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MG MG Y Type - Sill Rust

Hi guys
Today whilst I was pulling out the left-hand chip-board floor boards on my Y/T, I noticed dirt/rust falling onto the workshop floor. An inspection revealed a rust hole in the bottom of the left-hand sill in the area behind the door. (see attached photo.)

Is there any drain holes in the sill? LTBYs makes no mention of any drain holes.

I will need to take off the rear quarter trim to carry out a fuller inspection, and need to get it onto a hoist to carry out a full inspection of both sills.

More details tomorrow after a fuller inspection and talking to a sheet metal worker / rust repairer.

Stuart


Stuart Duncan

Stuart

No drain holes :)!

While our cars were not built to last, they most certainly have!!

Paul
Paul Barrow

Hi Stuart, There should be drain holes at the rear end of the sills.

It is a circular hole 3/4" in diameter & covered by a "vent plate" to prevent is catching water rather than draining it. I think someone sells the vent plates ?.

In the photo below you can see the rounded "vent plate.

Cheers

Tony

A L SLATTERY

Isnt that the sunroof rear left drain hose dangling down Tony? Think Stuart is referring to holes in the box section to drain the box section. I didn't think there are any in the section are there? The Sunroof though has front and rear hoses which pass through the section to drain out for sure. Its been a while since I have been under my Y.

Paul
Paul Barrow

This morning I have been removing parts off the Y/T, so I can get a better look at the rust. It would appear both sills have had their bottoms replaced previously. Now the rear half of both sills have rust and will need replacing. see attached photo of left sill from rear. The hole has been enlarged and is now about 100mm long.

Other then the 3 front and one rear bolts holding the running boards to the guards my running boards are held against the sills with self tapper screws. is this correct?

Stuart Duncan

Forgot to mention that it would appear the sills have been used previously as jacking points as they have a number of 1/4" deep indentations in them.

Paul, my Y/T has a hole (about 5/8" dia) in the bottom of each front quarter panel. blurry Photo attached

Stuart

Stuart Duncan

Now that the running boards are off the car, I can see cut bolts sticking through the wall of the sills.

For future restorers.
> Each running board is held onto the sills by 5 - 5/16" BSF bolts. (thank you Tony for the information) Probably 1/2" long.
> The sills have 5/16" BSF captive nuts inside them.
> The running boards have strengthening brackets where the bolts hold the running boards to the sills.

I will have holes drilled into the sills and 5/16" nuts tacked to the inside of the new sills and use stainless steel bolts to hold the running boards against the sills.

I read in the Archives that someone had run a solid steel box section inside the Sill. Is it worth doing?

Stuart
Stuart Duncan

OOPs
Just looked at the Nuts and Bolts list on the imgytr website. It would appear there are only 4 Running Boards to Sill bolts each side and they are either 7/8" long or 3/4" long pointed.

Stuart
Stuart Duncan

Stuart, I suggest you make the effort to fit captive nuts rather than weld nuts to the sills. Without the slight movement of the captives, you will find it very difficult to get multiple bolts/holes to line up.

The combination of captive nuts and pointed bolts were installed by the factory for good engineering practice & speed/ease of assembly !.

Keep going !. You will get there.

A L SLATTERY

Stuart

I feel your pain with the original captive nuts. I used CLINCH NUTS. They come in a variety of types but I used this insert and crush type.

http://www.dkhardware.com/product-16660-rn1420-1-4-20-rivet-nut.html?gclid=CP3r8LWN5tACFUSRfgodPckJuQ

Paul
Paul Barrow

Paul
I looked at the clinch nuts as a replacement for the caged nuts, but Classic Fasteners in Adelaide (Sth Aust) where I buy all my BSF bolts and nuts from, has Caged MS BSW nuts, ready for welding. This will keep the car near standard.

I was looking at using these BSW caged nuts, but after discussions with the fellow who I am getting to replace the sills, I decided to cut the existing cages and BSF nuts out of the sills and using easy outs to try and remove the cut bolts from the nuts and reuse the cages and nuts.

The sills will be replaced during January, by someone who builds hot rods from the frame up. His business is in the same complex as my workshed, so I can drive the YT without L/H floor and R/H floor and seat just sitting in the frame.

Investigation today found up to 1" of dirt / rust in the rear of the R/H sill. I am wondering if over the past 20 years that the YT has not been on the road, swallows or wasps have used the sill as a nest site, entering via the area in front of the door.

Investigation also showed there may be an inner second skin inside the sills. I will take some photos next week after cutting the cages and captive nuts out.

Does anyone have any information / cross section drawing of the sills?

Stuart
Stuart Duncan

Stuart, You can make your own BSF captive nuts.

Just get some strip steel locally that will fit in the cages from Classic fasteners, drill and tap BSF, cut to length & swap out the BSW. Sorted !. Classic Fasteners will even sell you the BSF taps !.

The "crud" builds up in the back of the sill because there is no drain hole - refer the picture in my earlier post. There should be a rubber grommet in the drain tube hole in the front of the sill too. If this is lost, that's where all the "crud" get in.

BTW - "crud" is a technical term - it is a combination of crap, road grime, sand and mud that finds it's way into any cavity & solidifys into semi-rock !.

Keep going

Tony
A L SLATTERY

Tony,
Mark at CCC had suggested that option.
As it will take some time to remove the cut off bolts from the nuts, making my own BSF nuts and swapping out the BSW nuts may be more time effective. That way the threads will be the same throughout the car.

I already have a set of BSF taps and dies (small size purchased and larger sizes are in a box my Grandfather was given by the Govt after WWI when he started employment as a machinist).

FYI - a PO had threaded SAE nuts onto the studs which hold the Hood hinge to the side of the car behind the doors. They are now back to BSF.

FYI - the threads in the cover around the gearbox lever are the same as the bolts holding ID plates to the battery box (ie 1/8" BSF according to "Nuts and Bolts" pdf) - added for future searchers - not listed anywhere.

Stuart
Stuart Duncan

There is a form of captive nut, that snaps into a square hole.
I replaced the TD rear, inner, fender wells. The new ones had no evidence of the need for captive nuts. I sent them off to the painters and only when I started reassembly did I realize I needed something to fasten the rear wings on.
Since the wells were freshly painted, I did not want to weld.
I looked around and found these at McMasters. You drill a round hole, square the corners up with a file and they snap in but the nuts have movement.

I did replace the UNC nuts with shop made BSF nuts however.

Just my approach.

Jim B.

JA Benjamin

Re Activated for an update

This morning the rusted sills on my YT were cut off and coated in kill rust.
I was surprised to find that the sills consist of 2 box sections - a smaller inner and larger out, as can be seen in the photo.

Although I had used a compressor and blown a lot of dirt out, there was still a lot in the sills. Also found a T key which we partly cut into whilst cutting the metal out. (Warning to anyone who drops anything inside the front quarter panel - it ends up in the sill.)

Stuart

I know the exhaust is not in the correct location. That will be fixed.

Stuart Duncan

2nd photo - shows new partial outer sills, made from one piece of metal. We will be drilling holes in the larger rear (closest) ends to allow for drainage.

Stuart Duncan

R/H new partial sill against car.



Stuart Duncan

This thread was discussed between 01/12/2016 and 11/02/2017

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