transfer case ratio for 1983, 110 V8 pickup

[bodumatau]

Greetings All, my fun drive is a 1983 110 Hardtop with a RR mega squirted efi that I have run for the past 10 years on an ashcroft R380 and 1,667 transfer box. 

has been a LOT of fun, mainly short commutes, lots of forest work, awesome having a vehicle that drives like a race car and is a working mule all in high range.

my mission profile is changing in the next few years and I would like to do some exploring around europe and hence my question to all of you..... wise V8 owners.....

should I go for the standard 1,4 transfer case or should I jump in the deep end and put a 1,2 ration transfer case in?

vehicle is relatively light, no hard top roof on and will never have much more than spare wheel, recovery gear, luggage, tent and very light camping gear and a couple days food. no big overland rig or roof rack or the like, my madame prefers staying in B&B or hotel and the camping gear will be for the odd trail night where we don't make it to the next destination (well this is the story I have told her 😉 )

got standard 235/85R16 wheels on

my excel ratio calculator tells me that with a 1,2 I will be at 2000rpm for 96kph and 2500 for 120kph which is about the max speed I would drive at.

with a 1,4 I would be at 2500 for 103kph and 3000 for 123kph

currently with the 1,667 I am at 3000 for 104kph and 3500 for 122kph

 

next question would be whether it is worth it putting an ATB into the transfer case? mission profile would primarily be tar road with the odd bit of off-road.

[smallfry]

What size engine ? Assume its 3.5 ?

[Bowie69]

If its a 3.9 or more, then 1.2, 3.5 may want the 1.4.

[Paul C]

I used to run a 1.2 with my 3.9 auto but swapped back to 1.4 with 32in tyres, now have 1.3 gears with a 4.6 auto and 32s. My 300tdi has 1.2 and 235 70 16s and it is a little tall for taking off, especially when towing, I have plans to put the 1.4 box back in it with a higher ratio 5th in the R380.

[Chicken Drumstick]

If you have been running a 1.6:1 transfer box. Changing it will make it feel a lot less peppy. I suspect a 1.2 would make you think you have major engine issues. 
 

Honestly it is a tough one to call though. We have a factory V8 90 with the 1.192:1 transfer box and LT-85. It now has a 3.9 Efi. It goes well, but does feel over geared. Quite relaxing and pulls from nothing. But isn’t anywhere near the fun you’d think it should be. 
 

On the other end of the scale. I have a Triumph TR7 V8. I used to run the factory V8 axle of 3.08:1. It went well and I clocked it at 144mph. Which is plenty quick for a 1970’s sports car. I broke the axle though and swapped on a 3.90:1 axle. What a riot it resulted in. Felt like I’d gained 50-70hp. But totally useless for cruising. 
 

I think on this basis I’d be tempted to look at an over drive unit and retain the 1.6 transfer box. They are rather spendy sadly. But at least would give you better cruising ability while retaining the peppy performance. Ashcroft Transmissions should also be able to offer to a taller 5th gear too which might help even more. 
 

If you really want to go new transfer box. My vote would be 1.4

As for the ATB. Really depends what you plan to do. I suspect you can probably spin a wheel quite well with the V8 and short gearing. The ATB may help here. Although axle diff ATBs probably more so. You might also find off road you won’t need to lock the centre diff. The p38 or RRC used the Borg Warner transfer box with has a viscous LSD and doesn’t fully lock. I’d expect the ATB to work similar, but have not tried one. On sand and the like if you are going in dunes the ATB would again save you needing to lock the diff. But ultimately unless you have a specific use case I’d expect only limited benefits. You really need to be sliding the vehicle or wheel spin or on a loose slippery surface. Cars like the Celia GT-Four or Impreza Turbo benefit from a lsd centre diff. The Jaguar X-Type had one in early years, but they dropped it for an open diff later on. On road you’d not really know unless drifting or driving in snow. But of course in a Land Rover you can always lock the diff if it is slippery out. 

[bodumatau]

yeah sorry guys, should have put down all the facts 

it has a 3,5 and a ATB ashcroft rear diff, it is VERY peppy !! 😎 through a traffic circle gunning it it will understeer and pick up the inner front wheel, lots of fun even if it isnt completely social behaviour 🤣.

I rarely tow on tar and if then something light like a glider trailer at 1,6t, any off-road work in the forest I am a happy low range user, need to let those little gears work too

oh and I rarely use 1st gear when town driving anyway so I do think my 1,667 is overgeared. remember she is very light, no body and no roof rack etc.

I think the consensus is the same as I was leaning towards which is the 1,4 transfer case, thanks to everyone who took the time to help out with info 🙏

[ped]

my v8 auto has 1.2 borg warner t case it's too tall a gearing if i could find another mpi t box i'd swap it to that

[Bowie69]

With what tyres @ped?

They make all the difference. 

[ped]

i run 31 10.5 15's on both my 110's

if i 205's on it would be the same as the range rover i took the auto box out of but a 110 looks wierd on the 205's

[Bowie69]

Yup, 1.4 for a truck with those tyres and weight. 

[ped]

it's been on my list to do but tbh for normal driving it is fine but if i put my trailer on it's dire up hill unless i hold it in gear and rev it's proverbials off

[FridgeFreezer]

I'd vote 1.4 as well for a 3.5, if you can stretch to it a roamerdrive + 1.4 tcase gives you the best of both worlds but it's quite spendy.

Remember the 1.2 boxes were fitted to RR + Disco that ran 205 size tyres, you can compare gearing on the ashcroft website to see how close you get to a stock RR or Disco.