About to tackle the gearbox, anyone got any tips?

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MarinaCoupe
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Re: About to tackle the gearbox, anyone got any tips?

Post by MarinaCoupe » Wed Jan 17, 2018 7:30 pm

Bren, I quoted all the part numbers earlier in the topic.

Here’s an original BL one on EBay

https://www.ebay.co.uk/itm/MG-Midget-15 ... ng-13H6968

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Re: About to tackle the gearbox, anyone got any tips?

Post by MarinaCoupe » Wed Jan 17, 2018 7:47 pm

I have been doing some more research and turned this up on the net, dated 1975. It confirms the engine number for the change of bearing and the order of fitment of the earlier bearing and spacer. The spacer definitely is fitted onto the main shaft before the bearing.

If the old spacer is trapped in the first motion shaft, I have found that old dental picks are really useful. You can pick them up at autojumbles and on eBay.
3E9C8B56-E1D1-4C02-9F32-379D0A9E70EA.jpeg

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Re: About to tackle the gearbox, anyone got any tips?

Post by david painter » Wed Jan 17, 2018 8:45 pm

The way I read the TSB its the early small diameter, but wide bearing did not have a spacer fitted. I would fit a new 13H6968 bearing and put it back together as it came apart. Having another close look at the photo what I thought initially looked to be wear. could well be assembly grease
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Re: About to tackle the gearbox, anyone got any tips?

Post by MarinaCoupe » Wed Jan 17, 2018 9:02 pm

True David, deffo need to buy a spacer and small caged bearing.

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Re: About to tackle the gearbox, anyone got any tips?

Post by Brenjacques » Thu Jan 18, 2018 11:41 am

Thanks again both, David, that is correct the score marks are actually assembly grease that I applied, it is only a 40k box and it looks to have had quite an easy life. It looks to me like that is correct, the earlier caged bearing looks to have not had a spacer fitted, I have bought the caged bearing that Chris found for me so I'll fit that and assemble it again hopefully that will be the solution. I'm going to try and find some data on the earlier 1st motion shafts and see if I am correct that the earlier types are machined differently to the later types.

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Re: About to tackle the gearbox, anyone got any tips?

Post by balmy » Thu Jan 18, 2018 12:12 pm

Yes the motion shafts are different


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Re: About to tackle the gearbox, anyone got any tips?

Post by Brenjacques » Sat Jan 20, 2018 3:18 pm

I'm now at the point of refitting the speedo drive ring, can anyone give me some advice on how to fit this without breaking it? I broke the original getting it off and I broke a new one trying to refit it, they are extremely tight.

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Re: About to tackle the gearbox, anyone got any tips?

Post by david painter » Sat Jan 20, 2018 4:37 pm

I would get a nice snug metal tube, that contacts the inner metal ring of the worm gear, not the plastic. Use that to drive the gear home. I would also help fitting if the gear is heated up in hot water prior to fitting.
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Re: About to tackle the gearbox, anyone got any tips?

Post by Brenjacques » Sat Feb 03, 2018 2:15 pm

Well I am more than ready to give up on this now. I have ordered two ring gears from Rimmer bros and they have both split. It seems to me that the inner diameter is too small, I had the gear only 3mm away from its seated position before it split, the same as the other I tried to fit. I have asked them to replace them as at £15 a pop they aren't cheap, especially as they seem to be quite prone to failure. So what do I do now? The marina has been off the road since december because of this and it needs much more work than this but this is holding it all up. What other BL boxes can be fitted to them as I am inclined to replace it now, which is a shame but this is just taking the p**s.

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Re: About to tackle the gearbox, anyone got any tips?

Post by MARINAMADBAZ » Sat Feb 03, 2018 3:15 pm

loads of 1.3 gearboxes here sadly no 1.7/1.8 could you fit a 1.3 clutch plate and then a 1.3 gearbox I know the gearing in top gear is the same
barry

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Re: About to tackle the gearbox, anyone got any tips?

Post by Brenjacques » Sat Feb 03, 2018 3:20 pm

Hi Barry,
Not too sure about that, would it be possible to build one good one out of the two? I could switch the first motion shaft with the one on mine although this would have to be on a gearbox with an early type mainshaft and roller bearimg (pre 1974 I think)

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Re: About to tackle the gearbox, anyone got any tips?

Post by MARINAMADBAZ » Sat Feb 03, 2018 3:25 pm

again mate not sure I've heard somebody did put a 1.3 in a bigger engined car and just used a 1300 clutch plate I've got 5 or 6 1300 gearboxes

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Re: About to tackle the gearbox, anyone got any tips?

Post by Brenjacques » Sat Feb 03, 2018 3:38 pm

Neither am I if I'm honest, not a clue what the differences are. I'll see if I can find out as it may be easier going down this route. I could try ordering one more ring gear and grinding the inner diameter to help ease it on but I don't know how effective or easy that'll actually be. I want to find who has the hoard of 1.8 boxes, it's unbelievable how much harder to find they are!

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Re: About to tackle the gearbox, anyone got any tips?

Post by JubileeNut » Sat Feb 03, 2018 5:44 pm

If you strugle to get the spacer out of the first motion shaft try filling the spacer hole with grease and tap the main shaft in to where the grease is as this may hydraulic the spacer out. This technique is used very sucessfully on the spigot bear in the fly wheel. Saves damaging surfaces trying to pick it out.
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