How to make rubber softer ????

[John Timmins]

Hi. I am restoring a 1957 Mercury outboard motor. The engine mounting "discs" , called Dyna-Floats are a vibration isolating part made of aluminum and rubber. It is a disc of about 1/8 inch of aluminum, 1/4 inch of rubber, then another layer of aluminum. The disc is inserted into it's position and pressed enough to insert a snap ring to hold it.

The rubber is hard and hard to squash down into place. It has expanded too much. What I want to do is make the rubber softer and squish it using a large C clamp.

On another outboard forum web site a guy said he heats these discs in hot water to soften them. I wonder if I should heat them in oil so the water doesn't affect the rubber...or will the oil affect the rubber????

I thought of heating these disc things in a old crock pot with about an inch of water or oil. I am told heating them will soften them up.

Does anyone have any info to share about this problem?

Also what does vulcanize the rubber mean? What does "re-vulcanize" the rubber mean? Does this mean rubber is cooked in an oven?

Will I harm the rubber heating it up? in oil? in water?

Some web sites about rubber don't help since I don't have a degree in chemical engineering !

 

[stinkythings.com]

I was going to suggest hot water also.If you feel you must use oil I think I would use vegetable oil instead of a petroleum based oil which in my mind would break down the rubber in time. I am not a chemical engineer though.

 

[Stuey]

There is a chance that manipulating or attempting to further modify the rubber will lead to its further destruction.

Is this something that can be replaced?

Rubber degrades and becomes hard and brittle over time.

Oil destroys many types of rubber.

 

[JebNY]

I have no idea if this will make your problem better, worse or do nothing. Now that I have put in the disclaimer. I was told by a friend that has done unbelievable things restoring very old tires for display that he used glycerin that you can buy at a drug store. It will soften and allow old dry/hard rubber to seal cracks and become flexible.

He has brought back some rare size tires that are not available at any price soaking them in glycerin but said you have to be careful because to long and the rubber turns into mush. He made a special pan that he could sit the tires in vertically and rotate ever so often so that it didn't take as much glycerin.

I have used the technique to fuse age cracks back together on some tractor tires by just brushing it on every few hours till the cracks melted back together.

Before someone waves the safety flag on fixing old tires, none of the tires that my friend or I repaired were used on the road after the repair, they were for slow speed or display purposes only.

Jeb

 

[Uncle Buck]

I have no idea if this will make your problem better, worse or do nothing. Now that I have put in the disclaimer. I was told by a friend that has done unbelievable things restoring very old tires for display that he used glycerin that you can buy at a drug store. It will soften and allow old dry/hard rubber to seal cracks and become flexible.

He has brought back some rare size tires that are not available at any price soaking them in glycerin but said you have to be careful because to long and the rubber turns into mush. He made a special pan that he could sit the tires in vertically and rotate ever so often so that it didn't take as much glycerin.

I have used the technique to fuse age cracks back together on some tractor tires by just brushing it on every few hours till the cracks melted back together.

Before someone waves the safety flag on fixing old tires, none of the tires that my friend or I repaired were used on the road after the repair, they were for slow speed or display purposes only.

Jeb

My job is safety, and I give you an official OSHA nod!

 

[HetrickElectric]

I raced go-kart for years. We were always trying to get our tires softer without damaging the rubber. WD40 worked the best and actually keep the tires from getting old longer. We would paint the WD40 on with a brush and than wrap them with saran wrap so the WD40 couldn't evaporate only soak in.

In you case I would simply put WD40 in a can a leave your pieces soak in there and just check them each day. Good Luck

 

[Kevin54]

Heating the rubber will soften it but onlt temporarily. Since the rubber is over 50 years old, it is pretty much shot. If it is not a replacement piece that you can purchase, I would look into having some new ones made. Places like McMaster-Carr, Grainger, Danly, sells urethane bars that you could probably have someone with a lathe turn out a couple. There are also companies out there that can take the existing part and make a temporary mold to make a couple of new parts. By the way you describe it, it kind of sounds like a shock mount rubber only a little thinner. Maybe that is something you could adapt. The bad thing about rubber is that once it deteriorates, there is not much you can do to make it new again.

 

[idoine in toronto]

BMW dealers sells a restorer/conditioner for rubber seals and trim.

http://www.z3bimmer.com/OffTopic/E24Bimmer/Gummi/

Carbaflo also makes rubber conditioners.

http://www.carbaflo.com

I imagine these are both pricey products & I don't know if these will bring back life to old rubber, but it may be worth a try.

 

[buening]

303 makes a good protectant, but I'm not sure how well it'd do after the rubber is already hard.

http://www.303products.com/tech/index.cfm?fuseaction=product.display&Product_ID=428

FAQ


I've also heard that hand lotion or vaseline softens rubber, but have not tried this myself.

 

[CraigFL]

I've used mounts like that before from Lord Engineering. See if you can find something here:
http://www.lord.com/Home/ProductsSe...cts/IndustrialCatalog/tabid/3300/Default.aspx

 

[pmiranda]

I'll give the smart-aleck answer... Soak it in gasoline

 

[John Timmins]

Update

I took the rubber discs and placed them in an old crock pot with an inch of water and cooked them in the hot water for about an hour. I am not sure if heating up the old rubber or using a bigger C clamp was the biggest help, but I got the parts installed today. It was still a pain in the ***.

The parts are not available new. I know that using hot hot water did not harm them. Maybe the rubber was not as bad as I thought.

I spoke with a friend with antique cars and the rubber I had is nothing like the old stuff he runs into. Anyway the crock pot was a good way to gently heat the water and parts to just under boiling.