Gearbox troubles!

Maestro, SEI-V
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Gearbox troubles!

Post by penman »

Hi guys,
I am having some problems with my gearbox, this is an early 5 speed 500. I have a few questions, which I'll put at the end, but first the problems. When I got it, the bike had been unused for 20+ years, so there is certainly scope for corrosion to have crept in and that was my initial thought. The bike whines in 3rd gear and over the 4000km or so since I got it on the road, that has got slightly worse. More of an issue is gear selection and/or indexing. I hit false neutrals all the time and it doesn't seem to make much difference if I change gear quickly or slowly, gently or with force. Also, it often refuses to change up. Say I want to go up from 3rd to 4th. I flick the pedal up, it feels normal, but the bike is still in 3rd gear, after which the pedal feels loose and I have to change down a gear before it will start changing normally again. It never does this when changing down. Another problem is that if it lands on a false neutral, subsequent changes can go from neutral to neutral, skipping over the gears. All this has, if anything got slightly worse with use - I was hoping it would improve! I should add that for at least 70% of the time, gear changing is fine - not "great" but certainly OK. Ironically, I can always find neutral easily at rest!

Of course I have no experience of this gearbox, and the diagram in the parts book takes a bit of deciphering! There is nothing external though, so it looks as if I'll be stripping it down this winter. Prime suspects must be the double-ended selector pawl, the indexing arm and associated springs and the toothed cog affair on the end of the cam cylinder. I would appreciate any advice and in particular:

1. I'm assuming this gearbox doesn't normally behave like this - can someone confirm that it's normally a good gearchange?
2. Are the problems I'm seeing common?
3. Is there ever a problem of wear to the tips of the selector pawl and index arm or to the teeth they engage with?
4. Is there scope for any of this to stick or jam?
5. The big question - are replacement parts readily available?

Any other comments and advice will be most gratefully received!!

Oh, one last thing. I will of course use this opportunity to clear the sludge trap(s) in the crankshaft. Do the plugs come out easily or is it a fight as usual, often involving a drill or other violence!

Many thanks in advance,

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Gearbox troubles!

Post by harrymuffin »

If it has not been used for some time then most likely the ball bearings could be worn due to corrosion with lack of oil and condensation and possibly the PB bush/shaft in the third gear has play throwing the gears out of mesh. There is an indent plate on the right hand side of the box which has a pawl that locates in notches that correspond to whatever gear you as supposed to be in. If the spring is weeks, broken or the one end is not located where it should be, then as you select whichever way, the index plate will overshoot giving false neutrals. regrettably there is nothing you can do about it but strip the engine and survey the workings of the gearbox. You may as well do everything else why you are about it, replace the big ends, ball bearings GACO shaft seals, etc. Good luck!
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

Thanks harrymuffin, you are pointing to the same areas I had guessed at and you are right, the truth will be revealed when I take it to bits! I suppose it’s good advice to service all parts of the engine and gearbox while it’s all in bits, though that doesn’t sound like a cheap project! What am I talking about? When was anything to do with classic bikes ever cheap?? :(
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
User avatar
72degrees
Posts: 1549
Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Gearbox troubles!

Post by 72degrees »

I'd also suspect a problem with the selector arm springs. I worried a lot about that part of the assembly when I rebuilt the racer 350 engine.
Harrymuffin is right about doing everything when you are in there, but it might be advisable to check on availability of Morini specific parts first. I couldn't source new gear bushes, but perhaps you or Harrymuffin can get replacements machined up. They aren't just plain bushes, but the lubrication 'slots' possibly don't present an insurmountable problem for someone with the appropriate machine tools.
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Gearbox troubles!

Post by harrymuffin »

All the plain bearings can be made without problems, I never buy when I can make. The only bearing you may have problems with is the split ball bearing on the input, it is a special - now obsolete, but as I have mentioned somewhere else, Adrian Crimp got the SKF rep to modify a standard ISO series bearing as a substitute and it has it's own designated number, so you will have to go to SKF if yours is knackered. All the other bearings and seals are standard 6000 series and don't forget the big ends on the 500 et al are the same as FIAT Multpla 1960's bigends and are better quality than the remanufactured one available, try PistonBroke in Bristol, also you will get 4 pairs for the price of one half from NLM. Replace the valve guides with Aluminium-Bronze preferably produced from cast rod rather than the sintered iron ones as fitted. Also. don't forget there are annealed copper washers under the Allen screw heads that are buried in holes inserted from the drive side, if you forget to fit them then the oil makes it's way through the hole and drips our the other end by the gearbox sprocket. Warning: the five speed is different from the six speed and that although there are some parts that are common, such as some bearings and the selector mechanism. If you have the 500 parts book then you can see how everything goes together, if you need a copy of the 5 speed box parts section let me know and I will copy it and send it to you. I also have a 6speed parts picture if it helps so you can see the differences, but not the parts listing.
If you are desperate for any special tools such as the assembly seal sleeves, crankshaft primary gear holding spanner or a crude engine cradle, let me know and you can borrow them.
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

harrymuffin, once again, many thanks for the information. I do have a 500 parts book, so I have a fair idea of how this gearbox works and fits together. Of course I won’t know exactly what’s wrong until I have it in pieces. I think I have (at least) two faults, one causing the whine and one or more causing the selection and/or indexing problem.

Thanks for the offer of borrowing tools, I may well take you up on that! Interesting to hear about this special bearing from SKF - that might well be worth getting even if I don’t need it, you never know how much longer they’ll do it. If you have any more info on that, part number, etc., I’d be more than interested.

I plan to use the bike for another month or so during which time my workshop is in theory having a clear-out (hahaha, it’s been tried before without success!) after that, I’ll start work on the Morini. As for an engine stand, I am hoping to adapt my Triumph T160 stand, it’ll be quite deluxe if it works out!

The engine is very quiet mechanically, apart from a bit of valvegear clatter and it used no oil at all in the 1200 miles I did in Spain. I was assuming from this that I can leave the valve guides alone - do you think it’s worth changing them? I had a close look at two other Morinis over in Spain and both had more rattly valvegear than mine and it sounds pretty typical of a pushrod engine to me. As for pistons, barrels, big ends etc, I think I’ll see how worn they are and make a decision based on that -unless anyone warns me of impending problems. Apart from following up that SKF bearing and getting a gasket set, I don’t think there’s much else I can buy until I’ve had it apart.

Thanks again for all the info, folks!

Joe
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

Hi all,
A complete Morini 500 gearbox has appeared on ebay, which may be worth me taking a gambol on. The item number is 282662498460. I have sent a few questions to the seller. This assembly is from a 1981 bike and from examining the photos it is a 5 speed cluster. Does anyone know if there was any change to the gearbox between mine (1978) and this one (1981)?

Obviously you take a bit of a chance buying second hand on ebay, but from the photos it looks to be in good shape and it doesn’t need to yield many parts to pay for itself. Comments welcome!

Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Gearbox troubles!

Post by norbert »

harrymuffin wrote: ... and don't forget the big ends on the 500 et al are the same as FIAT Multpla 1960's bigends and are better quality than the remanufactured one available, try PistonBroke in Bristol, also you will get 4 pairs for the price of one half from NLM.
Theses shells from the Fiat Multipla fit "plug and play" for the 500/501 crankshafts or do you have to modify them ? This would be what I´m looking for for years :roll: :D

I don´t want to ocupy this tread that is about the gearbox, so maybe you can send me a pm answering my question? Thanks!

norbert
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

No, please make the reply to Norbert’s question public! I need to know the answer as well, having been encouraged to replace the shells while I have the engine apart. If the big end shells are being replaced, the crank will have to be checked, presumably oversize Fiat shells are available as well?

While I’m at it, this special “split” bearing on the gearbox input, is that item 59 on page 20 of the parts book? I’m getting to the point where I can’t wait to tear this apart to see what it all looks like!

Regards,
Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Gearbox troubles!

Post by harrymuffin »

The main bearings from the vintage Multipla fit straight into the conrods, The other advantage with these shells is that they are slightly wider, I believe the person who put me onto to them filed them to the same width, but I have not when using them as I have mentioned before the loading on the bearings are getting to borderline and the extra width reduces the loading slightly. Note: These shells follow the old standard practice of regrinds being in thousands of an inch, Morini and most other 'modern' practice is in 0.1mm which is about 0.007", if you do regrind then make sure the engine machinist knows this. Someone gave his barrels for reboring and the machinist did not seem to know that the clearance is in the piston and so the pistons fell through the cylinder.
The bearing part number that I have is Glacier B4242SA and you may pick up a set of four on eBay. You could look up on the Hasting website and see if they have cross references for the different bearing manufactures. If you can access the AE catalogue at your local friendly engine machinist then you can cross reference from them. Not sure if you have them in Germany Hubert. I have just picked up sets of bearing infinitely superior Vandervell bearing for the Hillman Avenger for £20 that just so happen to Bristol engines where they normally cost £350 are are made in an inferior material in Israel. So all you people using a phone for idiots (iPhone and the replicas) stop using them as they are using up the indium needed for our bearings and with only known reserves left of around 700 tonnes the earth is due to run out in roughly ten years time at the current rate of must have got to have mentality.
There is a chap selling off a relations years of engine machining bits and pieces under the name of 'tonybeerkat'. When I went to see him for more bearings he had only a small collection at his house but they filled a shelf 8' long and were piled up ten bearing sets high, he may have these bearings on the shelf.
I currently have these shells in -0.010" four pairs and -0.020" which I hope to see my days out.
Hope this is of help?
Regarding the tappetty top end, it is usually valve guides that are worn, so, as you have that symptom then budget for a set, but use the ones as I suggested, as the valves are stainless steel and although modern engines use cast iron the best material is the aluminium- bronze ones for 'classic' engines with poor lubrication systems. Modern engines have designed obsolescence built in.
The replacement bearing I will have to look up again in my very carefully detailed, put away in a in a safe place, filing system that I now cannot lay my hands on. Will keep you posted. Yes, the item number is 59 the bearing number is 633245 is obsolete. My parts book came from P A Booth in Australia. It is the inside diameter of the standard bearing that has to be increased. Same goes for the drive side main shaft bearing, that is obsolete also, but I know these became rocking horse shit in the last century when I bought the last one. Again, SKF may alter a standard bearing if enough interest was shewn to make a run, of say a dozen. The alternative would be to find a friendly tool room who could grind out the inner race to fit the main shaft. Nothing is insurmountable as all the problems now inflicted on Morini owners, were also inflicted on owners of OHC Velocette owners with the special Hoffman drive side main bearings in the 1960's.
The change over point is when Morini found that the 5 speed box had too high a first gear, so no good when two up and touring in the Dolomites, so went for the 6 speed and lower first gear, I can get 55mph in first on my 5 speeder with long distance gearing. I would probably go for it just for the spares but now you have advertised the posting everyone will be after it - dog eat dog. When you dismantle the box don't remove the gear locking plate (14) as this is set at the factory and decides how good your selection works. Those engines that have finding neutral difficult were probably assemble by some bloke just before the four hour lunch break and wanted to get finished, the other when he came back under the influence. They have to be set using a cut away crankcase so it canbe adjusted, better the devil you know scenario!
Also, if you have pitting on the cam followers you can use a piece of plate glass and grinding paste and lap them in. The cam followers fitted to Morinis are flat ones, to most other 'flat tappet' engines they are usually ground convex to aide rotation.
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

Harrymuffin,
Once again, thank you for your invaluable information. Snippets like not removing the locking plate are most helpful, I’d have had it off before you could blink! And selecting neutral is the one thing this gearbox really does well!

The Fiat Multipla shells seem quite available, so I can wait until I see the condition of the existing ones and decide if a grind is necessary. Likewise the bearings can wait until I have the existing ones out. My gearbox whine is confined to 3rd gear, all the others are quiet, so unless there is damage or wear to the gear teeth or splines, the only other component I can see which is particular to 3rd is the splined bush, item 43. Something is wrong in the selection or indexing though, and again, I won’t really know until it’s all laid out on the bench. I hope it’s a nice clear fault, I hate it when you strip it all down and you still can’t see what’s wrong!

If you manage to find the info on the bearing 59, that would be great, but don’t waste too much time on it. Your filing system sounds a bit like mine, very secure!

Thanks also for your comments on the valve guides, I’ll have a close look at them. I suppose I’m too used to Triumph engines, where any wear to valve stems or guides leads to serious oil burning - this Morini uses no oil at all.

I bought that gearbox by the way! I’ve been looking on ebay for months and that’s the first 500 gear assembly I’ve seen, though I’ve seen several 350s.

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Gearbox troubles!

Post by harrymuffin »

Rather than have my brain mushed watching the endless crap on television, I looked through all the stuff on Morini and found the information on the split bearing on the gearbox. The original number is 633245A and has the dimensions of 21.8 x 47 x 14. The replacement is a 6204/22 and had the standard dimensions of 20 x 47 x 14, so the inner race has been opened up to fit on the shaft.
The main bearing original number 633250C has dimensions of 33 x 72 x 19 and the possible replacement would be the 6306 which has the dimensions of 30 x 72 x 19 so the inner race needs opening up to 33mm. If you have access to any bearing specification catalogue, then the nearest bearings to the standard obsolete bearings have load and speed characteristics very little different from the standard 6000 series bearings from which the replacement gearbox has been made and possible modified one for the mainshaft. As far as I know no problems have been encountered with the modified gearbox bearing, but I have not been in touch with Ade Crimp for some long time, but I think he sold the bike. If those who live in the Bristol area or who bought the bike off him, then they may be able to comment on this modification or get in touch with him to see if it has worked satisfactorily.
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

Many thanks Harrymuffin!
I’m pretty well armed with information now. The gearbox I just bought on ebay has only done less than 10,000km so there is more than a good chance that all the parts will be in good shape. Unfortunately the bearings didn’t come with it, I have to buy the crankcase if I want those! Next move is to strip it down, but that won’t happen for a while yet.

Joe
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Gearbox troubles!

Post by penman »

Hi all,

I contacted SKF today regarding the modified bearing mentioned by harrymuffin, here is the text of their reply:

"Thank you for your enquiry 1-3970303232
Date Opened: 10/10/2017 09:56:23

Please see below relevant information:
Unfortunately the 6204/22 has itself been obsolete since 1990 and I can see no alternative.
The only chance would maybe requesting a special from our factory, you would need to go through your local authorize SKF distributor to facilitate this."

Unless the bearing is shot, I will not be following this up any further, I am guessing that SKF will want an order for 10 or more bearings to set up a "special" - I may be wrong of course. If that bearing is dodgy, I will of course have to look at all options!

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
harrymuffin
Posts: 292
Joined: 07 Apr 2014 16:06
Location: west midlands

Re: Gearbox troubles!

Post by harrymuffin »

Strange that it was obsolete in 1990. I can only assume that the one Adrian Crimp bought was one still on the shelf, as he certainly bought it this century in the naughties through the SKF Rep, You should have asked them what constitutes a special and what is the minimum order. When I did the 500 piston manufacture, Omega Pistons wanted a minimum run of 10. I know the 500 SEI I bought in bits with around 27000 on the clock and was seven years old, needed new main and gearbox bearings. The hybrid also got new main and gearbox bearings when I built that up in 1998.
I did consider pursuing the modification of the standard bearings through having the inner races ground out, which if I became desperate is what I would do. In the Black Country there an awful lot of small one man band toolmakers who. if they could not do it themselves, certainly would know someone who could do it. It would be a case of investing a day chasing up leads. The inner race could certainly be held in a chuck with modified pin jaws and then locating into a spindle grinding machine.
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