LT77 5 Speed Overhaul

The remote lever assembly had too much play in it for my liking. There are actual replacement bearings that can be fitted but at the time I searched I couldn’t see hide nor tail of any replacement, hence I proceeded to obtain materials to make them instead. Subsequently when I searched last week some original bearing sets appeared (typical).

I ended up purchasing a couple of bush options just in case from these guys. Simply Bearings Ltd ~ Oil Seals SKF FAG TIMKEN KOYO NTN NKE TRULOC Needle Rollers Taper Rollers Rod Ends Oil Filled Bushes Loose Balls O Rings Grease Plain Thrust

I began by making up a drift to remove the original well worn bushes. The shaft was relatively unworn, just a bit shinier where the bush has been running.



I thought these maybe suitable having a wider surface area, but they have a ptfe innner which might not have the longevity required, photo shows original against the new potential bush.



Alternative solid bronze bush. Note I turned down the one on the right already. Preferred this bush as it had an even longer surface area and self lubricating too.



Fitted the first stepped bush with the drift I made earlier.

Fully home


Next I made up a little insert tool with threaded bar, nuts and washers for the bush due to it being stepped.



Shaft fitted and a nice tight sliding fit. Will be plenty of grease used once in place. Hopefully gear change will be more precise in future.
 
Oops nearly forgot. I also made up new rubber bush steel inserts for the remote too as I had only one remaining, so used this original as a measurement for the others as again these parts are not available anymore. I fitted brand new DAF rubber bushes at the same time. Overall gear change appears very precise now, just need to fit to the car now!

 
One thing that always niggles me on the LT77 is the oil leak from the selector shaft where it enters the box, this leaks down and can make the rear mounting rubbers soggy.

Years ago someone made a thick washer to fit over the shaft with a step turned in one side into which fitted an O ring. A couple of small holes in the washer screwed it the the box casing and nipped the O ring against the case and shaft. It worked very well.
Something that a man of your turning skills could whip up no bother.
 
Now I need some help from one who has opened an LT77 please. Picked up a cheapish box - no bellhousing, but remote, lever and throwout parts. They told me rear cover was loose because they wanted to look at the gear condition. Delivered in a tailor mode box, tight fit. Getting it out was a struggle....then I found bad stuff. Stuck in gear somehow. Managed to get the rear cover right off. Still cant turn output shaft. The selector shaft will, at some orientations go in back/fwd, and on one push fwd it actually punched the sealing cup out of the front of the case. When pulled fully rearward it can be turned ~ 160 degrees. have tried turning output shaft while I wriggle the selector shaft back and forth, no luck. Seems to me the selector peg inside is not where it should be and cant move the actual selectors?
Any suggestions ?
 
Now I need some help from one who has opened an LT77 please. Picked up a cheapish box - no bellhousing, but remote, lever and throwout parts. They told me rear cover was loose because they wanted to look at the gear condition. Delivered in a tailor mode box, tight fit. Getting it out was a struggle....then I found bad stuff. Stuck in gear somehow. Managed to get the rear cover right off. Still cant turn output shaft. The selector shaft will, at some orientations go in back/fwd, and on one push fwd it actually punched the sealing cup out of the front of the case. When pulled fully rearward it can be turned ~ 160 degrees. have tried turning output shaft while I wriggle the selector shaft back and forth, no luck. Seems to me the selector peg inside is not where it should be and cant move the actual selectors?
Any suggestions ?

Perhaps try backing off or removing the set screws in the bearing retaining housing at the bell housing end?

Remove the detention spring and ball from the selector shaft?
 
IIRC There's a small plate on the top of the box retained by two bolts, if you remove that there's a shaft on the bottom with a female slot on the bottom (like a RV8 oil pump), if one side breaks off it allows the box to engage 2 gears at the same time, which locks it up.
 
The little plate on top is OK. After loosening the front cover and lots of wriggling I got the main case off. Looked like it was in 2nd gear and something else was binding the shafts. Now all turns fine. All the gears look OK - no pitting or irregular wear. Primary pinion bearing looks OK. Do I need any special tools to complete the dismantle? I have a dial gauge so I ought to be able to put it back together...? There are some youtube vids on this seem to be detailed...?
thanks
 
More info. With case off, find the washer on end of reverse idle shaft is missing, and the detent spring. I think I have the locating spool in the selectors in the right orientation - was upside down or something. Next question - whats the orientation of the locating spool outside the plate when its correct ? Cant quite see how it works. Its a bit difficult to get the pin into the 5th gear selector - there is obvious polished metal in the groove on the selector (the iron bit that toggles the synchro) that indicates its been like that for a while. Any known issues that can cause this ?
On the upside the remote selector shaft bushes are in very good shape, very little wear evident, unlike Lovel's unit. Also opened the oil pump and thats all good, no cracks etc.

Lovel - did you see the "oil catcher" on the front cover - TKC5779? Or are these peculiar to LR type boxes? It gets a mention on one of the Britannia youtube videos, and it makes sense to me - catches oil inside the case and carries it out into the front cover area for the seal.
My shim on the layshaft bearing is also a bit narrow, so it will need replacing, but the bigger one is OK. Both are around 70 thou. I tried the link above for shims, which says will post to Oz, but when I tried to buy it rejected my address.

thanks
 
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Another question. The LR exploded lt77 diagrams show and list a washer on the front of the reverse idler shaft, on the short narrow section of the shaft that goes into a support cast inside the main case. The SD1 book diagrams of the box dont show (or list) this washer, and my 2wd box doesnt have it. Is it likely that this washer was only fitted to later variants of the box (mine is a suffix C), or it just wasnt used in 2wd types? I cant see a reason for it, as the idler gear cant move that far under the control of its selector arm.

EDIT:- The front shaft bearings look fine, so far havent removed shafts from centre plate. The manual says, re the layshaft, pull the washer and driving 5th gear off with a special tool, but on reassembly does not mention anything special - just says 'fit 5th gear and spacer, fit circlip'. Whats your experience here please? Main reason I ask is while the mainshaft is rigid in the centre plate the layshaft moves fore-aft some 3mm - can see that much of the bearing rollers when pulled forward, and when pushed backwards the layshaft 5th has 3mm of teeth not meshed with the driven gear - Bearing issue?

thanks
 
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Well I have spent way too much money and hours rebuilding the 5 speed box, including sourcing all the parts, but I’m at a stage now where I am beginning to think it is such a shame to remove the old original 4 speed box, and in order to preserve the cars original character I have parked the idea of the conversion. After a beautiful sunny (but cold) run today it has driven home to me just how well she runs.
 
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