1998 90 SW - rear tub to chassis corrosion (repair options?) + sill to tub fixings

[Northwards]

Hi folks,

Hoping for a bit of bodywork help on a 90 - for someone who's never owned one. 

This is the current project: a friend's 1998 300Tdi. Mainly a bulkhead swap, but of course there's always mission creep. I've done two bulkhead swaps in the past, but they were both on 110's. A 90 is new territory..

 

My current questions relate to where the front of the rear tub mounts onto the chassis via brackets, and where the seatbelt brackets to to. This panel here:

 

It's not just so bad where the seatbelt brackets go, but as you can see, the chassis outrigger to tub bracket location has gone the way of all steel/alu/steel sandwiches. It's the same on the other side behind the fuel tank.

As I say, I'm not so familiar with a 90 so I've looked at the YRM site and found this: https://yrmit.co.uk/product/vertical-front-of-rear-tub-replacement-lr-defender/  This looks like the right thing, and a pretty close match in the sense that it has what looks like all the correct holes, but a) the one on the car has at least a couple of angular/triangular braces at the rear of this panel, between it and the rear floor, b) I think it might be spot welded to the side of the tub, and c) It also looks like the original one is attached to the floor by 'Huck' rivets, and I know from experience these are a real pain in the **** to remove.

Have I linked to the right part, and has anyone fitted one? Would I just ignore the bracing on the OEM one?? Or, try and leave it in place and bond/pop rivet them together? 

Until I'd seen that a replacement panel was available, we were just thinking of getting a piece of flat alu. plate and bonding/riveting that onto the forward face of the panel. It would throw the seatbelt mountings forward by the thickness of the repair panel, maybe 2 or 3 mm, but it would avoid having to remove the thing altogether. So any words of advice very welcome. 

I see that YRM also do a replacement for the horizontal section in the pic below. In our case this isn't 'dreadful', so I'd pondered the same as above, bonding/rivetting in a second aluminium panel on top of what's here. As far as I can see this wouldn't affect or misalign anything else. Has anyone fitted this part https://yrmit.co.uk/product/horizontal-front-of-rear-tub-replacement-lr-defender/ and is it OK or a bit of a nightmare? 

 

 

Two final quick questions.

Is this meant to be an exhaust mount? Always used? There is an anchor point at the rear of the silencer, but looks like there's never been a connection to the chassis.... 

And finally.... where the side/floor sill attaches to the bottom of the B pillar. As you can see there was a bit of corrosion here. I have put a small piece of alu. in behind this, intended to give the MOT man a bit of comfort that there's some kind of structure, but the main question is -does this rearward fixing for the sill, a hefty bit of steel, just mount straight onto the alu. B pillar?? It seems odd that there's a pretty substantial chassis outrigger not too far away which could be used as an anchor point, but that the sill is just into alu. ?

 

Thanks very much. 

[Northwards]

Hmmm. 

I've probably answered one of my own questions by exploring a bit further on the YRM site.

I found this: https://yrmit.co.uk/product/rear-tub-vertical-to-floor-support-end-lr-defender-90-110-van-series-88-109-van/

And associated with it, a picture showing the underneath of the tub

The braces I was talking about are 428 and 429. 

So it's all available I suppose, but what sort of job are we talking about? It gets to the stage where you'd almost think of taking the tub off entirely, though I'm completely sure that would just throw up other problems that would need to be dealt with.... 

Aarrgh!

[Stellaghost]

One thing for sure those braces will be more easily dealt with with the tub removed, sure that will probably result in other work to do, but if the tub is off you will get sorted with everything quicker and not have to revisit in a few months to do stuff you wished you had done initially, belts and braces will save you grief in the long run I would think

I've had to do a massive amount of work on my tub in my mog axle thread as it was way worse than I thought but on the upside I probably won't have to do it ever again regards Stephen

[Northwards]

Hi Stephen, 

Thanks for that. As soon as I posted the last bit, I googled "How to remove a rear tub from a Defender 90" and a thread on here popped up at the top of the list.

Someone summarised it as:

"10 bolts across the rear x member, 4 bolts on the chassis outriggers at the front, 4 bolts into the cill uprights, 9 m6's across the top of the seat box, 2 bolts on the seat belt brackets, disconnect electics, fuel filler, seat belt, outer cills and it should pop off."

Given that we've already done some of them, there really isn't that much left...

"10 bolts across the rear x member, 4 bolts on the chassis outriggers at the front, 4 bolts into the cill uprights, 9 m6's across the top of the seat box, 2 bolts on the seat belt brackets, disconnect electics, fuel filler, seat belt, outer cills and it should pop off."

I think one of my problems will be convincing my friend that this is the best option. There's mission creep, and there's mission creep! On the other hand, I know the car was originally bought from Peterhead, and who knows how much salt water and air it was exposed to there. 

I would put good money on the X member bolts being a pain to remove and probably require more repair panels to boost YRM's profits but I'd hate to walk away from a job that wasn't done right. 

[Stellaghost]

4 minutes ago, Northwards said:

 

I think one of my problems will be convincing my friend that this is the best option

I get that, you just need to emphasise that what your doing now will all have to be done again in the not too distant future if shortcuts are taken, also who knows the future you might not have the spare time when he needs it done again, doing it now is the right thing to do, once tub is off your looking at hours as appose to days amounts of work, so much easier and quicker with full access to bottom of tub

Regards Stephen

[Northwards]

^^ We have discussed those points - do it now to save time in the long run. The other advantage to a tub removal is that I would be able to take it back to my own garage, with all my own tools. 

However, the plot thickens... I have done even more wandering about the YRM site and found these 

They would allow a repair with the tub in-situ, just a little clamping, drilling and bolting. I'm a little put off that they are galved steel. It's obviously a whole lot better than mild steel, but still, it's steel being mounted to aluminium, underneath a car. I think I'd probably slather it in 'japlac' or something, or even make up full length PVC gaskets to keep the metals apart. I have to say it is tempting. 

And they do these, which would allow for a  much better repair of the striker plate, but still leave me looking for a 'datum' for the sill hanging brackets.

I'm not entirely sure how easy it would be to fit these, and as I say the car is 20 miles away, not just out the back. 

By the way this wasn't intended to be a big advert for YRM - hope I'm not breaking any rules -but they do seem to offer precisely the things I'm looking for.

Anyone on here used these panels at all??

[Bowie69]

YRM make excellent stuff in general, but I've not used those specific panels myself.

[Northwards]

Absolutely. I’ve used a lot over the years on my own 110, and even on this 90 we’ve gone for their battery box, galved sills, galved cappings, and so on. So my questions really aren’t related to the quality of their stuff, more about working/repairing these specific panels. 

[Snagger]

You could bond those steel panels to the existing panel and the glue would serve both as bonding and as isolation, as long as you use plenty of it.  A reasonable number of mechanical fixings would guarantee its integrity.  
 

The seat belt lower anchors do just bolt to the bracket on the back of the sill (one bolt) and vertically through the sill itself (two bolts).  It’s surprising how little the cage nuts that fit those square holes overlap the bracket itself - you’d think they run the risk of pulling through, but they can’t.

[cackshifter]

I have used the steel repair panels and they certainly seem to do the job. They are a very neat fit, there are pieces to fit inside above as well and those needed the merest of trimming, otherwise everything fitted like a new jigsaw. I painted it all before fitting and put sealer on the old aluminium having cleaned it up and primed so that water 'couldn't' get in under the steel part. I put some delrin sheet between the brackets on the tubular outriggers and the new parts. They have been in use now about 4 years and when I last looked didn't look much different to when I fixed them in, just muddier. If you don't have all the seatbelts (eg you may have a cubby) you may need bolts to block the holes for the 3rd set's belt. Although it is a 300tdi, the tank on mine is at the rear in the TD5/Puma position so I had no issues with access - not sure if the tank under the driver's seat would get in the way.

I had previously put a new floor in using all YRM bits without removing the tub. It's obviously easier if you can remove the tub, but perfectly possible without. There is a tutorial on doing it on YRM's site. The only extra thing I did apart from painting thoroughly was to insulate between floor supports and crossmembers with helicopter tape.

[Northwards]

1 hour ago, Snagger said:

You could bond those steel panels to the existing panel and the glue would serve both as bonding and as isolation, as long as you use plenty of it.  A reasonable number of mechanical fixings would guarantee its integrity.  
 

The seat belt lower anchors do just bolt to the bracket on the back of the sill (one bolt) and vertically through the sill itself (two bolts).  It’s surprising how little the cage nuts that fit those square holes overlap the bracket itself - you’d think they run the risk of pulling through, but they can’t.

Thanks Snagger, I think the kit 'option' is a set of 48 bolts/nuts - and even to someone like me who's prone to over-engineer a solution, that struck me as a "reasonable number of mechanical fixings"!

5 minutes ago, cackshifter said:

I have used the steel repair panels and they certainly seem to do the job. They are a very neat fit, there are pieces to fit inside above as well and those needed the merest of trimming, otherwise everything fitted like a new jigsaw. I painted it all before fitting and put sealer on the old aluminium having cleaned it up and primed so that water 'couldn't' get in under the steel part. I put some delrin sheet between the brackets on the tubular outriggers and the new parts. They have been in use now about 4 years and when I last looked didn't look much different to when I fixed them in, just muddier. If you don't have all the seatbelts (eg you may have a cubby) you may need bolts to block the holes for the 3rd set's belt. Although it is a 300tdi, the tank on mine is at the rear in the TD5/Puma position so I had no issues with access - not sure if the tank under the driver's seat would get in the way.

I had previously put a new floor in using all YRM bits without removing the tub. It's obviously easier if you can remove the tub, but perfectly possible without. There is a tutorial on doing it on YRM's site. The only extra thing I did apart from painting thoroughly was to insulate between floor supports and crossmembers with helicopter tape.

Thanks very much for that - getting a first hand opinion is appreciated. I definitely would be cleaning/painting/bonding it all, and I've found that some 'PVC' kitchen chopping boards are just the thing for making separating gaskets! They're even colour coded! We will need to take the fuel tank out to get access. A bit of a pain, but unavoidable. 

I did the floor on my 110 using the YRM kit - not "easy" but that was nothing to do with the kit. 

For me I think the question's answered now. If it was my car, and I was doing a "proper" restoration I'd have the tub off and try and make it as original as possible, but time and circumstances mean that some compromise is needed here, and functionally it sounds like there's no real downside as long as the steel and aluminium are kept apart. 

Would still be good to hear from anyone who might have used the striker panel repairs... but I guess I'll figure that out if I have to. 

[Snagger]

Those repair panels will be mostly cosmetic, but they will help rigidity if rivets are used through the ledge of the tub “shelf”.

[Retroanaconda]

Regards your question on the steel sill member/channel - yes it does just bolt to the bottom of the tub pillar. It only carries the floor and seatbox on a 90. And yes that exhaust mount is often unused, depending on age of vehicle and type of exhaust fitted.

I have used the galv steel repair/reinforcement panels on mine, there are some photos in my rebuild thread in the members vehicles forum. They are an excellent solution.

[Northwards]

^^ Thanks Retro - found those pics in your thread and they just confirm the decision to use those repair panels. Your tub looks like it was actually in better shape than the one I’m working on, but it was a good point about letting in repair ‘spacer’ sections instead of the crumbled aluminium, to make up the thickness.

Also, I’d realised that the repair panel would replace the outrigger to inertia reel bracket, but I hadn’t quite twigged that they could replace the seatbelt latch brackets too - which is a good job as ours aren’t great, and galved replacements aren’t available. But I will need to find the replacement seatbelt latches on the rear bendy stalks.

On the question of the sill to tub mounting then, is there any ‘datum’ point to use? The holes in the original striker panel are so corroded as to be useless and no guide at all. The seatbox itself is off so I can’t use that, and even if it hadn’t moved I’ve replaced the corroded battery box with another YRM part. I could just leave these till nearer the end and then have more material around them to provide some guidance, but if there are some reference points that would be handy.

[Stellaghost]

23 hours ago, Northwards said:

 to someone like me who's prone to over-engineer a solution

Yaaaay a kindred spirit..........

Regards Stephen

[Northwards]

1 hour ago, Stellaghost said:

Yaaaay a kindred spirit..........

Regards Stephen

A kindred 'spirit' perhaps - but I've no doubt there would then be a huge gulf between our abilities to put those solutions into practice! I tinker (and bodge) it looks like you'll have forgotten more than I'll ever know.

Still, as long as it stays in one piece and keeps the MOT man happy....🤠

[Northwards]

I thought I'd bring this one back to life again... 

I'm happy with the galv steel lower rear tub repair bracket now. I popped it into place last weekend, drilled all the holes in the tub, and then took the repair brackets home and painted them in Buzzweld 'Galv in one' to give it some further protection down there. Meanwhile I'm hoping my pal will have brushed down, etch primed and painted the original alu. so that we can get the repair panel fitted this weekend (properly isolated from the alu.).

Thoughts are now turning to the striker panel repair. I put the pic in up above, but these guys:

As you'll all know, they go here: 

Because the car's about 30 miles away (and mine's a 110) I can't just nip out to check, but I'm trying to figure out how to handle this. I have welded in the 'dim and distant' but I don't have a welder, so that's one thing, I'm also not sure if that panel is single or double skin (ignore the wee thing at the very bottom suggesting a double skin - that's a little panel I pop riveted in, and is gone now).

Looking at Ianmayco's rebuild thread here: 

seems to show that it's a double skin. There was a second panel left once he pulled off the front facing one. I can also remember that there are some spot-welds involved onto the outside skin - but what I can't remember is whether they are into the striker panel or potentially the second layer behind it. I obviously don't want to drill them from the outside - just make a mess, and more work for myself. I guess I might be able to cut them between the panels if needed?? 

So, how would you guys tackle this? If I can't get that first panel off, I'd wondered about just leaving it in place, and cutting a space/hole in the repair panel for the door latching bar/plate? Then bonding/pop-riveting the repair panel into place. That feels a bit 'bodgy' and I'd prefer to remove it to fit the repair panel in place intact. My concern then is how to make good the little lip that sits alongside the door seal flange on the outer skin. I probably haven't explained that too well? I think I know what I'm trying to describe, but not sure I'm managing.

I'm hoping to get this done this weekend so that we can get the seatbox back in and start speeding up the rebuild. 

As always, any insights and advice greatly received. 

[Snagger]

The panel doesn’t look to be significantly compromised, just a bit of cosmetic corrosion at its bottom.  That means that it would be structurally sound to remove the flange on the new panel and bond it over the original as a finishing piece.  Like you say, not ideal, but without a spot welding tool, you’d have real problems getting a decent appearance doing a full panel replacement.  The new top panel would provide additional strength, too, if proper preparation is done and an automotive panel bond used.  Even a good quality PU adhesive will stick it strongly enough to significantly enhance strength.

[Northwards]

Thanks very much for that.

I think, because of the thin "patches" I'd rivetted in place behind it, the current panel looks better in the photo than in real life. It's a lot more than cosmetic corrosion, but at least it is still there. 

As you say, above the line of the seatbox there's no issue at all with it - it's essentially intact. The problem is all lower down where the sills bolt into place - good old electrolytic corrosion again. There's currently no strength at all in the remaining metal here - on both sides.

Very good to get an experience second opinion that removing the lip from the repair panel and bonding/rivetting it into place would be a valid way forward. That's my weekend sorted!

 

[Snagger]

That area of aluminium doesn’t need a lot of strength.  The tub is held to the chassis outrigger by the vertical flange under the shelf (rotted away on the red tub in the photos), and steel brackets hold the seat belt inertia reel to the same chassis outrigger and reinforce the tub mounting..  Depending on the age of the age of the vehicle, the lower anchor for the seat belt is either incorporated in the inertia reel bracket (late type) or is on a triangular bracket the bolts to the front of the seat base corner through the corroded area you are worried about, but there are no significant loads on that part of the tub - the forces of the seat belt go through the sill and the 90 degree upright immediately behind the tub B-pillar section you are working on.  It is sandwiched there but doesn’t carry any significant load.

If you want peace of mind, you could cut out the rotten areas, bond in the repair panels to the front of the B pillars, then add aluminium rectangles behind to fill the void left by the cut away rot.  You could do that with aluminium plate bent through 90 degrees to attach to the underside of the tub shelf and the back of the new B pillar panel with panel bins, PU or rivets, and once all cured, drill the bolt holes for the sill and seat belt anchor.