differencial
Hi - I have a 1985 460 to which we are converting to use a TD5 engine, gearbox and transfer box. A has anyone else tried this? Also has anyone any thoughts or experience of the the front and rear differencial ratios - is the orginal ratio ok or will I need to change them and if so to what ratio or from what model.
Thats a brave swap. I think its been done before though, and in a 460 there is less to worry about.
For the diffs and ratios, the Forum has some exchanges about it, and I found this elsewhere:
The front and rear differentials typically used the same ratio in a given vehicle (matched for the full-time 4WD system with lockable diffs).
Common factory differential ratios for the W460 included:
- 4.875:1 (often rounded to 4.9:1 or listed as 44:9 teeth) — This was the most common "standard" ratio, especially on many petrol models like the 230 GE, 280 GE, and the 300 GD diesel.
- 5.286:1 (often 48:9) — Frequently used on various diesel models and some configurations.
- 5.33:1 (often 48:9 or similar) — Common on certain diesels like the 240 GD and some 250 GD variants, or as an option/medium ratio.
- 6.17:1 — Used mainly on heavy-duty or lower-powered diesel variants like some 250 GD models (shorter gearing for better low-end torque).
Other less common or optional ratios that appear in parts listings, manuals, or swaps for the W460 platform include:
- 4.857:1 (close variant of 4.9, sometimes 34:7 or similar)
- 4.375:1 (34:8 or 35:8 in some references, more typical later but occasionally fitted)
- 4.111:1 (37:9, higher/"taller" gearing, often aftermarket or for specific swaps like turbo diesel conversions)
The ratio was often stamped on a metal tag/rivet plate attached to the front and rear axle housings, so checking your specific vehicle is the most accurate way (e.g., 44/9 = 4.889 ≈ 4.9:1).
These ratios were paired with the transfer case (typically 1:1 high range, with low range around 2.0–2.3:1 depending on variant) and various gearbox options (4- or 5-speed manual, or 4-speed auto). Diesel models generally favored shorter (numerically higher) ratios for torque, while petrols often used taller ones for cruising.
Also, it is more common for a Merc OM engine to be dropped into a Landrover. But to do what you are doing:
- Physical fit: The TD5 is a relatively compact inline-5 diesel (similar in overall size/weight to some Mercedes OM-series engines like the OM617 or OM602 that are commonly swapped into W460s). The G460 engine bay is spacious and has been used for larger engines (e.g., OM606 inline-6, M117 V8, even modern LT V8s in high-end restorations).
- Mounting: Custom engine mounts would be required (fabricated or adapted). The W460 uses a longitudinal layout with the engine tilted slightly, so adjustments are needed but doable.
- Transmission/transfer case: The biggest hurdle. The TD5 typically mates to an R380 manual or ZF 4HP22/24 auto, while the W460 uses Mercedes 4- or 5-speed manuals (e.g., 717.x series) or 722.3/4 autos, plus the proprietary G-Wagen transfer case and driveline. You'd likely need:
- An adapter plate (bellhousing/flywheel/clutch) — none exists commercially for TD5-to-Mercedes trans or vice versa.
- Or keep the TD5's gearbox and adapt it to the G's transfer case (very custom machining/splines).
- Many swaps retain the original Mercedes drivetrain for simplicity.
- Electronics & ancillaries: The TD5 uses an EDC electronic diesel control system (ECU, wiring harness, sensors, immobilizer). You'd need to wire it in, possibly bypass or spoof the immobilizer, adapt gauges/fuel system, and handle glow plugs/exhaust. It's more complex than mechanical-injection Mercedes diesels (OM617/OM602) that are favored for W460 swaps.
- Cooling, exhaust, steering, etc.: Radiator relocation, custom exhaust routing, possible power steering pump swap, and driveshaft length adjustments would be needed.
So not that easy, but with a lump hammer and some fabrication, you can do it.
Lots of great info from John... AI is getting better!?! I assume...
The big difference is the LR uses a TC built into the Gearbox where the 460 it is a stand alone unit
Maybe easier to use a stock LR box to fit the engine but remove the TC and put a stock rear end housing on to use a prop to the 460 TC.. seem to remember somewhere back in the 00's putting a LR V8 into an MGB and used the LR box and took the TC off and used some car rear housing... memory fails me if it was an R380 or LT77!?!
I did have laying around a front 460 prop with G (8 bolt) TC flange and a LR (4 bolt?) gearbox flange at some point (long skipped) so it has been done before...
As for axle ratio generally the manual 300GD were 5.3 and the manual 230/280GE's were 4.8 with some auto's being 4.4's
But nearly every G was bespoke spec so any variations are possible
Not sure I have seen a factory 460 with 4.1's but thats the normal go to for a high ouput motor conversion for comfortable motorway cruising, not available new (front at least) and aftermarket supply seems to have dried up so used the only real option
Obviously Gearbox ratios, especially an overdrive 5th can help along with a taller tyre
Bigger tyre will loose acceleration but gain on cruising capability, but if the engine has ample power then this is acceptable
So it all depends on what your 460 has as stock (axle plate will tell you if still attached - or it is punched into the end of the pinion - or count the teeth - or drop me a PM with VIN and I should be able to tell you)
4.1's are reasonably hard to source and usually are £1500 or so a pair plus £150 in seals etc plus fitting
4.4's are an option but still not easy to find (but half the price if you can) but with the right box / tyre combo can work just as well
All 460 TC are the same ratios... only the later 463 had a couple of ratio options but these mount differently also
And then a big question is what is the intended usage? Mainly road work and motorway cruising probably 4.1 is necessary... mainly off road usage stock ratio and then play with gearbox / tyre combo
A mixture of both then a 4.4 or even 4.8 with the right box and tyre may work too.. I have some cheap 4.8 sets
Good luck and keep us posted!
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