spacer for rear axle rubber buffer 110-320-05-44 Bumper, Rear Axle

[merrill]

hello
i went to replace the 110-320-05-44 Bumper, Rear Axle (item 92 in attached below) which is above the rear axle each side in the arch this weekend.  (on one the rubber had fallen off after 50 years)

of course all of the bolts were frozen and broke off.  as I tried to drill out and tap new holes one of the spacers crumbled.

my question is do the bolts hold both the spacer and rubber bumper in place?   when i removed the old bumpers the spacers stayed in place probably due to corrosion.

sls has 3 variations on the spacers (other attachment)   i have reached out to K&K and the classic center to check on their options for the spacer.

thank you - matt

[mbzse]

.../...do the bolts hold both the spacer and rubber bumper in place? ../...

Yes, this is a M8 bolt holding both end bumper and the spacer, entering a M8 thread in the floor plate of the SL chassis.

This oval spacer part was made from zink on your SL, from factory. Purpose was to serve as a corrosion inhibitor (galvanic anode).
Today, alloy or even plastic parts (spacers) are offered by vendors

[merrill]

wow, the spacer 113-325-01-84 is over $100 each from the classic center and K&K.

I will have to seriously look at ordering from SLS.

[merrill]

i ended up buying the plastic reproductions from SLS.   $87 total for 2 spacers including shipping.

their metal version would have ended up being the same price as the classic center.

[stickandrudderman]

On a tangent:
Many people,, when replacing the rear brake lines, fail to notice that the brake lines are run along the BACK of the axle, not the TOP. Lines that are run at the top of the axle are in danger of being sandwiched between the axle and the bump stop in the event of full suspension movement.
If you're driving hard enough to get full suspension movement, you really don't want to have your rear brakes locking on!

[merrill]

Stick
hi,
that is good feedback   

the brake lines on my 66' run on top of the axle which is how they have been since at least 1978 if not originally.

[Shvegel]

There is a break in production somewhere as I have seen factory pictures with it both ways but as the assumption is they did it to correct a safety issue no matter how they are run now they should be behind the top of the axle.

[stickandrudderman]

Also, I think the aluminium (aloominum to some...) base is a sacrificial anode.

[doitwright]

If the spacer is a sacrificial anode, does that mean that is is supposed to deteriorate before the body of the car starts rusting? Would that also mean that there should be bare metal contact between the chassis and the spacer?

[mbzse]

.../...a sacrificial anode, does that mean that is is supposed to deteriorate before the body of the car starts rusting?

Precisely. Commonly used on boats. See for instance https://en.wikipedia.org/wiki/Galvanic_anode

Would that also mean that there should be bare metal contact between the chassis and the spacer?

There certainly was body primer present on the body of the cars I have dis-assembled. I guess the corrosion works its way through...
Some more info and good pictures here:
https://www.sl113.org/forums/index.php?topic=13885.msg94686#msg94686

[doitwright]

Water heaters have anode rods to protect the tank. Most homes have an electrical ground from the electrical panel to the pipe where the water service enters the house. I managed 20 years of service from my gas water heater by replacing the anode rod (not a recommendation). Most water heaters are warranted for 7 years of use because that is the amount of time it take for the anode to deteriorate.

Steel car bodies have electrical systems that are grounded to the metal body. Is it true that this metal grounding contributes to corrosion of the metal?

During my cars restoration we had to do some rust repair although this was mainly in areas where erosion from road debris may have exposed previously protected metal. I do recall the bumper spacers having some efflorescence but they were mainly intact and I plan to reuse them.

In order for the spacers to serve their sacrificial purpose, it seems it would make sense to create a clean metal to metal contact surface. I would be curious to know if anyone who has performed substantial rust repair on these cars what was the condition the spacers. Also, is it common to have an anode on a car? What typically are their forms or placement? Should the anode be inspected to prevent body rust?

[merrill]

new bumpers and spacers are installed.   

with the exception of having to drill out and tap all 4 bolt holes it was an easy job.
not much space between the axle and frame to get a drill in there.

I also checked the routing of my brake lines.  mine did route along the rear of the axle not top so there is no concern of bottoming out the axle and crushing the line.

some photos attached