Lt77 Output Shaft Wear levels

Defender91 · Apr 25, 2020

Hi,
I appreciate there is a lot out there about the wear on the output shaft of the Lt 77, but I couldn't find the answer.
After finally getting the time to work on it, I'm currently fitting a Disco transfer box to my 200 tdi Defender. I got the old transfer box out today and noticed the wear on the output shaft of the gearbox.
Could anyone advise me on how bad my gearbox looks,and if the disco transfer box is going to be damaged by the old gearbox even though it has the cross drillings.
Thanks for any replies

lynall · Apr 25, 2020

I would fit that no worries, new gear will help a lot with play.

tottot · Apr 25, 2020

Plenty of life in that shaft.

Defender91 · Apr 25, 2020

Hi
Thanks, couldn't find out how bad they have to be to need changing and had no experience of this.
Means I can get the disco box in tomorrow now.
Thanks again

lynall · Apr 25, 2020

Defender91 said:
Hi
Thanks, couldn't find out how bad they have to be to need changing and had no experience of this.
Means I can get the disco box in tomorrow now.
Thanks again

I have found it easier to remove input gear, refit tfer box, then refit gear, saves messing about lining stuff up whilst balancing the tfer box.

Some amazing pics of shagged splines on google images etc, some with splines half worn away, some with no spliens at all.

I can remember years ago, ones guys spline were so fubared he stuck masonary nails in the worn away parts of the splines, then fitted a washer and nut to hold the nails in.
I said at the time it wont last, but you just know it is still driving around somewhere!

jamesmartin · Apr 25, 2020

lynall said:
I have found it easier to remove input gear, refit tfer box, then refit gear, saves messing about lining stuff up whilst balancing the tfer box.

Some amazing pics of shagged splines on google images etc, some with splines half worn away, some with no spliens at all.

I can remember years ago, ones guys spline were so fubared he stuck masonary nails in the worn away parts of the splines, then fitted a washer and nut to hold the nails in.
I said at the time it wont last, but you just know it is still driving around somewhere!

youd have to be careful not to knock the input seal when fitting,whilst you do have to align the splines the shaft acts as a guide

Hicap phill · Apr 25, 2020

If you do remove the input gear for ease. Make sure you re fit it the correct way round.

lynall · Apr 25, 2020

Hicap phill said:
If you do remove the input gear for ease. Make sure you re fit it the correct way round.

I know someone who has actually done that cough cough, apparently it made a huge howling noise on the test drive, allegedly!

Defender91 · Apr 25, 2020

Will try not to mess it up,no guarantees though.I didn't remove the input gear when I split it from the gearbox , read somewhere that the lower ratio disco box's had to be realigned once the gear had been removed.
While I'm here,how much should the rear propshaft be compressed when fitted?
I've just fitted the front and rear axle off the same disco, and the propshaft was almost fully compressed when in a driving position. Sure it wasn't like this before.
Thanks

Hicap phill · Apr 25, 2020

lynall said:
I know someone who has actually done that cough cough, apparently it made a huge howling noise on the test drive, allegedly!

I only got 3 gears (3/4/5)& reverse. Bit of head scratching till I realised the mrs had use of the rattle gun & removed the back plate & gear for easy fit.

Hicap phill · Apr 25, 2020

Are you changing the handbrake back plates over?
Disco & defenders have different cables

Measure props you have removed off the LR to disco to ensure correct length

Defender91 · Apr 25, 2020

No, didn't know about the backplates, the cable looked similar though. I'll look in the morning though.
The props were the same ones ive using for the last couple of years, just wondered if the diffs fitted to discos were slightly longer.

Defender91 · Apr 25, 2020

Just had a look at the backplates, the cables seem to be the same. Is this likely to mean I had a disco box in the first place?
Old one on right,Disco box on left.
Thanks to everyone who has replied, much appreciated.

Hicap phill · Apr 25, 2020

Look at where the cables go into the back plate. This is where they differ.

jamesmartin · Apr 25, 2020

Defender91 said:
Will try not to mess it up,no guarantees though.I didn't remove the input gear when I split it from the gearbox , read somewhere that the lower ratio disco box's had to be realigned once the gear had been removed.
While I'm here,how much should the rear propshaft be compressed when fitted?
I've just fitted the front and rear axle off the same disco, and the propshaft was almost fully compressed when in a driving position. Sure it wasn't like this before.
Thanks

you read some uniformed drivel,fitting disco axles or t/box wont effect the props,if props are fully compressed yoyhave wrong props or some other issue

jamesmartin · Apr 25, 2020

Hicap phill said:
Look at where the cables go into the back plate. This is where they differ.

they dont its just the cable,length and fitting to the lever

Hicap phill · Apr 25, 2020

jamesmartin said:
they dont its just the cable,length and fitting to the lever

I thought the LR had a bracket & adjuster and the disco went straight in ?
( I like to ask Qs it helps ID scrap in my shed)

jamesmartin · Apr 25, 2020

Hicap phill said:
I thought the LR had a bracket & adjuster and the disco went straight in ?
( I like to ask Qs it helps ID scrap in my shed)

pre 300tdi back plate assembly were the same but bracket that held cable and pivot assembly differed, in that the rear support of the bracket bolted to the rear face of the output housing for disco/rrc and side face for defender
300tdi had direct cable just cable differed,length and how it secured to lever bracket

if you look at many back plates they have 5 holes so they fit borg warner boxes too

Rougharse Racing · Apr 26, 2020

The prefix on the transfer box serial number will tell you what it is out of and the ratio. I think Ashcroft Transmissions lists them.
Don't forget to fit the appropriate speedo drive gear for your tyre size, hopefully the one in your current box will be correct and the Disco one may be for lower ratio tyres.
I have also heard of people temporarily fitting a couple of lengths of threaded bar to bolt holes to help align the box when re-fitting it.
Also make sure that all the locating dowels are in their correct places, sometimes you can find a dowel on the main gearbox and one in the corresponding position on the transfer box when fitting a replacement.

Defender91 · Apr 26, 2020

Box is now in,just got to finish setting the high/ low range and the diff lock selector.
Sure it's the lower ratio as it's got a land rover sticker with 1.2 on it.
Went in fairly easily in the end,thanks for the tips about the input gear.
As for the Speedo drive,I was going to use the one the disco box came with. I'm running 265/75/R16s. To be honest I always treat the speed it says as a rough guess so it if it's a bit out won't matter.

Lt77 Output Shaft Wear levels

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