rear diff leaks

[Suebian330]

John,

sure I have my axle apart, you doubt it?

I replacxed the seals with the type with additional dust seal. I usually fill the gap between dust seal and inner seal with bearing grease. This serves as a reservoir to avoid the real seal from dry running. Also I assume the seal will last longer because of some more protection of dust and debris. I always try to replace the momolip seals by a model with dust seal when one side goes to the ambient. But only in cases with low reving shafts with no direct oil volume on inner side of seal ring.

Dieter

[tyang]

Has anyone tried substituting the standard shaft lip seals with double lipped type? Would there be an advantage? Thanks.

john

Hi John,

I've tried to source a part number for this seal with a double lip and failed, so I went with what was widely available from the parts suppliers. Changing the location of the seal by shimming the axle plate a little with a gasket may help move the seal away from the wear groove on the hub.

Tom

[Suebian330]

Hi John,
sorry for my very general comment before. The more I read in this forum I get the feeling that you are a real expert (beside others)as you have a long term experience with those GT´s. I am just a greenhorn on those cars. So I apologize for some unqualified comments.
But anyway now after Toms comment I get closer to your concerns on the assembly of seals with dust covers at the rear hubs. I just also do reassembling of the rear axle. I guess you want to know if the seal with dust over fits also in this small space. I just come up from my shop floor with the dimensions.
For the sealing ring (48x62x8) the distance between seal lip and dust lip is 6.3mm. This dimension may vary after assembly a little bit. The straight grinded surface at the hub, any radius already deducted, is 8,8mm. This means you need to run either the seal lip or the dust lip right at the edge. You need to add spacers without regrinding the hub for the ring with dust seal if you want to touch both lips at the straight mchined surface. Without spacer the dust seal will touch nonmachined rough surface. You can regrind the hub towards the outward area if you want to avoid spacers and getting some more safety distance from the edge.
I am talking about the dimensions I measured at my hubs, not knowing if anybody did some remachining of the surfaces at my part. May be you will find different geometrie.
A source or those double lip seals in this dimension is no problem over here.

Dieter

[John Vardanian]

Thanks Dieter, I am by no means an expert, just a grease monkey, that's all. What is this dust cover you are talking about?

Tom, my shaft is in nearly perfect shape, I just wanted the added oil proofing of the second lip. Whatever little oil that finds its way past the lip gets flung outward and after some time I end up with a fine spray of axle oil on the underside of the car. This is why I asked about a double-lip seal.

john

[DWR46]

Double lip seals are the way to go. We use them every chance we get. You have to do some searching in seal catalogs to find them in certain sizes, but there is no question they will seal better and for a longer time.

[Suebian330]

Hi John,

I am not so familiar with american technical terms. I guess when you talk about double lip seal it is what you see in my added picture. In our german terms we call the outer seal "dust lip" and the inner "sealing lip" because function and also contact force is different, but this you know .

btw: In my records I found I had to add a spacer with 1,8mm

Dieter

[250GT]

I give this tip before, a few years back.
I use SKF bearings who are " closed " on the outside.
I make them my self because these are not standard bearings.
the shafts before 1958 are bigger in diameter as the later ones f.i PF coupe.
no problems with "splash oil" at all.
there is no real oilpressure here.
but have no expierance with douple lips so far.
I use to drive over 30K km a year.( no joke)

C.

[John Vardanian]

Hi Cornelis, what is that casing, a grease packing device?

john

[250GT]

Hi Cornelis, what is that casing, a grease packing device?

john

John,
To find these special bearings in the past(80th) it was only possible at special brearingshops
with waiting lists of 2 month......
So I decided to make them my self.
this "grease packing" makes it possible to fixate the" turning" bearing
so you can produce out of 2 standard Bearing the 2 special ones..... before lunch.
A lathe is necessarry of course but you have one I think ?

C.

[John Vardanian]

One more post to the thread that doesn’t die… after finishing the axle de-leaking project I ended up having to replace the pinion seal twice to stop the weeping of oil that was coming from the seal after driving the car less than 10 miles. The seepage was very small, but because it was at a spinning part, with the help of the wind flow under the car, you’d end up with a nice mist of oil landing on everything in that region.

I found the reason why oil was finding its way past the seal. Then I realized that the problem was not the seal or any other component. I learned no lip seal in the world could do what it is meant to do given the design of that particular Ferrari axle. I can explain more if anyone is interested.

But, anyhow, the main reason why I am making this post is to thank Cornelis for giving me an idea. I replaced the front pinion shaft bearing with a permanently sealed Japanese unit. This bearing in effect became a hard barrier to the oil. Leak is gone.

john