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The car I'm rebuilding (Skoda Estelle/120, 70's, RWD, rear-mounted engine), uses half axles for the transmission, that goes inside housing elements (thick "pipes"). These axles uses pin-and-guiding blocks as link to the differential (housed together with the gear box), and a woodruf key in the conical-profile tip where the wheel hub gets secured. The main problem I always have with this design is that the woodruf key/hub/nut assembly gets loose very often, so I want to try a different design.

The half axles I can have are from Ladas. The design is different: the Lada axle is a typical front-mounted engine with rear transmission. However the bearing is the same and its size gives me room for adaptations.

In the inside tip, Lada's has splines, Skoda has pin-and-guide block. I'm aware about precision that this needs, I know it needs to be done in a lathe, welding by hand turning the aligned parts, etc.

I can

  • cut both axles and weld together the appropriate sides, reinforcing the joint by welding a sleeve, or
  • cut the Lada axle and add a reinforcement ring at the pin side (probably an inner track of an old roller bearing).

The main issue: the diameter in the Lada axle, where the pin hole would be drilled is less than 30 mm; the Skoda's diameter there is 32 mm. So somehow I need to add body or reinforce that tip.

My question is: how should I work the inside tip?

When answering, please keep in mind I don't have access to much more than what I describe.

Engine is 1200cc...See the diagrams I made to support the question:

enter image description here

EDIT: added more pics of what I'm after :)

enter image description here

  • I'm not exactly positive which part of the axle you're worried about? You say the "inside tip", but I'm not positive which part you actually mean. – Pᴀᴜʟsᴛᴇʀ2 May 25 '17 at 1:19
  • I need: Lada axle's outside extreme where the wheel hub gets attached AND the inside extreme either from Skoda, by cutting both axles and welding the parts, or just drilling the Lada's axle and possibly reinforce it because the pin. – Aram Alvarez May 25 '17 at 1:26
  • You are wondering which way would be the best way to go? Sleeve or pin? – Pᴀᴜʟsᴛᴇʀ2 May 25 '17 at 2:27
  • If you weld the parts on the lathe, make sure your earth is connected directly to the part. If the current travels through the bearings it can damage them. Really it is bad practice to weld on a lathe : weld spatter etc but you paid for it so treat it how you want. – Solar Mike May 25 '17 at 6:00
  • Not an answer, just a suggestion. Perhaps it would be another possibility to not weld the axle, shrink fit a sleeve over it and weld the sleeve? Contra: perhaps not as strong as a welded axle Pro: no centering issues – Martin May 25 '17 at 12:03
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I can only suggest this as I've not done it myself nor have I seen it done. I do, however, know your situation, so I believe this is your best bet (considering).

My suggestion to you is to go the sleeved route. The only problem with it will be it should be heat treated after welding is done. The weld will mess with the hardening which is done to the axle when it is manufactured. Know a little bit (but not a lot) about how metal behaves, you'll never get the end strong enough to survive the torque put to the axle if you tried to drill and reenforce. It just wouldn't hold to my line of thinking.

The hardest part about going the sleeved route is centering the two axles. If they are out of alignment even a little bit, you'll get a wobble which will run a vibration through the vehicle when you get it up to speed. You can possibly friction fit a sleeve on there by heating the sleeve and getting it onto the axle fairly quickly. You wouldn't be able to weld the center of the axle together if you do this though.

It looks as though at least the Lada axle side is tapered. This should make things a little easier in the long run. To prepare the sleeve, you want to have some holes drilled into it. You will be plug welding the holes to the axle to create greater grip on the axle. I would cross drill twice (four holes) in each end. Maybe even offset the holes some, maybe 1/2" difference from the end of the sleeve. Ensure the holes are big enough for the plug welds to get some traction. You will want to weld the ends (around the exterior on the end) on each side on the axles. Make sure your tube is at least 1/4" thick, a bit thicker if you can find it. If the one end is tapered, you could possibly put the tube over the tapered end, sliding it toward the narrow side, then weld the two ends together, sliding the tube over the welded portion, then plug weld the holes, then the ends. Heat treat if possible.

This obviously isn't going to be as strong as a solid shaft, but like I said, I understand the limitations of what you have to work with. I really feel this is your best bet considering. You won't get the strength by just welding the two ends together by themselves, nor with putting drilling the end with pin, even with reinforcing it. Would not take much to break it loose.

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I worked these and that part did not work loose often. Either you have excessive wear / damage due to it running loose or it was not tightened sufficiently. The parts need to be clean, then tightened to the correct torque - can't remember the setting but it did need a large torque wrench and you might consider the use of loctite.

This link : http://www.dsw.co.uk/paul/images/tech/Rear%20Axle.pdf

suggests 220Nm for the rear nut.

  • The hubs are a single part that includes the drum, in other words, hub and drums together. They are cast iron as usually and perhaps they are having the excessive wear you describe. As I'm planning for adapting caliper breaks in there, I need to make new hubs and here they use mild steel. Maybe those would fit better, if I clean the original shafts' cone. – Aram Alvarez May 26 '17 at 14:39

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