Gearbox whine

Maestro, SEI-V

Gearbox whine

Postby penman » 08 Jun 2017 09:47

Now I've managed to find something new to worry about. My gearbox whines in 3rd gear only. The whine is worst when just maintaining speed. It doesn't whine on the over-run and it whines less under strong acceleration. There is no problem engaging 3rd gear and with the engine stopped I can't detect any excessive backlash. Any ideas? I'm not (yet) familiar with this gearbox but looking at the diagram I don't see anything particular to 3rd apart from the gears themselves, so I'm guessing this is just a bit of wear and not particularly dangerous, though it'll probably get gradually worse.
1985 Morini 350 K2
1978 Triumph T140 E Bonneville
1975 Triumph T160 Trident
2014 BMW F800GT
1978 Morini 500
penman
 
Posts: 226
Joined: 08 Mar 2016 09:20
Location: Milton Keynes

Re: Gearbox whine

Postby Clive » 13 Jun 2017 20:00

Mine appears to do that as well.
Could be the first signs of impending disaster, which will almost certainly be expensive too, or it could just be a little quirk.
I'm going for the quirk until it goes pop, then I'll worry about it.
Clive
 
Posts: 50
Joined: 14 Nov 2014 15:00
Location: West Yorkshire

Re: Gearbox whine

Postby penman » 15 Jun 2017 13:44

Hi Clive,
Interesting! Is yours confined to 3rd gear as well? I like the "quirk" theory, though I've used it before and found it unreliable! I don't know anything about this bike's previous life, but if it was used in a mainly built up area, I can imagine 3rd gear getting a bit of a hammering, and the whine is probably down to wear and tear. I think I'll keep an eye on it for the time being. If it starts to get worse it'll have to come to pieces, but that's a full strip-down on this engine as far as I can see. They do keep you busy, these old bikes!
1985 Morini 350 K2
1978 Triumph T140 E Bonneville
1975 Triumph T160 Trident
2014 BMW F800GT
1978 Morini 500
penman
 
Posts: 226
Joined: 08 Mar 2016 09:20
Location: Milton Keynes

Re: Gearbox whine

Postby 72degrees » 15 Jun 2017 17:57

penman wrote:Hi Clive,
Interesting! Is yours confined to 3rd gear as well? I like the "quirk" theory, though I've used it before and found it unreliable! I don't know anything about this bike's previous life, but if it was used in a mainly built up area, I can imagine 3rd gear getting a bit of a hammering, and the whine is probably down to wear and tear. I think I'll keep an eye on it for the time being. If it starts to get worse it'll have to come to pieces, but that's a full strip-down on this engine as far as I can see. They do keep you busy, these old bikes!


Pretty much a full strip down, though if the crank & rods are 'known good' you don't need to get them out to remove the gear cluster/selectors. The bad news is that whilst the ball bearings are obviously 'off the shelf' I couldn't find a supply of new gear bushes when I rebuilt the forgotten error 350. I suppose someone with the right equipment and skills could machine them up, but they are not just simple plain phosphor bronze (or something of that ilk) but have s sort of spiral slots in them. More likely to rattle perhaps (like mine ) than whine though.
User avatar
72degrees
 
Posts: 688
Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Gearbox whine

Postby harrymuffin » 16 Jun 2017 17:23

The 500 gearbox has a split angular bearing made by SKF which is now obsolete. There is however, a modified standard bearing that Adrian Crimp got SKF to make for him, and is listed in their catalogue as a standard special and you should be able to order. If you do strip the engine then you will be silly not to inspect the big end bearings and clean out the crankpin sludge trap which is the usual cause of the Morini big end failures as the sludge build up cuts off the oil supply to the bearings. The big end bearing from the FIAT Multiplas from the 1960s are the same size and slightly wider and better quality than the 'official' bearings, try any engine bearing stockists or specialists. I get mine from Piston Broke in Bristol, a box of four complete bearing are half the price of one shell from NLM or they were when I last bought some.
harrymuffin
 
Posts: 55
Joined: 07 Apr 2014 16:06

Re: Gearbox whine

Postby Clive » 18 Jun 2017 17:02

Hi Penman.
Yes it is confined to 3rd gear. My bike had been stood for quite a time before I got it also, although I have done over 10,000 miles on it now with no gearbox issues - (I change the oil approx every 12 - 15 hundred mile) so I'm pretty sure it's ok. For the time being any way.

I'm considering a full strip and re-furb over the coming winter although I'm definitely a don't fix it if it's not broke type of person.

In my opinion the worse thing you can do is to be busy 'fixing them' rather than busy riding them.

I must admit the more, and harder, it is used the better it seems to run but committing that statement to ink is probably the kiss of death and it will now turn into molten shrapnel leaving me stranded 200 miles from home. Ha ha
Clive
 
Posts: 50
Joined: 14 Nov 2014 15:00
Location: West Yorkshire

Re: Gearbox whine

Postby penman » 20 Jun 2017 09:26

Hi Guys,
Many thanks for all the informative replies and my apologies for going quiet, I have had no time for interesting things the last couple of weeks!

I think I will ride it over the summer with an ear cocked for any change in this whine and maybe a strip down will be a winter job if I am still worrying about it. If I do that, I will certainly attend to the sludge trap, I'm familiar with the idea and potential problems from my Triumphs. I am obliged for the snippets of info on bearing shells, gearbox bearings and so on - these forums can be invaluable for details like this.

This whining doesn't sound good but it doesn't sound as if I have an imminent failure looming either, hopefully it'll last until winter! There are no ominous sparkly bits in the oil thank goodness. Yet!
Regards,
Joe.
1985 Morini 350 K2
1978 Triumph T140 E Bonneville
1975 Triumph T160 Trident
2014 BMW F800GT
1978 Morini 500
penman
 
Posts: 226
Joined: 08 Mar 2016 09:20
Location: Milton Keynes


Return to The 500

Who is online

Users browsing this forum: No registered users and 1 guest