Gearbox Rebuild

[Mr Rusty850]

Hi Everyone,
I've started my first ever attempt to refurbish a gearbox. It's a magic wand box fitted with B type gears. The stripdown has progressed with few dramas and it's clear that all the bearings need replacing as well as the layshaft. The re are a couple of issues that I need your thoughts on:

1. The faces that the baulk rings face against are black and there appears to be some sort of residue on them. I've attached a photo which hopefully shows this. Is this normal? I'm assuming the residue should be removed as I intend to fit new baulk rings and the residue could make everything on the re-assembled mainshaft a bit tight. Any thoughts on the best way to remove the residue?

2. The helical gears are in good condition and although 1st gear is worn it doesn't look too bad unless you think otherwise. First gear on the layshaft looks badly worn and so the layshaft needs replacing. Its a 22G231 and they appear to be in short supply. Any ideas where I might try to get one or does anyone have a decent used one that they are prepared to sell?

3. Finally the box is fully stripped except for the selector rods. The locknuts come undone o.k but the small pinch bolts seem very tight and I'm worried about snapping one off. Any tips for shifting them or just I just leave the rods in place?

Any advice much appreciated; I'm sure there'll be more questions when re-assembly commences.
Thanks,
Barry

[iain1967s]

The friction faces on the original gears are heat coated with molybdenum intended when steel baulk rings [sintered or forged] are used. Do not remove the coating - the surfaces should be smooth light-black coloured, no galling or cracks.

Note: non-moly coated gears are designed to be used with bronze baulk rings.

Quality of modern baulk rings is variable. If they aren’t machined properly, it can cause them to stand off the face too much and bind up. There are some vendors [john guess, david ainley] who sell machined-to-spec rings.

[cmiller]

You are correct on the laygear. It is toast. Good luck on your quest to find one. They do turn up every so often.

Chris Miller

[Lakeland997]

1. As Iain says.
The one you've pictured doesn't look too good - the coating appears to be worn however you may have no choice but to re-use them as 3-synchro helical gears are hard to come by.
2. 3-synchro first gear is now available. As you say, yours doesn't look totally worn out but if you're going to the trouble of rebuilding...
The lay gear certainly looks like it needs replacing.
Have you sourced all the bearings? If not, then John Guess (Guessworks) is probably your best bet.
He may have a laygear too.
3. The benefit of removing the shift rods (or at least the reverse one) is to remove the reverse detent/spring and clean them as they can become seized in muck. I've never snapped one of those screws - they seem to be quite a good spec - but if you did, then it could get a bit awkward.
Perhaps others have experience?

Andy

[CooperTune]

Some how as a kid 12 years old I got a chance to help rebuild a couple M/C trannys. Jawa and Honda and I just loved it. I bough a couple trannys and on Friday nights I'd strip one and reassemble just for fun. Fast forward, at 18 I bought my first mini. I have been digging into mini gear boxes since. My last tranny clean up with in the last 20 years I stripped all 19 mini trannys I had on hand. Those that could be rebuilt were. Those with bad idler bearing bores or other damage were salvaged for parts. The magic wand diff housings are used to convert AA style 1128s to magic wand for Mokes. Any Cooper type remote housing form bad cases are boxed and I mail it around for others wanting to convert to remote by select fit.
A couple friends have agreed to join me in another major strip down. I have not yet gotten a complete count but I know 8 1128s, 2 333s, 1 190, and several early three and four sync numbers I'm not sure about. I'm sure there are another five or six in storage off site. Power washer, and both solvent tanks freshened and ready. I have and continue to collect NOS parts as they show up. Steve (CTR)

PS remove the fork grub screws and clean it properly.

[iain1967s]

First gear on the layshaft looks badly worn and so the layshaft needs replacing. Its a 22G231 and they appear to be in short supply. Any ideas where I might try to get one

https://www.ebay.co.uk/itm/173708025470

[251 ENG]

I have some NOS 3 syncro bits available.

May have a laygear

Email me at orx77@yahoo.co.uk

[Andrew1967]

If Simon can't help with a laygear, I may be able to .. will have a look. I did have a NOS one a while back.

Also check the reverse gear as that may have suffered, looking at the state of the 1st gear and laygear.

Totally strip the box. Check how worn the brass 1st/2nd selector fork is, the sides of the fork where the side of the 1st gear contacts when changing gear can be worn quite thin.

[Gary Schulz]

Some how as a kid 12 years old I got a chance to help rebuild a couple M/C trannys. Jawa and Honda and I just loved it. I bough a couple trannys and on Friday nights I'd strip one and reassemble just for fun. Fast forward, at 18 I bought my first mini. I have been digging into mini gear boxes since. My last tranny clean up with in the last 20 years I stripped all 19 mini trannys I had on hand. Those that could be rebuilt were. Those with bad idler bearing bores or other damage were salvaged for parts. The magic wand diff housings are used to convert AA style 1128s to magic wand for Mokes. Any Cooper type remote housing form bad cases are boxed and I mail it around for others wanting to convert to remote by select fit.
A couple friends have agreed to join me in another major strip down. I have not yet gotten a complete count but I know 8 1128s, 2 333s, 1 190, and several early three and four sync numbers I'm not sure about. I'm sure there are another five or six in storage off site. Power washer, and both solvent tanks freshened and ready. I have and continue to collect NOS parts as they show up. Steve (CTR)

PS remove the fork grub screws and clean it properly.

Some pics of stripped gearbox components from CooperTune...

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[Andrew1967]

PM sent regarding a NOS laygear I have available

[Mr Rusty850]

A quick update on progress; but first a huge thank you to everyone who responded to my post especially Andrew who has come up trumps with a NOS laygear. I've also found a much better used 1st gear and the shopping list I'm writing for Guessworks is also growing.

Anyway, bolstered by your comments I've removed all the selector rods and the case is now completely stripped down except for the detents which don't want to come out. I've sprayed plenty of GT85 onto them and they slide easily for a few mm down the bores but then stop. I think I might have to resort to compressed air unless anyone has other suggestions? Finally does the reverse gear detent exit down the hole for the 1st/2nd gear detent?
Thanks,
Barry

[floormanager]

I struggled but managed to get the detents out that the selector rods interface with, using a pick and then some stout wire. Weird as they would not budge, then suddenly, out they came.

Try as I might I could not get the reverse one out on the front of the gearbox. I even tried feeding a wire down the hole and pulling but it would not budge. In the end, I gave up. Stupid, another g/box they all come out with ease!

[Lakeland997]

I found that the detents often get stuck as they reach the thread. It seems that the soft alloy thread gets distorted when you tighten the plug.
I run a drill (I think 9.5mm or 10mm - whichever one is about the same diameter as the detent just fits the ID of the thread) into the thread and that clears it.

Failing that, it's welding wire, a magnet, and plenty of WD40.

Andy

[Mr Rusty850]

Bingo, the 9.5mm drill helped clear out some gunge and then a flexible wire and gravity did the rest. Thanks Andy, good call.

Barry

[Mr Rusty850]

Hi Folks,
While I'm waiting for the new parts to arrive I decided I could start the rebuild bu assembling part of the mainshaft. The third gear went on no problem and was secured with the locking washer. 2nd gear has been somewhat more challenging. The 26 rollers went into position no problem and the spring and locking pegs fitted as per photo 3. The second gear slipped on nicely and then the two C washers (or retaining collars) as shown in photo 2 were positioned onto of the ends of the rollers and the locking washer slid down the mainshaft splines (photo 1). I believe the technique to get the locking waser in position is to take two probes to depress the pegs whilst pushing down on the locking washer until it slips under the splines on the mainshaft when it can be rotated freeing the pegs to secure it in place. So much for theory. The little cut outs on the underside of the locking washer mean I can get the probes on the ends of the plugs but I can't get the plugs in far enough whilst also pushing the washer down to retain them. Am I missing something or is it just a case of persevering? Any advice or suggestions very welcome.

Barry (Currently frustrated of Rufford)

[Andrew1967]

Its a bit of a bugger of a job really Barry and much easier with two people.

One to press the pegs in from both sides and one to push down and carefully rotate the lock ring.

Edit ..

I used two small watchmakers screwdrivers to press the pegs in .. 1/16" welding rod would suffice.

[gogsymac]

Hi Folks,
While I'm waiting for the new parts to arrive I decided I could start the rebuild bu assembling part of the mainshaft. The third gear went on no problem and was secured with the locking washer. 2nd gear has been somewhat more challenging. The 26 rollers went into position no problem and the spring and locking pegs fitted as per photo 3. The second gear slipped on nicely and then the two C washers (or retaining collars) as shown in photo 2 were positioned onto of the ends of the rollers and the locking washer slid down the mainshaft splines (photo 1). I believe the technique to get the locking waser in position is to take two probes to depress the pegs whilst pushing down on the locking washer until it slips under the splines on the mainshaft when it can be rotated freeing the pegs to secure it in place. So much for theory. The little cut outs on the underside of the locking washer mean I can get the probes on the ends of the plugs but I can't get the plugs in far enough whilst also pushing the washer down to retain them. Am I missing something or is it just a case of persevering? Any advice or suggestions very welcome.

Barry (Currently frustrated of Rufford)

I have just done this procedure on the 3 synchro box for my car. It took me hours of trying to finally get the gear fixed in place (and a lot of bad language too). I did it myself and I used an old, cut down hack saw blade (as recommended to me by fellow member Dearg 1275) to push the little detent spigot things into the holes.

I was able to get the thrust washer down on one side with one of the spigots fully in no problem. It become really tricky trying to do the other one as when I seemed to succeed with that the other one popped out. At first I thought the spring was maybe the wrong type as it seemed to need a huge amount of pressure to try and push the second spigot into the body of the gear so I tried different springs - didn't help as I continued to have problems.

I persevered. I did it finally yesterday after deciding to give it "one last go" and it worked. This is what i did - mind you I just repeated the process which I used before and expected a different result which some would say is a sign of madness.

Anyway I pushed in one spigot and got the thrust washer down enough to hold that in place whilst I tackled the other side. I held down this first side as best as I could and used the hacksaw blade to push the second one into the body of the shaft. It went in most of the way but seemed to get stuck before it went in enough to allow the washer to go down enough to hold it in place. I kept pushing and finally I felt that it moved in enough to enable the washer to fall down enough to hold it in place (and not pop out as before). This needed a fair push. I found it a little tricky to ensure that I was hitting the spigot full on to enable me to push it in all the way but after keeping on at it, it finally pushed in all of the way. When I had done that I used a thin junior hacksaw blade to move the two C shaped spacer washers round so that they aligned exactly with the cut out in the thrust washer - ie the space where you can use your blade or other tool to push the spigots into the body of the shaft. I used a torch to see what I was doing here. After a bit of fiddling about in this way the thrust washer magically moved down with a little pressure and I was able to rotate it to secure the gear in place.

It was one of the trickiest jobs which I have done and it needed much time and patience. Keep trying and eventually it should work.

[Mr Rusty850]

Thanks guys. Firstly for assuring me its a pig of a job and to persevere. Gogsymac's experiences made me smile as it mirrored my own experiences. The hacksaw blade suggestion was superb. It only took a few minutes to create two suitable pointers and with the help of my son it took us about 20 minutes tonight to get it all back together. Such a good feeling when it suddenly works. It caps off a good day as this morning using a jubilee clip and a large G clamp I got the synchroniser hubs back together (thanks Andrew).
Now where are those deliveries.

Barry

[gogsymac]

Thanks guys. Firstly for assuring me its a pig of a job and to persevere. Gogsymac's experiences made me smile as it mirrored my own experiences. The hacksaw blade suggestion was superb. It only took a few minutes to create two suitable pointers and with the help of my son it took us about 20 minutes tonight to get it all back together. Such a good feeling when it suddenly works. It caps off a good day as this morning using a jubilee clip and a large G clamp I got the synchroniser hubs back together (thanks Andrew).
Now where are those deliveries.

Barry

Oh - just one other thing which might help people when rebuilding the gearbox. I had to build up the two synchro hubs and it took ages because I am pretty useless at that sort of thing. The springs and balls kept popping out and I spent much time scrabbling about the garage floor trying to find them.

I then solved that problem by rebuilding the hubs in a cardboard box (not me - the hubs). When the fitting up failed the balls and springs were contained in the box so no more feeling about on the garage floor looking for the errant bits.

[Andrew1967]

Good to hear you managed it Barry.

Gordon, I upgraded to a plastic ice cream tub a while ago .. That with a good jubilee clip is as good as the special tool available