Discovery Gearbox

Hi, I am new to this great website that I have just came across and was hoping someone could give me a bit of advice on a Discovery gearbox problem. What I am trying to establsh is what gearbox I have, the car is an N reg 3.9 v8i - after a long run a couple of days ago, the gearbox is making some horrible crunching and grinding noises, so I have decided to replace the gearbox rather than have it rebuilt. I have been told that it could be a LT77 box OR a 230? The other question is would a diesel box fit my petrol model?

Any help/suggestions would be appreciated and can anyone recommend where to get a second-hand gearbox or re-con?
Cheers
Ian

There are three types of 5 speed mainbox, LT77, R380 and LT85 (Santana). The following questions will help identify which type of box you have.

1) Is reverse underneath 5th gear?

If yes, you have an R380 . Please go to point (a) to identify which type.

If no go to question 2.

2) Is reverse gear next to 1st gear?

You either have an LT77 or LT85. Question 3 will identify which one.

3) Is the maincasting black or aluminium?

If black you have an LT77, please go to point (a) to identify which type.

If aluminium, you have a LT85, Santana box. Please go to point (b) to identify which type.

(a) The gearbox number will be stamped or dot punched on the oval machined flat directly below the filler level plug, on the right hand side of the gearbox main casing. The relevant numbers we require are the first two and the last letter, i.e. the number may be 56A1234567G, we would call this a 56G. Click here to see a video of where to find this number. In some cases it may not be possible to read this number in which case we will need precise details about the type of vehicle you have, engine fitted and year to help identify it.

(b) The sides of the aluminium housing will either be smooth, which will be a 20C, Solid Case, or cross hatched, which will be a 22C, Split Case

Didn't think they fittd the santana box to disco's. ? as Santana only built the defender clones. so it' a choice between LT77 & R380

yu is right Pikey, but it dont mean someone hasnt fitted one tho?

The Mad Hat Man said:

yu is right Pikey, but it dont mean someone hasnt fitted one tho?

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True but they'd have to change the disco gear linkage from a Lt77 over anorl as the sticks is in the wrong place on a Defender box.

Yu are, as usual, on the ball .

racing22 said:

The other question is would a diesel box fit my petrol model?

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No. It will have to be a petrol gearbox. Bell housing and input shafts are different between the two.

andyb66 said:

No. It will have to be a petrol gearbox. Bell housing and input shafts are different between the two.

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Some of the ratios are different too.

Thanks for all that information, I think the way forward is to have my original box repaired, I have found a local guy in the North East and will call him tomorrow.
Cheers again, greatly appreciated

It has been mentioned to me that it is possible to do certain repairs to the gearbox whilst still in the vehicle ie layshaft bearings and borque rings, it sounds a bit unlikely to me but does anyone know if this is actually possible?
Thanks
Ian
(Ps before I go to the trouble of taking the box out, by the way is that a big job - any advice?)

racing22 said:

(Ps before I go to the trouble of taking the box out, by the way is that a big job - any advice?)

Click to expand...

Some say splitting the transfer box off the main box makes things easier. Pros, Two smaller lighter lumps. Cons, you will have to support the main box as all the mounts are on the transfer box. There is also an oil seal between the two which can be damaged on refit.

Remove fan cowling so that you tip the engine back without damaging fan, this helps getting to the bell housing bolts. A couple of long extensions and a deep socket helps too.

Finally, do all the internal console removal etc first, when you are still relatively clean.

andyb66 said:

Finally, do all the internal console removal etc first, when you are still relatively clean.

Click to expand...

Heheheh, and how would you know that ???



"ooh mum, that dirty mans just left oil all over your seat" ...

Paul D said:

Heheheh, and how would you know that ???

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It wasn't oil, but thank goodness for workshop vacumn cleaner.

Dropping the Transfer off 1st makes things SO much easier. I've done it both ways now, and although it's a bit more time consuming, it makes it all a lot more manageable under the vehicle