TR77 Gearbox issue

[rick_watts]

Hi Guys,

I have an issue with my TR77 350 clutch is working okay select 1st gear ok pull away but while moving can not go up the gearbox, the same when I stop moving and the bike is running. when the bike is not running I can click it up the gears by hand. ??? anyone had this before or know what the issue could be, im unable to split the crankcase as do have the know-how leave that to the pro`s.

Any suggestions of good engine builder who could have a look, im based in Hemel hempstead.

Many thanks

Rick

 

[carl ekblom]

Have a look at your clutch. Your clutch plates may not disengage as they should.

A common problem

Basket and hub must be free from notches. Plates flat and free from muck. Oil should be thin. I was using engine oil 0W-20 now HTX740(also for Bultaco Gearbox)

For this check you don´t have to split the cases

[Old Gezzer]

9 hours ago, rick_watts said:

Hi Guys,

I have an issue with my TR77 350 clutch is working okay select 1st gear ok pull away but while moving can not go up the gearbox, the same when I stop moving and the bike is running. when the bike is not running I can click it up the gears by hand. ??? anyone had this before or know what the issue could be, im unable to split the crankcase as do have the know-how leave that to the pro`s.

Any suggestions of good engine builder who could have a look, im based in Hemel hempstead.

Many thanks

Rick

 

There is a guy in Liverpool called Chris Bond. He has a reputation as an experienced Engine builder. If you want to contact him PM me and I will put you in touch.

Old Geezer.

[woody]

On 8/14/2022 at 8:40 AM, rick_watts said:

Hi Guys,

I have an issue with my TR77 350 clutch is working okay select 1st gear ok pull away but while moving can not go up the gearbox, the same when I stop moving and the bike is running. when the bike is not running I can click it up the gears by hand. ??? anyone had this before or know what the issue could be, im unable to split the crankcase as do have the know-how leave that to the pro`s.

Any suggestions of good engine builder who could have a look, im based in Hemel hempstead.

Many thanks

Rick

 

You don't say if you have just got the bike or whether this problem has just ocurred

It's difficult to see how the clutch can cause this as if you select 1st gear ok without clutch drag causing the bike to jump forward then the clutch is working. In addition you don't need the clutch to change gear, if you ride off in 1st gear you can change up the gears without using the clutch, so the clutch shouldn't be the cause of the problem.

It's hard to pin point a cause from what you describe but here are a couple of things to check that could be a cause, but if not it's likely to be internal.

The Ossa gear lever has a long throw on it, check you don't have the lever position too high (angled upwards) If it is it's possible that when you try and engage 2nd it touches the kickstart and prevents it from fully engaging.  It's best to set the lever horizontal, not angled. Also check that there is no end float on the gear shaft by holding the gear lever and pulling the shaft outwards - you shouldn't be able to as there is a wave washer held by a circlip on the shaft inside the case which stops the shaft moving outwards. If this is missing the shaft can float and if it is too far out the selector fork on the shaft loses contact with the selector drum so there is no selection. With the shaft correctly located the gear lever should be up against the case, there shouldn't be a significant gap. It's possible that when you're changing by hand with a dead engine you're holding the shaft in, whereas with the engine running and changing by foot the vibration of the running engine is moving the shaft outwards. When you try with the engine running make sure the shaft is fully 'home'.

If you can select all gears by hand then the gearbox itself must be ok but also, there is no load on the gearbox components when you do it like this. It's possible that there may be some wear on the selctor fork or drum, or maybe the return spring itself which doesn't hamper selction by hand with a dead engine. 

[rick_watts]

Hi Guy`s  Thanks for the response, 

I`m sure the clutch is Okay as it disengages the drive when i put into 1st gear and there is no drag and once in gear it operates as expected, just cannot then get the bike into 2nd and up the box.

I will check the gear shaft float as that looks a good place to start and make sense this could be where the problem is, unfortunately i've pulled the engine out of the bike so will not be able to test under load.

Thanks

Rick

 

[rick_watts]

HI Woody,

I have about 2-3mm movment on the gear sharft, and when pulled out fully you canot select gears, So this looks like it could be the issue.

Does anybody know someone who could fix this, as i said before splitting the crankcase is way above my paygrade.

I suppose the issue will be if the required parts would be available even on Ebay.

Rick

 

 

 

 

 

[woody]

You don't need to split the engine for this, just remove the clutch cover and look on the gear shaft. There should be a circlip, a shim washer and a wave washer in that order from the inside outwards. When the case is fitted it sits against the wave washer which stops the shaft moving. If they aren't there, this is why the shaft can be pulled outwards.  I'm not sure anyone in the UK would have the specific washers but all you need is to buy a thin washer and wave washer of the correct ID (probably have to buy them as small packs) and a circlip if that is missing too. Normally the circlip is there, people just forget to refit the washers

Gary at Ossa Stuff might be able to help with the washers  https://www.ossastuff.com/

Edited August 16, 2022 by woody

[rick_watts]

Thanks Woody, 

I don't remember seeing the shim or washer last time the clutch cover was off.

I`ll check out Gary once i know whats needed. 

Always good to get another source for Ossa bits.