Big bang, lots of bits, no go!

[brewnog]

Hello all,

My SJ410 has just failed. There was a transmission whine on the over-run, then a rattling/shuddering at low revs (at which point I thought getting home was a good idea), and two minutes later, a very loud bang accompanied by bits of universal joint coming through the transmission tunnel.

Looking underneath the car, it seems that the transfer box is intact and working, but the short shaft from the gearbox to the transfer box is smashed up, and I have a very wobbly gear lever and am unable to select any gears. One of the transfer box mounts has also sheared.

I am concluding that the gearbox failed, causing something to jam, and the shaft failure and transfer box failure were secondary events after the gearbox failed.

So:

1. Do you agree that it sounds like the gearbox has failed?
2. Where can I get another one? It's a 4 speed and I'm not interested in upgrading it.

Any wisdom would be gratefully received!

[ScottieJ]

It's more likely that the UJ failing has damaged the gearbox to be honest.

Have you removed the intermediate shaft and then tried to select gears?

If the gearstick is very wobbly then chances are the locating bolt has snapped, you need to undo the small 12mm bolt behind the gear lever and see if you can get the machined end of the bolt out that way, if not you'll need to pull the gear lever out but be careful not to drop the broken end into the gearbox. these are robust little gearboxes so sudden failure is very rare.

I should have a 410 gearbox I could send if you do need one, I'd do a bit more investigation first though, it might be ok.

[brewnog]

Thanks for the quick reply. I've got it in the garage and am now taking it to bits.

The short propshaft from the gearbox to the transfer box has failed, and this has smashed the gearbox casing (at the selector unit) up so this explains why I can't engage any gears. It does mean I'll be needing a new gearbox casing at least.

So why did the short propshaft fail? I have now found that most of the transfer box mounts have sheared, but this seems consequential to the propshaft failure.

[brewnog]

Right, the gearbox internals seem okay (all gears can be selected) but it's been smashed by the failed intermediate shaft as per the photos below. The transfer box rubber mounts look to have been sheared for a while, so I guess all that wobbling about took its toll on the shaft universal joints. So I need new mounts, a new intermediate shaft, and a new gearbox. Argh!

[ScottieJ]

Ouch! That's not the first time I've seen it rip the back of the gearbox off though, happened to a guy on another forum I go on a whole back.

the tbox mounts wouldn't have helped but after a 10+ years in service the bearings in the UJs can go dry then wear out and fail, must've been on its way out for quite a long time for it to fail completely though, I'm surprised you didn't notice bad vibrations pulling away and driving.

UJs for the prop are about £25 new for a good one, is any of the intermediate prop still useable? Or has it destroyed the yokes?

[brewnog]

It's given the yokes on the 'drive' end of the shaft a good walloping; I would be more comfortable changing the whole shaft out.

I did have some vibrations pulling away, but they only started about 2 miles before ultimate failure! Then again I haven't had the car long enough to 'tune in' to normal/abnormal noises.

[Darrell]

"So I need new mounts, a new intermediate shaft, and a new gearbox. Argh!"
And new underpants looking at the transmission tunnel.
When a UJ fails completely it can do a lot of damage, I've never seen one break the gearbox though. The only one I've seen completely fail was the rear prop one from the transfer box, this smashed the transfer box apart and chopped through the wiring loom.
As you said the transfer box mounts letting go put extra stress on the propshaft.
Hope you can get it sorted.

[brewnog]

Thanks Darrell! Pants are in the magic basket...

[ScottieJ]

Yeah I was just thinking when you said that you only had it for a month that you might not know quite how they should be normally. I think the main section of the prop would be ok looking at it in the pics but ill see if I have one anyway for you.

[Darrell]

You can get a bolt through type of mounting that are stronger, but can't say if there any good or not.
I know Dave at http://www.llama4x4.com/page5.htm has them and has a good reputation.
The intermediate propshaft shouldn't be hard to find, there's a few guys selling parts in the classified section.

The 2 that Dave sells.