roads, we should all buy Sherman tanks, not cars.
Geoffrey M Baker

Geoffrey, you never know she may be into bondage in a restrained sort of way JK!

Cheers
W. A. Chasser Jr

I did not know If I should post this, since it not truly about 3,4,5 point belts. but it might be useful since some comments were made about mounting the belts on the floor.

Back in 65 or 66 when I purchased the TE I, almost immediately added a pair of competition belts. I used the wooden floor boards which I now recognize as a poor choice.

Putting them back I added some brackets to strengthen them
These were weldments. (Leftmost frame)
I used the old holes since they seem to fit well (Middle top fame)
On the outer sides, I arranged the brackets to be next to the angle that the tie bar mounts to. There is a dog leg to hold the anchor bolt.
On the tunnel side I got a close to the tunnel as possible again another dog leg.

The brackets are, normally painted with red rust proofing paint, which is not quite MG red.
Bottom one is not yet painted.

This may be of sme interest, its just what I did.


JA Benjamin

You have mail Geoffrey.
Cheers
Dave
D Moore

Thanks Dave, those are much clearer!
Geoffrey M Baker

Bill's here a pic of me in the car with the rollbar. For anyone thinking about building one, you can go maybe two inches higher without obstructing the top!
Geoffrey M Baker

Sorry, here's the pic


Geoffrey M Baker

I finished building the central seat belt bracket yesterday and the paint is drying. It is a very heavy duty unit which bolts directly to my transverse rollbar mounting system (under the plywood rear floor) and consists of square .126 tubing welded to a flat 1/4 plate drilled for the seat belt holes. The seat belt mounts will be on either side of the tranny tunnel. It is cut out to fit over the top 1/4 countersunk screw w/capture nut over the tranny tunnel, and is out of the way of the handbrake cables. It is indestructible - probably the most complex piece of welding I've done, and all heavy stock. I'll post a picture; but it is a good solution to the problem. Now all I have to do is reposition the outer seat belt anchors so they mount to the frame, as per Mike Fritsch's pictures - and I could probably race her - but then again, with the rollbar and all the weight of the additional metal, I wouldn't win many races I suspect :)
Geoffrey M Baker

Glad to hear your continuing to make good progress. My tub is mounted and I'm slowly getting pieces in place. I have yet to bring out the two bow hood and mount them so as to get an idea of how much clear space is available for my planned bar.

Re racing, for me its about the competition. Beating my best lap times. Being in the front of the pack would be nice but swapping spots in the middle of the pack is a greater challenge and much more entertaining than bringing up the rear. Then again the rear is fine too, if I'm beating my own best efforts.

Cheers
TD4834
W. A. Chasser Jr

Here are pictures of the central seat belt mount. The first picture shows the seat belt plate mount on the right and the plate mounting to the bracket on the left. Nice paint work, eh? I slopped it on a bit thick last night and then it got cold.


Geoffrey M Baker

And an angled view. I also added the mounting points to the rollbar itself; a 3/16 weld tab on the outside of both bars and a right angle bracket on the outside bases, to hold the inertial reel on the bottom and the shoulder mount on the top. I also took the opportunity to add 3 small tabs on the inside of the hoops, for a headrest at some future point. I'll post pics of those later.


Geoffrey M Baker

And an angled view.


Geoffrey M Baker

Geoffrey, I'm wondering if your expectation is that the roll hoops will provide safety in the event the car rolls? I would seem to me that the red line here would be the best case senerio and most likely go even lower in the event of a roll over.

Thoughts?


MG LaVerne

LaVerne, I agree with your analysis. Look at the rollbars in a Miata or any other modern convertible; they suffer from the same problem. Even though my BMW Z3 (since sold due to excessive speeding tickets) claimed to have a solid steel pillar windshield, the angle of it always made me believe that in the event of a rollover the windshield would simply bend down and you would have the same 'triangle' of safety that you have drawn.
Still, my rollbar is HIGHER than that of most modern convertibles (many of them don't even come up as high as your head) and my hope is that in a rollover there is some expectation that you might survive - and pretty much zero hope of survival WITHOUT them.
Anyway, keep in mind the principal reason I've done this... it makes my girlfriend comfortable in the car. I've told her that hey, we'd most likely burn to death (exposed gas tank) or die from side impacts (no protection on sides) or have the steering wheel crush me... she's still happier with the thought of a rollbar.
And frankly, so am I. And as it was a fun engineering project, brought in for under $200, I feel a considerable sense of satisfaction. It let me practice my welding and design skills!
Lastly, it will let me put speakers right behind my head and give me decent audio sound!!! I plan on building a headrest with Miata millennium speakers built in wired to a mini amp in the rear running music via Bluetooth off my phone.
Priceless!
Geoffrey M Baker

Here are the seat belts fully installed. The inertia reel base mounts to the base of the rollbar on a flange; the top shoulder points are directly welded to the rollbar hoops on the outside, the midpoint mounts are mounted directly to the chassis via my rollbar crossmember and a bolted plate; and the side points now mount to the metal crosspoints between the rear tiebar and the outer frame. All in all, about as solid as one could hope to get. Here's a photo with my daughter modelling :)


Geoffrey M Baker

That looks very solid indeed and takes away the problem that the upper mount is below shoulder height which is the case in most installations.

Will you fill out the complete bar with padding? That should take away a lot of the reverse draft to the neck, which is a nice comfort improvement. Not as needed in Arizona as it is here, though..

Rgds, Mike
Mike Fritsch

A little concerned that some of those welds are "in shear" especially the top brackets, they should be fitted and welded behind the pipe.

Graeme
G Evans

Mike there are three tabs welded inside each hoop which will hold headrests...
Geoffrey M Baker

This thread was discussed between 24/11/2014 and 16/12/2014

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