Disco auto with Mercedes 3 litre

Hi

For complicated reasons I now have a Disco 300Tdi auto fitted with a Mercedes 300D six cylinder diesel.

We are having problems balancing the modified torque converter and I need to reduce the gearing, as the Mercedes has identical power but less torque than the old 300Tid and needs to rev.

I think that the current transfer box and auto, on 235/70 tyres, gave about 22mph per thousand revs. I have it on 235/85 tyres now, possibly the best thing I ever did to it - better ride, higher gearing which the 300Tdi loved, and more clearance off road. It's geared at about 24mph per thousand revs.

Anyway, a few questions:

Do auto 300Tdi's have the 1:4 ratio high range? If so can I substitute the Defender 1.66:1 ratios or box?

Could I put the LT77 or R380 manual gearbox in?

Or could I put the Mercedes auto or manual box in and 'divorce' it from the transfer case.

We've got excellent fabrication and machining facilities and lots of Merc parts, which are cheap - Land Rover parts are much more expensive.

Any ideas?

Uncle Fes said:

Hi
................................................................I think that the current transfer box and auto, on 235/70 tyres, gave about 22mph per thousand revs. I have it on 235/85 tyres now, possibly the best thing I ever did to it - better ride, higher gearing which the 300Tdi loved, and more clearance off road. It's geared at about 24mph per thousand revs.

Anyway, a few questions:

Do auto 300Tdi's have the 1:14 ratio high range? If so can I substitute the Defender 1.66:1 ratios or box?

Could I put the LT77 or R380 manual gearbox in?

Or could I put the Mercedes auto or manual box in and 'divorce' it from the transfer case.

We've got excellent fabrication and machining facilities and lots of Merc parts, which are cheap - Land Rover parts are much more expensive.

Any ideas?

Click to expand...

Disco TDi 300 auto has the 1:12 transfer box.

I'm guessing here, but my old manual 200tdi Disco pulled about 25mph for every thousand revs in 5th - 50mph was 2,000 revs.

The automatic 300Tdi is much busier - 2,300 revs at 50mph.

The auto has 'locked up' by this time so there's no slip.

The ZF auto has a very slightly higher 4th than the manual's fifth, too, hence I'd assumed it must have a lower ratio high range?

I think the best in this case is to go on a manual gearbox

seen them merc engines they is way wrong for an auto really.....

if you get lucky you may find an old G-wagon box and make the props otherwise i can make you a plate for R380 to merc if you send me the dimensions....