Where do these bolts go onto, and what do I need to replace them

Discodevon · Jul 30, 2022

Hello everybody, on a mission with the landy again, I’ve been renewing some of the rusty bolts with stainless steel to make my old defender look a bit more presentable, also with the intention that before my lovely mechanic retires in the next decade he would be swapping my chassis for a galvanised one so would make it easier for him if all the bolts will come out with less effort, anyway where do these go? It looks as if they go into a chassis mount or something with some weird captive clips, I would ideally like to replace as they look ugly here is a picture

Hicap phill · Jul 30, 2022

They bolt into the sill upright.

300bhp/ton · Jul 31, 2022

Be careful swapping all the bolts. Stainless are not very strong. You shouldn’t replace high tensile bolts with stainless really.

As for a chassis swap. Most of the bolts you can see you will not touch when swapping the chassis. And the ones that do hold it all together most certainly should be of the correct tensile strength.

Dippypud · Jul 31, 2022

Discodevon said:
Hello everybody, on a mission with the landy again, I’ve been renewing some of the rusty bolts with stainless steel to make my old defender look a bit more presentable, also with the intention that before my lovely mechanic retires in the next decade he would be swapping my chassis for a galvanised one so would make it easier for him if all the bolts will come out with less effort, anyway where do these go? It looks as if they go into a chassis mount or something with some weird captive clips, I would ideally like to replace as they look ugly here is a picture

Nowt wrong with them ...

Discodevon · Jul 31, 2022

300bhp/ton said:
Be careful swapping all the bolts. Stainless are not very strong. You shouldn’t replace high tensile bolts with stainless really.

As for a chassis swap. Most of the bolts you can see you will not touch when swapping the chassis. And the ones that do hold it all together most certainly should be of the correct tensile strength.

Thank you, I’ve used yrm for most of the fixings which seem to use the correct tensile, but for some I’ve just used stainless nut and bolts from a assorted kit I got

Discodevon · Jul 31, 2022

Dippypud said:
Nowt wrong with them ...

It was kind of good I checked where they go as there is a pretty big mud trap up there which I blatantly missed when spending hours cleaning my underside a couple of weeks back

Discodevon · Aug 1, 2022

Well I managed to drill them out, the captive nuts were rusted to hell so just kept spinning, someone in our local fasteners shop recommended cobalt drill bits it made life so much easier

Al2O3 · Aug 1, 2022

Discodevon said:
Well I managed to drill them out, the captive nuts were rusted to hell so just kept spinning, someone in our local fasteners shop recommended cobalt drill bits it made life so much easier View attachment 270643

Those bolts fasten the bottom, front corners of the tub to the tubular outrigger, under the behind seat bulkhead. It's one of the first places to start rotting. Yours looks immaculate

It's a good indication that the rest of your Defender is in great condition. What year is it? If it's as good as that seat box end indicates, then I'd be giving it a good clean underneath once a year, followed by a dinitrol treatment on the key rot areas, including through the chassis rails and up through the main bulkhead cavities. That way you probably won't need to do a galv chassis swap. Mine was too far gone when I bought it. Yours looks maintainable

miktdish · Aug 2, 2022

Those A2-70 bolts you have used are about 12% lower tensile strength and about 30% lower shear strength than 8.8 steel.
I think the originals were 10.9 steel so you have essentially repaced the original fasteners with something that is probably less than half it's strength.
Being stainless it will also 'react' with the alluminium and rot it away.

Use either nickel plated or (better still) spun galvanised HT bolts.

A4-80 is close to an 8.8 HT steel and (if you insist on using stainless to fasten alluminium) would be a much better bet than A2-70

Discodevon · Aug 2, 2022

Al2O3 said:
Those bolts fasten the bottom, front corners of the tub to the tubular outrigger, under the behind seat bulkhead. It's one of the first places to start rotting. Yours looks immaculate It's a good indication that the rest of your Defender is in great condition. What year is it? If it's as good as that seat box end indicates, then I'd be giving it a good clean underneath once a year, followed by a dinitrol treatment on the key rot areas, including through the chassis rails and up through the main bulkhead cavities. That way you probably won't need to do a galv chassis swap. Mine was too far gone when I bought it. Yours looks maintainable

Thank you it is a 2005 in pretty good nick really even underneath

Discodevon · Aug 2, 2022

Th

miktdish said:
Those A2-70 bolts you have used are about 12% lower tensile strength and about 30% lower shear strength than 8.8 steel.
I think the originals were 10.9 steel so you have essentially repaced the original fasteners with something that is probably less than half it's strength.
Being stainless it will also 'react' with the alluminium and rot it away.

Use either nickel plated or (better still) spun galvanised HT bolts.

A4-80 is close to an 8.8 HT steel and (if you insist on using stainless to fasten alluminium) would be a much better bet than A2-70

Thanks for the heads up with that! The last bolts said 8.8 on the head but they were 10mm with an awful captive nut, I put in 13mm bolts and a bigger captive nut and loads of grease behind the washer and in the fixings would it not be strong enough then or should I replace?

miktdish · Aug 2, 2022

If the head of the bolt was 10mm, then it is likely that it was an M6.
If the head is 13mm then it is likey an M8 - there are exceptions to this rule but they are unusual.

There are two forces in play with bolts. Compression/Tension (or clamping) where you are holding 2 things together and to get them apart you have to push them away from each other or shear where the applied force tries to make them slide apart.
Stainless steel (specifically A2) is pretty soft (in the scheme of things) and tears, to test this clamp a bolt in a vice and wind a nut on, keep going and you will twist the head off the bolt. Try the same with a steel nut and bolt.

Use a stainless bolt to hold you brake calipers on and the fist dab of the brakes, the system will fail ..... put a stainless bolt in to hold the seatbelt on, the first sudden stop you come to will be your last ... use a stainless bolt to hold the front grill on and it will look pretty for a long time

Discodevon · Aug 6, 2022

miktdish said:
If the head of the bolt was 10mm, then it is likely that it was an M6.
If the head is 13mm then it is likey an M8 - there are exceptions to this rule but they are unusual.

There are two forces in play with bolts. Compression/Tension (or clamping) where you are holding 2 things together and to get them apart you have to push them away from each other or shear where the applied force tries to make them slide apart.
Stainless steel (specifically A2) is pretty soft (in the scheme of things) and tears, to test this clamp a bolt in a vice and wind a nut on, keep going and you will twist the head off the bolt. Try the same with a steel nut and bolt.

Use a stainless bolt to hold you brake calipers on and the fist dab of the brakes, the system will fail ..... put a stainless bolt in to hold the seatbelt on, the first sudden stop you come to will be your last ... use a stainless bolt to hold the front grill on and it will look pretty for a long time

Thanks if it were you, would you be taking the bolts out and changing them then?

miktdish · Aug 6, 2022

Yes.
https://www.ebay.co.uk/itm/254965442754?hash=item3b5d1fe8c2:g:NmcAAOSwIV1gkAN2
In strength terms A4-80 is close to an 8.8 HT steel (if you insist on using stainless to fasten alluminium), and 13mm bolts (as you called them) offer greater strength than the smaller original.
https://www.ebay.co.uk/itm/372090349446?hash=item56a2502786:g:UwMAAOSwrlRZziCY

I would encouage you to use the right terminolgy ... M10 spanner fits an M6 bolt, M13 spanner fits an M13 bolt ... https://www.slsbearings.com/slsbnn/spanner.html
Lots of people are interested in your rebuild - keep sending in pics etc.

steve24v · Aug 6, 2022

I might be looking at the picture wrong but should there be an angled bracket for the seat belt to fix to?

Discodevon · Aug 6, 2022

miktdish said:
Yes.
https://www.ebay.co.uk/itm/254965442754?hash=item3b5d1fe8c2:g:NmcAAOSwIV1gkAN2
In strength terms A4-80 is close to an 8.8 HT steel (if you insist on using stainless to fasten alluminium), and 13mm bolts (as you called them) offer greater strength than the smaller original.
https://www.ebay.co.uk/itm/372090349446?hash=item56a2502786:g:UwMAAOSwrlRZziCY

I would encouage you to use the right terminolgy ... M10 spanner fits an M6 bolt, M13 spanner fits an M13 bolt ... https://www.slsbearings.com/slsbnn/spanner.html
Lots of people are interested in your rebuild - keep sending in pics etc.

Thanks I will get them ordered in tomorrow when I measure the length, Land Rover left far to many threads hanging out originally so that all went rusty, want to use shorter bolts this time if I can so hopefully if they need undoing in the future it will be a bit easier to do so

Discodevon · Aug 6, 2022

steve24v said:
I might be looking at the picture wrong but should there be an angled bracket for the seat belt to fix to?

I don’t think so? It’s an ex Raf td5 it hasn’t been messed about with at all by what my family mechanic says (who is nuts about Land rovers lol)

steve24v · Aug 6, 2022

Discodevon said:
I don’t think so? It’s an ex Raf td5 it hasn’t been messed about with at all by what my family mechanic says (who is nuts about Land rovers lol)

Maybe it was just the earlier ones had them. My 1988 did, like this

Discodevon · Aug 6, 2022

That’s awesome to see thank you, I think mine is a different configuration being 2005 but yours looks great nether the less

Discodevon · Aug 7, 2022

miktdish said:
Yes.
https://www.ebay.co.uk/itm/254965442754?hash=item3b5d1fe8c2:g:NmcAAOSwIV1gkAN2
In strength terms A4-80 is close to an 8.8 HT steel (if you insist on using stainless to fasten alluminium), and 13mm bolts (as you called them) offer greater strength than the smaller original.
https://www.ebay.co.uk/itm/372090349446?hash=item56a2502786:g:UwMAAOSwrlRZziCY

I would encouage you to use the right terminolgy ... M10 spanner fits an M6 bolt, M13 spanner fits an M13 bolt ... https://www.slsbearings.com/slsbnn/spanner.html
Lots of people are interested in your rebuild - keep sending in pics etc.

I have just ordered them bolts, also some nylon washers to go under the washers, I’ve got a kit but none were exactly the right size, was thinking of putting a small bit of shrink wrap on the bolt where it goes through the aluminium ( so it does not touch it directly)before the bracket do you think that will suffice? I fitted floor pan screws from yrm a few years ago they are A4 stainless, after what you said last week just fitted nylon washers under the stainless washers but can’t see any corrosion under them yet is that because I used a tonne of grease do you think?

Where do these bolts go onto, and what do I need to replace them

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