Bang/crunch whilst driving

[Mitching]

I was just driving, only left the house 2 minutes and as I was driving along a road (30mph, 4th or 5th gear) and the car sort of jolted and a crunching bang came from the engine bay.

I pulled up at a red light and was going to pull into a little retail park so I could check it out, and as I pulled off the gearbox was a bit crunchy, I was being careful with the clutch so wasn't sure if it was slipping or not.

I had a brief look in the engine bay but everything seemed normal, nothing was smouldering or sticking out where it shouldn't be!
I gave it a full service about 4k ago so all plugs/leads/caps/filters are new, and the clutch has been on there about a year.
CV joints are nearly a year old but the driveshafts can wobble side to side, hub to gearbox direction, is that normal?

The gear box crunches in second and a bit stiff getting into first, so could it be that?
Or something a bit more sinister like the cambelt wearing ready to snap?

[Mitching]

Oh, but once I pulled into the car park, switched the engine off and looked in the engine bay I then careful turned around and drove home and there were no more problems... 

[Sam]

Sounds like it simply popped out of gear to me, was the bang an engine bang (heard from the zaust too?) or gearbox bang

[Mitching]

I imagine it was just the gearbox, I don't think any noises came from the exhaust.
I just took it around the block and there's a bit of a whine coming from the gearbox now at higher revs.

Maybe I'm just being paranoid!

[clipperjay]

When was the gear box oil changed last?
Do it and check for any swarf from the oil.
If its clear nothing to worry about there are bits then investigate further.
New oil, jack 30 mins job done 

[Mitching]

I haven't changed it during the 15k I've done in it since I got it 
I'll give that a go over the weekend, how do I change the oil?

[clipperjay]

Its on the side of the gear box massive 19-22mm nut if I remember correctly!
Drain it side ways first i.e drivers side jacked up first, then jack the passenger side to fill up thats the hard part trying to squeeze as much oil in the hole as possible until it starts to leak out by itself.
Once it looks like you have overfilled (i.e it starts to pour out of the hole itself, thats the right amount of fluid in there. I use a ramp much easier TBH, but a jack and axal stands will suffice!
If you have some pipe you can attach it to the feeder oil bottle and stuff the tube further in to get as much fluid as possible in there!
 

[Mitching]

Cheers
What oil should I get?
Would halfords be ok or should I get some from a stealer?

[clipperjay]

Cheers
What oil should I get?
Would halfords be ok or should I get some from a stealer?

Valvo line is good stuff just get the correct SAE rating search on here I can't remember the rating off top head.
Upto U stealer prices or aftermarket oil is oil to me if its the right rating I use it.
When you are down there try and see if the gearbox mounting is tight I'm guessing the mount might be loose it only a few bolts check them anyways!