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ET: Engine (Twin) Chopped engine, reunited with original gearbox.

greg brillus

Well Known and Active Website User
VOC Member
Well this is a very scary topic.........has anyone done it, with any success. Or is the grief of trying to do it way over the top. The welding, massive distortion, not to mention the large chunks that are missing, cut off and thrown in the bin.........Does it remind you of when the Titanic broke up at the surface, basically split in two with large chunks spread out over the ocean floor........I am asking in all seriousness.......... Any comments or pictures of said repair would be great to see. Cheers............ Greg.
 

vin998

Well Known and Active Website User
VOC Member
VOC Forum Moderator
I know Bob Dunn has achieved it in the past in UK but I don't know what problems occured along the way. There is also a Shadow in Australia which has had the gearbox reattached, but again I don't know if there was any major problems.

Simon
 

Chris Launders

Well Known and Active Website User
VOC Member
I suppose it depends on how much is missing, if you could repair one so it's a good match to the other before joining I would think its feasible, joining and then filling in the missing sections would give too much distortion I think, the good thing is they are primary chain drive and not gears so you have some leeway.
Try calling Allen Millyard, see how he joins engine cases.
 

Vincent Brake

Well Known and Active Website User
VOC Member
I made meself a tick dead flat steel plate 30mm.
Bolt up all mating bolts with M6.(sorry marcus 1/4) so it gives a bit as steel/alu diff expansion
Than when welding to be done. Heat it up.to 250 or so.
Weld
And slowly cool down.
Nice thing is one can determine position really good.
But remachining is def. Necessary.

But going the efford is not my decision. But yours.
Not done by me yet2020-05-26 20.43.03.jpg
 

Nigel Spaxman

Well Known and Active Website User
VOC Member
Well this is a very scary topic.........has anyone done it, with any success. Or is the grief of trying to do it way over the top. The welding, massive distortion, not to mention the large chunks that are missing, cut off and thrown in the bin.........Does it remind you of when the Titanic broke up at the surface, basically split in two with large chunks spread out over the ocean floor........I am asking in all seriousness.......... Any comments or pictures of said repair would be great to see. Cheers............ Greg.
I have a set of castings un machined intended especially for this job. I acquired them with the intention of welding them back onto my chopped cases, but have since decided to weld on an HD Sportster gearbox and primary more or less the way Chriss Knibbs did. If you want these castings tell me and we could make a deal.
 

vibrac

Well Known and Active Website User
VOC Member
What you really need is G200/1 but everyone is out of stock at the moment;) once those old featherbeds rust away the demand will return:D. Here is the only one I have seen
1590588098390.jpeg :p
 

greg brillus

Well Known and Active Website User
VOC Member
Thanks for the replies guy's........yes i don't think it has been a common thing to reunite an engine and gearbox. It is probably far too much work to carry out unless the engine is a rare one or you are able to carry out the repairs yourself. My thoughts are that you really need to jig the crankcase and gear box half as a pair and be able to get to the inside and outside.........If you did it this way, I feel the distortion would possibly be less, as you could alternate the welding from the inside and outside a bit at a time. I have 3 chopped crankcases, one original gearbox.......one of the cases is a genuine series "B" Shadow engine.........it is the one where the entire section of the inner primary housing has been cut off........this is the case we want to reunite with the gearbox.
 

Black Flash

Well Known and Active Website User
VOC Member
If I remember correctly, Bob Dunn had castings made that he welded back on.
Maybe worth a try asking him. Probably best to write a letter.
 

Pushrod Twin

Well Known and Active Website User
VOC Member
Yep, it's scary! Hence my reluctance to follow through with the idea. I think Vince's idea of using a thick jig plate is smart, but I would lean towards making an aluminium one for exactly the reason he recognised, it will expand at the same rate as the casings. Vince also recognised the process required, pre-heat, weld, post cool. The original Vincent case material actually welds quite well.
Then there is the decision to be made regarding post weld heat treatment. This was the part which scared me off as I was heat treating aircraft parts during the period of my career when I started work on my B cases. Heating the serviceable engine front half case to something near 500 C and biffing it in a tank of water knowing that it was going to change shape put me off. I could never be sure that the distortion could be machined out of it.
 

Vincent Brake

Well Known and Active Website User
VOC Member
Yes one can skim the whole lot.
Cylinder surface and mains in one go.
Never more as 0.3mm..
I have done about 5-6 cases both the ugly whoop whoop warping D...
But only once i had to sand the mating faces by total 0.5 mm.
That took some time.
Than after done all saw the gear selector silly half bevel thingy needed to be 0.3 mm deeper.

Of course only saw when whole lot was joined....

Learing curve...
 

Phil Davies

Well Known and Active Website User
Non-VOC Member
Sorry to be a late starter to this thread.
Bob did not make any castings.
What happend was a customer had a set of brand new cases and he wanted to remove the gearbox and for Bob to build the engine, which Bob did, Bob being Bob he kept the 'new' gearbox shell as a curio.

Subsequently an owner from Norway with a chopped Shadow engine asked Bob if it was ever possible to find and attach a gearbox back on for a standard chassis set up - Bob produced the 'new' gearbox shell and duly set about welding it on to the Shadow engine. Bob had to shorten an original outer chaincase by 1/32 from the middle to make it fit the repaired engine - what a fantastic achievement.
I saw the finished item and you had to look very hard to be able to know!
That was Bob at his old usual outstanding best, happy days.
 

Cyborg

Well Known and Active Website User
VOC Member
Do you know what Bob used for welding? Oxy acetylene or TIG?
 

Phil Davies

Well Known and Active Website User
Non-VOC Member
I know he did use a lot of 'warming heat' to reduce temperature differentials and hot spots and welded in precise short runs at a time, the welder was a TIG welder (you would not use anything else really), which make of welder I cannot recall, but it was big and did look like something from a Star Wars space ship flight deck, which Bob said allowed him to weld anything he wished, how he wished.
 

Cyborg

Well Known and Active Website User
VOC Member
It would have been interesting to watch. I assumed it would be TIG, but I do remember my oxy acetylene instructor welding up cast aluminum. I will never get close to his level of skill. I imagine you would need a fairly healthy TIG along with a water cooled torch to tackle something like that. Maybe some helium added to the mix.
 

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