LT77 Synchro Hub Question

Britcyclerider · May 11, 2020

Whilst rebuilding my LT77, I notice that the inner hub of the 1st/2nd synchro was fitted the opposite of what the manual describes, i.e. it should be fitted with the radial groove on the inner hub facing the reverse gear but was fitted the other way up. I was intending to rebuild it as per the manual, but in view of the number of mistakes that can be found in this document, can anyone please confirm this is correct? There are (subtle) steps on the inner hub splines and I want to be sure that they are facing the correct way. Many thanks.

Britcyclerider · May 11, 2020

Forgot to say, picture above is the position the manual sescribes, i.e. groove to gear side.

jamesmartin · May 11, 2020

top pic has inner hub wrong way round

Britcyclerider · May 11, 2020

Thanks James. Interesting you say that because when I took it apart, it was opposite to the above picture, but, as mentioned, the manual states the machined groove on the inner hub should face the gear teeth on the outer member (as above). I'm inclined to put it back as dismantled but don't want to get it wrong. Is the book wrong (again!) James?

Alpinejim · May 11, 2020

I also found an annomaly when I rebuilt my R380.
Pretty sure it was to do with 4th gear. Something was opposite from the manual. I seem to remember that I rebuilt as per manual, since there was deep groove being worn on the gear.
I've had no problems since, but then, there were no problems before, not with 4th gear at least. Odd.

jamesmartin · May 11, 2020

Britcyclerider said:
Thanks James. Interesting you say that because when I took it apart, it was opposite to the above picture, but, as mentioned, the manual states the machined groove on the inner hub should face the gear teeth on the outer member (as above). I'm inclined to put it back as dismantled but don't want to get it wrong. Is the book wrong (again!) James?

if you look at the splines carefully youll see theres a slight step that side of the splines is slightly thicker and should sit under the gear teeth on outer hub,its not unusual for anything thats been apart to be put back together wrong, when i was working at the landy reconditioners we had training from lr that pointed out all those little things that youd often not notice, also that youd mark both halves before disessembly so it wasnt reassembled incorrectly , though generally youd not notice in normal use so isnt generally vital but i like to know things are as they should be

jamesmartin · May 11, 2020

Alpinejim said:
I also found an annomaly when I rebuilt my R380.
Pretty sure it was to do with 4th gear. Something was opposite from the manual. I seem to remember that I rebuilt as per manual, since there was deep groove being worn on the gear.
I've had no problems since, but then, there were no problems before, not with 4th gear at least. Odd.

outer hub could be fitted wrong way round but as long as it slides over inner ok youd never notice any issue,some synchro hubs if moved from their original match will become stiff when trying to change gear

Britcyclerider · May 11, 2020

Yes, I had planned to mark it but the synchro outer separated before I got the chance when I removed the first motion shaft and naturally hit the deck before I could do so. Next time I will mark up as soon as the casing is off! Thanks for your comments, I will follow your advice.

jamesmartin · May 11, 2020

Britcyclerider said:
Yes, I had planned to mark it but the synchro outer separated before I got the chance when I removed the first motion shaft and naturally hit the deck before I could do so. Next time I will mark up as soon as the casing is off! Thanks for your comments, I will follow your advice.

the problem now is that most boxes have been to pieces several times so things been exactly correct cant be relied on

Britcyclerider · May 11, 2020

Well it's been a useful exercise and I've learnt a lot. Got my new mainshaft now so it's going back together Asap.

LT77 Synchro Hub Question

Britcyclerider

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