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Synchro hub assembly tool.
https://ausmini.com/forums/viewtopic.php?f=5&t=11928		 Page 1 of 2
Author:  drmini in aust [ Sat Oct 08, 2005 7:51 am ]
Post subject:  Synchro hub assembly tool.
What's the most feared noise during gearbox assembly?
"PING........."

I posted this in reply in gallery forum, but it's worth putting here.
One of the most worthwhile tools I've made, IMO.

ASSEMBLY TOOL FOR BALLS INTO SYNCHRO HUBS
I have not lost a synchro ball on assembly since making this tool up.

TO MAKE:
1. Get an old 1st gear, either a 3 synchro one will do. (all the splines are same inside anyhow).
2. Look inside where the balls ran, there are 3 shiny marks, between the cutouts for the baulk ring.
3. hold gear in a vice with the cutouts facing downwards.
4. Take a 4" angle grinder with a well worn cutting or grinding disc on it.
5. Grind a 45* (approx) angle about 6mm wide, into each gear tooth where the marks are. ie equal spaced.... 3 required.

TO ASSEMBLE:
1. Put this tool on the bench with the 3 grooves facing up.
2. Fit your synchro hub (either one you are assembling) inside it from top. Fit the 3 springs. Sit the 3 balls in the grooves.
3. Push the hub into the tool. the balls will run down the grooves and into the hub.
4. Put the outer part of your synchro hub on the bench. Put the tool and hub assy on top. align the synchro cutouts of ring with those on the hub and then push the hub down thru the `tool' into your synchro outer ring.

See pics..... sorry they are a bit dark... :wink:
Image
Image
Author:  Wolfman [ Sat Oct 08, 2005 9:02 am ]
Post subject: 
Here ya go Doc, added a little light on the subject for you :wink:
Image
Image
Author:  drmini in aust [ Sat Oct 08, 2005 9:28 am ]
Post subject: 
Thanks for that... :wink:
Author:  minster [ Tue Oct 11, 2005 8:19 am ]
Post subject: 
Thanks for that Dr Mini. Have not rebuilt a mini box yet so I havent experienced the 'ping' but Im sure it will come in handy. Now to find a spare first gear........
Author:  Drekkus [ Tue Oct 11, 2005 9:18 am ]
Post subject: 
I've got my gerbox apart again and I had to put new springs into the hub.It took 3 people 10 minutes to get the thing in again.The balls kept going everywhere.

BTW what is the purpose of the springs and balls. I've been told part of my problem in crunching from 3rd to 2nd was weak springs.
Author:  Circus_Maximus [ Tue Oct 11, 2005 12:43 pm ]
Post subject: 
Positive detent , locates the gear and stops it from dis-engaging by itself, that is popping out when backing off the throttle. Crunching when engaging gears would be synchro rings.
Author:  Drekkus [ Tue Oct 11, 2005 5:21 pm ]
Post subject: 
Circus_Maximus wrote:
Positive detent , locates the gear and stops it from dis-engaging by itself, that is popping out when backing off the throttle. Crunching when engaging gears would be synchro rings.


Synchros looked within specs but I have changed them anyway.The primary gear end float was also out, now fixed.
Author:  drmini in aust [ Wed Oct 12, 2005 4:23 pm ]
Post subject: 
Circus_Maximus wrote:
Positive detent , locates the gear and stops it from dis-engaging by itself, that is popping out when backing off the throttle.

No, sorry, that function is the selector balls & springs...

It's more involved..
Reason for the 3 inside the synchro assy is to apply an axial load to the baulk ring when you engage that gear. Gear cone friction then drags the baulk ring around, until the outer synchro sleeve can apply direct load to the ring via the 3 lugs. When gear speed is equalised the synchro cone will centre and allow the gear to be engaged.

If these springs are weak you will crunch gears, even with new baulk rings.... :cry: Check 'em while they are out.

Trivia... early 850 `cone synchro' boxes had 6 springs in each synchro ... and the synchros were friggin' useless. :lol:
Author:  Drekkus [ Wed Oct 12, 2005 7:47 pm ]
Post subject: 
drmini in aust wrote:

If these springs are weak you will crunch gears, even with new baulk rings.... :cry: Check 'em while they are out.



So the advise I got could be right.Soon find out I guess.I hope to have the box back in in the next couple of weeks,just waiting on my new 1st/2nd selector fork to arrive.
Author:  drmini in aust [ Wed Oct 12, 2005 9:40 pm ]
Post subject: 
Use the longest springs you have. Any that are short, chuck 'em.

If you buy the current MiniWorld mag, there's some pics of how to check their strength with a bench drill and bathroom scales.. :wink:
Author:  TheMiniMan [ Wed Oct 12, 2005 10:10 pm ]
Post subject: 
haa haa hee hee,,,Ahh,,,,the young Doc is still learning :-) :-) :-)

But!!!!!!!!!!,,,,If you`d like a way better tool for the job Kev,,,do yourself a favour & grind those 3 slots a little different,,,,one of them only about a ball width deep,,,,the second one about 2 balls width deep & then the third one about 3 balls width deep

hee hee,,,that way you can easy fit in one ball&spring at a time then move the outer ring a tad & fit the second,,,then move the outer ring a tad more & fit the third

it`s way ways better,,,we`ve done it this way since 1965 :-)

If you can get the drift of what i typed here then cool,,,if not then i can take a pic of my tool (mmm maybe my tool isn`t the right word here :-) )

anyways, let me know if you`re confused & i`ll stick a pic up :-)
Author:  drmini in aust [ Wed Oct 12, 2005 10:21 pm ]
Post subject: 
I know what you mean Matt, but mine works.. & I haven't `lost a ball' since I made it! (1995 I think). :wink:
Author:  Drekkus [ Thu Oct 13, 2005 7:20 am ]
Post subject: 
drmini in aust wrote:
Use the longest springs you have. Any that are short, chuck 'em.

If you buy the current MiniWorld mag, there's some pics of how to check their strength with a bench drill and bathroom scales.. :wink:


I bought six new ones and they are longer.Last time I was able to actually put the springs and balls in by myself, this time not a chance so I'd say there is a bit more strength in them. For a few dollars each its not worth not changing them.
Author:  Mick [ Fri Oct 14, 2005 8:50 am ]
Post subject: 
These tidbits are so cool, I wish I broke gearboxes more than once every ten years so I could play with one of these tools.

I feel like pulling apart my engine just for some excitement now.

I feel so disapointed with myself :cry:
Author:  CPOCSM [ Fri Oct 14, 2005 9:53 am ]
Post subject: 
Great after the fact - I had the tool ready to go(thanks kev) but thought I would be right now the box was nearly together. Had all the bits in place but not the clutch end. Anyways checking(more like fiddling!!)to see if everthing worked well, pushed the 3/4 synchro hub a little too far...WHACK!! WHACK!!, both cheeks this time...those little ball bearings really hurt when they fly out - and I am thinking the springs are ok as they were following soon after at a great rate of knots!!

If it is in place and all is well....LEAVE IT ALONE ROBERT!!

I just never learn!!

Hooroo

Rob Forsyth
Miniot!!
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