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1937 running board rubber repair


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Hi there,

when I look at my 37 Roadmaster convertible, I do appreciate the various witnesses of her age, like a bit dull paint, wear on the leather etc. - as long as the general state is still very good. My running boards however do concern me a little bit. The rubber is cracked, hard like a stone and I am a bit concerned that it´ll get worse over time. While I do like that look, I don´t want it do go on like that.

Do you know any method to repair / restore / soften up the old rubber without replacing it? Is there any "miracle gum" that reverses the process of ageing for a little bit?

Anyone any idea or experience?

Thanks and happy Easter break!


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Meguiars has a product for vinyl and rubber. It won't do any magic overnight, but with a few applications may help out. If you go to Meguiars.com they have links to their products...if I remember it may be #40. If you can't find it, I may be able to dig out a bottle this weekend to verify the name and number.

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I know an owner of a 1937 Buick Special coupe that repaired his running boards with body filler ("Bondo"). He then carefully block sanded the repaired areas and painted the whole rubber surface with a mix of black paint and gray primer. The result looked very good and original, except that it was rock hard.


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I have the same problem with cracking and spotty rubber loss, with my 38 running board rubber. I am going to try that black rubberized adhesive called GOOP. It seems to cure into a flexible rubbery material. You may want to give that a try in a small spot to see if that gives you the results you are looking for. Added benefit could be bonding to the old remaining rubber and adhesion to the metal base.


you can wait till I actually try it and report back. I am still waiting for the winter snow to melt away to get to my 38, so it could be a few weeks yet!

As for the rubber hardness.... no tips to offer.

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  • 2 weeks later...
  • 1 year later...

ok, I have experimented and found a repair that I think is quite satisfactory.

My running board rubber ( on a 38) had minor cracking, some small 'divots' breaking out, and, a couple of areas a few inches in length where pieces were breaking away from the metal 'tray'.

To start, I used rust check rust converter, to seal rust under the rubber where it was cracked or where I could see I could get the liquid down to the metal 'tray'

Use this sparingly and only in small areas where you need to stop obvious rust. ( it is very aggressive chemical and I'm not sure about its long term affect on the old rubber.

After the rust converter was soaked in for about 10 minutes, I flushed the whole area off with lots of clear water and let the boards dry over night.

I then used a product called Black Knight, all season rubberized premium, 'Roof Repair'

It comes in a tube for a caulking gun.

I applied is sparingly, and worked it in to the cracks by 'massaging it in ( with my finger).

On the larger areas I squeezed out the material and slowly levelled it out and shaped it with a combination of tools ( finger, small trowel, and a knife).

It is sticky and you have to work it back and forth, take your time and blend it in to the adjacent surfaces.

The let it dry over night. It will be still pliable in a day and then I did some final shaping by pressing the material to better match the contours of the running board ribs.

I then sprayed the whole rubber top on the running board with a good layer of 'Dupli Color, bumper coating, CFB105, flex.Bumper coating black' and while still damp, I rubbed the paint in long strokes to blend in the paint and dull it a bit.

The next day I gave it another coat of the ( bumper black) paint and same wiping technique.

In a few days the compound applied is quite stiff, like the hard rubber, and the running boards look amazing.

The cracks are filled and the delam bits and divots are all filled.

The added bonus is that they are sealed ( for now) for water getting under and continuing to deteriorate the boards.

The boards look like new . and I'll post a few pictures when I get some.

Now I wish I had taken before, during and after pictures, but the after pictures I think will show what a great repair this made on my running boards.

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  • 1 month later...

First of all, save some time and money, nothing you put on such as Meguires etc. will restore the rubber on your boards.

I am quite sure that one of my boards on my 38 is a fibreglass cover, the other may be an original that has hardened to the consistancy of plastic or fibreglass.

My solution? This winter I am going to take them off and have them sprayed with "truck box liner" they can apply it in various thicknesses and various finishes. It stays flexible (rubber consistancy) I have seen samples and it looks like an answer...stay tuned

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How are you going to achieve the ribs?


I was thinking the same thing but it would take a lot of taping and masking to have enough build up. I wonder if you could pour the liner material in thin troughs, something like a pipe of small diameter pipe split lengthwise, let them harden. Then spray the boards and while still tacky, carefully apply the ribs made in the troughs, then spray a couple of sealing coats of liner over all the boards.

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