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Gazzar

Series III gearbox rebuild

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Thanks all for the info re the mystery box of parts.

The rear diff is a salsbury and it seemed ok???? I am not sure how many degrees of backlash/movement it should have though. I would like to know if anyone can tell me.

With regard to the rest I will hunt down the other things you guys have suggested but I'm thinking its the layshaft.

I can tell you that all axles and drive flanges (flanges are new))are tight.

The front prop is off the vehicle to eliminate the front diff/prop shaft and the front swivels have just been rebuilt.

The yoke on the rear prop is a new genuine land rover NOS unit and the UJ is new. The rear UJ was tight.

The overdrive does give a small vibration in high if the drive train is low in revs under load. This is coming off to be A) eliminated B) overhauled.

The hand brake needs sorting, the rear of it looks like an oil drip tray so there's an issue there for certain.

I haven't had a close look at the mounts yet but will give them the once over. I think they are ok though.

I can defiantly say that when its in 4th on the open road I can let the foot off the accelerator so it slows and dump it again and there is very little to no noise in the drivetrain. In second and third there is a clunk. This I think tell us the layshaft is the problem.

Unfortunately the lay shaft in the mystery box has 2 broken teeth now I have had a close look at it :(

When I get time I'm going to remove both Series 3 boxes and build a "budget" box out of them, hopefully is just a matter of replacing the bearings and seals and I can get one good set of internals from the pair.

I'm toying with the idea of just replacing the springs and balls in the sectors of the series 3 box in the donor but I don't know about that. The previous owner said "it dropped out of gear every so often" but was not very specific. I would have a cursory look at the gears but if I put it in and it was a bad box I would kick myself.

Looks like I need to spend some quality time under the landy.... the wife loves it when I do that

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.

Looks like I need to spend some quality time under the landy.... the wife loves it when I do that

Just remind her that love comes before hobby, and thats why she will have to wait... :hysterical:

Mine is encouraging me at the moment as she has no one to tow her donkey thing about.

but i still cant get the insurance cheap enough to have both it and the "chevy" insured

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I test drove my 109 yesterday having just rebuilt the gear box for failed leaf springs on the 3rd/4th synchro unit. I put a new main shaft in because of a small amount of wear on its output splines. I also omitted the overdrive. The reduction in backlash noise is incredible - there is none, but it was a bit clacky if clumsy with the clutch before. I think most of it was from the overdrive - turning the removed unit by hand was a little clattery. You may find a lot of your backlash disappears with the overdrive too - they introduce a lot more through their gear sets and splined joints, especially the wear prone fine splines on the clutch sleeve and inside its main shaft.

However, I'm still a little concerned that the noise is significantly lower in 4th, which as we discussed suggests a lay shaft issue. With luck, it'll just be a worn bearing or even a loose front end bolt allowing the shaft to slide fore and aft (it has happened before).

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Clonk when going on and off the drive can be down to end float on the transfer box idler.

pardon my ignorance Phil but which one is the idler? I am keen to explore this if its could be a cause.

#3 is the high

#7 is the low

#24 is the intermediate

but no idler? is the intermediate also called the idler?

TRANSFER_BOX_SERIES_LAND_ROVER.JPG

or do you mean the main shaft gear #30 (below)

GEARBOX_SERIES_3_WITH_CLIP_A___bush.JPG

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I think Phil means the "intermediate gear cluster", which is part number 24 on the upper diagram. It has thrust bushes at either end, which have to be set for correct end float by the shims between them and the casing, parts 21.

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i would agree with that, 24 would be said "idler", although that would only show symptoms in all gears whereas you say no problem in 4th?

definately worth checking though!

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I say no problem with 4th but there is a noise in 4th sometimes now I am focused on listening, it does seem to come an go.

I think there maybe a bit of diff back lash. That accounts for the backward and forward noise but it not the "main" noise.

When I press the clutch in and it releases the pressure on the drive there is a clonk type noise. More noticeable when in the low gears and when stationary or moving at low speeds.

I cant get to it until the week end but I will check the transfer box gears when I take the overdrive off just out of interest.

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Everything in your last post is normal - the lower the gear selected, the greater the torque. The greater the torque, the more the force on the components and the louder the backlash. Any slack will sound worse in lower gears. This is very different from reporting that the noise only existed in 1st-3rd, if the noise is also in 4th but just less, then we are no longer limited to looking at lay shaft faults but at just a little wear in the overall system that may be nothing to worry about.

What is needed is a comparison to another SIII or even a Defender. If you are used to a normal road car, then you will have a significant increase in noise, but that is normal and unavoidable. It is determining the baseline noise level that is important now. If you fill out your profile properly, then some local members may be able to take a look.

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Hey Snagger, its hard to explain. What you say about torque is quite correct. I've owned 4 series landys so I have a bit of an idea what's normal and what's not. I think its the transfer idler the more I think about it. I haven't checked it yet but that makes the most sense. I remember giving it a wobble when I changed the gasket a while back and it did have a slight movement. It wasn't the bugger all 0.004-0.006 inch I now know the book states. I didn't think much off being a bee keeper rather than a mechanic :P

Like I said when I let the pressure off I am getting a loud knock noise in low gears at low speed. It has an echo about it as well. I think that's the "idler" gear moving and banging on the case. Too much end float as Phil has suggested. If I'm very gentle on the clutch and it is almost not noticeable but it is there if you use it "normally"

Also when it goes into reverse I wonder if it pushes the idler to the other side of the case giving the impression of a backlash type noise.

When im in 4th on the road at speed it doesn't make the noise when you press in the clutch, I think that's because of inertia in the system holding the idler gear against the thrust washer and it doesn't float as much.

Question - when I remove the overdrive and put the standard main shaft gear back on does the nut on the main shaft have to be at a correct torque or can I just knock it on with a screwdriver/drift? Does it matter if it's tightened too much? I don't have the correct tool but I could modify a bit of pipe and socket and torque it if its a must do.

I updated the profile as you suggested not that it will help, although I will be in England on holiday in August but the landy wont be :i-m_so_happy:

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Yep, Tasmania is a bit far for me to have a look, but I'll come if you pay for the flight!

The castellated nut is meant to be torqued up to a specific value, but then if the tabs on the washer don't line up with the slots, you have to tighten it more or slacken it anyway. I have always used the drift and hammer with no ill-effect.

The noise generated by a floating intermediate cluster is quite considerable, so it's well worth pursuing as prime candidate. You might be able to measure the end float with feeler gauges through the top cover once the overdrive is removed, saving you the trouble of draining it down to remove the bottom plate. You will have to remove the plate to remove the cluster if it does need shimming, and if shimming is necessary, then replace the thrust bearings as they're probably worn, hence the need for shimming!

Just so you know, to get the intermediate shaft out of the casing to drop the cluster and get at the shims and bearings, you need to take the hand brake off the transmission, which means rear prop and flange off, drum off, disconnect the hand brake's horizontal rod from the relay arm and then undo the four nuts holding the brake plate onto the speedo housing. It's worth replacing the rear seal if there is any sign of sweating or weeping, and make sure you cean out the oil drain in the plate (under the main shaft hole) and the drain slot in the speedo housing - these allow any oil that does get past the seal to drain away outside the brake, but they gunge up with dust and oil.

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Its on the job list for tomorrow. I'm hoping I don't have to take the bottom plate off as well.

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Any chance of this tread getting back on track ??

would very much like to see the rest of the rebuild, before i start on my own.

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Yeh, good point. The box is finished, I must see what photos I've taken of the rest of the build, and post them up. The photobucket is full so I may have to host them somewhere else, though.

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You can post directly to the thread and the photos will remain here :) Just upload them from the more reply options button

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Hi all

I have a mod 1983 LR Series III and i have been informed that the gearbox OIL must be labeling ''yellow metal friendly''

Know something , someone from you ?

If yes , what type is this OIL?

Thanks

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Hi all I have a mod 1983 LR Series III and i have been informed that the gearbox OIL must be labeling ''yellow metal friendly'' Know something , someone from you ? If yes , what type is this OIL? Thanks

You will need EP90 or 80W90 gear oil with API-GL4 specs.

The common gear oils nowadays are GL5 specs and it is said that the phosphor content in GL5 oil is aggressive on the brass parts.

An engineer,which I hold in high regard, ones told me that the phosphor only starts to be aggressive on brass when the oil reaches 120 degrees C. Now when the gearbox oil in your LT76 reaches 120 C then there definitely is something wrong with the box. Even on hot days the oil will only get to 70 C.

As GL4 gear oils are still readily available you best be on the save side and use that.

Cheers,

Eric.

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I know that this is an ancient thread, but I've been using it as a guide while I rebuild my gearbox and it is so amazingly helpful that I simply have to say "Thank you". The official manual isn't wrong, but it doesn't really explain how to perform each step: the photographs are brilliant.

I even copied your idea of making a mainshaft clamp with an old clutch and a length of angle iron. To my amazement, I find that I can still weld after a fashion.

Thanks again,

Nick

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Delighted to help. I will be doing a couple more rebuilds soon. I need to find a lightweight box to rebuild first. This will be a cheap and cheerful rebuild, re using as many parts as possible, just to see how cheaply I can do a box.

G.

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Hi there Gazzer,

 

The pictures of your first post seem to have disappeared, is there anywhere else where I can see the pictures?

 

 

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Something to do with photo bucket. If I have time I'll try to find them, but time is precious.

Plus I'm not sure if I could re edit the posts.

 

G.

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Hi there Gazzer,

Thanks a lot!!

The pictures are visible again :)

 

cheers

 

 

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On 11/28/2018 at 6:01 AM, Gazzar said:

Something to do with photo bucket. If I have time I'll try to find them, but time is precious.

Plus I'm not sure if I could re edit the posts.

 

G.

Gazzar.....

I've amended your profile so you can edit the post and upload the pictures directly to the server here etc.

Hopefully the post will be good for others for many years then....

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Thanks, time to try to get into photo bucket and see if they are still there.

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I'm confused by this photobucket thing.

I've looked at some of this thread on another browser and the pictures are there.  Why are they there for me and not others?

 

The main problem is I can't remember the login for the photobucket account!!  I'll try something else.

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