1275 Gearbox rebuild

[brucek]

Thanks Les. Appreciate that. MarkyB see photo below. Number is stamped on the 1st motion shaft just behind the release bearing area on the smooth part of the shaft before it enters the main gearbox casing. You may need to wipe the shaft to see the number 9assuming the 'box is out of the car, of course)[frame][/frame]

[IslipMinor]

1098 Midget boxes have exactly the same ratios as the 1275 Midget boxes

Bruce,

No they do not - please see the earlier posting for the ratios. The later smoothcase Frogeye and all 1098 and 1275 Spridgets had the closer ratio boxes AND the needle roller mainshaft gears.

[brucek]

Wasn't that what I said Richard? That the 1098/1275 Midget boxes had the same ratios but were different from the 1098? Minor?

[bmcecosse]

It's not how it reads - but I do think that's what you meant!

[brucek]

Ah OK well, apologies to all for any confusion that may have caused. Hopefully folks will follow what I meant ;-)

[welshrat]

Time for a quick update: Spent most of this week researching gearboxes! Sad I know but true. I have to make some use of that anorak I have

I was fascinated by the fact that 1098 Midget boxes have exactly the same ratios as the 1275 Midget boxes but, from the outside, at least, they are identical to each other and to the 1098 Minor box too. As mentioned before, the 1098 & 1275 Midget use the stronger needle roller bearings and are more resilient, esp when using the greater power of the 1275 engine. After some trawling I think it is possible to identify which are Minor and which are Midget boxes without having to rip them apart.

The key is to look for a stamped serial number on the first motion shaft just behind the splines on the smooth part which can be seen when the box is out of the car, or, if you are lucky, with a torch through either the top or side inspection hatches.

If your 'box has the number 22G171 - this is a Minor 1098 box and has the standard bronze bush bearings. Perfectly adequate for the 1098 Minor but not so good on a 1275 engine.

If your box has 22G172 or 22G229 then this indicates a Midget 1098/1275 box. It seems there were two gearsets used in the 1275 - an A and a B gearset. Not sure what the difference is but the two numbers allow you to determine whether you have A or B sets.

So, to complete the research, I need to ask you for your help in confirming whether this number check is accurate. If you are in your garage over the next week or so, here's how you can help.

If you KNOW you have a Minor 1098 gearbox in your car or in the garage, please check and post whether your number agrees with mine (from the 'box in the photo in an earlier post). I'm almost certain that this is right for the Minor but a few others to confirm would be great

If you KNOW or THINK you have a 1098 Midget or 1275 Midget box in your car or garage, please check and post to confirm the first motion shaft number. These are the ones I'm most interested in.

Why all this hassle??? well, if the numbers above are correct and you can determine which box is which from them, there could be a few benefits:

i) you will know if you have the 'stronger' box in your car or in your spares to use when the time comes
ii) you will be able to identify the best box for your use from the pile of gearboxes you have in the garage (and maybe sell the rest to make a few quid?)
iii) you will be able to quickly and easily identify which box is available when you go to see a job lot of spares in amongst which are a bunch of old gearboxes

But most importantly, you will be able to pick up the odd bargain at an auto jumble when you see someone advertising a 'Minor' gearbox for £30 and you discover that it is actually the better Midget box!

So, I think I'm going to put my rebuild on hold for now until I can source one of the stronger boxes to rebuild, otherwise the costs will be huge in changing both the bearings and gearsets for the 1275 into a Minor 1098 case. As soon as I have the right box, I'll start the strip down so I know the completed box is completely refurbished.

Please do help with the ID numbers if you can

THIS PUBLIC SERVICE ANNOUNCEMENT WAS BROUGHT TO ALL FORUM MEMBERS BY BRUCE K - general good ol' bean and will happily welcome a pint from anyone who seriously benefits from this

The numbers you have listed on the first motion shaft are correct, however not read anything about the G172, could be the earliest version of the 1275 box. I have been 'on the look out' for 1275 boxes for years and finding a G229 is always a buzz, again there is always a risk as this information is available on most part lists so beware of spending lots of cash and later finding out that the only 1275 part is the bit with G229 on it. Also must say that I have run both a 1098 and 1275 box with my midget motor, can't say I noticed or experience a great deal of difference, 1275 boxes have been silly money for some time now and looks as if the 1098's are going the same way.

[Chipper]

My Midget gearbox has suffered issues with 1st and reverse, so I whipped it out of the Traveller this weekend, to swap a standard Minor gearbox in instead until I can fix it.

However, I noticed that the input shaft just appears to read 'XOWOG', where X is a pair of numbers stamped across what I presume should be an 'M', i.e., to read 'MOWOG'.

[IslipMinor]

These are the primary or first motion shaft part numbers that I have:
[frame][/frame]
In summary the first motion shafts are:

948 Minor/A35/A40 + Frogeye Sprite all use 22A141 (smooth case)
1098 Minor/A40 uses 22G171 (rib case)
948 Sprite II/Midget I uses AEA3032 (close ratio box) (smooth case)
1098 Sprite III/Midget II uses 22G172 (close ratio box) 'A' type gears (rib case)
1275 Sprite IV/Midget III uses 22G229 (close ratio box) 'B' type gears (rib case)

I have heard, but not confirmed, that the 'A' to 'B' type gears were not changed at the exactly same time as the 1098 to 1275 change, but is that true?

The part number is stamped on the input shaft as in the photo below:[frame][/frame]

[Chipper]

I discovered my reverse cog on my Midget 1275cc gearbox has been partially worn down, with angled teeth on the innermost cog, whereas they should be horizontal.

Is it acceptable to use a standard Minor 1098cc reverse gear (part no. 22A453) in the Midget gearbox?

Also, are there any stronger/toughened ones available, as they do seem a bit on the weak side.

[Chipper]

Anyone know the answer to the above? The standard Minor 1098cc gearbox reverse idler gears (22A453) have 14 and 18 teeth, not sure about the Midget 1275cc 'box though...

[IslipMinor]

The reverse idler Pt. No. 22A453 is common to the 1098 Minor and Midget gearboxes, but the 1275 Midget has a different part number - 22G1114. What the difference is I do not know. The idler shaft is common across all the gearboxes and is 88G216.

[Chipper]

Thanks for that. I'm guessing that maybe the Midget 1275 one has needle rollers in, or possibly different teeth count.

Hopefully, I'll find out soon; I washed down my 1275 Midget gearbox yesterday with petrol to get it nice and clean prior to a (partial) strip-down...

[les]

The 1275 box that I have has reverse gear 22G240 it has 18 & 14 teeth, presumably b type.

[Chipper]

That's interesting to hear, thanks, les.

[les]

------and plain bush.

[Chipper]

Sounds as though the Minor reverse gear idler could be used (same number of teeth), but maybe there's some difference in the strength of Minor vs. Midget cogs...

[bmcecosse]

Or perhaps a profile difference.

[Chipper]

Indeed. I gather some (possibly all) cogs in the Midget 'box have a different angle of slant on the teeth compared to a standard Minor 'box.

[IslipMinor]

Maurice,

Yes, there are 'A' and 'B' type gears, which applies to the helical gears, but I do not believe to the straight cut gears of first and reverse.

[Chipper]

Today, I partially stripped the 1275 Midget 'box, and found it to be rather more worn than I expected, which I suspect is down to some parts probably being re-conditioned replacements, with some, such as the reverse idler cogs and layshaft cluster, being marked 'HS...'.

The 1st gear cog is badly worn, as are the outer reverse idler cog and also the first (smallest) cog on the layshaft cluster.

So, I now have four A-series 'boxes (3X standard 1098cc Minor ones and 1X 1275cc MG Midget one), all with various maladies.

Maybe I might be able to cobble together one good one out of the lot...