DIY Sills - what size box?

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mick 1986

mick 1986

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I have been looking at various threads from various sites about repairing sills on 90/110s. I have a feeling mine will be in quite poor state, and when I strip it to replace the bulkhead, I would like to investigate the sills too.

The problem I’m having is that I don’t really have the funds for a new pair at £1K each side, so would rather build my own from box section. The problem I’m having is what size should I use? I have seen sizes from 40 x 40 up to 60 x 80, with someone saying 65 x 80 would have been perfect for their repair.

What size is most commonly used? I can fabricate, and have access to very good welding facilities, so building them myself isn’t an issue, only what size to order?
 
mick 1986 said:
I have been looking at various threads from various sites about repairing sills on 90/110s. I have a feeling mine will be in quite poor state, and when I strip it to replace the bulkhead, I would like to investigate the sills too.

The problem I’m having is that I don’t really have the funds for a new pair at £1K each side, so would rather build my own from box section. The problem I’m having is what size should I use? I have seen sizes from 40 x 40 up to 60 x 80, with someone saying 65 x 80 would have been perfect for their repair.

What size is most commonly used? I can fabricate, and have access to very good welding facilities, so building them myself isn’t an issue, only what size to order?
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Can you not measure the existing Sills for an external size and then determine what gauge you want to use?
 
It all depends on the wall thickness of your box!!?you could get a 60x80 with 3 mm wall
And the 40x40 with a 6 mm wall is stronger!!
And weighs the same !! Personally what ever looks in proportion with the thickest wall you can get
 
Retroanaconda said:
YRM sell repair sections for them.
Click to expand...

I have seen the repair sections from them, first hand when I picked up my stainless bolts. The quality is excellent, but they will still end up rotting out due to the same design as the originals. Personally speaking, a welded tube should outlast any repair I can muster, shouldn’t it?
 
A box section will still rot, fair enough maybe not as fast.

If you’re concerned about corrosion then repair them and have them galvanised, that’s my plan for the ones on my 110.
 
Retroanaconda said:
A box section will still rot, fair enough maybe not as fast.

If you’re concerned about corrosion then repair them and have them galvanised, that’s my plan for the ones on my 110.
Click to expand...

My 110 is my only car, and daily driver, so can’t really afford to have it off the road for more than a weekend. I have access to my wife’s car, but she uses hers for work too, so restricted with that one.

I read one of your posts, I think it was yours on another forum (I have read so many recently) about removing and rebuilding the rear body back to the chassis in a weekend. That got me thinking that I should probably do mine and inspect the chassis and sills before I tackle the bulkhead. I hope I can do the bulkhead in a weekend.
 
I used 3mm 50 x 50 for mine, it's what I acquired extremely competitively .. ;)

Have a look at this post and a few more a few posts further on .. Rocksliders ...
 
mick 1986 said:
My 110 is my only car, and daily driver, so can’t really afford to have it off the road for more than a weekend. I have access to my wife’s car, but she uses hers for work too, so restricted with that one.

I read one of your posts, I think it was yours on another forum (I have read so many recently) about removing and rebuilding the rear body back to the chassis in a weekend. That got me thinking that I should probably do mine and inspect the chassis and sills before I tackle the bulkhead. I hope I can do the bulkhead in a weekend.
Click to expand...
What are you hoping to do to the bulkhead in a weekend?
 
Al2O3 said:
What are you hoping to do to the bulkhead in a weekend?
Click to expand...

I’m hoping to swap it out for the galvanised one I have just bought. I don’t have the space at the minute, but a farmer friend has an old barn I can use, it’s a question of when I can get it cleared enough to do the job.
 
Paul D said:
I used 3mm 50 x 50 for mine, it's what I acquired extremely competitively .. ;)

Have a look at this post and a few more a few posts further on .. Rocksliders ...
Click to expand...

Thanks for that reply. I will have a proper look through that thread today. Some of the photos appear to missing, but some are there.

Do you trust the 50 x 50 to be strong enough to jack the vehicle up? I use 40 x 40 x 2.5 a lot for building machine guards at work, and it’s very flexible over a 6’ length.
 
mick 1986 said:
These ones!
https://www.famousfour.co.uk/new_parts/partslist?veh=defender&sec=rpan&sub_sec=sills
Click to expand...

Right, when you said sills I was thinking, sills: https://www.famousfour.co.uk/new_parts/ff_part?part=21400 ouch! 1K!

I would buy the proper sills for £40-60 then make up the other bits. Speak to a metal fab shop and they will make you up the pieces all cut and bent and welded up for not a lot of money, it's all very well bodging in box sections and things but it never looks right.

If you were closer I would have them made for you using our fabrication shop we use, he is about to make me a custom, from scratch rear door with a new style lock and all sorts. I could always ask, I would need old bits or very serious measurements to get them done well, you can't use ACAD can you?

I reckon you would be looking at £200-250 for the 2 sides, I'd have them made in mild steel and galved or make them in Zintec and have them well painted.
 
Last edited:
mick 1986 said:
Thanks for that reply. I will have a proper look through that thread today. Some of the photos appear to missing, but some are there.

Do you trust the 50 x 50 to be strong enough to jack the vehicle up? I use 40 x 40 x 2.5 a lot for building machine guards at work, and it’s very flexible over a 6’ length.
Click to expand...

Jacking up the vehicle on the sills? I may be misunderstanding what "sills" are being discussed, but if we are talking about the Defender body sills then you should not be jacking from these. They are not designed for that, if you jack from the sill, apart from the fact I reckon it would collapse, you are then relying on the body to chassis mounting to transfer the lift through to the chassis and then lift all that is subsequently attached to the chassis. Let's face it, most of the body to chassis mountings will be badly corroded holes in aluminium that really are only fit to hold the body down to the chassis when they are new, let alone when they have deteriorated.
 
discomania said:
Jacking up the vehicle on the sills? I may be misunderstanding what "sills" are being discussed, but if we are talking about the Defender body sills then you should not be jacking from these. They are not designed for that, if you jack from the sill, apart from the fact I reckon it would collapse, you are then relying on the body to chassis mounting to transfer the lift through to the chassis and then lift all that is subsequently attached to the chassis. Let's face it, most of the body to chassis mountings will be badly corroded holes in aluminium that really are only fit to hold the body down to the chassis when they are new, let alone when they have deteriorated.
Click to expand...

I think we are talking about different things, or what I’m talking about isn’t a sill?

Hopefully I have attached a photo of a 90 being jacked up “on a home made sill”? If not, it’s on this website.
http://forum.difflock.com/viewtopic.php?t=33426&sid=f4d8cb1667173863e229de9460fa0ee1

Is that what is being used to jack the vehicle a sill? Is it connected at the bulkhead, and body/tub mount? Would it be connected to the B post on a 110 CSW? I probably should have established all these answers before making the thread.

Making the bits up isn’t a problem for me, thanks for the offer though, it’s appreciated.
 

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mick 1986 said:
I think we are talking about different things, or what I’m talking about isn’t a sill?

Hopefully I have attached a photo of a 90 being jacked up “on a home made sill”? If not, it’s on this website.
http://forum.difflock.com/viewtopic.php?t=33426&sid=f4d8cb1667173863e229de9460fa0ee1

Is that what is being used to jack the vehicle a sill? Is it connected at the bulkhead, and body/tub mount? Would it be connected to the B post on a 110 CSW? I probably should have established all these answers before making the thread.

Making the bits up isn’t a problem for me, thanks for the offer though, it’s appreciated.
Click to expand...

Ah those are called various things like, rocksliders, outer sills etc. these are a whole different beast to the body sills, these are additional to the original body make up of a Defender and are in place of the normal little aluminium trim piece that sits below the doors and covers the inner sill (the bit you posted the link too).

These rocksliders are held very solidly to the chassis and are very solid themselves indeed. I have a pair on my 90 (original aluminium sills were shot) and they are bolted to the front outrigger at the same point the bulkhead mounts and then a bracket towards the back of the chassis and a connection to the tubular outrigger.

I made mine up with quite neat box section, I wanted a low profile look but some protection and boy did they save me a couple of times, at a guess about 50mm box, 3mm wall, 5mm plates for bracket and had them hot dipped. I tapered them in at the arches so they end up sitting flush with the wing panels, I did this but cutting a small wedge piece out the steel, bending them and welding them back up.
 
mick 1986 said:
Thanks for that reply. I will have a proper look through that thread today. Some of the photos appear to missing, but some are there.

Do you trust the 50 x 50 to be strong enough to jack the vehicle up? I use 40 x 40 x 2.5 a lot for building machine guards at work, and it’s very flexible over a 6’ length.
Click to expand...

Yes, very much so .. we've done it, and dragged the 90 sideways from the treeslider/step bit too .. :) The only thing that flexed was the tubular chassis outrigger where the passenger seatbelt mounts from, it was rusted through, which we didn't realise ... see the video Rusty stuff ... ;)

The main thing is attaching them to the chassis. I used a tube to slot into the tube outrigger from the chassis, then a 6mm plate to the front where the bulkhead bolts to the sill/bodywork and two more 6mm thick 'tabs' bolted underneath to the existing sill. Not the flimsy sill covers, the square section sill proper.

One thing I also did was capped one end with a welded cap, stood the sill up then poured some engine oil into the tube and capped the other end .. hopefully means they won't rust from inside out .. :)
 
o_Oo_O
mick 1986 said:
I think we are talking about different things, or what I’m talking about isn’t a sill?

Hopefully I have attached a photo of a 90 being jacked up “on a home made sill”? If not, it’s on this website.
http://forum.difflock.com/viewtopic.php?t=33426&sid=f4d8cb1667173863e229de9460fa0ee1

Is that what is being used to jack the vehicle a sill? Is it connected at the bulkhead, and body/tub mount? Would it be connected to the B post on a 110 CSW? I probably should have established all these answers before making the thread.

Making the bits up isn’t a problem for me, thanks for the offer though, it’s appreciated.
Click to expand...
Nice "Safe" working practices going on there! o_O
 
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