Lt77 versions

what is the difference between an lt77 from an sd1 2300/2600 and one from a v8 ?

I'm fairly certain that the boxes for the 6 and 8 cylinder cars were the same, i.e. same ratios, same bearings, same strength etc. The bellhousing is different, obviously and there were different 'models' which improved as they went along. The suffix 'A' were the first ones and had a taller fifth gear, while suffix 'D' were generally accepted to be the best ones.

Then of course there were later ones used in 4x4s, the R380, and god knows what, but I don't know much about those.

Richard
 
Richard is right and you can see it in the V8 owners forum.
It helped me, because it was impossible to find a LT77 box here in Germany, it's always linked to SD1 Rovers.
With this thread I saw, that TR7 5speed is also a LT (but has different code, it's C or CL...).
Looking for TR7 gearbox, I found one very quickly, because here the meaning of LT77 is not that known.
Found my gearbox in good condition for GBP 150,00, but then you must look for a bellhousing.
Luckily found one some days before from a TVR350 for 15,00 (but with a cut-in inspection opening...).
If your SD box from 2.3/2.6 looks ok, take it !!!
If it's, beside the bellhousing fact a complete box (remote, gearstick etc), you will be a lucky man.
 
They make a nice difference to the P6, but be careful of high mileage ones. The input bearing is a weak point and it's best
to have yours opened up beforehand to replace if needed. Also, the internal oil pump starts to take strain if the 'box is getting
tired because of the metal in the oil. I don't know if you can get a set of metal gears for the pump like the R380 has, though.
 
The small conical bearing between the input shaft and the mainshaft can be a problem and is not easy to replace. The bearing pulls off of the mainshaft ok, but I have never managed to find an easy way to get the race out of the input shaft :mad:

Yes, you can get steel oil pump gears

Sparky's winter/spring/summer/autumn work
 
I will open the box as soon as I have all parts together. At the moment I´m waiting on the remote unit and hopefully it has a gearstick. With the pedalbox and some brackets etc around, Geoff from Wins helped me (again :)).
First I thought, the box is the problem to get one, but now I can see, it´s the stuff all around it.
Ok, it´s a work for next winter.
By the way, I can see no reservoir on the clutch master cylinder (I have none, I can see none on photos). Is it not an independent system to the brake system ??
 
Hi, The manual 3500s brake fluid reservoir has two outlets on the bottom, one for brake and one for clutch master cylinders. There's a division in the bottom ½" to avoid brake failure in the event of clutch system fluid loss. A second remote reservoir could be used instead.

Colin
 
Early boxes had a lower fifth than later ones, 0.82 as opposed to 0.792 IIRC. Diesels had an even taller fifth.

As I said when I sat on some tippex, "I stand corrected." :)

When researching the LT77 back when I rebuilt it, I must have read this bit wrong - "Some have stronger internals than the earlier 'boxes and are fitted with a higher 5th gear - 0.793 instead of 0.833."
 
Check if there is too much clearance on the input shaft. If so it will need new bearings. I have opened several and the reverse gear is often damaged and this is part of the main shaft and cannot be replaced without replacing the whole shaft. The best thing would be if you are allowed to open the box before purchase as i believe a least 50% of the boxes now offered for sale are scrap due to damaged or worn gears. The earlier SD1 boxes have a mechanical speedo, the later ones an electronic speedo. The mechanical speedo parts are not easy to find now a days so best to try to buy a complete box.
Ashcroft Transmissions is a good source for overhaul kits. If you overhaul the box, don't forget to replace the O-ring in the gearbox housing for the selector shaft as it can leak threw this shaft. Don't ask me how i know. This O ring is not in the overhaul kit and has to be bought separately.
If new bearings have been fitted, you should check end float and correct it with shims which are not easy to get now a days. Normally one should expect that the original shims can be refitted but with the last box i overhauled this was not the case.
You read a lot about LT77's not being a strong box. I have an LT77 in my MGB V8 conversion and its 15 years in it and 30000km's and no problems. A R380 is definitely a stronger box but this in 2wd form is more rare than an LT77

Peter
 
Regarding the bell housing being different between the 6 and 8 cylinder cars. Someone I was speaking to yesterday told me that the 8 cyl bell housing won't fit to a box from a 6 cylinder car because the mounting points are different. Can anyone confirm or deny this ?
 
It would make no sense to make LT77 boxes with different housings. The adaption to different motors is effected by the bellhousing, also by the length of the bellhousing (which means, that you cannot use i.e. a V8 Landrover bellhousing on a P6, SD1). If you can get hold of an LT77 box, do it (ok, check, what Peter said) but be prepared, that search for the bellhousing also is not so easy. But it´s the first step...
I think, in the UK it´s still a little bit easier. You should have the part no. of the correct bellhousing, when looking for it.
 
The box doesn't have a bell housing or remote with it. The seller says the only differences between the different boxes are bell housings and pivot posts, but Rimmer Bros sell them apparently. Do I need an Sd1 manual bell housing and remote as well ? If I were to fit this to a P6B auto would I also need an SD1 clutch and flywheel ? I know I'd need the pedal box etc.
 
Do I need an Sd1 manual bell housing and remote as well ? If I were to fit this to a P6B auto would I also need an SD1 clutch and flywheel ? I know I'd need the pedal box etc.

Flywheel is the same as a 3500S, you'll need an SD1 V8 bellhousing and remote, SD1V8 clutch complete, and an LT77 spigot bush.
 
I used my old automatic bellhousing for my LT77 conversion. I had an adapter plate made up that adjusted for the length difference and
alignment issues and then cut a hole in the side for the release arm and made a bracket for the slave.
Easy peasy, particularly as I had a mate with a full machinist shop and half a dozen apprentices......:)
 
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