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[zirk]

My car is already a manual and as far as I can tell has the same diff ratio as the 3L.

I have actually contemplated putting in the auto diff to get a bit more acceleration.

As right now it sits at about 2800rpm at 70mph.

Thanks

In a 3.0 set up with the correct Diff, both the Manual (3.7) and the Auto (3.9) will run around the 2625 to 2650 RPM mark at 70MPH allowing for some Speedo error, your probably find your 70MPH is actually around 67/68 in true speed as the speedo's tend to read high, even on the Ex Police with Calibrated Speedo's they run around the same RPM at a tue speed of 70.

What I can tell you is if you run a Manual set up with a Auto diff (3.9) on the 3.0 setups you be doing around 3000RPm at 70, which is a tad anoying on a Motorway Cruise IMHO.

I cant remember now if the 2.5 (never owned one) had the same 5th gear ratio as the 3.0's, seem to remember hearing the very early ones were and the later prior to going to 2.6 were slightly different. 

[GrahamT]

My car is already a manual and as far as I can tell has the same diff ratio as the 3L.

I have actually contemplated putting in the auto diff to get a bit more acceleration.

As right now it sits at about 2800rpm at 70mph.

Thanks

In a 3.0 set up with the correct Diff, both the Manual (3.7) and the Auto (3.9) will run around the 2625 to 2650 RPM mark at 70MPH allowing for some Speedo error, your probably find your 70MPH is actually around 67/68 in true speed as the speedo's tend to read high, even on the Ex Police with Calibrated Speedo's they run around the same RPM at a tue speed of 70.

What I can tell you is if you run a Manual set up with a Auto diff (3.9) on the 3.0 setups you be doing around 3000RPm at 70, which is a tad anoying on a Motorway Cruise IMHO.

I cant remember now if the 2.5 (never owned one) had the same 5th gear ratio as the 3.0's, seem to remember hearing the very early ones were and the later prior to going to 2.6 were slightly different. 

My sat navigation and my GPS on my phone both agree that at 70mph I am only doing 2800rpm.

Thanks

[GrahamT]

To find a decent engine now.

Thanks for all the advice. I have a week off work in nine weeks. Enough time to find engine clutch spigot bearing etc.

Thanks again.

Here ya go.  http://www.omegaowners.com/forum/index.php?topic=142594.0

I'm in North Wales so I will try and find one that can be delivered or is a little closer to collect.

Thanks

[zirk]

My car is already a manual and as far as I can tell has the same diff ratio as the 3L.

I have actually contemplated putting in the auto diff to get a bit more acceleration.

As right now it sits at about 2800rpm at 70mph.

Thanks

In a 3.0 set up with the correct Diff, both the Manual (3.7) and the Auto (3.9) will run around the 2625 to 2650 RPM mark at 70MPH allowing for some Speedo error, your probably find your 70MPH is actually around 67/68 in true speed as the speedo's tend to read high, even on the Ex Police with Calibrated Speedo's they run around the same RPM at a tue speed of 70.

What I can tell you is if you run a Manual set up with a Auto diff (3.9) on the 3.0 setups you be doing around 3000RPm at 70, which is a tad anoying on a Motorway Cruise IMHO.

I cant remember now if the 2.5 (never owned one) had the same 5th gear ratio as the 3.0's, seem to remember hearing the very early ones were and the later prior to going to 2.6 were slightly different. 

My sat navigation and my GPS on my phone both agree that at 70mph I am only doing 2800rpm.

Thanks

Ok, so what the speedo telling you?, 72/73? if so and without doing the Maths RPM sounds about right then, be it a tad high.

[Doctor Gollum]

Easy swap as plug and play but AR25 gearbox will not cope with 3.0 torque

Manual

It will be fine

[Kevin Wood]

One other question just to make life a little easier. I take it the wiring harness etc for the engine management is the same for the X25XE and the X30xe?

I have a feeling there is a gotcha with the throttle position sensor on some configs when swapping. Not sure if it was between 2.5 and 3.0 or long and short plenums but there is a combination where it won't work. If running with the 2.5 ECU, probably best to keep the 2.5 throttle body and wiring harness. (might need to keep the 2.5 plenum if it's a short one).

[GrahamT]

One other question just to make life a little easier. I take it the wiring harness etc for the engine management is the same for the X25XE and the X30xe?

I have a feeling there is a gotcha with the throttle position sensor on some configs when swapping. Not sure if it was between 2.5 and 3.0 or long and short plenums but there is a combination where it won't work. If running with the 2.5 ECU, probably best to keep the 2.5 throttle body and wiring harness. (might need to keep the 2.5 plenum if it's a short one).

That's good to know thank you

[omegod]

Just a point of order there are only 2 manual gearbox types fitted to petrol Migs, R25-28 and the super rare unicorn that is the R30, I've never seen one but believe it simply is an R25-28 with shot peened gearsets

[GrahamT]

Just a point of order there are only 2 manual gearbox types fitted to petrol Migs, R25-28 and the super rare unicorn that is the R30, I've never seen one but believe it simply is an R25-28 with shot peened gearsets

I have a few spare gearboxes so one day I might take one apart and look to see if I can spot any differences.

I was told that the V6 manual gearboxes had the shot peened gears and the four cylinder cars didn't.

Does anyone know for sure?

[tigers_gonads]

Just a point of order there are only 2 manual gearbox types fitted to petrol Migs, R25-28 and the super rare unicorn that is the R30, I've never seen one but believe it simply is an R25-28 with shot peened gearsets

I have a few spare gearboxes so one day I might take one apart and look to see if I can spot any differences.

I was told that the V6 manual gearboxes had the shot peened gears and the four cylinder cars didn't.

Does anyone know for sure?

R25 box cogs are forged, R28 / 30's are ground out from billet 

R25's are used on the 2ltr, 2.2, 2.5, 2.6 and 2.5 td.
R28's are used on 3ltr's and are good for a 3.2 conversion.

R30's was used exclusively for the 3.2 traffic cars 

[zirk]

R25 box cogs are forged, R28 / 30's are ground out from billet 

R25's are used on the 2ltr, 2.2, 2.5, 2.6 and 2.5 td.
R28's are used on 3ltr's and are good for a 3.2 conversion.

R30's was used exclusively for the 3.2 traffic cars 

They also used the R30 on the 2.5DTi 24V Euro Diesel, the one we never got in the UK, but Im guessing with different Gear Ratios though being a Oil Burner. 

[omegod]

Every box I've pulled from manual:

2.0 pet
2.2 Pet/Diesel
2.5 Pet
2.6 Pet
3.0 Pet

has been marked R25-28 ? Regardless they are tough buggers and have took some serious power

[Kevin Wood]

This might be handy when considering gear ratios:

[Kevin Wood]

.. and this: http://www.omegaowners.com/forum/index.php?topic=90497.0

[GrahamT]

Thanks

I do agree all the spare gearboxes I have are marked r25-r25.