Defender with overdrive

I've seen a 1995 Defender 300 TDi CSW on ebay which claims to have overdrive fitted - works with a little switch on top of the gear stick, and the seller claims it not only works on top gear as a genuine overdrive but also gives 20 gears in total.

Anyone know what this is all about as I've never seen it before on a TDi and my only experience of overdrive in the past has been on old Triumphs where you got a Laycock overdrive on third and top?

If seen before, is it reliable? Does it cause (costly) complications if it goes wrong?

Thanks.

didnt GKN do one ?

yes they did sean, eres how ter fit one if it elps - bloody expensive things mind

Fitting a GKN overdrive to aDefender - LR4x4 - The Land Rover Forum

I believe it is an epicyclic box, like the Laycocks, rather than a synchromesh like the old (Fairy) Series overdrives. 20 gears? I'd get a second opinion, perhaps the instruction book if he still has it, before using it in lower gears.
Cost nearly a grand to buy new.

I think the only complications if it goes wrong is not the stripping it out, it's sourcing the bits that no-one keeps that they have to take off when they fit an overdive!

I doubt the gain on a Tdi is huge unless you're doing a serious amount of motorway miles compared to fitting a 200 note overdrive to a thirsty Series vehicle.

If the rest of the vehicle is what you want I wouldn't be put off by the O/drive, but I wouldn't pay a premium for it neeva! I also wouldn't use it in lower gears, just cuz..............wots the point?

in theory, it does give 20 gears. but in reality it doesn't.

the unit is a gkn overdrive which is about 1k pounds for a new one. if you read the manual carefully, the OD unit will disengage itself when the speed falls below set km/h. i can't remember what it is. so you can never get it to give 20gears. ok, that aside you'll never use the unit when you're in low range.

it's used at a split between 3/4 and 4/5 and as an OD. this is a pretty good unit and is engaged electronically.

if you have a manual OD unit, which requires you to clutch in and pull a green knob lever, this is quite a bother and induces more noise than the gkn.

ODs are used when cruising on the highway which makes driving a defender more plesant as you don't have to rev the engine that much to get moving along with the rest of the traffic.

Thanks for those views. Well, I bought it, and have just driven it for 4 hours down the M6/M5, happily and effortlessly cruising at 80/85 in o/d top. It clicks in and out nicely in 4th and 5th with a slight jolt, no jolt at all if the clutch is used.

Only thing is, at the end of the run when shifting up into 4th and 5th in normal road use there's a slight jolt, and unless taken slowly a crunch from 1st to 2nd when starting off. Any views on this? Gearbox knackered or is this just normal Defender stuff?

You dont need to press the clutch when changing, just take the pressure off the accelerator, the jolt when changing may be just that you are not doing that, or its more likely its the backlash due wear in the land rover transmission components, which tends to be suggested by the other symptoms you mention. HTSH

Thanks for that.

I will try the o/d change as you suggest later.

Re the suspected wear in the transmission generally, is this sort of thing to be expected in a 12 year old 115k Defender and is it the sort of thing that is going to need imminent (expensive) surgery?

check yo UJ's fust - cheapest and easiest to fix

worth checking, driving members , they are the drive plates on the rear axle where the halfshafts connect to the hubs. Jack up wheel take off little plastic cover in center of wheel, try rotate wheel forward and back see if play in splines halfshaft to member, common problem, due to going from wet hubs . Easiest to fix , then diff play, then transbox play. Re g/box 1st to 2nd , how is oil , age type ? Could be just synchro wear.HTSH

tacr2man said:

worth checking, driving members , they are the drive plates on the rear axle where the halfshafts connect to the hubs. Jack up wheel take off little plastic cover in center of wheel, try rotate wheel forward and back see if play in splines halfshaft to member, common problem, due to going from wet hubs . Easiest to fix , then diff play, then transbox play. Re g/box 1st to 2nd , how is oil , age type ? Could be just synchro wear.HTSH

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and if you do find it is yer drive members/flanges let me know cos i've got about 50 of them sitting in me garage doing nothing

are they the same fur a series? coz my rear tbox seal still leaks after i replaced it - cud be the drive flange was worn too much.

dont know if i'm calling it the right thing now

it's these that i've got a pile of

Find LAND ROVER DEFENDER DISCOVERY DRIVE MEMBER FLANGE OEM on eBay within, Land Rover, Car Parts, Cars, Parts Vehicles (end time 01-Dec-07 07:05:13 GMT)

ah! - 24 splined flanges - i wos finkin of tbox drive flanges - nm

flange confusion

you sure you dont want any ? - they might come in handy even if you never use em

If it were UJs wouldn't I get the knock on all changes, rather than just 4th and 5th?

Thanks. Will check those points when I get a moment.

One last thing (I hope): when diff lock is engaged the light on the dashboard does not illuminate. Just a bulb or something more sinister?

"FLANGE" fnar fnar fnar

The Mad Hat Man said:

are they the same fur a series? coz my rear tbox seal still leaks after i replaced it - cud be the drive flange was worn too much.

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No, count the number of bolts!

crt said:

Thanks. Will check those points when I get a moment.

One last thing (I hope): when diff lock is engaged the light on the dashboard does not illuminate. Just a bulb or something more sinister?

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Well obviously check obvious stuff like fuses, bulbs etc (I don't know how easy bulbs are to get to on defenders) but if that looks alright you can check if your diff lock is engaging or not:
Instructions on bottom of page
Fixing a Land Rover Discovery Stuck Differential Lock or Transfer Case