Gearbox Grinding

[Shawn]

G'day All,

Have just test driven my '58 minor 1000 resto project (original engine & 'box). I'm getting a pretty good grind on gear changes (both up and down the 'box). I want to believe that this is not just worn syncromesh. I know that there is no syncro on first, but all the gears sound the same. It doesn't jump out of gears and has fresh oil, but I haven't touched the box beyond that. Wondering if maybe the clutch needs adjustment? Any thoughts, or just wishful thinking on my part?

[turbominor]

does it stop gringing if you put it in to neutral while the car is driving? or change if you dip the clutch

[Cam]

Try setting the clutch pedal free-play as described in the manual. If it's not opening the clutch enough then it will grind on gearchanges.

[rayofleamington]

A dragging clutch could give a 'crunching' sound as you apply pressure to get into the last bit of the gear. If it is a dragging clutch it needs to be fixed quickly before the synchros are wrecked.

Grinding sounds like something else - are you sure it is not something like the clutch release bearing?

[bmcecosse]

What oil did you use ? Should be engine oil - NOT EP90. What was the old oil looking like when you drained it - black horrible and full of metal bits ? Is there any 'grinding' when you drive along - or just when changing gear ? If the latter - then either the clutch is dragging horribly, or it needs adjusting. If grinding all the time - look for another box - quickly !

[newagetraveller]

The clutch plate should be free to slide up and down the splines on the first motion shaft of the gearbox. If the splines have any dirt or grease on them the clutch plate will not clear properly.

[Shawn]

G'day all,

I think perhaps 'crunching' rather than 'grinding' is the better term. Always going into gears, all the same. RE the oil, I used the same 20W50 mineral oil as I use in the engine. There were about three small slivers of metal when I changed the oil (I was worried about it when I changed it, so I strained the old oil to check - even changed it on a hot day to try and get as much muck out as possible.) It makes no difference wether I pause in neutral, let the clutch out and then proceed. The clutch free travel seems about right as per the manuals (Haynes & BL & SP). However, (and this might be important?) there are three return springs hooked up between the clutch operating rod and the engine plate instead of just one. I've found several bodges by the DPO, this could be another one.

[rayofleamington]

Well if the clutch is adjusted correctly and not dragging, and the oil is correct then I can only guess that the synchros are wrecked.
This can be achieved over a long period by changing gear without using the clutch or by shifting really really fast as this puts excessive load on them. Or they were faulty to start with or wrongly assembled during a box stripdown - or many other possibilities too

The 3 springs seems like the kind of thing someone would do if they thought the clutch hadn't been releasing properly - If you press the brake pedal hard, does the clutch still release smoothly when using one spring? If not then the pedal shaft has run dry and needs lubricating PDQ before you get any more wear on it.

[bigginger]

I'm sure Dan and I are both relieved that you, of course, meant 'darn' not 'damn' in PDQ...
http://www.acronymfinder.com - I like the definition of another favourite TLA as Washington Tennis Foundation!

[bmcecosse]

Usually it's only the second gear syncro that gets damaged - most unusual for third/top to be damaged. Try it with just one sensible spring - and try adjusting the mechanism to get a bit more travel. Could be the carbon ring has worn down and there is not enough travel. You may need to pull the engine out to investigate - or get your hands on another gearbox and do a swap. Is it the later 'ribbed' gearbox ?

[rayofleamington]

'58 minor 1000 resto project (original engine & 'box).

It shouldn't be a ribbed case box.

[Shawn]

Its not the ribbed box. I believe the lot to be the original runnning gear with about 97000 orig. miles on the clock. I've traced her ownership right back to the dealer in 1958, she'd been kept running but hadn't been driven in 18 years when I brought her. Thankfully she'd been garaged the whole time - a very lucky find!

I'll haven't looked at the adjustment beyond a check and clean, so I'll go back over it and make sure it's spot on. I do have a spare engine and gearbox but they came from a non-runner A40 and may be worse than what I've got. Still, I don't have much on next weekend...

[Shawn]

Ok, had a much closer look at the linkages and have found the problem - They are extraordinarilly worn and clogged with years worth of gunk that looks, at a glance, a bit like the surrounding metal. The clutch actuating rod was worn down by about 30% (approx 3mm), the previous link by about the same, Instead of lubricating the links the DPO had just adjusted out the slack, to the maximum possible adjustment. Total wear in the linkages accounts for at least 9mm of free play at the pedal (of 20mm specified in the manuals).

I won't mention that the Dumb Current Owner kept checking the free play on the brake pedal, and wondering why adjusting the nut on the linkage was making no difference...

Upon waking up to myself, I made up a copper bush to fill the wear on the actuating rod, held it in place with a couple of flat washers the same bore as the rod and put the lot back together with heaps of oil. It still requires the ajustment to be at max, but now the gears engage much more smoothly, with only a very slight crunch going up to third.

Can you still buy linkages for Mogs, or am I going to have to make more bushes or get really creative?

Thanks for all your collective help and suggestions!

[rayofleamington]

Can you still buy linkages for Mogs, or am I going to have to make more bushes or get really creative?

You can get all the bits - Bull Motif show the whole lot in their catalogue.
01386 831755