Tub crossmember replacement and seat belt mount/anchor

[Megaweasel]

Hi all,
I’ve been working away on fitting some new 3-point retractable seatbelts to my 1973 GS and thought I’d share where I’ve got to.
I’ve put the brackets between the outrigger and the underside of the tub so I can mount the retractable mechanism vertically on the floor of the tub. That felt a lot more solid than the tub capping, which didn’t really inspire confidence. I couldn’t track down a proper mil-spec bar, so I had a Series bar modified to give me a higher belt position.
That all seemed fine, but when I moved on to the lower anchor points, things started to go wrong. One of the bolts sheared off, and I discovered it was hiding behind a panel of aluminium riveted to the bulkhead behind the seats. Removing the panel opened a bit of a can of worms!

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Looks like a previous owner had struggled with the seatbelt mounts too. They’d put in a steel section over the tub crossmember (or what was left of it), made up a filleted bracket, riveted it to the bulkhead, and welded it onto the outrigger. Once I drilled out the rivets and unbolted everything, the whole plate just came away… and I realised the tub crossmember itself isn’t there anymore. I haven't opened the other side up but I'm pretty sure its the same as its also got a plate over the anchorage on the bulkhead.

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So now I think I’m into repairing the front of the tub – crossmember and rear bulkhead included. The outriggers looks fine. I’m still fairly new to this, so I’d love a bit of advice:
When repairing the tub, does any welding come into it, or is it mostly rivets and bolts?
Are replacement sections for the tub crossmember available anywhere? I could probably fab something up, but as the important end of mine is missing, I’m not sure what joins to what.
I’ve read that the seatbelt anchors were originally two brackets that sandwich the aluminium of the tub crossmember. Is that right? And if so, does it not connect to the outrigger at all? That feels like a weak spot to me – how have others solved the lower seatbelt fixing?
Any pointers, photos, or just encouragement would be really appreciated. Never tackled this before, so I expect it’ll be a bit of an adventure!
Cheers,
Chris

[Megaweasel]

I noticed in the forum that the group might have had some tub crossmembers made at some point? Are there any remaining or where could i get one?

Failing that, are there any diagrams ir sizings etc - especially about the seat belt fixings?

Chris

[Megaweasel]

the nastiness continues. Opening up the other side, I'd say it's worse. Previous own has chopped off the aluminium crossmember, fabricated (I say fabricated, in reality folded a bit of steel over itself) a steel plate and welded the old seat belt bracket to it. Then literally wedged it under the Ali crossmember and welded the outer edge to the outrigger.

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so as I can't find an answer and it really does look lie these two brackets are designed to bolt through the aluminium cross member, I think I'm going to fabricate some brackets like the ones I have from the outrigger to the tub, only wider with a forward component to reach the back of the seat bulkhead, above the crossmember, to take the lower seatbelt mount.

Haven't decided what to do about the repair to the tub. Not sure If I can make this good with the tub in place or not yet.

any thought ideas or images of how its supposed to be would be a great help.

[AR4412]

Hi Chris,

That's some nice rot you have there, Mine wasn't as bad, but it was crusty and damaged, so it was renewed along with the rotten floor panel.

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I used mine as a template to get a copy made by a local tame engineering company. This company was then used by another forum member to have a batch of about twenty made for other interested forum members to purchase. Alas, illness and bereavements forced the business to close last year. Another forum member also had some made by a local company to him a few years ago. I cut out the rot and ali welded in fresh aluminium to repair the corrosion around the holes for the lower seatbelt bolts. The panel was fixed to the tub with a mixture of rivets and metal bonding epoxy.

A few pics of the one I had made for me so you can see how it should look.( Mine is for the FFR vehicle.).

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The extra angle strip you see atteched to the vertical face is where the tub floor mounts to it and was spot welded on by the engineering company. Unfortunately, in the pics you can't see where the ends of the panel are folded downwards to form the vertical side fixings points.

To repair, or replace the panel you will need to remove the tub for access so that you can drill out the pop rivets fitted from below, and tackle the thirty-odd spot welds along the front edge. I used a wallpaper/paint scraper and a hammer to split them.

The panel itself is an easy part to fabricate, with just two folds to make it's shape, and two 30mm deep downwards folds at the ends where it is spot welded to the tub's side panels. As yours isn't full length I did a quick measure of the important bits of mine for you.

The panel where it is folded down vertically and then rearwards to form the lower lip is 1500mm. The outer edge width where it is folded down at the ends is 1506mm. The other measurements of the horizontal and vertical widths you should be able to take from yours, but I can measure mine for you if needs be.

The brackets you have bolted the outrigger and the underside of the wheelbox are where the inertia reel bolts to.

Regards,

[AR4412]

A pic of it being fitted. Clamps are being used to hold it in place as the epoxy dries. The replacement for the rotten side panel has yet to be fitted in this pic.

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A pic of the two parts of the lower seatbelt bracket set up, orientated as they would be in situ.

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Regards,

[Megaweasel]

Thanks! - thats a big help! So i’ve moved forward slightly now and bought another tub. It has a good bulkhead (a few extra holes) and the cross member looks ‘ok’ - at least its there unlike mine! It might need a little fettling - one of the mounting holes is a bit ripped but otherwise, its ok.

I can see the two brackets, and reading one of the posts on here I saw mention of a spacer (346056) that goes between the lower bracket and the outrigger. Perhaps I’m being dim - but not having anything there to look at on mine as its all rotted out, I can quite figure how this goes together. Any clues how the lower bracket fits to the outrigger?

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Tub has rear of floor missing but at least floors are easy to find and i might be able to re-use mine. The supports look good too. I think given the rear is missing and it has yellow on it it was possibly used on an airfield with a winch?

Anyway - fun project ahead!

Cheers,

Chris

[AR4412]

There are two types of spacer under the tub.

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346056 is the top one in the picture, and fits inder the tub, on top of the chassis where the seatbelt stalk bolts through.
346221 is the lower one in the picture, and these are the ones that go under the tub where it bolts to the outriggers.

The number of shims you require depends on how many it takes to get the tub height aligned correctly. Mine had a different number of each type on each side when I dismantled it.

Regards,

[Megaweasel]

Thanks for that - getting a much clearer view of this now!

[Megaweasel]

been a long time, saving pennies but I'm now getting on restoring the replacement tub. It's going ok, except I'm confused about the floor panel. On the replacement tub I got, the rear of the floor had been cut away - I assume (given the yellow colour) to fit a winch directly to the chassis rails for glider recovery duty. Anyway - I got a replacement floor from YRM and it's the one with the longitudinal supports (top hats?) spot welded on. The top hats are joggled which I am assuming fit over the lip at the bulkhead end.

When I trial fit it it seems ok - except the rails it sit on seem to be about 5mm higher than the rear rail under the crossmember. It will bend down enough to rivet it across the rear but it will slop up at each edge - surely thats not how it's supposed to be?

here's a pic of the difference between the crossmember at the rear of the tub and the right-hand rail the floor sits on

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on my existing tub, the rear seems to have a 90 degree bend in it - but I've been looking through pic on the forum and plenty of tubs have floors that finish above the tailgate crossmember and are riveted. Can anyone tell me what its supposed to be like, and what is the right 'bodge' Should I just get a bit of Ali as a a spacer?

cheers

Chris

[AR4412]

The original floors are spot welded to the tub along the rear edge. When I rebuilt the tub on mine and put a new floor into it, it sat about 3mm above the rear cross rail. I ran a bead of two part epoxy resin bonder along it's length and clamped it down until it set. I did toy with the idea of fixing it down with countersunk rivets or screws, but it held okay with just being bonded in place. It might be woth a trial fit with a couple of bolts through rivet holes along the front and sides of yours to temporarily hold it in place, and see if the rear pulls down okay with clamps, and how much force is required to get it to touch. You can then decide if bonding or rivetting would be the best course to take for you tub.

Regards,