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#Post#: 72247--------------------------------------------------
Gearbox refurb essentials
DIR By: espacekiller
Date: August 27, 2013, 6:47 am
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I am about ready to throw a S3 gearbox in to my chassis, it will
be sitting behind a gay TDi engine, it is supposed to "drive
fine" according to the PO and has no leaks.
I am going to have a delve inside (my first) gearbox and see
what condition it is in , the plan is to do the bare minimum,
funds for the project are pretty much non existant so it will be
a budget rebuild (fingers crossed).
Which parts are essential to replace whilst in there as a matter
of course?
Which bits cause problems and need checking carefully?
Can I inspect and check the end floats with the gears out of the
box but fully assembled on the main and layshats?
There is very slight play in the primary pinion shaft I assume
this is because it only has a single bearing supporting it, is
this normal?
#Post#: 72362--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: estwdjhn
Date: August 27, 2013, 5:15 pm
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--- Quote from: espacekiller link ---
>
> Which parts are essential to replace whilst in there as a
matter of course?
> Which bits cause problems and need checking carefully?
> [quote]
>
> Shot rear layshaft bearings are the most common cause of
failure. Decent quality replacements can be hard/expensive to
get, so if it looks like an original bearing (metal roller cage
rather than plastic) and the bearing surfaces look OK, I'd be
tempted to leave well alone.
> Reverse laygear and idler can have the hardening break down -
if this happens, the box tends to be very noisy in reverse and
in my experience the teeth eventually let go and leave you with
no reverse. (Try driving round for a week without reverse - it's
surprisingly difficult!)
> 3rd/4th scyncro unit has 3 spring clips that tend to break and
fall out. If you replace them, replace with genuine items only.
If it's been run for a bit with one or two of the clips broken
you often get nasty eccentric wear on the syncro cones and
3rd/4th dog clutch gear, which may mean you really need to
replace the whole item.
>
> It's worth replacing the oil seal where the mainshaft goes
into the top of the transferbox, as when the boxes get a bit
worn they tend empty the mainbox oil out into the transfer box.
>
> [quote]
> There is very slight play in the primary pinion shaft I assume
this is because it only has a single bearing supporting it, is
this normal?
>
--- End Quote ---
Yep, totally normal. Probably would do no harm to change the oil
seal on the input shaft while your working on the box.
#Post#: 72368--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: espacekiller
Date: August 27, 2013, 6:01 pm
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Cheers :thumbs: just tidied the workshop so I can see the floor
and started cleaning the outside.
What about detent springs should I change them as a matter of
course?
Also found a number on the box which has a 'D' at the end I
assume this means it is a suffix D box.
#Post#: 72379--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: Lucy
Date: August 28, 2013, 1:48 am
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Check for wear on the 1st/2nd selector hub dog teeth, can cause
jumping out of 2nd, also the bushes that the gears run on can
break.
#Post#: 72383--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: logrover
Date: August 28, 2013, 2:28 am
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hardest part of the job i find is working out what is "too worn"
???
stripping the box and replacing clearly broken bits is straight
forward enough, but identifying partly worn bits is the tricky
bit.
i took a lot of photos and put them on the logrover site, so
that may help with knowing what to expect and what some of the
new bits look like for comparing with what you find (like
synchro cones for example):
HTML http://www.log-rover.co.uk/Putting%20things%20together/index9.html
HTML http://www.log-rover.co.uk/Putting%20things%20together/index9.html
for example, an old and new synchro hub showing what new teeth
should look like:
HTML http://www.log-rover.co.uk/Putting%20things%20together/slides/28th%20february%202008%20005.jpg
#Post#: 72452--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: espacekiller
Date: August 28, 2013, 10:02 am
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:thumbs: excellent many thanks, with Lucys technical guide and
the log rover photos I have a resonable idea what to look out
for, the photos showing worn components against new is very
useful.
I don't want to know what it cost to rebuild that logrover box
:eek:
#Post#: 72455--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: Gozo_Joseph
Date: August 28, 2013, 10:17 am
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hi
you got a later model then, the D suffix is the last of series
three i believe, i have one in the non runner, needs a rebuilt.
it is different from suffix A and B and C. due to use of electro
chemical machining and should be stronger, I am not sure if Bits
of early suffix gearboxes are interchangeable.
have you got a A proper land rover manual ? do have a look at
sites like ebay (can i mention it? ) and if you dont have just
try buy a manual in PDF on CD pretty cheap and gives you details
etc about endfloat etc :) you can check float with parts out if
i am not wrong.
i got one some years back it also had a parts manual - good for
ordering bits online using the land rover part numbers for
reference.
>> I would go for new BEARINGS? i did it in 2008 and i am
looking into doing it again it has seen some work and it feels
rattly enough.
>> check for the three SPRINGS on the 3/4 synchro hub - the one
log rover showed. from my experience they tend to split :( my
runner has two missing. so it is balancing off on just one. if
it fails it is much more double clutching for help.
>> new GASKETS and SEALS. in my opinion change seal and related
bearing. leaving the old bearing in leaves opportunity for
stress on seal anyhow. plus check the part that rubs against
seal for grooving etc.
joseph
#Post#: 72462--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: Albert Ross
Date: August 28, 2013, 11:57 am
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Be aware that the 3/4 synchro hub has a front and a back. In the
pic above, both show the front. There is a milling on the very
outer end of the inner splines to fit over a ring on the
mainshaft. Get it wrong, and it will either hop out of third, or
indeed fail to select it at all.
#Post#: 72509--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: espacekiller
Date: August 28, 2013, 3:42 pm
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--- Quote from: Albert Ross link ---
>
> Be aware that the 3/4 synchro hub has a front and a back. In
the pic above, both show the front. There is a milling on the
very outer end of the inner splines to fit over a ring on the
mainshaft. Get it wrong, and it will either hop out of third, or
indeed fail to select it at all.
>
--- End Quote ---
OK noted thanks :thumbs:
I have several manuals including the S3 workshop and parts
books, free online.
I am beginning to think my plan of a cheap rebuild might be
unrealistic, might have to free up some funds :-?
#Post#: 72760--------------------------------------------------
Re: Gearbox refurb essentials
DIR By: Donk
Date: August 30, 2013, 8:41 am
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Some people call them gearboxes I call them pandoras box. Don't
forget to check reverse gear and the layshaft gear it meshes
to. I didn't check mine properly and it jumps out of reverse. I
think its the layshaft that's hammered. rebuilt mine 2 years ago
and its a noisy bastard thing from day 1. Rattles like buggery.
Still goes though. Spent close to $1000AUD on parts , new
mainshaft and components, bearings , gaskets, new output shaft,
the lot. If I replaced the layshaft and reverse gear it would
have been a full recoed box. Im disappointed with the result as
its unnervingly noisy and rattles. I have to use a bottle of
Moreys gearbox additive to aid in keeping the noise down which
it does. The noises has never been adequately understood or
explained.
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