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Author Topic: Model 9 gearbox removal & Strip down  (Read 3577 times)

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shorrog

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Re: Model 9 gearbox removal & Strip down
« Reply #12 on: December 01, 2014, 08:00:33 PM »
I must admit I had exactly the same question as the studs on mine are also pinned

I have looked at the pins in my gearbox and I don't think they are brass they look like steel.

Graham

singleminded

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Re: Model 9 gearbox removal & Strip down
« Reply #11 on: November 30, 2014, 03:20:24 PM »
I have not worked on a BT box.My '32 4 speeder had stripped threads but the studs did not appear to be pinned..As the pins do not go straight through, and there would always be a chance the studs need renewing, I would have thought that the pins would be soft enough to shear off  when the studs are unscrewed..
I suppose we will have to wait to hear from someone like Chris Odling to be sure..John

gefrench

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Re: Model 9 gearbox removal & Strip down
« Reply #10 on: November 29, 2014, 07:47:24 PM »
Question about the BT gearbox: There are three studs to mount the primary chaincase to the gearbox. I need to replace one, with stripped threads. They are apparently threaded into the gearbox case, but locked in place with tiny pins (perhaps brass?) I removed the main bearing, hoping that the pin holes went right through so I could drive the pin out. Not so and the pin appears to be in a blind hole. How do I get this tiny pin out the remove and replace the stud? Drilling it out would appear to be a very tricky job.

phutton

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Re: Model 9 gearbox removal & Strip down
« Reply #9 on: September 18, 2014, 09:07:24 PM »
Good job Chris Odling/Sean Kelly are getting some BT internals made! Great pictures, Graham. How about an article for Beaming!

Iansmart

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Re: Model 9 gearbox removal & Strip down
« Reply #8 on: September 18, 2014, 04:42:18 PM »
Absolutely brilliant! Especially the videos. Thanks for posting them.

Ian

VicYouel

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Re: Model 9 gearbox removal
« Reply #7 on: September 17, 2014, 08:55:17 PM »
What superb pictures.

Vic

shorrog

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Re: Model 9 gearbox removal
« Reply #6 on: September 17, 2014, 08:01:19 PM »
Thanks Vic, I shall put into the oven when the coast is clear!

I have now put together a series of photos and a couple of videos of the strip down which you can see on the main Marston website http://www.marston-sunbeam.org/technicalNotes/Model9GearboxStrip.html

VicYouel

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Re: Model 9 gearbox removal
« Reply #5 on: September 16, 2014, 09:17:44 PM »
Graham

Apply some heat to the casing and get lucky! 

Vic

shorrog

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Re: Model 9 gearbox removal and Strip Down
« Reply #4 on: September 16, 2014, 07:40:16 PM »
Well I have managed to strip the gearbox and surprise surprise second gear is buggered!
My next question though is how do you remove the ball races from the casing, the big one does not look too bad I guess if I heat up the casing a gentle tap will drift it out. But how do you do the small one as it sits in a blind hole?
Graham

shorrog

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Re: Model 9 gearbox removal
« Reply #3 on: September 15, 2014, 10:06:20 PM »
Thanks vic, I have managed to remove the clutch assembly, It was not too tight I put an adjustable spanner on the offside nut applied the rear brake and then it came off reasonably easy. I am now just waiting for the tool to remove the front Cush drive which les Hobbs has posted today and the gear box will be off.

I have taken lots of pictures so I will post them on to the website in the not too distant future.
Graham

VicYouel

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Re: Model 9 gearbox removal
« Reply #2 on: September 15, 2014, 10:00:29 AM »
Morning Graham,

Just wondering how much experience you have and more importantly the condition of the bike. It could be quite a challenge and you are likely to find other things wrong.

You will need to remove the rear enclosed chaincase (if this fitted) and the primary chaincase and clutch assembly and engine shock absorber and  chains etc. Do the front drive first as you may need to lock the rear drive to assist undoing the tight drive shaft clutch nut and shock absorber nut. But loosen the drive sprocket nut whilst the front drive is still whole. Leave the rear drive gearbox sprocket and chain till last. It would be a good idea to remove the oil pipes and perhaps oil tank and give it a good flush.  There is a special puller needed for the front shock absorber (available through the club) and you will probably find the clutch is assembled on two gear shaft key ways that may take judicious use of tyre leverage techniques..

The gearbox is pretty straight forward and should not present problems.

Good luck

vic

shorrog

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Model 9 gearbox removal & Strip down
« Reply #1 on: September 14, 2014, 09:25:29 PM »
Hi folks, I am looking to strip down my gearbox on my 1930 model 9.    Can anyone tell me the steps needed to remove the gearbox from the bike?

Also any hints on stripping the gearbox?
Graham
« Last Edit: September 18, 2014, 12:21:59 PM by shorrog »