Driving Without Gearbox Oil...

[jonah 1]

I fitted a Quaife ATB diff a couple of weeks ago, and gave it its first proper test on the Plains Rally in Wales yesterday.

 

Was going fine until a short way into an 8-mile stage when I suddenly got a strong whiff of gearbox oil. The smell disappeared after a few seconds so I hoped it had been a puddle of oil left by someone else, and carried on at full pelt. Wasn't until the stage finish that I knew for sure that something was wrong, as the smell came back when stopped and with the helmet off I could now hear the gearbox whine (couldn't hear it on the stage above the gravel noise).

 

Had to do another 5 miles on the road before meeting our service crew, so took it gently, coasting with the clutch down wherever possible, but the whine was getting worse and it started getting difficult to select gears. The most worrying thing was that a couple of times when it wouldn't go into gear, I let the clutch out in neutral and heard a clunk, as if the gearbox input shaft had momentarily seized and letting the clutch out had unstuck it.

 

Soon found the problem once we'd stopped - the drain plug had fallen out!! So the loss of oil would have been sudden and complete.

 

We plugged the hole with an undersized bolt wrapped in duct tape (!), refilled the box and got going again. Have done about 250 miles since then, it all feels ok but there is definitely more gear whine than before. The new Quaife diff still seems to be doing its thing, thankfully.

 

The question is though, is this box now likely to fail at any moment? Anyone else run their gearbox dry and got away with it? I will of course drain it again and refill it to get as much of the swarf out as possible, but would I be better off just scrapping it and getting a new one?

 

Thanks,

Jonah

[matt1900 0]

hard to say what amount of damage has been done, but if it carries on whining like a bitch it must have sustained some, and the whine would get on my tits so i'd change it.

[cybernck 400 1 Cars]

i've had this many years ago when a mechanic forgot to put the oil in after the mi16 converison.

 

the gearbox had sounded all rattly, that's how we discovered it.

 

five years and many races down the line, i just want to replace all the shaft bearings.

 

haven't ever had any whine though .

[Miles 331 1 Cars]

The gears run on a plain bush and these are known to weld themselves together, There are neddle roller bearing mod's to avoid this but this is only really needed for C/R gear sets,

Other than that the bearing's could have lost some of there case hardening and or the Syn hub's could have melted as they are only ally.

If you need a hand let me know.

[pugpete1108 62 1 Cars]

you were a bit lucky i think, (the car i own) previous owner (freind of mine) went over a road cone and without checking had ripped a big hole in the g/box, and drove round like it for a couple of weeks , when took it to a garage they put new oil in and it pis**d out oil filled with metal shards ,needless to say the box was shagged. still probably done some lasting damage by the sounds of it

[jonD6B 0]

I personally would make sure it is well flushed out and continue to use it as long as the gear selection is still smooth. It depends on how competitive you need to be and whether you can afford to take the chance. I would imagine that the box is going to wear alot quicker now than before though as you will have probably scored the shaft and bearings slightly.

[jonah 1]

Thanks for the replies, the whine isn't too bad at the moment (the rest of the car is noisy enough anyway!), don't like the sound of welded bushings though, maybe that's what was happening when it was starting to seize up Synchros should be ok as I never tried to force it into gear.

 

I think I will just flush it out and drive it around for a while to see if it gets any worse, gear selection is ok at the moment. And keep an eye out for a spare 'box in the meantime. Really hope I haven't cooked the diff though, they are not cheap...

[Anthony 1,000]

My old 405 'box I found to have no oil in when I eventually broke the car, and it had never leaked a drop in my 11000 miles of ownership - and the guy before me had never touched the gearbox oil either.

 

Apart from the synchro in 3rd being completely shot and 2nd/4th synchros on their way out, the box still plodded along and worked, although the rattle it was making at idle with the clutch out was appaling...

[jonah 1]

Hmmm well that's some reassurance I suppose, but it must have had SOME oil in it to last thousands and thousands of miles!?? Mine was noticeably degrading over the space of 5 miles on the road section!!

 

Will try and lockwire the drain plug for next time - I think it came undone because it is constantly bashing against the sump guard when the car is being shaken around. Or I might have just forgotten to tighten it when I fitted the diff thought I had though.

[jackherer 543]

Hmmm well that's some reassurance I suppose, but it must have had SOME oil in it to last thousands and thousands of miles!??

 

my mate forgot to put gearoil in his 205 and covered a lot of miles over quite a long time with it totally dry. When I took the bolt out not one drop came out! It had run fine up to that point but about 5 miles after I put the oil in the synchros started clunking in most gears.

[Baz 421]

Bono ran his 306 for around 18 months with just some Molyslip thick grease treatment stuff, but no oil!! Was on its way out anyway before then i believe, sounded rather 'motorsport' but still worked fine all those miles and didn't seize etc! Finally gave up the ghost and started to lunch itself on the way to Chepstow for the Wales Motor Show last month, then promptly let go of it's innards out the side as he got near home, luckily!!

[Turbo7379 3]

Considering that you've just spent a lot of money on the quaife diff I would fit another gearbox . If the gearbox starts to break up it could send bits of bearing/syncro/gear into the quaife & wreck it as well . Makes more sense spending £100 on a gearbox rather than £500 on another diff .

[richard 0]

I too have had the sump plug pop out.

 

I'd like to know why it can be forced out to be honest. I know its a pressure thing, but what is causing the pressure? something mechanical in the first place?

[welshpug 1,627]

doubt its a pressure thing as theres a vent in the top.

 

hit something hard enough or nor replace the copper washer or just not torque it up properly (that includes over tightening) can all cause it to come off, being a rally car all of these are possible!

[davemar 16]

If the plug had been cross-threaded in the past it may have weakened the thread in the gearbox casing.

 

I once had my diff let go on me (one of the planet gears exploded in two) which ripped a hole in the casing and let all the oil out. The car was still driveable, so I just kept going for 100 miles until the noises got too disturbing and let the nice recovery truck take me home. I'm sure I could have driven further, but I prefered to break down by a pub rather than in the middle of nowhere! That was pre-eBay days when replacement gearboxes were still really expensive though.

[jonah 1]

I'm pretty sure I know why it came out - as I said the drain plug is always knocking against the sumpguard (it's worn a good sized gouge out of the guard over time), so that must have loosened it, and once it's loose it will just work its way out from the vibration and the weight of the oil behind it. It was not cross-threaded, it had a copper washer, and I'm pretty sure I had torqued it up properly. It's definitely not a pressure problem - even if the vent was blocked it would take an unimaginable amount of pressure to pop a drain plug out of its thread!