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Oversills, What They Are And Why You Want To Avoid Them


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#31 miniyellowmini

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Posted 18 October 2014 - 04:45 PM

About to cut the remaining oversill off the nearside of my Mini :unsure: Done the offside 18 months ago, hopefully it'll be no worse than that one was!



#32 benm

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Posted 23 October 2014 - 09:01 PM

started to remove mine! :ohno:

 

 

received_10152789064320050_zpssqgjradn.j

received_10152789126965050_zpssqzteixm.j

 

 

hopefully the inner sill will be ok..

 

20141022_194230_zpsfx5o2sdv.jpg

 

poxy oversill botch job!



#33 Gadgets

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Posted 24 October 2014 - 06:57 AM

Horrible things, a quick short cut that creates a massive job resulting in lots of Minis being scrapped. Buyer beware!



#34 Carlos W

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Posted 24 October 2014 - 09:09 AM

It was only down to this forum that I didn't fit oversills to mine.

 

Thanks TMF



#35 RossKnight

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Posted 24 October 2014 - 10:30 AM

It was only down to this forum that I spent thousands of pounds, became an insomniac and drive around in a bouncy, loud, rusty car that likes to break a lot.

 

Thanks TMF

 

 

 

 

 

But honestly, if tmf wasn't around loads of people would have fitted oversills haha.



#36 Ben_O

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Posted 24 October 2014 - 11:29 AM

It was only down to this forum that I didn't fit oversills to mine.

 

Thanks TMF

I was going to say that if you did because the forum didn't exist, then i would have noticed and told you to change them but then i got to thinking........

 

.............. If TMF didn't exist, then i wouldn't even know you  >_<

 

So thanks TMF!



#37 finch661

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Posted 24 October 2014 - 12:40 PM

this is what oversills did to my motor

 

innersill3_zps3b03286c.jpg



#38 miniyellowmini

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Posted 24 October 2014 - 10:42 PM

About to cut the remaining oversill off the nearside of my Mini :unsure: Done the offside 18 months ago, hopefully it'll be no worse than that one was!

 

Well I removed the oversill. Massive bodge. :ohno:  Once I started cutting them off it became clear they were bolted on rather than welded along the length, bolt heads had been ground down slightly so they didn't protrude so much then filler slapped on top to hide what remained of the bolts heads. Then covered with a generous coating underseal.

 

Expected it to be bad as it's never looked right, but didn't expect it to be quite so bad as it was.

 

 

I now need to replace the doorstep, inner sill, A Panel, bottom of the rear quarter and the closing panel at the front of the rear arch and patch the bottom of the flitch panel. Partly down to the oversills, which had actually started rotting too but there must have been at least 3 tubs of filler under there as well!

 

Got the panels today, let the work begin!



#39 benm

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Posted 25 October 2014 - 01:26 PM

 

About to cut the remaining oversill off the nearside of my Mini :unsure: Done the offside 18 months ago, hopefully it'll be no worse than that one was!

 

Well I removed the oversill. Massive bodge. :ohno:  Once I started cutting them off it became clear they were bolted on rather than welded along the length, bolt heads had been ground down slightly so they didn't protrude so much then filler slapped on top to hide what remained of the bolts heads. Then covered with a generous coating underseal.

 

Expected it to be bad as it's never looked right, but didn't expect it to be quite so bad as it was.

 

 

I now need to replace the doorstep, inner sill, A Panel, bottom of the rear quarter and the closing panel at the front of the rear arch and patch the bottom of the flitch panel. Partly down to the oversills, which had actually started rotting too but there must have been at least 3 tubs of filler under there as well!

 

Got the panels today, let the work begin!

 

If you have chance, would you mind sending me a few pics of the work as you complete the various stages, itd be a massive help for me as im about to do the exact same thing! :)



#40 sonikk4

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Posted 26 October 2014 - 10:07 PM

 

 

About to cut the remaining oversill off the nearside of my Mini :unsure: Done the offside 18 months ago, hopefully it'll be no worse than that one was!

 

Well I removed the oversill. Massive bodge. :ohno:  Once I started cutting them off it became clear they were bolted on rather than welded along the length, bolt heads had been ground down slightly so they didn't protrude so much then filler slapped on top to hide what remained of the bolts heads. Then covered with a generous coating underseal.

 

Expected it to be bad as it's never looked right, but didn't expect it to be quite so bad as it was.

 

 

I now need to replace the doorstep, inner sill, A Panel, bottom of the rear quarter and the closing panel at the front of the rear arch and patch the bottom of the flitch panel. Partly down to the oversills, which had actually started rotting too but there must have been at least 3 tubs of filler under there as well!

 

Got the panels today, let the work begin!

 

If you have chance, would you mind sending me a few pics of the work as you complete the various stages, itd be a massive help for me as im about to do the exact same thing! :)

 

 

Have a look at this thread, it will cover everything you need to do

http://www.theminifo...s-mini-special/



#41 spiguy

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Posted 27 October 2014 - 01:52 PM

Oversills! Don’t fit them if you want your Mini to retain its originality, and you want to fetch more money when you come to sell it. However, whatever sills you fit, make sure you inject them with wax something like Dynax S 50. Apparently this stuff is used in steel cavities on oil rigs, so it should be good enough for your Mini.

 

In theory, an oversill should preserve the sills from corrosion better than the original vented sills. This is purely because an oversill will retain moisture longer than original vented sills. It’s a fact that when steel is repeatedly exposed to water, and then allowed to dry, this speeds up the corrosion. If steel is immersed in water, and not allowed to dry, then the corrosion is reduced by a considerable amount. I carried out a test quite some time ago using a couple off-cuts of seam trim from my Mini.

 

Before carrying out the test, both pieces of steel was first cleaned with brake cleaner to ensure both pieces had nothing to protect the steel. One piece was placed in a container, and immersed in approx ½” of water, and the other piece placed next to the container (not in water, but exposed to weather in August 2012).

 

So if an oversill retains moisture, it will probably last longer than a vented sill. Personally, I believe a lot of the corrosion discovered beneath an oversill was there before the sill was welded on, and not necessarily caused by the oversill it self, but there because someone wanted a quick fix and couldn’t be bothered to fix things properly.

 

I personally fitted oversills to my Mini, simply because I’m not particularly bothered about originality or resale value. Providing the sill is welded at the lower point approximately 5” down from the sill seam lip, then the original strength should be retained. I believe a non vented sill (oversill) adds strength to the structure because it has metal throughout the length of the sill, as opposed to the original sill with vents.

 

So, in my opinion, if you want to retain originality and or resale value, then fit the original vented sill. If you’re not bothered either way, then I don’t see a problem with oversills, providing you weld approx 5” down from the sill seam lip. If like me, you intend to use your Mini on stage rallies, and it’s strength you’re after, then fit the full 9” sill, and weld along the bottom as well as 5” down instead of cutting it off. Don’t forget to add a few drain holes at the bottom of the sill to allow condensation to drain, you don’t want to carry around unnecessary weight.

 

I guess, if vented sills were a good idea, then I would expect modern cars to have them, but they don’t.

 

Anyway, we are all entitled to have an opinion, so I thought I would add mine :-)

 

 

It's an interesting point you make. I suspect that in your test, this happened because by immersing a piece of steel in water you remove it's exposure to oxygen - as found in air. Assuming you used clean plain water, there won't be many oxygen ions moving around to take part in the process. I imagine though that in the oversill, it won't actually be full of water, just wet and also in contact with air. Add to the mix the likely presence of previous rusty metalwork, and that will be a worse condition than putting a vented sill over freshly repaired and painted metalwork.

 

That said though I suppose using the 'correct' sill on top of rusty floor / inner sill sections probably wouldn't be much better than using an oversill. I think this is where the black and white argument about oversills becomes a bit more grey. I would say that if you made good all the metalwork underneath the oversill, then filled it with cavity wax, it would probably be fine. In most cases, oversills are covering nightmares, so it is inevitable that this situation will continue to get worse.

 

I think the point about modern cars is that they are just all out better designed - the mini has various routes into the sill box section for water draining off other parts of the car, so probably the vents are one way to minimise the impact of that shortcoming. Modern cars will be designed such they don't need venting of the box section, through better sealing of panels etc.

 

I actually noticed the other day when out in heavy heavy rain (lots of surface water and puddles) on a mini run, that at the end some splashes of water had actually found their way IN via the vents! I've S50'd my sills box sections anyway, so hopefully not an issue.

 

So basically, if using an oversill, fill the box section full of water and make water tight. Or your other suggestion of filling with S50 might be better :lol:


Edited by carlukemini, 27 October 2014 - 01:52 PM.


#42 Ben_O

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Posted 27 October 2014 - 05:00 PM

Just for the record, most modern cars do have vented sills. Just not anything like the Mini.

 

If you look along the flange where the bottom of the outer sill spot welds to the floor/inner sill, you will usually find a couple of vent 'bumps' on the flange itself. One towards the front and one towards the back



#43 nick1989mini

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Posted 03 November 2014 - 06:34 PM

Silly sill! Just been introduced to these over sills on my project. I'm fairly new to bodywork so thanks to these over sills its put me straight in the deep end! New flitch, inner sill, outer Sill, front floor, sill strengthener things & repairs. oh well learning curve here we go!

#44 Pottrell

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Posted 04 November 2014 - 11:01 AM

Just about to get inner and outer sills fitted. How much should I expect? I've already got the sills etc.

My welder is saying he's asked around and it seems to be £700 a side! What... :/

#45 Ben_O

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Posted 04 November 2014 - 11:19 AM

Just about to get inner and outer sills fitted. How much should I expect? I've already got the sills etc.

My welder is saying he's asked around and it seems to be £700 a side! What... :/

It is a big job so won't be cheap if done by a pro. I think £700 is high but you can always shop around.

 

This is where it is a good idea to invest in the tools and learn to do it yourself. But that always depends on you though, I know alot of people either don't have time, anywhere to do it or simply have no interest in doing welding/bodywork.






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