Redherring Posted March 6, 2012 Share Posted March 6, 2012 The gearbox in the photo is from my 4-6 ton RAF-family Leyland. It's the only box I have. Two of the aluminium gearbox-support castings are broken. Of the similar Leylands in Australia, at least two others have the same problem, and have been given very 'ugly' fixes. Does anyone have a neat solution to this problem? Quote Link to comment Share on other sites More sharing options...
Redherring Posted March 6, 2012 Author Share Posted March 6, 2012 Better photos... I hope Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted March 7, 2012 Share Posted March 7, 2012 (edited) There are other members of this Forum much more experienced and qualified than I - but from what we have learned, it is very difficult to do a lot with this very old aluminium. We had a problem with the Dennis Gearbox where the cast-in "prongs" to hold the steel pivot pins for the Transmission Brake had either broken away or corroded away - but that Gearbox by the nature of its shape loaned itself to have that aluminium cut completely away and a steel fabrication - not aluminium - bolted to the Gearbox as a replacement. There were flat surfaces available in the appropriate place on the gearbox for the new steel replacement to be bolted to it. Looking at the shape of yours, it seems almost impossible to see an available surface that you could bolt anything to which would also be strong enough to hold such a fabrication - bearing in mind all the stresses that would be placed on it in use. We found from experience that it is impossible even to repair an old aluminium Radiator - despite all the great trouble that we went to, to seal it on the inside. It still leaks and when we get around to it, we must make patterns to have new top and bottom tanks cast. Again, I must stress that I am not an expert and although I understand that it is possible to weld aluminium, this very old aluminium is not really good for that. I hope that perhaps now, the knowledgable and professional members of the Forum might come in and comment and advise but unless you are fortunate enough to find a better gearbox I reckon that you might have to bite the bullet on this one and do some pattern making so that a new case can be cast - and then machined. Not good news as machining such a thing is not going to be cheap or easy. I do hope that the professionals will come in now and comment as there is a lot to be learned here! Tony Edited March 7, 2012 by Minesweeper Quote Link to comment Share on other sites More sharing options...
8_10 Brass Cleaner Posted March 7, 2012 Share Posted March 7, 2012 Perhaps some sort of steel cage?. Remove the old aluminium lugs, make us some new in steel. Then make up an external frame picking up the studs for the lid, and the studs for the bits and pieces for the output and input shafts, with say a strap underneath for good measure, fixed additionally say with nuts and bolts to the sides of the case also? It would very much be a painstaking job of making the plates to pick up the existing studs, modifying the existing covers etc to suit, then making the framework a piece at a time welding, drilling and painting as you go until it is done. Quote Link to comment Share on other sites More sharing options...
nz2 Posted March 7, 2012 Share Posted March 7, 2012 Looking over the gearboxes here its much the same problem, especially on the lighter 2 /3 tonners. It would appear to be a common fault , in design all those years ago. Somewhere we have seen a gearbox with metal straps about it, but are unable to locate any photos at this time. This was a repair undertaken many years ago when the truck was in service. One thought I have had was to cut the broken lug off and rebuild another in its place attaching it with bolts right through the casting, from inside the gear box. This is just a thought , having not removed the top cover to check as to clearance inside the box for the mounting bolts. Doug;) Quote Link to comment Share on other sites More sharing options...
Old Bill Posted March 7, 2012 Share Posted March 7, 2012 You have a nasty problem there! As Father says, nearly all of this old aluminium won't weld due, I believe, to excess zinc in the mix. (Put me right somebody!). However, just occasionally, you get a batch which is OK so it might be worth having a gentle go at a corner to see what happens. If it looks promising, you could make up some lumps to weld on and then machine them back. Failing that, I would feel inclined to dress back the broken area to a nice flat surface and then make up a steel replacement to bolt on. It will be a really weird shape and will have to extend in all directions to give you enough bolts to spread the load into the case. I would also dowel it onto the case as well. It will be a very painstaking exercise to get a good fit as the box is such an awkward shape but you will be able to do it with care. Look inside the box to see what space you have for bolt heads. Also, I would recommend split pinning the nuts to avoid any risk of them coming loose and falling inside the box, potentially spoiling the gears. This case is not beyond hope but it will take a lot of care and persistence to bring back. Good luck! Steve Quote Link to comment Share on other sites More sharing options...
Redherring Posted March 7, 2012 Author Share Posted March 7, 2012 Tony, Doug, Steve, et.al. I shall certainly attempt to make repairs before I go down the path of remanufacture. Thank you very much for your thoughts. Robert Quote Link to comment Share on other sites More sharing options...
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