Rear sill rusty
 

On close inspection of the sill yesterday I noticed the rubberised coating bulging slightly on a newly acquired ZTT. I tapped it with the handle of my wire brush as I was cleaning the rear wheel arch at the time and it went through and perforated the paper thin metal to my horror. By the time I had pulled it all away, there was a hole big enough to put a fist through.
My own fault for buying it unseen as I couldn't travel after a recent stroke.
Can someone please remind me where the water comes from to rust the inside rear of the sill and how to stop it?
Thanks,
Adrian.

Rear sill rusty
 

You need a trip to derby to see tom Hobbs .


http://www.tjhobbs.com

Hi Adrian.
You will not be alone with this problem, all owners should be checking around the jacking pads/points for any bubbling which is the first sign of rust occurring under the protective seal in that area.

For some reason there are no drain hole before & aft of these jacking points, I am also convinced because of this fact the jacking pads do not help :shrug: I could be wrong.

Only last week I decided to do my usual yearly under body check, ie check the rear upper arms brake pipes etc, I noticed that around the rear jacking points a slight bubbling & tiny rust line.

I then poked the area with a blunt tool and to my big surprise around the jacking point it gave way, the same test last year I did and that sill area was solid so it shows just how quick the rust can eat through the metal, now due to the up coming nano meet I have crudely repaired the area with some new metal after cleaning back to bare metal and treating it.

This will give me time to decide before the next MOT January as to do I have the sills repaired properly or do I call it a day on the car.

It's a dirt trap in behind the liner. Mine was full of dirt & after cleaning it out, I found this :o https://i.imgur.com/aE4vhjRl.jpg
Cleaned it back to metal, undersealed & repainted. What I do every year is wash behind all the liners, remove jacking pads & spray Dinitrol inside all the cavities, including the drain holes.

I am convinced that the large cupped jack tops, as used by most garages, when used at the jacking points, actually lift around the reinforced section, distorting the metal and break the paint seal. Once the metal is exposed (either internally or externally) rusting is inevitable. I have had all four jacking points repaired with a larger and thicker sill section, supported by the inner reinforcing section. The inside of the sill is now coated (annually) with Bilt Hamner with added Waxoyl, applied using the 360 degree flexible lance which is supplied with the tin, via the drain holes and the holes in the ends of the sills (which have a rubber bung in them), accessible by removing the bottom of the arch liners. I use clear protectant for the doors, bonnet and boot cavities using the same principal.
https://i.imgur.com/GH4ni5J.jpg

Nottingham!

That's where I'm going tomorrow :bowdown:

You will be impressed!

I know, I've seen the repairs done Dawns white one, and it looks as good as new. I'm not worried about having black sills like Cowley cars, more interested in having good solid metal instead of crumbly rusty metal :D

Look forward to seeing the results at the nano Martyn 😀

Sent from my SM-G950F using Tapatalk

Hi Ron.
You were lucky there it had not eaten it's way through, were the under side parts ok where you jack the car up? sadly I was not so lucky :eek:

https://i.imgur.com/fLQrpSSl.jpg1

https://i.imgur.com/VaGcFzCl.jpg2

Corroded both sides at the rear.
https://i.imgur.com/7QysCjel.jpg3

My temporary fix for the Nano meet :( both out of one piece of metal, worked into shape
https://i.imgur.com/Rf0MTbql.jpg4



https://i.imgur.com/PnQZc9Gl.jpg

Ouch!!! That looks bad Steve:o Fortunately I caught mine before too much damage:cool: Noticed a few ginger bits in the paint & when I scraped back found just metal, hadn't got as bad as yours, dodged a bullet methinks:o

Same difference...

Bit like Sunderland & Newcastle :getmecoat:

Likely source ?
 

The question was raised as to the source of the water rotting the sill rear. I VERY much suspect the Chrome finisher strips running along the cars and especially over the rear wings.
When I bought one of my 75’s I found a considerable boot leak . Naturally , I first cleaned and treated / sealed the rear window grips ( see excellent How to by Rich) . Then I turned to the Finisher Strips and traced the source to the associated grips / holes. I forced the finishers away from the car bodywork ( actually used Costa Coffee wooden stirrers !) and then applied thick Silicone Sealant all behind the chrome strips . Killed the boot leak dead! Now I note that some of the finisher strip grips / holes lay directly above the when arches / Rear jack points. I have now repeated the Silicone down the entire car length behind the finishers. With regard to the :-
• Sills , I now have them thickly internally coated with Dinitrol Wax
• Jack points , I have lifted the rubbers , removed any rust on the plinth just above them , then applied rust converter , then Epoxy Mastic and , finally a thick layer of Dinitrol. Then , off course , replaced the rubber seal.
If a couple of finisher grip /holes can flood a boot think what they can do with water running down into a sill ?
Any observations welcome.

It's completely normal for water to enter the internal cavities of a car bodyshell (there are simply too many access points for manufacturers to be able to seal everything completely). Couple that to the condensation that will naturally occur on the inside of panels in the winter and you can see it's inevitable that damp will get inside and run to the bottom, due to gravity.

There has been plenty of discussion about why the rear sills on 75/ZT rot out and having completed quite extensive repairs previously on my Tourer, my own thoughts are as follows:

Firstly, there is a drain hole at the rear of the sill, so as long as this isn't blocked, water should eventually escape. However, just ahead of this is the internal jacking bracket. Surprisingly, this is welded to the vertical part of the inner sill, but NOT to the flat lower section of the outer sill. Here, it just rests against it. This leaves a very small gap between the two (the outer sill being far thinner metal), but it's enough space for the water to collect between the two panels and not dry out.

Secondly, if the jacking pads are not fitted, the remaining (quite large) hole that's left in the sill, will allow water and mud that's thrown up to collect inside the internal jacking bracket. Unfortunately, the edges of this are turned up to increase it's strength but this then means that anything that's wet and corrosive will collect inside and can't get out.

Lastly, the rear section of sill (unlike the front jacking point, although these are starting to go on older 75's nowadays) are connected directly to the rear quarter panel. Any moisture that collects inside this panel (from trim clips, condensation, etc.) and is over the front half of the rear wheelarch, HAS to run into the rear of the sill before it can escape out onto the road - hence the back section gets more than it's fair share of moisture to deal with.

Personally, I'm a fan of leaving the jacking pads fitted to keep the worst of the muck spray out, but leaving them out in the hot summer months to allow warmer air to circulate and dry things out as. There are also various holes where wax/oil can be inserted - behind the arch liner, on the inner sill and from behind the sill chrome strip, so any thin rust prevention fluid that'll squeeze itself under the jacking bracket has got to be good news if the sills are dried out properly first.

It's always a shame to hear of good cars possibly being scrapped just because this small area is starting to rust. Younger members of this forum will not be aware of corrosion in the 70's and 80's, when you could end up spending your weekends welding on complete length sills (not just 12" ;)) and continuing on to add rear wheelarches, spare wheel wells, door pillar bottoms, inner door frames and skins, front suspension top mounts, front panels and even footwells that had tin plate pop-riveted on to cover the holes !

Just ask Oxford Blue about a certain green Renault 12 estate... ;):getmecoat:

Hello Artic,
The jacking point is solid. I quickly checked as the car is jacked up currently with rear wheel off. It was caked in muck under the arch liner. I had removed the muck with a hose, wire brushed and rubbed down rust spots and put 3 coats of Hammerite on before I saw the sill. I was wire brushing the suspension when I noticed the sill.
The inner sill is solid so just going to cut metal patch to fit and Mig weld in. Just hoping I can match the paint as it is Posiedon flip paint.

Hello Trikey,
I have checked out Tom Hobbs website but no pictures of completed spray jobs. Does he only panel beat?
Adrian

The rubber pad was missing so I suspect some damage was from that. My other ZT/ZTTs are soaked in Dynax S50 using the lance to reach into box sections. Done annually. Haven't got round to doing this one yet. Only had it 4 weeks. Gradually working my way around. A lot to put right externally, mostly paint scratches and stone chips and a very rusty slam panel under bonnet. I suspect it has been stored or lived near the seaside. Certainly not loved as the door edges and hinges were filthy including B pillar and tailgate edges.
Will check the trim for leaks as you suggest.

Tom will paint sills and bits but not full resprays. He says a big cause of the corrosion is a foam pad in the sill. He removes it when doing the job. He charges £100 a side for sills like Arctics. My Cowley was worse and that was the price. She will be at the Nano Satvif anyone wants a peek!

Hello Roverbarmy,
I usually use Dynax on my box sections but I have only had this ZTT 4 weeks and not had chance yet doing other things to it. It is good stuff. I have just ordered 2 cans to do it.

Why do you add Waxoyl to Dynax?

Adrian

That’s a great price. I was chatting to someone last night who told me about a member who has fitted mirrors underneath the chassis to make it easier to look out for dirt and rust behind the sills and wheel arches.

All done, not had a close look at the repair yet but I'm sure it's as good as new.
I've now got to paint the other will to match my Cowley look alike sill:p:

You can have a look at the work on Saturday Scott, Dawn is also supposed to be coming.

I hope she is I've got her bumper in the garden !

Yep me and Shaz should be there 10.30-11.00. ☺ Hoping Steve can help with my droplinks after a failed attempt already lol!

Could use it as a planter :D:getmecoat::duh:

Dawn.
We will have them off your car and you news ones on before you leave ;) I will have a look at your sills then I have seen the photo's but real life is better

Thanks so much Steve. ☺ You wont see where Tom did the sills. Ive slapped waxoyl along the bottom edge and inside but other than that it looks original. He does a fab job.

I took my '51' tourer in for some welding around the N/S rear jack point and have since discovered that it's more extensive than thought and that the O/S JP is also badly affected. Looks like £700+ worth of repair work coming my way to get it all fixed. My garage also advised me not to replace the jacking pads as they have excerbated the problem. Good job I really like my car and intend keeping it!

If it was me I would have a drive down to Nottingham and talk to Tom Hobbs.
He repaired my off side rear sill for £100 and made a superb job. Unfortunately I can't attach the photographs of the repair.

Also did a great job on my nearside rear sill, the only thing was the jacking pad is very loose and won't stay in. So I've stuck it in with butyl gutter sealant so should be easy to remove and clean up when required.
As Tom doesn't really do paint I've gone for black sills like Cowley cars, now got to paint the other side to match. I've asked Tom for photos but not got them yet, will give him a few days and ask him again.

Richards Body shop in Newtown did my rear offside sill and wheel arch, you would not even know that it had been repaired, looks as good as new, cut out a section as big as a hockey stick then phoned me to say the inner sill had gone as well, all fixed, brilliant job. There are some really good tradesmen out there. He specialises in Porches and rally cars.

Go and see tom and save yourself a load of money!!

I agree!
Too short a message??? Is that long enough??

Hi David.
Here are your photo's below ;) Arctic.

David.
These are the other photo's from your visit to Tom, he as done a quality job I am sure he is going to be a very bust chap over the coming months from members finding out the same problem.

Check those sills before the winter salt is thrown down :eek: the last photo is of my jack point for comparison

Thanks Steve.
You will have to explain to me where I was going wrong when I tried to post the photographs.
I hope he is not going to be too busy as I would like him to restore my 1968 MG Midget bodyshell.
Regards David

I'm off to Tom today to pick up my car and by the looks of the photos he's sent it is a fantastic job.

That looks great work, good that he provides photos too. Did he paint it as well? Thought he only did black.
(Anyone tried asking Tom to join the forum? He seems to be saving a lot of 75’s)

When he replaced my sill he said he did not do paintwork and that the repair would be finished in black. However he just happened to have a can of silver paint so he painted mine as well. Tom is a really nice bloke and his dad is a canny bloke as well.

I'm sure he'll do your MG - but he told me that full restos take time, and he usually doesn't get paid until the end, so he enjoys fitting in our 75's as it gives him pocket money in between! I think he will paint the sills the colour of the car if you get the paint mixed yourself and take it along. my V6 will need doing next year I think, and that is my plan. :)

Arctic, my sills were in worse condition than that and I also had a nasty dent, which as it turns out, had made the problem a lot worse on one side, taken out. The shop I've taken the car to does both metalwork and painting and while certainly more expensive, is highly trustworthy. He's also fairly local, which is easier for me. Thanks anyway to you both!

I remember rust well,, I ran a few alfa suds in my time. One time when jacking the car, the sill just crumbled and the jack went right into the car between the door and sill.

I took my FL 2 for it's mot at 11.30 am today passed again no advisories :D nine in a row now and no advisories well chuffed.

I did mention the MGZT and how the sill had corrosion round the jacking point, he did no seem concerned, then went on to state because it is not in an area classed as dangerous ie the suspension, seat anchor area & so on he said it would not be a fail.

This is what greeted me a few weeks back when I cut off the outer sill of my MGB. I have just finished the welding- complete floor pan edge, sill floor (castle) rail, inner sill , outer sill, central cross member end, and rear wheel arch front section all repaired or replaced. I have now got to start on the other side ! The car looked clean and solid from the outside apart from a few rust bubbles starting to come through at the end of the NS sill.
I have painted all of the inner surfaces with Bondaprimer and chassis paint, and when the painting is finished, I will blast Dinitrol 3125 into all the enclosed sill sections.

Pete

Afternoon,
It is interesting to note that one MOT inspector has a different view to another as my 75 failed the MOT on the corroded sill. Never mind it needed to be repaired.

Hi David.
Yes I was quite surprised when he stated it to me, and he a MOT tester that is thorough, he also lets you stand next to the car while he is testing it, there is a viewing lane in which you stand behind a barrier.

I think I will still take it down to the garage where he tests and get him to have a look in real life, see if his mind changes ;)

Another happy customer
 

Of: http://www.tjhobbs.com

Saw Tom on Monday after reading about him here and having been told about him by Phil (thanks).

He is a really nice guy (as his dad who was also around) and did a fabulous job rebuilding the rear end of the drivers side sill which had corroded.

Highly recommended!

I can only fully endorse your comments regarding Tom's work, had my nearside will jacking point repaired by him. Excellent job done and totally recommended.

Martyn

Quick update on this took car to MOT station one look at it and decided yes it would be a fail with the plates as they are pop riveted.

The repair as to be a continuous weld, for it to pass a MOT.

I reckon it is in the manufacture and design. My tourer has never been used in winter, sits in the garage from November till end of March. Hole in the sill on one side discovered at MOT a few weeks ago, other side solid. Same sill, same place seems to be a theme. Almost new when I bought it, only used for pleasure in nice weather. Chap who welded it said the inside of the sills have a good coat of Waxoil, so if it is going to go it is going to go.

Our cars are getting old so rot is to be expected. My 82 Cavalier had half rotted away by ten years old. I think as a whole our cars are doing well and Tom Hobbs is cheap enough to get a repair rather than scrap. ☺

Dawn
Yes it is worth the £100 each side, but if you have to add that to other jobs such as belts, back plates, upper arms, fuel tank straps, A/C compressor, re-gas, you are looking at least £1000 + add some labour to that if you can not do the jobs your self then it becomes expensive for a car that is only used about 3/4 months of year spread out over that year.

Its all about what you use it for and what you can afford. I just meant that rot-wise they're not too expensive to fix compared to some cars. ☺

So are some of the owners :smiley:

I agree with you both :icon_lol: change is as good as a rest :laugh:

Small change is as good as a rust! :icon_lol:

Do you think mud guards would help stop muck getting into the wheel arch liner? Would they be a slight help to the rear sills?

Not really as a rear mudguard fits to the bumper, which is plastic:shrug::}

Bearing in mind that all Rover 75s seem to rust at the rear jacking sills, and that they are a complex shape, is there anybody that makes replacement panels ?

I would guess that most of the forum members would happily buy replacement panels to make their prized cars last a few years more.

There was someone on eBay selling galvanised sill panels! (That would be a joy for the person welding them)

If possible, get in touch with Tom hobbs, he makes replacement sections and fits them at a very reasonable price.

I’m a keeper and recently spent £800 doing both sills (extensively rusted) and a good paint job thereafter. I will have it undersealed soon too. The sills are the weakest point for rust but after 18 years on the road, I can’t complain too much.