Lt77 conversion requirements

My LT77 conversion was to an auto base unit, with the BW bell housing and an adapter plate to make up length and position the input shaft. A hole was milled for the release arm and the slave was mounted to a made up bracket. We used the auto shaft, and it is still there now, except the cogs are now mixed up by a Jag 4speed overdrive box.
My master cylinder is mounted at the front next to the radiator and actuated via a long push rod, simply because back when I did the conversion in the mid 90's I had never seen a manual or pictures of what it all looked like.
I have subsequently bought the pedal box, master and mountings etc to do it properly and once I decide what I plan on doing with my P38 vis-a-vis do I fix it up or break it and stick the donk in the P6, or do I keep the 3.5 and fit the 2 Nissan Exa turbos I have or what do I do.
 
While I am no where near doing this yet, I am trying to ensure I have everything I need in hand. Just re-reading the conversion guide I sent in recently it re-uses all the P6B bellhousing bolts, which is OK with a P6B block. Question - will I need a new set of metric bolts if I go to an SD1 or later engine ? There are people on ebay selling bolt sets that they say will fit P5B, and Sd1, Rangie etc...Surely the SD1 has metric threads all over?
thanks
 
[QUOTE="jp928, post: 388300, P5B, and Sd1, Rangie etc...Surely the SD1 has metric threads all over?
thanks[/QUOTE]

Nope, late stuff has a mishmash of metric and imperial threads, but bellhousing bolts are same whatever the block is from
 
Hi, Everything that screws into the block and heads is Imperial as per P6b including the front cover and inlet manifold. It's replacement or aftermarket stuff like downdraught carb inlet manifolds that are variable. Water pumps are another with new ones having 6mm threads for the pulley and fan fixing bolts as has been documented by a peeved member on here. It's enough to make Harvey spit. See simple isn't it?;)

Colin
 
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Good to know that, so I can safely buy one of the bolt sets that abound. My previous experience with unexpected bolts was on a Chevy Blazer - everything imperial until I found an earth strap bolted to the firewall with a 10mm headed M6 set screw. Wonder what the rate of water pump bolt breakages on removal is ?
thanks
 
The flywheel will be OK, but the 3500S pressure plate won't be, you need an SD1 V8 clutch complete. You,ll also need an SD1 slave cylinder, or a 1/4" thick spacer plate for the 3500S cylinder.

Can you advise why the recommendation to change the clutch pressure plate and the slave. I have been reading the LT77 conversion guide which mentions no need to change the pressure plate or the use of a spacer on the slave.
 
The splines on the LT77 are different, hence the plate change, and the pressure plate is to match the new clutch plate.
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?
 
All I can say is that when I converted mine over 35 years ago I thought there was no reason to have to use the SD1 pressure plate, so I fitted the 3500S one, and had to take the box out again and change it. I think it's because of the distance between the fingers and the flywheel being different. As for the slave cyl, you can use either, but the 3500S slave needs a 1/4" spacer between the slave and the bellhousing.
 
All I can say is that when I converted mine over 35 years ago I thought there was no reason to have to use the SD1 pressure plate, so I fitted the 3500S one, and had to take the box out again and change it. I think it's because of the distance between the fingers and the flywheel being different. As for the slave cyl, you can use either, but the 3500S slave needs a 1/4" spacer between the slave and the bellhousing.

Ok thank you, will order up a pressure plate too, and manufacture a spacer.
 
I was also curious about the differences - when I did my first conversion some 30 years ago I didnt know any of this stuff, and I finished up with a VERY heavy clutch that I never solved before selling the car to go OS for work. I have since learned lots. Re the 'self centering' clutch thing -I believe this is the go. Some clutch pressure plates have straight diaphragm fingers and rely on the throwout bearing to have a curved face, and others have fingers with curved ends and the throwout has a flat face. You should make sure the throwout matches the pressure plate. Now I may be wrong here - some throwout makers say their bearings may look eccentric, but thats how the self centring units look. Talk to your clutch supplier!
 
Here is a pic of mine. I used an SD1 rear mount, cut the ends off and welded new ends to mate up with the floor brackets. No cutting was done to the car as far as I can remember.
1610284170551.jpegAny chance you can clarify what the bracket is from? The top half looks to be SD1, but the bottom part looks like something else, and no matter which way I plan to cut up my SD1 bracket I can’t see how the lower part is fabricated from just one bracket?

This photo below from another installation seems to show there maybe a slightly different SD1 bracket which has folds that perhaps matches yours?
1610284683917.jpeg
 
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That looks like a BW65 mounting bracket.
 
View attachment 18274Any chance you can clarify what the bracket is from? The top half looks to be SD1, but the bottom part looks like something else, and no matter which way I plan to cut up my SD1 bracket I can’t see how the lower part is fabricated from just one bracket?

This photo below from another installation seems to show there maybe a slightly different SD1 bracket which has folds that perhaps matches yours?
View attachment 18275
Mine was a stock SD1 bracket as stated. The outer ends were cut off and a couple of bits of shaped flat plate welded on with a pair of holes drilled in each going through the existing chassis mounts.
A fellow on here called Mr task added an extension bracket to bolt on to the slotted existing mount at the bottom of my picture as a belt, braces and bondage measure - cos that's how he rolls !
 
Exactly as Cobraboy has described, I started with an LT77 rear crossmember that came out of an SD1, chopped the outer edges off, welded some flat plate to either side, and just for fun added a third mounting point taken from the BW35 mountings that I was replacing. Can't find a pic of the part I used before it got chopped and changed, but I can say it didn't look like the pressing in post number 93. I'm sure Harvey is correct, that must be a piece off a BW35 ??? Here's a snap of what I cobblefabbled together (with a fair bit of help from Luc in the garage opposite, who can weld, which I can't!) and how it holds the tail of the box in place, more or less, albeit with a few additional packing washers!! I was changing from an automatic to a manual and re-used the mounting points in the tunnel so as not to change too much.

modified-SD1-rear-crossmember.jpgmodified-crossmember-in-auto-tunnel.jpg

P.S. No bondage was involved! Not my cuppa. Owning a car that consumes money and parts like mine does is quite enough pain for me!

P.P.S: Shamelessly stolen from elsewhere on the interwebs, here's what my rear crossmember looked like before I adapted it:

unmolested-SD1-rear-crossmember.jpg
 
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The previous photo supplied by mrtask shows a slightly different mount compared to the one I have, and I think that is the one that was used by cobraboy, that clears it up for me. Seems that is a stronger mount with the extra web.
Here’s mine in the same position.
 
As you say slightly different model, but you should be able to get it to work. IIRC I fitted the engine and box together, offered into the car, and connected up the front engine mounts. When I was happy with the angle of the engine / box I fitted the cut down rear mount to the box using the cotton reels, and then made up the new end plates and tacked them to the SDI mount plate, removed the mount plate, welded up and job done.
One thing you need to be careful of is flange angles, ideally the angle of the gearbox output flange should be the same as the diff flange. I measured the auto box flange height carefully before removal and made my manual box the same height. When testing afterward I was plagued with a driveline vibration, now as it was not there before I was concerned it was due to my conversion.
Doing research on propshaft angles revealed the flange angles needed to be equal, and on measuring mine I found that they were 5 degrees apart. So I shimmed the gearbox up as much as I could, and altered the diff angle as much as I could and got the flanges to 1 degree apart.
The auto prop I used was also at full stretch and the spline was wobbly, so I fitted a 25mm Britpart prop spacer from a Land rover and closed up the prop which made the spline joint a lot tighter.

This along with a comprehensive overhaul of all the universal joints made the car vibration free.
 
Based on the above, are you able to give us a measurement relating to the position of the LT77 output shaft vertically, so we can modify the mounting bracket to get close quickly please? Would prefer not to cut any of the original brackets off. I plan to do similar install with gearbox mounted on engine .
thanks
 
Always happy to help, but currently raising the car enough to get under it is a challenge. However, I can offer the following. I made the flange height the same distance down from the top of the tunnel as the auto box, I measured the distance with the prop removed vertically down to the centre of the output shaft.
When it came to raising the rear of the box I was limited to the length of the studs on the cotton reels, as no way was I going to re make the steel mount. I cut two nylon discs and slipped them under the cotton reels, they are @ 6mm thick. Nothing fouled above the box.
This was in a bid to equalise the flange angles, I also raised the front of the diff, and lowered the rear.
Now I was asking myself why I should have to be doing all this ? Well it is documented that Rover did have driveline vibration issues.

I my case with a two owner car in bog standard form it should have been plain sailing, but there was one possibly contributing factor - the arrows on my propshaft wont line up, they are out by a few degrees which ever way it is put together. this may be causing a vibration, as I have said, it was not noticed before the conversion. It was so bad however that on my first rolling road session the rpms had to be limited as at 5k it was getting serious.
Another clue is the fact that I had to buy a spacer to close up the splines on the prop, as the prop was at full stretch, everyone else seems to use an auto prop without any issue, so maybe my prop has had problems in the past.

You may find that you do not have any issues, but I would certainly measure the flange angles during a conversion as it is quick to do and may go a way to ensuring a smooth ride.
 
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