lost drive in second... what's likely to have failed?

[Mini-geek]

Recently had my gearbox let go, I've got drive in 1st but making a lot of metal churning noise, and no drive in 2nd....

that's all I know I've not tried any other gears, I switched it off straight after (I was on track when it went with a bang, I'm sure I was in second when it went) there was a bit of a whine for a bit beforehand

hoping I can get an idea of what I'm going to need to fix it before I strip it down.

[minibitz]

Any answer you get is purely going to be a guess. You will need to do some investigation yourself to find the answer.

Could be a simple as a pot joint popping off the output flange if running that style of axel to broken gears etc. Start with an external inspection and if nothing shows then it's a motor out and strip down.

Once you can see the gearbox internals it will be pretty obvious what's come adrift.

[Mini-geek]

It’s not a pot joint, that’s the first thing I checked.

[EMOKID]

Jack the car up on passenger side and drain oil out. If you have a magnetic sump plug you may find cuttings on plug or in oil. Once drained try using one of the small extendable flexible magnets to poke around inside gear box for any shrapnel. However fairly sure it is an engine / gear box out job.

[Mini-geek]

Jack the car up on passenger side and drain oil out. If you have a magnetic sump plug you may find cuttings on plug or in oil. Once drained try using one of the small extendable flexible magnets to poke around inside gear box for any shrapnel. However fairly sure it is an engine / gear box out job.

Oh it’s definitely an engine out job it will need a full rebuild thanks to the the shared oil being contaminated

I was hopping someone might be able to give an indication of what’s likely to have failed either a the selection mechanism or the teeth..

[Oneball]

I’d guess you’ve stripped the teeth off second.

It goes into first so selector is working and as it’s shared 1/2 probably not an issue.

The synchro hub is also shared 1/2 so if you’ve got noise when in 1st it’s unlikely that the 2nd part of that would be touching anything to make noise and as it’s transmitting drive in first probably not the mainshaft itself.

As it makes a noise in first and is a constant mesh box so second is always turning with the laygear even when not transmitting drive, second gear could be stripped.

[Mini-geek]

I’d guess you’ve stripped the teeth off second.

It goes into first so selector is working and as it’s shared 1/2 probably not an issue.

The synchro hub is also shared 1/2 so if you’ve got noise when in 1st it’s unlikely that the 2nd part of that would be touching anything to make noise and as it’s transmitting drive in first probably not the mainshaft itself.

As it makes a noise in first and is a constant mesh box so second is always turning with the laygear even when not transmitting drive, second gear could be stripped.

thanks so there's a good chance the synchro hubs will have survived? I take it they'll be ok having run in the contaminated oil ?


Im planning on fitting a full gear set (http://www.minispares.com/product/Class ... 77EVO.aspx) I'm just trying to gauge how much this is all going to cost and if I can get it all done before the MK1 action day.. I can't strip the engine for a couple of months

[Oneball]

I wouldn’t like to hazard a guess. Problem is that even if I’m right about the stripped gear it doesn’t explain the why.

[GraemeC]

Does it have drive in 3rd or 4th? (put it in gear with plugs out and see if pushing it turns the enge over)
Does the speedo work? (You'd need to be brave and run it in gear with the wheels off the ground)

Could be the pinion come off the end of the main shaft
Could be a stripped gear or layshaft

[indigo]

Not sure of the fault, but stripped 2nd gear sounds logical.
However; regarding your budget, if you are planning on the new gear set I would also allow for a 1/2nd synchroniser, as i find these are one of the high wear items in the box. 3/4th assemblies have a longer life. Then there are all the bearings, syncro cones, etc.

[Mini-geek]

Does it have drive in 3rd or 4th? (put it in gear with plugs out and see if pushing it turns the enge over)
Does the speedo work? (You'd need to be brave and run it in gear with the wheels off the ground)

Could be the pinion come off the end of the main shaft
Could be a stripped gear or layshaft

Not tried 3rd or 4th
I didn’t notice if it was working to be honest

I’ve had a tooth come off the crown wheel once before this felt very similar, when I tried to move to a place of safety it definitely felt like a chunk of metal when through a gear mesh

[Tim]

I had something similar once. First the gearbox got noisy (I was interstate, with two long drives seperated by an overnight ferry crossing between me and home). Then it started to get difficult to select gears. I managed to nurse it to the ferry and get on (phew, at worst we can roll it off at the other end) then gently get it off, getting noisier all the time. I carefully drove the last 300km home, with it getting notchier and sicker all the time. Next day, almost exactly as I drove past my mechanic's workshop, I lost all gear selection except 3rd. I rolled it into his driveway and walked home.

It turned out to be where the idler gear bearing runs in the end cover of the gearbox. It was completely flogged out. I don't know why it prevented gear selection but it was fairly catestrophic, but at least it got me home.

Tim