M90 Gearbox Ratios / ID

[Badger vs Bodgers]

Hi all, here's a quick conundrum for the experts on here. The first 940 I bought came with a load of spares, including a spare red block M90 gearbox with no identification on it. From my research (and the engine) it should be an L1 or L2 version.

Checking the ratios on 5th to identify it, I get 0.76:1 rather than the 0.7 (L2) or 0.81 (L1). I've double and triple checked this, so I'm fairly certain in my results. Any ideas what I've got here?!

[Laird Scooby]

Originally Posted by Badger vs Bodgers

Hi all, here's a quick conundrum for the experts on here. The first 940 I bought came with a load of spares, including a spare red block M90 gearbox with no identification on it. From my research (and the engine) it should be an L1 or L2 version.

Checking the ratios on 5th to identify it, I get 0.76:1 rather than the 0.7 (L2) or 0.81 (L1). I've double and triple checked this, so I'm fairly certain in my results. Any ideas what I've got here?!

Check pg 103 on this pdf for the correct ratios for the M90H and M90L as none of the 5th gear ratios you mention apply to any M90 listed according to Volvo.

http://www.myvolvolibrary.info/Tech_...DataPocket.pdf

Easiest way of checking it's an M90 is if reverse is right and back rather than left and forwards and if it is definitely an M90, i'd hazard a guess it is a prototype gearbox. It's not unknown for prototype boxes to escape into the world but obviously very rare. It could also be a box built for motorposrt use by Volvo that has escaped.

[Badger vs Bodgers]

Originally Posted by Laird Scooby

Check pg 103 on this pdf for the correct ratios for the M90H and M90L as none of the 5th gear ratios you mention apply to any M90 listed according to Volvo.

http://www.myvolvolibrary.info/Tech_...DataPocket.pdf

Easiest way of checking it's an M90 is if reverse is right and back rather than left and forwards and if it is definitely an M90, i'd hazard a guess it is a prototype gearbox. It's not unknown for prototype boxes to escape into the world but obviously very rare. It could also be a box built for motorposrt use by Volvo that has escaped.

That's a useful resource! I was going off what I found on Wikipedia and turbobricks, which always has the chance of being a bit flakey to be fair.
All the gears are in the correct place to be an M90, but the only identifier on it is the number 1023650-12, which I can't seem to match up to anything. :

Maybe it's a prototype then? I'll check the ratios of the other gears when I get the chance. The engine it came attached to is of unknown providence, but is a B230FK.

[baggy798]

How are you measuring it?

You could use a degree wheel. 0.70 is 252° and 0.81 is 292°.

https://i.pinimg.com/originals/65/41...e5ddd4f67c.gif

Turn the input one revolution and see how far the output moves, that'll be easier to see. 360°+70° = L1, 360°+110° = L2.

[Laird Scooby]

Originally Posted by Badger vs Bodgers

That's a useful resource! I was going off what I found on Wikipedia and turbobricks, which always has the chance of being a bit flakey to be fair.
All the gears are in the correct place to be an M90, but the only identifier on it is the number 1023650-12, which I can't seem to match up to anything. :

Maybe it's a prototype then? I'll check the ratios of the other gears when I get the chance. The engine it came attached to is of unknown providence, but is a B230FK.

I've found quite a few "incorrect facts" on both turbobricks and Wikipedia - i used the quote marks round the words as they may actually be correct in the country where the person added that information lives just not for here.

I would think the 1023650-12 number is the complete assembly part number for the gearbox, especially if it's on the label underneath the box. However, searching gcp.se and volvopartswebstore.com doesn't bring anything up but in fairness the M90 gearbox doesn't have a listing so is presumably NLA.
Someone like Luke may be able to confirm the part number if he has another M90 floating around and can look, that said i wouldn't be surprised to learn the last 2 digits are different which would be down to the odd ratios. In my theory at least!

The main thing is the condition overall of the gearbox and if it's worth your while keeping it as a spare or polishing to put on the mantelpiece as an ornament?

[360beast]

The weak point is the 3rd gear stop ring, it can go beyond where it is meant to so you lose 3rd gear. The solution is to weld it in place and is what is needed for high power applications, I need to do it for my 940 when I get my spare engine built up with the Holset turbo etc.

I've whatsapped Ben about this.

[Badger vs Bodgers]

Originally Posted by baggy798

How are you measuring it?

You could use a degree wheel. 0.70 is 252° and 0.81 is 292°.

https://i.pinimg.com/originals/65/41...e5ddd4f67c.gif

Turn the input one revolution and see how far the output moves, that'll be easier to see. 360°+70° = L1, 360°+110° = L2.

I basically did the latter version - I marked up input and output, then turned the input 5 times. Should have been a little over 6 if it was a 0.81, a bit over 7 if it was a 0.7.

Of course it came out at a little over 6.5 turns... lovely.

Looking at the pictures and talking to Luke, it's definitely an M90 of some shape or another. It seems to be in good nick, but of course it's very difficult to say without putting it behind an engine!

I'm going to count the ratios on the other gears to see what they're like, and if it's favourable consider swapping it into mine. I'll crack it and eyeball the inside before I do that - at least with a borescope to check for signs of damage.

Thanks for the help guys