The astoria Flexx boots go on over their supplied funnel. I have done 4 of these.You do have to pull the axles to do it easily. On many cars you can do it on the car but not on the 300D from 78-85. U se the 3001 boots. It is a two man job to do the stretching to get over the funnel they supply. Spray it with pledge. Flexx supplies the grease. Their clamps are cheap chinese junk ear type clamps. Get the thicker axle boot clamps from places like Carquest/napa. Replace the axle seals. A few tricks to know: Put a tiny wire thru the circlip which has an eye on it to avoid loosing it in the dif when you push it off with 2 screwdrivers. Jack the dif up once you remove the cover. This will give you enough clearance to pull the axles out of the wheel side.Replace the MB boots if they are badly cracked. Avoid the junk cheap chinese axles if you can but that is the cheap and fast way to go and they last 50 to 100K.

the answer is No.

Are you 100% sure about that?

I went the cheap and fast way. My original boots with 3M 5200 repair were still intact, but I had a friend with a lift who needed some income, so had him put on a pair of GSP axles. After a few years, still good.

Idea was to rebuild the OE axles while they are out. But how? Options are:
- buying an OE type kit from MBsauce and replacing cans. Crimp suspect?
- cheap stretch type with funnel from Aliexpress (China).
- Flexx - but those really require the expander tool.
- what seems good quality boots from Australia but they likely need expander.

Cheap Chinese pneumatic expanders are available for probably under $100. But, I seem to recall that they don't quite open enough.

So the axles just sit here :(

a guy on fleabay sells reconditioned mbz w123 axles
$249 each..SoCal.. so local pick up ok...

The use of poly sealants is a good idea.
I just have one question.
Will adding a sealant coating over a part or entire rubber boot induce stress on whatever is not covered on the boot? (therefore possible new tearing)
I figure that since the rubber consistency of any original section may contrast to the new coating and not 'flex' the same.
I do understand that the likes of the 3M poly 5200 etc does stretch.

I also had at some point in time or other thread suggested GACO silicone roof coating.

Thanks!

The 3M 5200 is very tenacious adhesive. Provided surface is clean and abraded, it will add a rubber-like layer over the existing boot while also filling any cracks. It can't be peeled off! No problem with different elasticity - the coating is thin compared with the boot and the 5200 is elastic.

I coated the entire boot using small brush. Did this with car jacked up and rotating the wheel. Because I used the slow-cure version, I had to go out and rotate the wheel every few hours during the initial cure (actually did it for a day or so). I think I applied three coats in all. There is a fast cure version which should make for faster application.

I had my coated boots on car for a couple of years and they never failed.

Provided the boots only have surface cracking, I think it is a way of extending boot life until opportunity arises to replace. One thing I liked, was that it retained the OE axles. That is why I kept the original axles and will reboot those if Chinese ones fail.

Thanks Graham!

It makes sense that the 3M poly is a thin application compared to the boot rubber original thickness.

Thanks for this insight!

Another hold over is to treat the boots that are in good condition (minor surface cracks) with liquid silicone (lubricant from can sprayed into container and brushed on).
It does seep in nicely and enhances natural resiliency.