How to measure a bellhousing bolt pattern?

Cartboard plus paint applied to the gearbox, press them together like a stamp on a document, to get a template.

I doubt they made a polycarb adapter, but a polycarb template to make a steel adapter.

Yeah that's what I meant. The transparent polycarb was used to make the template. I'm not sre how accurate the template would be even then... I guess it depends on the person making it! There'd be some play in the input shaft I'd assume, so how they ensure the shaft is centred I don't know.



Mercedes OM606 to Nissan L-series gearbox.

Make sure the spigot/bearing is gonna fit properly then sit the engine on its nose and bolt the adaptor plate on with countersunk bolts. Sit the gearbag on top and align it then make a transfer punch to mark out the bolt pattern of the gearbox onto the adapter plate. You'll have to take the dowels out so it'll sit flat but can't think of a easier way of doing it by measuring.

Find an engineering firm with a Faro arm and they'll be able to map it straight into CAD.

Luke at DPUK sells an adapter kit which you might be able to use, assuming it is meant to work with the RB/RD engines which share a bell housing pattern with the L series. it looks expensive but isnt when you factor in the other work it saves.

www.dieselpumpuk.com/shop/transmissions/adaptor-kit-nissan-patrol-2-8-3-0-4-2/

I had thought about the DPUK kit, but I was a bit hesitant as the L-series and RB bellhousings are slightly different - according to what I've found, there are two bolt holes in the wrong place which need elongating, and the L-series sits at an angle whereas the RB is upright (or the other way around... I don't recall). I figured that it was a lot of money to spend on something that isn't quite right, and I'd be putting my faith in info collected from various parts of the internet about the bolt pattern similarities. I get what you're saying about potentially saving time though!

These are the 2 bolts and a dowel that are different between L series and RD, the rest bolt up.

I see what you mean about templating the bolt pattern not being affected by input shaft movement, but how do I ensure that once I transfer the bolt pattern to the adapter, the centre of the input shaft aligns exactly with the centre of the crank? As I understand it, runout tolerance is fairly critical. Finding the input shaft centre, with the shaft in the centre of its side-to-side play seems quite difficult. Unless I'm missing something (which is perfectly possible!)



That seems like it would work. The only obstacle I have is that the borrowed gearbox isn't from my vehicle, it just has the same bellhousing pattern, so I'd need to yank my 'box, find the right spigot bearing and go from there.
With the input shaft in the spigot bearing, how do I know that there is no sideways load on the input shaft by having the gearbox slightly misaligned and taking up the play in the shaft? Or am I worrying too much about that? Am I imagining there to be more play than there actually will be in a healthy, fairly low mileage gearbox?



I did consider Merc boxes, such as a Sprinter one, but I want to keep my 4x4 system and the transfer box is integral. Plus even if I wanted to make my life easier and go 2wd, the axles are offset so that option is out, sadly!