- Hello this Davin with Hagerty and our DIY series.
I'm in the middle of putting up gear,
install an old 12-bolt on our SS396 car,
and I ran into a small snag with the seal.
Now if you wanna see that full install,
that video will be right up here.
But, we wanted to highlight a little issue here
we ran into directly with the seal.
In '69 there's actually two seals,
and they carried it on for X amount of years.
But there was two seals.
One for the truck and one for the car.
And the snout on the housing's slightly different,
and that's why there was two different seals
in the inset where the sealing surface is at.
Now what's happened is, the car seal,
for whatever reason, has been discontinued,
and the only one available now is the truck seal.
Typically speaking, your pinion bearing here
should be free-floating by about,
at least a quarter inch or eighth inch,
somewhere in that ballpark.
And what I caught was, this doesn't have any
when this seal is installed fully like it's supposed to be,
where this surface hits the surface of the housing.
So come over here to the workbench,
I've done a little homework.
I've come up with these three different seals
that are of three different manufacturers.
This one happened to be in out initial kit,
and these are two other aftermarket, a Timken and a SKF.
But the point is, all three of these are slightly different,
but none of them will actually function
the way their supposed to if fully installed.
And you can see a good witness of that.
So here's your sealing surface on the yolk,
and it has this chamfer that's roughly an eighth of an inch.
If I put this on here, I'll flip this over
so you can see it.
That sealing surface, the ridge, I'll pull back.
The ridge that actually seals,
is not on the large diameter of the yolk.
It's still riding on the chamfered edge.
So, yes it'll go on there.
It has a marginal seal relative to the dust side of things,
but not on the grease seal side.
So this will install, everything will go together
like I showed you over on the axle,
but this is still gonna leak.
Now, what I found is, you can do three different things.
You can install this and not install it fully,
so you would leave a gap.
Now it my opinion, that leaves for a lot of margin of error
because it's easy to have it rocked
inside the housing slightly.
Second area is you can take a piece or welding rod.
This happens to be a little small,
but the point is the same.
Use a, say a eight-inch welding rod,
bend it up and slip it over the top of this.
Now you have a firm stop,
and you'll have a gap when you're done.
And then the third option,
which I think is probably the best option,
is actually a solid ring.
I happened to machine this out
of a piece of steel I had laying around.
Luckily I have access to a lathe.
And this will go in here then,
and act as a physical stop.
That'll give me an eighth inch of a gap,
and if you can see here, now my eighth inch
forces that sealing ring up onto the sealing surface.
I'm sure somebody's out there thinking
boy, that sure is a hack way to install that,
and you know, that's probably right,
but at the same token, it is the only way to do it
because there are no seals available
that brings this sealing surface toward the yolk further.
They're all inset like this, so the only way to do it
is to short install it.
If you an aftermarket housing, for instance,
like a Moser or Strange, they've actually increased
the length on that casting and that gets away with that
so it's only on the stock 12-bolt housings from GM
that are short, that needed that longer,
we'll call it longer seal this way
to install these correctly and make a good seal.
So if you have a stock housing,
you're subject to only having access to these
because this is what's available,
then you'll have to short install it by an eight inch.
And you can use space or you can use
a couple different ways to use a spacer,
and that'll create a good seal.
And you won't have any leak problems.
All right, hopefully that was a good explanation,
and it helps somebody out there because
quite frankly, there's a lot of 12-bolts out there,
and I betcha a lot of them are leaking
if they're not installed correctly.
Again, hopefully this was helpful.
Click the link, share it, and you can be the hero
at the next car show when you see that drippy 12-bolt.
(funky music)
Oh, look at that.
Now it actually has a float like it should.