Crack in bell housing

[AustHaflinger]

I could be wrong but I thought that once the gearbox was pulled apart you needed jigs like these to put the gears and shafts all back together.

I believe the above pics come from a post on this forum a few years back on rebuilding the gearbox so if you find it I am sure it will be helpful.

Garry

[Adam]

Oh shit!!!!! Way out of my league!! Have transmission out and right hand swing axle off, having dramas with left, have it loose but something seems like it is stopping it?? Do I have to do anything with diff lock actuator or does it just pull out????

[Adam]

Sorted!!! Fingers crossed for welding now!!!

[heinkeljb]

Well done!

I hope you can find an expert at Ali welding now. Take some pictures of the cracks now that you have the transmission out and you can get to see all of it. Some cleaning to remove the paint so the cracks stand out would help. I, for one would like to see where and how far the cracks run.

I am still trying to figure out how they got there in the first place. If the engine had taken a bash, that should have destroyed the sump of the engine not the gearbox.
So I would like to see where the cracks are to try and work out where it could have been bashed in order to cause the cracks. The other possibility is that the casting was poor to start with.

John

[AustHaflinger]

Was the crack welded on the inside of the bellhousing as well? Also is there any obvious reason in painting the gearbox bell housing black - was the whole thing painted or just in the weld area.

I hope it all goes OK

Garry

[Adam]

Whole chassis has been painted black, but of a duly overhaul!!
Bell housing was only welded on the outside and cracks aren’t obvious on the inside, although they definitely go right through as oil was visually weeping through cracks. I didn’t get any good photos of existing weld and cracks as I was in a big rush and vehicle has been left at mums place. I have some reasonable contacts who can hopefully put me in contact with experienced cast aliminium welders. Will try get some photos up soon. Everything looks great inside diff from what I can see, really don’t want to strip gearbox!!!
Thanks for everyone’s input,
Adam

[AustHaflinger]

While it is different, repairs to aircraft fuselages always include the use of a doubler plate to reinforce the repair.

So when the crack is welded up, on both sides, I would see if a thin plate (doubler plate) could be welded over the weld to reinforce it - ideally on the inside but there may be not be room. If not is these circumstances the cracks often come back next to the new weld.

Garry

[heinkeljb]

Talk to whomever you task with doing the repair welding about what Gary has mentioned. A cleaned up weld back down to original material level, then a thin Ali plate shaped to fit. Seam welded and possibly with some hole drilled in it so it can be "spot welded" to provide additional links between the extra "new" material and the old would help. If done on the inside, don't forget to take the flywheel dimensions with you to ensure it will fit!
If done on the outside not such a worry, but make sure you can get a spanner to all the bits that require it. Also try and make sure they know that the clutch lever really ought to stay in line where it is!! Wouldn't do to have the thing welded and then find the clutch doesn't work correctly because it is out of line and not pivoting correctly!!

John

[AustHaflinger]

The only reason I mention the doubler plate is that the original weld cracked - while the bell housing does support the engine, the bell housing is not all that stressed particularly where the cracks are - if cracks were to develop due the weight of the engine I would expect them around the studs that hold the engine - so something else is going on here.

[Adam]

Taking everything on board, thanks!! Welder is very highly regarded by a friend of the family who has restored plenty of cars! His thoughts were contamination of oil was one of the biggest issues. Said he would do initial weld and then grind that one back out to remove any contamination’s, then re weld?? I will mention the plate idea, anything to save me from trying to dismantle a good gearbox!!!!

[AustHaflinger]

I had a Rover V8 block welded a few years back - it was a straight weld next to cylinder and not heated/cooled as John suggested as it was not possible.

The weld goes down the side about 3 inches as the metal either side of the head bolt hole had cracked. The cracks were ground out on either side of the head bolt hole were cut out through to the water gallery. The entire thing was welded back up and the hole retapped and because the welder considered the new metal was a bit softer you can see a metal insert in the head bolt hole (not a helicoil).

My welder was actually a radiator/air con business and has a highly specialised tig welder for welding thin aluminium radiators etc - as such the tip is water cooled and the unit foot controlled - this results in precision welding with reduced heat transfer. It worked well on my job.

Now on the issue of oil contamination - I had that issue - the area obviously needs degreasing and cleaning but just welding the crack as is will result in failure. The whole crack needs to be cut out right through the bell housing so there is no metal to metal contact where oil can lurk - enlarging the crack so it is about 1/8" wide and you can see right through it and rewelding with minimum heat transfer will be needed.

This was my experience.

Garry

[Adam]

Cheers Gary, will pass on all this info to my welder

[heinkeljb]

Any news on how this is going? Would be nice to know.

John

[Adam]

I will get casing back in a week! Saw weld today and looks very professional and neat!
Am pretty much leaving it up to him as I have limited knowledge in this area and he has come very highly regarded by other restorers. He said the face had warped a little , most likely after previous weld and may have resulted in recracking when tensioning against motor??
He will true it up for me.
Also said something about a solution he covers bell housing in then paints over to check for any unseen cracks???
Hopefully start putting back together next week.

[heinkeljb]

That sounds like you have made use of a guy who knows what he is doing, the liquid he paints on afterwards then wipes the area clean and dry. When subjected to UV light the liquid will glow, so where it has seeped into a crack it won’t have been wiped off so you will see the crack.
Clever heh?

Sounds like he found the issue as to why the previous weld failed - they didn’t bother to check it was all square. Hopefully he will true it up against the differential side plate so not only is it nice and flat, it is also at 90degrees to the differential side plates.

John

[bernard callahan]

I have good second hand gearbox housings and a housing that has had sections cut out so you can set up the shimming when assembling gearbox back together

[Rabbit 16v]

as a subnote relating to the mention of needing jigs, those are only for rebuilding and if you are crafty, you dont need those either. Ive had tow of these gearboxes apart and reassembled them fine without jigs. Being careful and employing forethought about everything is key.