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18mm gearbox mainshaft ?
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Author:  MINImal effort [ Sat Dec 01, 2007 12:58 pm ]
Post subject:  18mm gearbox mainshaft ?
Hi,

Pulled the gearbox off one of my project cars - and found (as suspected) is standard ratio (laygear 22G927) and want to upgrade to "S" ratios.

This would require 22G1040 laygear and 22G1371 1st Motion shaft.

On a quick hunt round the usual suppliers the 22G1371 seems to be in short supply.

The alternative would be to substitue the 22G1371 with the DAM3167 - which uses the 18mm Mainshaft instead of 14mm. (Which I understand is better lasting/stronger anyway (?))

My question (finally) is - is it feasible to change to the 18mm mainshaft in a 22G1128 (remote change) box ?

If so - want else needs to be changed /done ???

Thanks in advance !
( I have to head off down the coast (late already) - so will review comments/advice on my return.)

Ken
Author:  drmini in aust [ Sat Dec 01, 2007 1:03 pm ]
Post subject: 
Yes it's feasible I run one in my Mk2 S box.
You can buy new 18mm shafts but they are $170 or so.
I'm modding a 14mm shaft to 18mm nose for my stroker on Monday, so I'll do 2 then. :lol:
Price will be $60 with a new 18mm `INA' inner race fitted.
PM me when you get back... :wink:
Author:  Smarty [ Sat Dec 01, 2007 4:31 pm ]
Post subject: 
I was just going to ask the same/similar question so might as well ask it here....

I have the same remote 4 synchro box as above, and would like to put in cooper s close ratios, but cant seem to find the right parts.

So Doc do you just make a bush of sorts to space out the mainshaft to 18mm?

Or

Is there somewhere that I can buy the correct bits?

Which part numbers would I need to get to do the conversion? ie for 1st motion and laygear?

Sorry for the silly questions, just that minispares and mini mania are not very clear on which gearboxes they suit. Or would I be better off getting them from Karcraft or the like?

here ends the hijack....... :roll:
Author:  drmini in aust [ Sat Dec 01, 2007 9:37 pm ]
Post subject: 
re the gears- Cooper S and late 1275GT both used the 22G1040 cluster gear. There are 2 different 1st motion shafts- 22G1371 and DAM3167.
The former uses the 14mm nose mainshaft and the latter uses an 18mm one.

The 18mm nose mainshaft is a bit shorter than the 14mm one.
To convert the early shaft I hard turn most of the boss next to the splines down to 15.012mm dia, and press fit a hardened `INA' inner bearing ring, which is 18mm OD x 15mm ID x 16.5mm long.
If it ever wears you can grind it off and replace it. :wink:

The 22G1371 is getting hard to find now, that's why I'm modifying the shaft to fit the DAM3167. There is no difference between these gears except the needle bearing size.

These gears fit both 4 synchro remote and A series rodchange boxes.
Author:  Smarty [ Sat Dec 01, 2007 10:23 pm ]
Post subject: 
Thanks Doc That makes sense now
Author:  justminis [ Sun Dec 02, 2007 7:21 am ]
Post subject: 
drmini in aust wrote:
The 18mm nose mainshaft is a bit shorter than the 14mm one.
To convert the early shaft I hard turn most of the boss next to the splines down to 15.012mm dia, and press fit a hardened `INA' inner bearing ring, which is 18mm OD x 15mm ID x 16.5mm long.
If it ever wears you can grind it off and replace it. :wink:



Was wondering how you were going to deal with the difference in length of the 2 mainshafts :D In days gone Mini Kingdom used to sell a kit that contained the S cluster, DAM 3167 and 18mm mainshaft. Is a very worthwhile swap.
Author:  drmini in aust [ Sun Dec 02, 2007 7:43 am ]
Post subject: 
justminis wrote:
drmini in aust wrote:
The 18mm nose mainshaft is a bit shorter than the 14mm one.
To convert the early shaft I hard turn most of the boss next to the splines down to 15.012mm dia, and press fit a hardened `INA' inner bearing ring, which is 18mm OD x 15mm ID x 16.5mm long.
If it ever wears you can grind it off and replace it. :wink:



Was wondering how you were going to deal with the difference in length of the 2 mainshafts :D In days gone Mini Kingdom used to sell a kit that contained the S cluster, DAM 3167 and 18mm mainshaft. Is a very worthwhile swap.

I'll leave the shaft its original length with its centre intact, it still fits up inside the new gear with plenty clearance, no problem.
Author:  miniron [ Sun Dec 02, 2007 9:30 am ]
Post subject: 
:?:
Hi Kevin,
A couple of questions re the conversion. Its quite a while since I had a 4 synchro box apart so I'm just trying to get a picture of what happens. Since you've done the conversion it obviously works so I'm missing something in my understanding.

1/. If the original nose of the mainshaft is 14mm dia and the inside dia of the hardened ring is 15mm there seems to be a 1mm difference in dia. What happened to the 1mm difference? What am I missing here?

2/. What does "INA" mean in the hardened ring reference?

Regards
Ron
Author:  drmini in aust [ Sun Dec 02, 2007 2:56 pm ]
Post subject: 
The gear that has the 14mm bearing has is buried inside the gear, roughly inside the big ball bearing.
The later gear has the 18mm bearing moved towards the 3rd/4th synchro hub, because the bearing is too big to go exactly where the 14mm one was. So, the shaft is shorter.
There is a large diameter boss on the old shaft next to the splines, the 18mm diameter on the late shaft starts 3mm from the splines, and is 15.5mm wide.
So I can turn that boss down to 15.012mm to take the 18mm bearing inner ring.
:wink:

<edit> if I wasn't CAD illiterate I'd throw a drawing up. :lol:
Author:  miniron [ Sun Dec 02, 2007 4:06 pm ]
Post subject: 
:D
Thanks for that Kevin,
I've never clapped eyes on any of the late rod change type boxes. In fact I've had nothing to do with any rod change boxes at all. Remote changes for me. It all makes sense now. The INA bit?

Regards
Ron
Author:  drmini in aust [ Sun Dec 02, 2007 5:41 pm ]
Post subject: 
INA makes needle roller bearings.
To run rollers direct on a shaft, the shaft hardness needs to be Rc61 or more, which Mini ones are- when new..
However, the mainshafts are case hardened- if you turn or grind them down you go through the hardness. Attempts then to run rollers direct will result in severe shaft damage.
Inner rings are made by the bearing manufacturers, INA, Torrington and others- they are ballrace steel to provide a hard surface for the rollers to run on. They are retained by being a light press fit.
As I said, a further advantage is that should they ever wear, they can be changed.
Author:  drmini in aust [ Mon Dec 03, 2007 2:36 pm ]
Post subject: 
OK here's a pic..
The shaft at back is a 14mm one (now ground down and fitted with a 14mm hardened bearing inner ring). I've done a few of these for people, even did a Mk1 S shaft once.

The front one I did today, it has had the big boss hard turned down and an 18mm hardened bearing inner ring press fitted.
The ring is 1mm wider than the journal on the later shaft, but that's no problem.
And the old 14mm diameter is no problem either it fits up inside the DAM3167 1st motion shaft with plenty of clearance.
Image
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