855R gearbox repair or swap?

Hi guys, I'm Justin from Belgium, I'm the proud owner of a dark olive green manual 855r,
Car has 235 000 kms and I'm affraid a gear box bearing has gone out (sort of dampened grinding noise following the speed of the car and increasing noise level on accelerations and decelerations).

Previous owner told me he rebuit the gearbox (a bearing and syncros) but has he couldn't find the correct bearing he used and Integra R type so he had to adapt the bore in the GB to accomodate the type R bearing. My guess is that the same bearing has gone out again...
I have two solutions:
1 rebuild the box or replace it with a 2d hand M56 GB fitted with a Quaife.

My question is: does all the 850 M56s are the same (except for those fitted with the2.5TDI that has a shorter ratio)? If yes I would find try a low mileage 2.0L NA 850 to source it's GB, assuming that the lower the output of the engine the better the GB!!!
Does that make sense??

Thanks in advance

Would definately go M56 with an LSD fitted. My 855R has done 180,000 miles and the viscous diff is definately now an open diff !. If memory serves the M56 boxes come with slight variations in ratios (at least in the first two gears). Think M56L has lower first and second, and M56H is slightly higher (not 100 percent sure but a Google search would probably confirm it). If you get a box from a later S70 or V70 be warned they have a concentric slave cylinder (slave and release bearing combined) which is inside the gearbox and your external slave can't be easily retrofited. You can make it work by modifying the hydraulic pipe feeding it which is what I did on my old 855 T5.

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Originally Posted by justinV

Hi guys, I'm Justin from Belgium, I'm the proud owner of a dark olive green manual 855r,
Car has 235 000 kms and I'm affraid a gear box bearing has gone out (sort of dampened grinding noise following the speed of the car and increasing noise level on accelerations and decelerations).

Previous owner told me he rebuit the gearbox (a bearing and syncros) but has he couldn't find the correct bearing he used and Integra R type so he had to adapt the bore in the GB to accomodate the type R bearing. My guess is that the same bearing has gone out again...
I have two solutions:
1 rebuild the box or replace it with a 2d hand M56 GB fitted with a Quaife.

My question is: does all the 850 M56s are the same (except for those fitted with the2.5TDI that has a shorter ratio)? If yes I would find try a low mileage 2.0L NA 850 to source it's GB, assuming that the lower the output of the engine the better the GB!!!
Does that make sense??

Thanks in advance

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I'm sorry to here of your gearbox troubles, your m59 with it's viscous coupling/diff is getting pretty rare these day and is going to be a bit difficult to rebuild, if the bore in the gearbox has been modified, unless you are able to get the same bearing again. As for fitting a M56 and fitting it with quaife that is a good option and gives you a lot of choice in what ratio's you can have, as mentioned above the ratio between the 1st and 2nd gears can be closer on some boxes. The lower output of the 2.0L could possibly lead to a better gearbox,as you assume that it's lower engine power output could mean the gearbox is less stressed, but that would really depend on who owned it and how they treated the car. M56's came in 3 final drive ratios (4.0:1 / 4.25:1 / 4.45:1) and 4.0:1 are typically found in T-5's etc and the lower final drive ratios in the 2.0l, in which the 10v model used the very low 4.45:1 with the closer 1st and 2nd gears, which I run in my 855 T-5R with a quaife and is super quick on acceleration due to the ratio's I selected. Also as mentioned above the clutch slave cylinders changed on the later stuff, but that is not really a problem and it is possible to fit an external slave to a later box, it just requires some careful drilling and tapping to allow you to bolt it in, or you can just modify the pipework and fit the later concentric clutch cylinder, but these can sometimes be a bit of a pain to bleed from my experience.

Great! Thank you guys for the advises...i think i will drop the m59 to open it and see what's going on inside. It willalso help me to practise a bit in the eventuality i have to open the m56 from the 2.5tdi i have on my donor car...