Gearbox Rebuild

Post any technical questions or queries here.
User avatar
Peter Laidler
1275 Cooper S
Posts: 6396
Joined: Sat Jul 15, 2017 5:35 pm
Location: Abingdon Oxfordshire
Has thanked: 138 times
Been thanked: 116 times

Re: Gearbox Rebuild

Post by Peter Laidler »

Gogsymacs cardboard box idea is good........ so is putting the bits into a big poly bag. You can see what's going on, see where the balls have flown and it's a bit more versatile too.

Great thread for ideas
User avatar
Costafortune
1275 Cooper S
Posts: 2083
Joined: Thu Feb 16, 2017 9:26 am
Location: Sheffield On Thames
Has thanked: 31 times
Been thanked: 38 times

Re: Gearbox Rebuild

Post by Costafortune »

I used a piston ring compressor for that job.
Mr Rusty850
Basic 850
Posts: 60
Joined: Sun Jun 23, 2019 10:54 pm
Location: West Lancs

Re: Gearbox Rebuild

Post by Mr Rusty850 »

I had hoped I wouldn't need to trouble you guys any further with this build but it wasn't to be. I've re-assembled the mainshaft and installed the laygear. As you can see in the photo below the 2nd and 3rd gears don't line up too well with the laygear. I'm at a loss to explain whats gone wrong. The second photo is just the same mainshaft after I've removed the laygear.
Any ideas please before I dive in and strip the mainshaft down again.
Thanks,
Barry
You do not have the required permissions to view the files attached to this post.
User avatar
Andrew1967
1275 Cooper S
Posts: 7927
Joined: Thu Jun 24, 2010 6:35 pm
Location: Usually in my garage on the east coast of Norfolk, UK
Been thanked: 8 times

Re: Gearbox Rebuild

Post by Andrew1967 »

It doesn't look like the third motion shaft is fully home yet as normally you can see a small part of the mainshaft bearing protruding into the gear area (and how you can normally start to tap the bearing out when stripping with a small punch)

This would push the shaft further in and line the 2nd and 3rd gears up with the laygear.

Also you can see that the 1st gear hub, although in line with the laygear, isn't fully over to the side of the inner hub for 1st/reverse and the rest of it all looks 'loose' around the 3rd/4th hub and baulk rings
gogsymac
850 Super
Posts: 183
Joined: Sun Nov 23, 2014 9:23 pm
Location: Aberdeenshire, UK
Been thanked: 1 time

Re: Gearbox Rebuild

Post by gogsymac »

Mr Rusty850 wrote: Tue Nov 09, 2021 5:45 pm I had hoped I wouldn't need to trouble you guys any further with this build but it wasn't to be. I've re-assembled the mainshaft and installed the laygear. As you can see in the photo below the 2nd and 3rd gears don't line up too well with the laygear. I'm at a loss to explain whats gone wrong. The second photo is just the same mainshaft after I've removed the laygear.
Any ideas please before I dive in and strip the mainshaft down again.
Thanks,
Barry
Exactly what Andrew said. I made the same mistake when doing my gearbox. The problem with mine was that I hadn't tapped the main double roller bearing right in to the gearbox central web.For some reason (total inexperience) I thought that when the clip that fits onto outer rim of the main bearing reached the central web of the casing that it was in far enough. I didn't appreciate that you need to keep tapping it in until the bearing hits the inner lip and is visible on the other side.I thought that I had done it OK - but when I came to fit the laygear it didn't line up very much as per your photo.

I then tried to sort it by tapping the mainshaft into place and then - being the eejit that I am I pushed the 3/4 synchro hub too far over and the balls and springs burst out. Great - I now need to remove the mainshaft and refit the balls and springs and then start again. I know now what to do.
Mr Rusty850
Basic 850
Posts: 60
Joined: Sun Jun 23, 2019 10:54 pm
Location: West Lancs

Re: Gearbox Rebuild

Post by Mr Rusty850 »

Thanks Guys. Your help is really appreciated. I won't be able to do any more work on the box until next Monday so I'll report back then.
Thanks,
Barry
LuisM
998 Cooper
Posts: 587
Joined: Tue May 27, 2014 3:47 pm
Location: Porto, Portugal
Has thanked: 1 time
Been thanked: 4 times

Re: Gearbox Rebuild

Post by LuisM »

As other said , the 3rd motion shaft seems not fully "home" against the bearing,
have you torqued up the pinion nut a bit ?

if not, just do that ... it should fix your problem.

cheers
Luis
Mr Rusty850
Basic 850
Posts: 60
Joined: Sun Jun 23, 2019 10:54 pm
Location: West Lancs

Re: Gearbox Rebuild

Post by Mr Rusty850 »

All sorted. I decided to whip everything out, check it and reassemble. It all went back together well. As suggested the twin ball bearing hadn't been driven in far enough. Looks ok to me now.
Thanks again everyone,
Barry
20211115_152948.jpg
You do not have the required permissions to view the files attached to this post.
Post Reply