Gearbox advice please - sticking in neutral

PostPost by: RichardS » Thu Jun 21, 2018 6:38 pm

Just put the gearbox and engine back in after a gearbox overhaul. Checked the gearbox before refitting and gears all selecting fine. No apparent problems when putting the gearbox back in, followed by the engine. Refilled the clutch fluid and clutch appears to be working ok. But on rechecking the gearshift the gears wouldn?t engage ie stuck in neutral. Rotated the crankshaft pulley by about 180 deg and the gears then selected ok. Rotated crankshaft again and stuck in neutral again. Repeated and gears ok again and seem ok now, selecting normally.

Before connecting everything else back up wonder if anyone has an explanation for the above symptoms. No oil in the gearbox yet but wouldn?t have thought this was the issue.

Any ideas?

Thanks

Richard
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PostPost by: elated » Thu Jun 21, 2018 7:03 pm

If the problem does not feel like a positive mechanical obstruction then my money would be upon the absent oil which can be very easily and inexpensively addressed and (hopefully) confirmed.
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PostPost by: RichardS » Thu Jun 21, 2018 8:08 pm

Thanks Gordon - didn?t want to connect everything back up again and then find I had missed something! Will pop some oil in before going further and check again
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PostPost by: alan.barker » Fri Jun 22, 2018 9:58 am

Have you screwed the reverse Light Switch in too far :wink:
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PostPost by: Frogelan » Fri Jun 22, 2018 1:21 pm

I'm no specialist...

Could this be a broken spring in the selectors?

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PostPost by: RichardS » Fri Jun 22, 2018 2:39 pm

Thanks Alan and Andrew
Reverse switch should be ok - checked with multimeter for minimum insertion with a connection. The gearbox has been fully rebuilt (by a gearbox specialist, not me!) so hopefully the springs are correct
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PostPost by: Craven » Fri Jun 22, 2018 3:31 pm

It is quite normal having difficulty in selecting a gear when the internals are stationary, you can cause damage to the dog teeth on the gear by forcing alignment between the gear and the hub.
FWIW Your gear box sounds OK.
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PostPost by: CBUEB1771 » Fri Jun 22, 2018 5:30 pm

The hollow dowels that establish alignment of the crankcase and bell housing were in place and in good condition?
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PostPost by: RichardS » Sat Jun 23, 2018 7:43 am

Thanks everyone - new dowels and treated myself to a new aluminium bell housing. We refitted the gearbox and engine gently, and didn?t force the gearshifts so hopefully the symptom was just down to a dry stationary gearbox.
I will go ahead and reconnect everything and sounds as though all ok (fingers crossed!)
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PostPost by: CBUEB1771 » Sat Jun 23, 2018 11:49 pm

RichardS wrote:treated myself to a new aluminium bell housing.


Hopefully the new bell housing has been machined properly. If the problem persists you might want to check once again with the original bell housing. Misalignment of the gearbox input shaft and the crankshaft could cause some sticking/tightness in gear election.
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PostPost by: nigelrbfurness » Sun Jun 24, 2018 8:41 am

You really need to check it with oil in it (as others have said) and with the engine running and the clutch depressed. Input shaft binding in the crankshaft spigot bush can make gear selection difficult, a symptom that sometimes occurs when the engine is hot, though I realise that's not what your problem is. You need to have spun the gears and got them properly lubricated before you decide you have a problem, IMHO. The rubber bush at the base of the gear lever can cause shift problems too, but you can check this by removing the lever and using a screwdriver or pry bar on the selectors rails directly to make sure you can get gears. From what you've said, though, it doesn't sound at this stage like you have a major problem.

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PostPost by: rgh0 » Mon Jun 25, 2018 11:56 am

Lack of lubrication of the interlock pins on the gear selection shafts can cause problems when a box is first assembled if they are not lubricated with gear oil during the assembly process. Once the box is running splash oil lubricated these but if assemble dry they may stick and make gear selection hard

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PostPost by: RichardS » Tue Jun 26, 2018 7:10 am

Have started connecting everything back so will hopefully be up and running again in a couple of weeks. Am reassured by the helpful advice!
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