Wanted: Ital Axle Guru

[IamScotticus]

Yes I have the amazing Ital axle in 3.6 built up by SP Components (Tracsport) for  Caterham's budget line of scholarship cars in the mid 90's.

These are famous for having the outer berrings welded to abate shaft egress whilst curbing on track.  Apparently the curb rumble strips are enough to dislodge the pressed bearings.

 

This of course makes the removal of half shafts an issue which makes upgrading the differential an issue as I can't remove it.

 

In all fairness,  I wish to state here that per Steve S. at S&P who did those jobs, it was Caterham's build specification to weld those bearings.  Also, none of those shafts were uprated.

Steve's advice was to upgrade the crown gear.

 

Rakeway had made a kit for Ital with captured and uprated shafts, and have been hinting more were forthcoming for a few years, but nothing yet.

 

I hope this is useful information to someone,  but on to my question:

Is it possible to separate the nose, or diff carrier, from the main tube housing enough to drain the oil and any other bits that may be loose in there?

I know of one, so I'm asking.

 

And, is it possible to remove the shafts?  I haven't seen these welds so I don't know if its a simple grinding job.

 

Thanks 

Scott

 

Edited January 20, 2022 by IamScotticus

[MXM]

I'm not sure if this is exactly what you mean by welded bearings, but from what I've seen, it was usually a tack weld to locate the inner race against the shaft. See attached image. This "fixes" the axial play that eventually develops. A proper fix would be to shim the hub to remove the play (or to get the Rakeway kit).

 

So the bearing is not welded to the case, and you can still pull the whole assembly out with the bearings.

 

EDIT: Oh, I didn't realize the topic was so old Found it in search and decided to reply.. Oh well, hope it helps.

Edited August 20, 2022 by MXM

[MV8]

No experience with the Ital axle. It is common for wheel bearing failures to cause the inner race to spin on the axle, wearing down the axle. The result is usually a "tramp" at highway speeds, like going over rumble strips that are spaced apart. There have been sleeves and special bearings used to move the bearing centering inboard, away from the worn area.

Hopefully the bearing was tacked on a good axle that requires some effort to press the bearing on, ensuring it is centered.

The tack or stitch weld can be cut to replace the bearing using a lathe or friction disc. If the axle is worn, it can be built back up, rough machined, heat treated, then final machined to spec.

Instead of repair, you can also have a new axle shaft made from better material. I've ordered custom axles from Moser Engineering with broaching service from Mark Williams.

Probably the most cost effective thing would be probably be to convert to a more durable and common Caterham axle from that era but I don't know if they have the same attachment points and there may be a driveshaft component change as well.

[IamScotticus]

@MXM 

Thanks! That is exactly the info I was looking for, at the time.  I eventually figured it out, but many others may have the same questions.  Your photo of that tack weld is very hard to come by.

@MV8 

Yes, the Ital / Marina axle half shaft inner bearing is a very tight press, but would walk off from latteral hammering due to a loose A frame, or just too much curbing on the race 7s.

In the 90s Caterham's spartan entry level scholarship academy Classic budget 7s were supplied with used Escort Sport boxes and Morris Ital axles reconditioned to Cat specs by SP Components (Steve Perks) which is now Raceline.  There is much criticism over the choice to weld the bearing.  I have read that it was solely Caterhams specification.

 

@ Everyone

Having gotten my answer, which was how to remove the axle depending on the weld location. I now wonder how to go about minimizing any damage to the bearing in the process?

Use a heat source to expand the case?  I would rather not have to remove the fuel tank so I can torch in the area.  Perhaps a heak block, but I don't know where to find something like that.  Ive seen blocks for heating pistons, etc.

 

The problem with sourcing a different axle is the long cockpit tunnel is too far back to clear better, larger axles.

There may be Mazda and Toyota options that have been used, but too much hassle for me.  The Ital axle is more than adequate as long as I keep a mild road Xflow.  Im just wanting to learn how to service it properly.

Edited August 25, 2022 by IamScotticus

[MV8]

I don't think the case is going to be an issue. The contact area is so much greater with greater leverage than the inner race is to the axle so if something is going to slip, it should be the inner. You can put the axle in the freezer and the bearing on a cookie sheet for a 1/2 hour at 150f. After cool/heating, the axle/bearing assy could be placed in the freezer again but it should not be an issue.

An alternative to welding the inner to the axle is to add a separate ring/sleeve to the axle as a shoulder, which could be tacked to the axle. If the bearing actually needs that much welding to stay in place, I'd fit a sleeve instead.

A moot point, but a new axle does not have to be thicker to be more durable. Alloys like 300m are more spring-like than traditional alloys so they give/absorb more energy instead of transferring torque spikes that can shear (and cause a loss of traction). A well designed axle is thinner than the splined ends with a gradual taper and no grooves.