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gearbox swap

Posted: Sat Oct 15, 2016 8:58 am
by scotty
Hi all just changed my 4spd box over for the spare, we did it without removeing the engine had prim case off my son is a pretty cluey bloke reconed it could be done and did it. Take off the 4 nuts at back of box this lets you slide box back half an inch then you can loosen the four studs with slip joint pliers put 2 nuts on a stud lock em together and unscrew stud, do the other 3 same box can then be lifted wiggled out.installation reverse nb top 2 studs are 110mm long btm ones 104mm would be easier to get another 2 top studs not enough room on btm ones to lock the 2 nuts together makes it better when screwing studs back into engine. Hardest part was the hex bar for the footrests soft as putty will make a new one with decent steel. I was really surprised took 25 mins to get box out much easier than lifting motor and gearbox out as one unit. Old box was locking up gears look ok suspect bearing on rhs.
Hope this helps others it really is quite easy, if you slacked the 2 big nuts that hold the top gearbox plates and take the 2 studs on the btm of the small plates they can be swung up out of the way.
Happy fiddeleing please use enfield approved swear words.

gearbox swap

Posted: Sun Oct 16, 2016 6:32 pm
by NicoV
Amazing ! I recently did a swap, and took the engine out. No problems, but a lot of work !

gearbox swap

Posted: Sun Oct 16, 2016 11:51 pm
by Tim NZ
Not wanting or meaning to belittle your efforts, but the gear box can be overhauled in placed, other than if the main bearing seat in the case is well and truly fornicated...

gearbox swap

Posted: Mon Oct 17, 2016 12:59 am
by scotty
Tim we had a spare box on the shelf, quicker to swap and fix other in spare time one taken out had hc close ratio gears.

gearbox swap

Posted: Wed Oct 19, 2016 3:55 pm
by Rodders
Hi Scotty, amazing that you have just posted that. This afternoon I have been trying to remove the remaining part of my 4 speed gearbox so I can replace it all and found exactly the problem you mentioned. I had worked out the only way is to get some pliers on the studs - having retreated to re-group you have given me hope this is the answer. Many thanks.

gearbox swap

Posted: Thu Oct 20, 2016 4:26 am
by Tim NZ
Less than 45 mins work to strip and rebuild the gbox insitu...


At one time I had thought about getting bolts made for the 4 x gbox studs. But typically double nutting them works just fine, easier to get at if you have removed the rear wheel and guard. Definitely the way to go when removing the engine, and you dont need to remove the center stand etc.

gearbox swap

Posted: Thu Oct 20, 2016 8:05 am
by Himself
Just a minor point, but the gearbox plates on my 2008 350 Bullet are attached to gearbox with long bolts, not studs. Would this be problematic?

gearbox swap

Posted: Thu Oct 20, 2016 10:11 pm
by Tim NZ
The use of Bolts is a PITA! Cheap and nasty to speed up assembly with no benefit to the owner. You can get away with them with the 5 sp box, but not quite so the 4; you have remove the inner chaincase to get the bolts out.


(I have in the past had reason to cut the heads off the bolts and refitted studs)

gearbox swap

Posted: Fri Oct 21, 2016 8:40 am
by Himself
Thanks Tim, After looking at my bike I can see the bolts wouldn't make any difference if removing the gearbox in the manner suggested in this thread. I too sawed the head off a bolt on the front engine plate when removing the engine/gearbox unit. It was impossible to get the bolt out without removing the the timing case.

gearbox swap

Posted: Sat Oct 22, 2016 11:29 am
by jefrs
The hexbar for the footrests is supposed to be soft so it bends if you scrape rather than bending the frame. It's a sacrificial component.



If you should drop the bike it will land on the footpegs, if they don't bend you will bend the frame which being firmly bolted to the engine can damage that too. The hexbar is an easily replace part.