Lt77 conversion requirements

Thanks for the above. I should have stated my problem more fully. I suspect that my current rear box mounts have sagged some - the gearchange mount seems lower than it should be, and the radiator fan runs close to the shroud at the top, and is definitely not parallel to the core -although that may be normal, but...The engine has a distinct incline to the rear. All this means I doubt that I have a reference for where the drive flange should be height wise. If I knew where it should be relative to the tunnel above I would have some idea how much the mounts have sagged, and if I should do them before I get the LT77 ready to go in. Havent had mine over 50mph/80kph yet, no vibration apparent so far. I have an auto prop shaft ready to go in with the LT77, and it took some cleaning and careful examination to locate the alignment arrows, and they do line up well now, although they werent a;ligned when I got it. IIRC the WSM specifies two different alignments of the UJs?
thanks
 
Harvey will know the prop specs. I see you have a 3500s, so the rear flange height may be different to an auto (which is what I started with)
All I can suggest is you put a jack under the box and raise the rear until the mounts look like they would un sagged and take a measurement.
I am not even sure if un sagged is a bona fide term, but you get my drift.
 
I have an auto prop shaft ready to go in with the LT77, and it took some cleaning and careful examination to locate the alignment arrows, and they do line up well now, although they werent a;ligned when I got it. IIRC the WSM specifies two different alignments of the UJs?

There are two different alignments, but if the 2 arrows are lined up, if the two parts of the prop are a matched pair you shouldn't have any problems. If you were to have problems then you could measure the angle of offset and compare it to the figures in the WM. Your car should have the later spec.
 
I have tried to look at the mounts, but have not found a way to see them - rear view is blocked by part of the brackets, so I cant assess how much they have sagged.
 
Understood the part about the splines difference between LT77 and 3500s, but the pressure plate seems to be acceptable in the conversion guide?

Also seems to be a self centering option for the SD1 Clutch pressure plate and bearing, I’m not sure of the subtle differences between them?
The pressure palate should be fine as long as the diameters and thicknesses of the driven plates is the same, IMO.
I'd fit a new one if uncertain about age and condition.
 
Almost every propshaft I have had eyes on has alignment arrows, many of them nowhere near the theoretical correct alignment - UJ crosses parallel.
Still no wiser as to correct gearbox output shaft height in tunnel....
 
Every propshaft I have looked at over the last 50 years has had alignment arrow, but they are often not that visible. It gets confusing if the input and outputs are not parallel, as then the UJ ,s may then have an offset
 
Almost every propshaft I have had eyes on has alignment arrows, many of them nowhere near the theoretical correct alignment - UJ crosses parallel.

The UJ's are not supposed to be in alignment, that's what the arrows are for.
 
Almost every propshaft I have had eyes on has alignment arrows, many of them nowhere near the theoretical correct alignment - UJ crosses parallel.
Still no wiser as to correct gearbox output shaft height in tunnel....

The height is somewhat irrelevant, it is the flange angle that matters.
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As can be seen, if using two universal joints, the gearbox and diff flange angles should be the same. In making them the same you will arrive at the height the gearbox needs to be, if it is possible to do so.
 
Harvey, I understand why the arrows are there, BUT - why did the alignment change sometime in the life of the model, and why is the alignment not what I call 'in phase' - UJ crosses parallel? Angle of the flanges ?
Re the pics of the LT77 rear mount bracket - in assembling bits for my conversion I got a bracket like the simple thin one shown before, and thought nothing more of it. Then later I picked up another LT77 and some bits cheaply (not working). On going through these bits I find another rear bracket with the extra fold as shown by MrTask - should be signifcantly stronger - I hope!
 
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On some later Land Rover products with beam axles ( One Tens etc) the front diff was angled up towards the gearbox and the front shaft still used only two UJ's but they were assembled out of phase to keep the input & output as a constant velocity. . This caught out an number of mechanics used to the Series vehicles who if they had them off reassembled with the UJ.s in phase causing considerable front end vibration until corrected.
 
Harvey, I understand why the arrows are there, BUT - why did the alignment change sometime in the life of the model, and why is the alignment not what I call 'in phase' - UJ crosses parallel? Angle of the flanges ?

The alignment changed because the diff changed. The reason for the out of alignment UJ's is Rover liked to over engineer, and AFAIK this was done because the pinion shaft isn't on the centreline of the car.

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Hi Paul,
How did you fare with the speedo cable/head issues, and everything else? Always good to hear. I’ve got one coming over from the U.K. and have assembled pretty much all I need.
Kind regards,
Tor
 
Are these plug and play on the back of a P6 speedo? Can’t remember ever hearing about this before.
Tor

Hi, yes and no. After taking the P6 speedo out of the cluster the SD1 actual head mechanism is a direct replacement after undoing the two screws that hold it into the shell of the housing. however there are a couple of proviso's, you need to pull the speedo needle off and change the face plate over. Be careful to mark it's rest position because the needle is lightly spring loaded down onto the end stop. The other issue is the milometer and the trip reading are transposed so you need to adjust the size of the windows.

It was quite number of years ago I did this so some details are a bit hazy. I had a couple of spare P6b and SD1 units so I just had a play, it was cheaper than getting it re-calibrated.

Colin

Edit: I've just remembered that you lose the trip operation because the SD1 operates through the front of the speedo instead of P6b's remote on the side of the cluster. On mine I wasn't worried about it so I deleted it.
 
Ok thanks Colin. That does sound a bit finicky, so I’ll take the drive off my spare P6 speedo and get it recalibrated by the mentioned outfit. I take it they’ve done them enough not to need specific details. Of which I have not many!
Tor
 
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