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I have removed the left hand outer sill on my 1965 Cooper S and will be replacing with a new sill due to slight damage and rust.

My problem is -- how do I separate the pinch weld flange of the outer sill from the outer flange of the lower door sill??

I do not want three layers of metal. Grinding the outer sill flange seems to be the only method? Tedious and laborious!

Any thoughts or advice??!

Thanks!

Jim Knight

Normally a spot weld removal drill should enable separation of the flange to remove the old one from outer sill. A thin sharp chisel helps after spot welds are removed, then a final clean up with a sanding disc on a grinder.

You covered it well Daz1968..exactly the way to do it.
I purchased some of those spot weld removal bits a few weeks ago...incredible..they do a first class job without messing up the panel underneath.

Thanks for your replies. However, I believe the welds to be a series of pinch welds along the entire length of where the flanges come together.
There maybe upwards of 75 small pinch welds. Probably many small holes to be drilled in an attempt to separate these two flanges.

Jim

if you intend to spot weld the new sill along this flange, then it is probably best to grind the remaining sill away ,leaving the flange with no holes ,as you say the spot welds can be very close together here ,and if they are all drilled, it would have to have mig/plug welds .strong but not original

There are many spot welds, I don't think 75 though.

Don't worry about drilling them out. If you use a spot weld cutter/drill, it does not go through the top panel. They cut (or saw) away the perimeter of the spot weld leaving a "disk" of metal behind on the panel that is not removed. You use a disk grinder with flap wheel to dress those spots down flush.

Yes, it takes a while to cut through all the spot welds and dress them flat but there are not holes through both panels when done.

Saw type spot weld cutter:


Spotface type spot weld cutter:

Gave up with the saw ones as they chew the drive section drills I use SKF Dormer ones very good quality

Nick W wrote:if you intend to spot weld the new sill along this flange, then it is probably best to grind the remaining sill away ,leaving the flange with no holes ,as you say the spot welds can be very close together here ,and if they are all drilled, it would have to have mig/plug welds .strong but not original

I agree with Nick here.
The seam is spot welded with a roller type machine which makes a solid row of welds same as on the roof. The spot weld remover tools are good for individual welds.

The original sills on my mk1 were just individual spot welds along the seam not a continuous weld.

Daz1968 wrote:The original sills on my mk1 were just individual spot welds along the seam not a continuous weld.

+1. That's what I found on my car. A lot of individual spot welds.

coop12g295 wrote:Gave up with the saw ones as they chew the drive section drills I use SKF Dormer ones very good quality

I just use a new, good quality drill bit as well, not a fan of spot weld cutters.

Also use the grind and peel back method where the spots cannot be easily seen or drill-able.

We've got one of those hand held spot removers , combining an air drill with a G clamp action , but would struggle on this flang as its often too narrow ,so the bit snags the edge!.
I've not seen a mini sill flange with a rolled weld , but I think the covered vertical seams on my mk2 are

Thanks for your many replies!! It appears that careful grinding is the only way to remove the rolled weld area of the remaining flange of the outer sill.
Yes, I believe the flange is too narrow for spot weld cutters. The roof has these same rolled pinch welds around the perimeter.
Doug, thank you for the pictures of various spot weld cutters.

Thanks again.

Jim Knight

dklawson wrote:

Daz1968 wrote:The original sills on my mk1 were just individual spot welds along the seam not a continuous weld.

+1. That's what I found on my car. A lot of individual spot welds.

I find that very strange. All that I work on have been a continuous welded. They are spot welded by a single spot machine to initially hold them, then run along by a machine, the roof, corners, sills and rear wheel arch.

IAIN wrote:

dklawson wrote:

Daz1968 wrote:The original sills on my mk1 were just individual spot welds along the seam not a continuous weld.

+1. That's what I found on my car. A lot of individual spot welds.

I find that very strange. All that I work on have been a continuous welded. They are spot welded by a single spot machine to initially hold them, then run along by a machine, the roof, corners, sills and rear wheel arch.

Iain
You are correct ,my 66 mk1 has the rolled spot welds round the arch and along the sill
Although my blue 68 cooper I can't see them , they may have been covered , but can't get to other side of car to check
Nick

The car is in the body shop. I used a spot weld remover on the lower edge and then an angle grinder to remove the remaining lip and the many rolled spot welds where
the sill and the door step meet. Ground through in a few places so will make a repair patch panel to fit the contour of the door step and weld in.
Thanks for the help!

Jim

Just to add my 2 penorth.

Nearly all the MK1's I have ever seen have original roller welded sill, vertical & roof seams. On later cars it is common to have spot welds though.

Later Mini sills being spot welded at Longbridge.


https://www.youtube.com/watch?v=okk9U_y4gyQ

This coroliner C type spot welder with a roller, is usefull to replicate the appearance of a continues rolled weld .we use it on modern cars in similar places .Its not the same but is better than a conventional type.