silicone on CV boot crazing to delay further crazing then cracking
 

My 300TD has CV axles quiet as a church, no play at all, in fact they are stiff as hell so much I thought I should replace. I assumed that was a problem.

There is some crazing on the boots so I'd like to delay further crazing, then cracking.

Elsewhere the venerable 300Dman has advocated brake part cleaner on a rag to clean the area, then silicone RTV the flexible "original" type over a puncture hole. He advocates it, that's good enough for me. I"m going to give that a shot, possibly a few thin coats with time to dry in between.

Silicone: good ****. I did not put the asterisks there.

2 trashy sets later both returned under warranty (one set from Cardone went crunch crunch the first 10 ft of milage .... the second EMPI set lost the lube out of one outboard side due to a flaky can. I've grown to love changing these half shafts every few months.

i"m putting the originals back in.

Any informed commentary about silicone for this?

I say go for it. What could it hurt? I doubt the silicone will bother the boot, and a thorough cleaning will make the silicone adhere good. This treatment should in theory buy some extra miles on those old boots.

I think its very possible. Especially since most "peaks" are near perfect, one has deep crazing .... oddly very much different than the rest .... the good ones wlll last a long while, the one crazed 'peak" needs a bit of help.

I am 300Dman over on Benzworld. I don't remember the circumstance I gave that advice in.

I recall someone saying they were going to stick the Boot with a Syringe and Inject lube into the Boot. For that purpose the Brake Cleaner and Silicone Sealant would be Ok.

But, it depends on how big the Hole is.
My Axles are filled with Grease so the patching the hole with Silicone would be worth trying for Me but I would inspect it frequently till it has proven itself.
Also be sure to let it cure several hours and also to spread it beyond the Hole so there is more surface area for it to hold on.

Someone also claims the cut a Boot and Super Glued the edges. I don't recommend that but if the ripped edges are free of Grease or other lube you could Super Glue the hole and then cover it with a layer of Silicone Sealant.

I have a different comment.

Since I had giving the Silicone Sealant advice the Hardware stores are selling a Black Spray Sealant that is rubbery.

I don't know what type of heat that stuff can take but one of the uses for it is on Roofs.

I bought some in the Paint Department from Home depot and used it on My Motor Home Roof.

I also ask a question a long time ago if Auto Tire Paint would work. But, apparently no one has ever tried that.

If you spray Brake Cleaner on the Rubber be sure to give it at least 15 minutes to dry as it may get absorbed into the Rubber a bit.

Isn't brake cleaner just ether? .... super rapid evaporation.

I did use the technique recommended and have high confidence it's a good move, well worth the tiny cost. That silicon does adhere like crazy to a well prepered surface. They are already installed but it would be reasonable to jack up the rear end, block or jack stands under the trailing arm so the wheels will spin at almost the same relative position as natural driving ... clean peaks and valleys again and add more silicon to existing and also to valleys where crazing has begun.

Ether smells different from Brake Cleaner and Ether is also extremely flammable. If you try starting your Car with Brake Cleaner I doubt if it will work. They are not the same thing.

For Silicone Sealant to stick you definitely need a good surface.

When Silicon Sealant was somewhat new in Auto Part stores I used some on a Water Pump Gasket.
I had scraped off the Old Gasket from the Block and wiped down the Block but that left a thin film of Oil on the Block.
I installed the Water Pump and about 3 Months later I looked and I saw a small Water (most People back then still used Water as Coolant) leak between the Block and Pump.

Water had rusted through under the Silicone as the Oil Film had prevented the Silicone from gluing itself to the Block.

What I learned from that is that if you cannot or don't want to degrease the area so the Silicone will work use the Old School type brown Permatex.
I have installed a lot of Freeze/Core Plugs with the old School Permatex and that stuff is extremely dependable.
The Silicone Sealant requires more carful use.
The