casing check

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casing check

Post  daz.h on Tue Jun 29, 2010 2:59 pm

this happens to be a weak point on the vega's check yours before rebuilding.
this was unfortunately not spotted untill the casing had been polished and powder coated in a clear laquer.
this weak area is where the end plate bolts down Crying or Very sad
its not hard to rectify, as long as you know a competent welder.
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Mine too

Post  Steve G on Tue Aug 03, 2010 12:20 pm

Finally after years of sitting I finished the restore on my 68 Cometta only to fill up the gear case and have it drip from the same crack you show. I opened the case back up and pulled the transmission out and welded the crack from the inside. Put it all back together and it still leaks. It appears that the crack runs into the hole where the alignment pin on the gear set fits. I may have to tear it back apart and fill that hole and then redrill it out. Do you have any other suggestion? I could weld the outside of the case but that would be rather ugly. Steve Greer

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Re: casing check

Post  daz.h on Tue Aug 03, 2010 3:42 pm

nice cometa, weld it from the outside, grind the crack out and fill.
if done well and tiedied up it should be very hard to notice, especially as its mainly hidden by the rear wheel.
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split casing..

Post  Lee on Thu Aug 05, 2010 4:15 am

Yeh Daz mines split also... Shocked
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Re: casing check

Post  Godfrey too on Sat Oct 27, 2012 12:41 pm

Yes checked my cases before building but still missed it. Same place but not so obvious. Oh well strip it down again.

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Re: casing check

Post  littlewilly on Sat Oct 27, 2012 3:36 pm

A word of warning gentlemen, All this talk about welding Lambretta casings
being straightforward, especially used one's! - is completely untrue. in-fact I cannot think of a
more suspect welding operation (off-hand) For all these reasons :
!. the casing is the main and only suspension arm, everything either runs off it, or is loaded on it.
2. cast aluminium is very porous and the zones of thermal disturbance which any kind of welding
causes around a weld, can easily make several of the small bubbles inerrant in cast aluminium
form into a large bubble and baring in mind that the whole c/case is a load bearing member,
a weakness like that in the metal is just unacceptable.
3. USED C/CASES,
on used cases the situation becomes considerably worse, as mentioned before cast aluminium
is very porous and there are thousands of small bubbles in the metal, being porous also means
that the used case's metal has absorbed oil,fuel, water etc.
this makes the metal spits back when you attempt to weld it, also it causes what are called
slag-inclusions and it's impossible to completely remove these absorbed foreign inclusions and
slag inclusions are very very bad strength-wise.
4.Insurance,
If an insurance company know or were to discover this type of repair, they may decline 2
insure or ask for the repair to be x-rayed before offering you cover.
If they were to discover it after an event, they would not pay-up on any claims made.

5. qualified as a radiographer in this field, I can tell you that a competent, time served,
welder would have about a 1 in 5 chance of passing an x-ray test attempting this work.

Just 4 interest I am also an A.P.I. A.S.M.E & Lloyd's coded Welder my company has,
@-times displayed test pieces of my work around the world, as examples of welding.



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Alternative Process

Post  littlewilly on Sun Oct 28, 2012 1:41 pm

An alternative method is to use the a relatively new process in welding which is an
odd cross between brazing, bronze welding and soldering. it is 4 times stronger than
aluminium and does not melt the base metal, an so does not have a surrounding
zone of thermal disturbance to worry about. Also the process does not cause
enough heat to turn the absorbed foreign inclusions in the case into slag.
It's much harder than aluminium and so is also ideally suited for repairing damaged
threads, making them stronger than the original ones.
many of you may be amazed to know that no welders services are even required,
as this is very little harder to acquire proficiency @ than soldering and may well
be one of the most useful skills you ever acquire & costs are quite low.
There are many how-2 videos on utube now - please follow the link 4 more info.

http://www.youtube.com/watch?v=G7yuIiZd0Ts

Remember to cut a v trench well beyond the limits of your cases fracture with a
suitable rotary file, then heat the casing and steam-out the crack with a domestic
type steamer to remove as much trapped crap as possible n' give it a few hours 2 -
dry-off before you begin your repair.


http://www.frost.co.uk/automotive-welding-tools/lumiweld-kit-10-rods.html?gclid=CLqcxMb817ACFYQMfAodOx7Pzw

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Re: casing check

Post  Godfrey too on Sun Oct 28, 2012 3:54 pm

When I get some time I will try this myself on some old Li cases. Have checked out the reviews for the durafix system and it sound too easy to be true but worth a try.

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