Chipped Gearbox Repair advice needed

[PerthMgf]

Hey Guys,

As some of you may recall, i unfortunately had a front end smash in my MGF and have been waiting for a donor car for about 3 years (preferably one with good body work but blown engine).
Well, I just managed to get my hands on one (not as easy as you may think in Australia) Engine is actually OK but gearbox has a chip out of it (slowly leaks oil)

See pictures below.

So... my plan was to swap the gearbox - then i thought id just swap out the rear sub-frame engine and all. But obviously, i thought it was easier than it actually is. so i did a bit of goggling.
Google informed me that JB Weld may be just the thing i need, and while it certainly sounds a little crazy, I'm actually thinking of giving it a go.

The gearbox is Aluminum right?

Any advice guys ?

[stuart]

In my opinion that gearbox is scrap- would advise swapping the entire assembly in one hit from your known good components off the old car- especially as it's a subframe off job to swap the gearbox anyway

[daz]

I, on the other hand have jb welded a gearbox in the past & it lasted several years till I scrapped the car, you pay your money, you make your choice, I wouldn't have travelled very far in it though & never really trusted it.

[PerthMgf]

In my opinion that gearbox is scrap- would advise swapping the entire assembly in one hit from your known good components off the old car- especially as it's a subframe off job to swap the gearbox anyway

Thanks Stuart - Would do this if:

A) had the right tools/space/experience
B) was planning on keeping the car

Thanks for the advice.

[PerthMgf]

I, on the other hand have jb welded a gearbox in the past & it lasted several years till I scrapped the car, you pay your money, you make your choice, I wouldn't have travelled very far in it though & never really trusted it.

Thanks Daz

Any advice on how best to clean/prep the area?
Also, would you use something to cover the gap first then apply jb weld?

How did you do yours?

[daz]

mine was a long thin split, from memory I cleaned it up with white spirits then just jb welded it along the length & left it for quite a while to make sure it was properly hardened before I filled the box up & used the car. I'd definitely find something to bridge that hole though, but, as I said I never trusted the repair I did on mine, even though it never went again it was always in the back of my mind

[Rob Bell]

I'm with Stuart here - you don't know how long that donor car was run without an adequate oil level, and therefore the bearings may be on their way out (although the PG1 is surprisingly tough old unit).

JB Weld and its ilk are never quite the miracle cures they propose to be: difficult to judge the size in the photo, but I'd be worried any material would simply fall out.

It might be adequate to get a quick sale if that is the target, but perhaps provide the new owner with some spares?

[willyphixitt]

You can get aluminium welding rods/kit as a diy project. I have successfully repaired an alloy carburettor many years ago. I didn't do a particularly neat job (my first time) but the repair is still good to this day.

Have a look here:-http://www.howtoweldaluminum.com/

willyphixitt

[nismo]

Another vote for Stuart on this one.

[stuart]

I think it's quite different to weld up a small crack- drill each end of the crack so it doesn't spread and shamfer along the crack to get a good strong weld- however even doing that i'd want the gearbox off the car to do a proper job.

The damage is just too extensive and too far gone to do a proper job, especially as presumably you'd want to do it in situ too- very difficult to look a prospective purchasor in the eye and take their money with any sort of confidence.

If you lack the skills necesary to do a subframe/running gear swap, then please don't even contemplate welding up a cavernous hole on what is a knackered gearbox and then pass it on to some poor unsuspecting bloke who would have paid you his hard earnt and then has the problem of fixing it properly..at least be up front and honest when you pass the car on- it's only fair buddy.

[Dell]

I work in the the white goods service industry & this stuff which is little more than epoxy putty has been around for years. It is actually very good & I have seen it used to repair punctured refrigeration systems in the past & it is currently used by manufactures to repair holes in washing machine drums above & below the water line among other things.

Having said all that I would echo what has been said previously if you thoroughly degrease the area I have no doubt it will seal the hole but it will never be a repair that you could rely on.

[robbie1003]

I have used a two pack material quite a few years ago, think it was called chemical metal, repaired a section of gearbox very well. just have to makesure everything is prepared correctly so the bond takes, can even drill and tap the stuff.

[RobboMC]

Since I have a subframe, engine and gearbox in my driveway in 3 separate pieces I can respond with some level of experience.
Drop the subfame, it's quite easy. Then swap the old gearbox for a replacement one, easier still.

Pop in a new clutch while you are at it. Then you can be sure the car will go for the next 10 years, barring disaster.

Once I had all the engine supply stuff like fuel lines, electricals, brake calipers and the like disconnected we jacked up the car and had t
he whole subframe with engine and gearbox attached out of the car in about 2 hours.

I see you're in Australia too, I'll pm my phone number.

I once snapped part of an aluminium bell housing. It is possible to properly weld up an aluminium casing using Argon arc welding.
That would require the gearbox to be removed and the casing stripped out. So don't go throwing the whole box in the bin just yet.
I wouldn't just be glueing it up though, needs to be repaired with proper metal.

[Rich in Vancouver]

I have plugged holes in engine blocks with JB Weld, drilled and tapped it to install a thermostat housing, and even used it to repair a rifle sight.
It's amazing stuff! They also make a "Marine Putty which I used to plug a leak in a fuel tank, then fiberglassed over.
If you do use it, even in the short term, it's not a bad idea to stop drill the cracks then rough the area up with sandpaper and clean it with something like lacquer thinner before applying the JB Weld.
For a long term repair I agree that a gearbox swap is the way to go