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MG TD TF 1500 - Floorboard underlayment

I'm cleaning up the car where the floorboards will sit. As I said in an earlier thread, there was evidence of felt underpayment used at different points. There are also two large rubber pieces that fit around the base of the under-cowl rollbar.
The result of this is that there seems to be a lot of variation in the heights of all the different bits that the floorboards sit on... the rubber pieces are about 1/8 thick and to match that all around I will definitely need to lay down quite a bit of felt or rubber or whatever.
Just wondering how people handled this. I searched the archives and looked on Dave Braun's site and couldn't find much info here.
Also, do people recommend putting a layer of something between the drive shaft tunnel cover and the angle pieces it bolts to? There is none on mine, but it might be a good sound deadener to put in a layer of rubber?
Geoffrey M Baker

I uncovered the remains of a coarse felt strip between the tunnel cover and the angle iron supports. I also have the original roll bar rubber pads.

M Magilton

I guess what would work best would be some kind of weatherstripping about 1 inch across and 1/8 deep. Any made particularly for the automotive industry that anybody would care to recommend?
Geoffrey M Baker

I found felt had been used between transmission tunnel and angle irons.
I think felt was also used were other metal plates were attached to frame members. Felt may have also been used under floor boards,

I am not restoring for originality and knew felt was prone to absorb moisture, I found rubberized belting material at an industrial supply house which I used in place of felt.
Also found that rubber sheeting used for landscape ponds works well.

R W Hinton

Yes, I don't like the idea of felt either. I've ordered some neoprene rubber stripping and will see if that works. Handles a wide range or temperatures and moisture and oil resistant.
Geoffrey M Baker


Here's a thought from a old car guy with a total of one year mgtf experience.

Why did the factory choose to put anything between the angle irons and the floor boards?
My guess would be to keep road sand/gravel from getting between the two surfaces and grinding away on each other. In my way of thinking felt is an excellent material for this job. Its a good barrier/insulator and it breathes. It will crush where it needs to and hold its shape where it doesn't.

You could use closed cell foam, but water will get trapped between the two surfaces with no way out. Foam doesn't breath.

When I stripped my car down to just the tub and frame remaining I found the original felt and cork shims to be in excellent shape for 61 years old. I will be reusing the felt with maybe a little oil added for good measure.

What ever is chosen its doubtful any of us will be around long enough to know what works best. And how many of us drive these cars for every day use. If it's cold and wet I'm driving the newer cars. But I'm a wuss.

Dan Nordstrom

The felt vs. closed cell foam has been hashed about here before. My two cents is rather than assume the factory either went on the cheap, were ignorant or had no better material is to think the Brits were only very recently removed from the hundreds of year old wooden coach building trade and were in fact using the best material for the job. Wood will last a long time if allowed to dry between episodes of getting wet..felt breathes. Open cell foam would be a disaster used in this application, but even open cell foam would not allow the damp wood to dry in that area..
No matter what coating is used, wood moves with temperature and moisture will absorb moisture and needs to breathe to dry out. I think the coach builders knew what they were doing with the felt. Regards, tom
tm peterson

What Tom and Dan said. +1

We need to be careful not to fix what is not broken.
Christopher Couper

I wonder on the advantages of attempting to seal floor boards on the underside versus sealing them on the top side. I took the latter option and sealed all components using adhesive backed sound deaden-er.
G Evans

Paints have come a long way since the 1950's, and when you add the care with which we apply them VS the quick factory methods which were clearly cost driven, then I don't think we have anything to worry about.


A damp situation ...

M Magilton

On using a sealer, I'd recommend sealing on both sides if you are going to use a sealer on the floor. Reason being timber will want to warp, cup or bow if one side can breathe & the other can't. Cheers
Peter TD 5801
P Hehir

On the rear angle irons that have the rear inner quarter panels attached by 4 - 1/4" screws and nuts, the felt and water ingress have badly rust pitted most cars we have restored, but the quality and type of paint used on the angle irons was possibly the reason these rusted. Modern epoxy paints could well prevent wet felt from causing rust.
Rod Brayshaw

I'm really not too concerned about damp. I live in one of the driest climates in the world, after all :)

I don't know that I subscribe to the theory that the original manufacturer had the perfect solution, either. Firstly, all manufacturers have to meet a price point to get their product to market, and that will be reflected in the material used. The felt lining, as well as the carpet, were simply the cheapest they could use.
Secondly, most of the solutions now used by car manufacturers simply didn't exist in 1951. The huge range of foams and plastics now available were not on the market back then.
It's fair to consider what manufacturers use NOW as suitable replacements... UNLESS you want to be absolutely original, which we all know is not possible today - and seldom desirable, considering improvements in designs and materials today for many our replacement parts. After all, just in this area alone, most owners are happily installing sound deadening mats that were never used in the original car. What effect will these have on floorboards and carpets in another 60 years? None of us know.
Yes, coach designers probably felt that felt (haha, pun intended) was a reasonable solution... breathable, cushioning, etc. Yet the condition of the floorboards, carpet and underside of my car after 60 years indicates that felt had its drawbacks. The floorboards were rotted (driver's side in particular) the felt was disintegrated, and the metal rusting.
In a damp climate, the continuous wicking of water through felt will destroy floorboards. It might well be better to use high quality paints, glues and sealants and completely seal the underside instead of letting it breathe.
I think a tight seal might be preferable, especially in wet climates. Here in Tucson, not so important.
At any rate, I'm pleased to think that with all the metal cleaned, primed and repainted, with the floorboards well sealed with varnish and paint, and some form of cushioning applied to seal and cushion the boards, I'm heading for another 60 years of driving pleasure.
Just my humble opinion, everyone is welcome to theirs!
Geoffrey M Baker

Great subject.

The ultimate answer to this is to use the best product available, originality and cost be damned.

Aircraft sandwich board would be an excellent choice. IMHO Strong, light weight and horribly expensive. lol
When Boeing had its surplus store open it was plentiful and reasonably priced. I used it for the floor of a Go-Kart I built many years ago.

Here is just one of many websites for this product.

or Google sandwich board

Dan Nordstrom

Dan: I remember this stuff from the late 60's and they are still going strong today.
Christopher Couper

Yes, if cost was no object I might have done the floorboards in aluminum diamond sheet. I looked at the aluminum honeycomb panels for something in the past but I can't remember what. And naturally, formed carbon fibre would be nice :)
But plywood (at $13 per floorboard) works fine too. :)
Geoffrey M Baker

Yep, that's it Christopher.

You could use this stuff in place of all the wood in our cars. Nah, just kidding.

I do wish Boeing still had its retail stores open though. I could spend the whole day there spending money. :)
Dan Nordstrom

You would be looking at a huge electrolysis problem if you were to combine steel and aluminium together with no barrier between them. Many aluminium sheeted sheds on a steel frame have disintegrated in a few years exposed to my local semi coastal climate.
G Evans

I know... I had a Landrover 😃
Geoffrey M Baker

This thread was discussed between 03/11/2015 and 05/11/2015

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