LT-85 transfer box swap

[Chicken Drumstick]

Does anyone know if it is a direct swap over or if I need to change anything.

Vehicle is a factory V8 (1985/6), it had a 3.5 on Strombergs, but now a 3.9 EFI. The gearing is a bit tall to make the most of the revs. It has the LT-85 (silver case) gearbox and I 'think' 27D LT230 (1.192:1). Looking to swap in a 22D (1.410:1) from a 2.5TD 90.

Thanks.

[mickeyw]

It is a simple swap over. 

There are however V8-specific brackets for the hi/low/diff lock lever and possibly handbrake lever that you will need to swap over too.

The 1.192:1 was intended to give better fuel consumption on the standard 205R16 tyres, but I don't know many folk that run them these days. My V8 90 managed OK on 7.50R16s but when I went auto and 255/85R16s I had to change to a 1.41:1 to achieve gear shifts in the right place.

[smallfry]

Tyre size will have a bearing on it, its very easy to undergear it and leave the engine revving too high.

Being used to diesels, I always think any petrol vehicle I drive needs an extra couple of gears !

Have a play with this along with the Ashcroft ratio calculator.

https://tiresize.com/comparison/

[Chicken Drumstick]

Thanks. Pretty happy the gearing will be better. I’d say I’m the opposite and often think vehicles are over geared. I have a 3.9 RV8 in a TR7. But that runs super short gears for 116mph at the red line in 5th. But it’s a riot to drive. 
 

Also the V8 won’t actually rev higher than a diesel with the same gears. But it will still have a wider rpm range. 

[smallfry]

10 hours ago, Chicken Drumstick said:

Also the V8 won’t actually rev higher than a diesel with the same gears. But it will still have a wider rpm range. 

I am aware of that, but I meant compared to other vehicles I have. For instance, my Trafic van is doing 1900 rpm at 70mph, and my Astra does 2250rpm at 70mph.

I guess its phycological. When I drive small engine petrol cars (1.3, 1.6 ish) that are doing 3500 rpm plus at the same speed it feels so wrong to me, and when I think of a big (in comparison) V8 doing similar rpms, it really bothers me, thinking about all those pistons and guzzling fuel ! Cant help it, I find myself keep looking at the tachometer all the time ! 

[L19MUD]

17 minutes ago, smallfry said:

I am aware of that, but I meant compared to other vehicles I have. For instance, my Trafic van is doing 1900 rpm at 70mph, and my Astra does 2250rpm at 70mph.

I guess its phycological. When I drive small engine petrol cars (1.3, 1.6 ish) that are doing 3500 rpm plus at the same speed it feels so wrong to me, and when I think of a big (in comparison) V8 doing similar rpms, it really bothers me, thinking about all those pistons and guzzling fuel ! Cant help it, I find myself keep looking at the tachometer all the time ! 

Glad I am not the only one. A 4.4 TDV8 sits at something like 1300 rpm at 70 mph!

[Chicken Drumstick]

3 hours ago, smallfry said:

I am aware of that, but I meant compared to other vehicles I have. For instance, my Trafic van is doing 1900 rpm at 70mph, and my Astra does 2250rpm at 70mph.

I guess its phycological. When I drive small engine petrol cars (1.3, 1.6 ish) that are doing 3500 rpm plus at the same speed it feels so wrong to me, and when I think of a big (in comparison) V8 doing similar rpms, it really bothers me, thinking about all those pistons and guzzling fuel ! Cant help it, I find myself keep looking at the tachometer all the time ! 

But the V8 90 isn't owned for mpg reasons.... and it isn't really the first choice vehicle for motorway cruising either. I do get where you are coming from, but a more perky gearset will liven the car up a lot and make it more fun for all other types of use.