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#Post#: 591--------------------------------------------------
A bit about Gearboxes
By: Lucy Date: January 5, 2012, 1:43 pm
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If anyone's interested, this is what the inside of a series 3
gearbox looks like.
The Mainshaft
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3831%20(Small).JPG[/img]
The skew cut gears are from left to right, 1st, 2nd and 3rd.
These gears when in neutral are free to rotate about the
mainshaft.
3rd/4th syncro unit
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3832%20(Small).JPG[/img]
1st/2nd gears and syncros, the one in the middle is the dog gear
that meshes with the reverse idler
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3833%20(Small).JPG[/img]
the reverse idler as viewed through the top cover of the main
box
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3862%20(Small).JPG[/img]
the layshaft
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3841%20(Small).JPG[/img]
the bearing at the right hand end sits in a recess in the end of
the gearbox next to the transfer box as seen below
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3863%20(Small).JPG[/img]
the image is on it's side the top of the box is to the right you
can see the reverse idler (top left) the rear mainshaft bearing
(in the middle) and the recess the layshaft bearing sits in.
the other end of the layshaft sits in a bearing in the bell
housing
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3842%20(Small).JPG[/img]
this is on the left, the bit on the right is the primary pinion,
this transmits the drive from the clutch to the gearbox, either,
for 1st, 2nd and 3rd via the gear you can see to the layshaft or
in the case of 4th as a direct drive through to the mainshaft
using the dog teeth visible in the top of primary pinion. The
plain silver part you can see is what engages with the syncro
cone, as below
primary pinion
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3860%20(Small).JPG[/img]
in the above photo 4th gear is engaged.
how it fits together
The photo below shows how the main shaft and layshaft engage
with each other, the primary pinion is on the right and the
transfer box end of the mainshaft on the left.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3844%20(Small).JPG[/img]
with the 1st/2nd gear selector
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3847%20(Small).JPG[/img]
3rd/4th selector
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3846%20(Small).JPG[/img]
both
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3845%20(Small).JPG[/img]
the reverse selector sits next to these two.
syncros
a closer look at teh 3rd/4th gear syncro unit
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3854%20(Small).JPG[/img]
The selector fork engages with the dark coloured disc in the
middle and moves this either forward for 4th gear or back for
3rd.
This photo shows it in the 'in gear position' the narrow parts
in the silver bars you can see are where the gear cluster detent
springs engage to hold the gear in neutral, whilst the box is in
1st, 2nd, reverse or neutral.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3855%20(Small).JPG[/img]
the teath you can see are the dog teeth that engage with the
gears. The photo below shows how 4th gear engages
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3861%20(Small).JPG[/img]
the syncro cones are the brass coloured rings you can see
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3857%20(Small).JPG[/img]
these rub against an area of the gear cluster prior to the dog
teeth engaging and help to equalise the speed of the gear and
the mainshaft.
to remove the mainshaft you have to undo this nut in the
transfer box
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3836%20(Small).JPG[/img]
to do this you need a special tool which you can buy or make,
either way a homebodged one looks a bit like this
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3837%20(Small).JPG[/img]
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/gearbox%20small/PICT3838%20(Small).JPG[/img]
That's the end of todays tour, you may see me in other such
epics as inside your transfer box soon!
#Post#: 637--------------------------------------------------
Re: A bit about Gearboxes
By: RMS Date: January 5, 2012, 3:19 pm
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Quote
"If anyone's interested, this is what the inside of a series 3
gearbox looks like."
No it doesn't! Mines all dirty and got chipped teeth ;)
#Post#: 719--------------------------------------------------
Re: A bit about Gearboxes
By: rbrtcrowther Date: January 5, 2012, 4:15 pm
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That's a suffix A by the looks of the reverse idler. Nice to
see the teeth on 3rd 4th syncro look the same as mine with the 4
king teeth next to each other....I wonder why they did that?
#Post#: 778--------------------------------------------------
Re: A bit about Gearboxes
By: Albert Ross Date: January 5, 2012, 4:55 pm
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Just to add, the 3/4 synchro unit does have a front and a back.
The back has a machined out flat edge to fit over a split
ring... get it wrong and you have difficulty keeping it in 3rd..
ask me how I know and I'll punch you in the bracket. (Never
build a box pissed)
#Post#: 814--------------------------------------------------
Re: A bit about Gearboxes
By: PJ Date: January 5, 2012, 5:27 pm
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Thanks for this Lucy... maybe I'll crack on and rebuild my spare
box now!
#Post#: 900--------------------------------------------------
Re: A bit about Gearboxes
By: seriesewan Date: January 6, 2012, 5:37 am
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Thats explained a lot! still cant find the mystery part that
plopped out in my oil though :(
#Post#: 911--------------------------------------------------
Re: A bit about Gearboxes
By: Lucy Date: January 6, 2012, 6:18 am
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What Mr Ross says is correct and the photo above shows it the
wrong way around :-[
#Post#: 922--------------------------------------------------
Re: A bit about Gearboxes
By: estwdjhn Date: January 6, 2012, 6:57 am
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[quote]still cant find the mystery part that plopped out in my
oil though[/quote]
Get a photo and post up in the normal technical section, and
someone will probably know what it is...
#Post#: 7790--------------------------------------------------
Re: A bit about Gearboxes
By: Lucy Date: January 26, 2012, 2:53 pm
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I'll add in some of the other bits I did...
Stripping my old box down now so I thought I'd open up the
transfer box and see how the 4wd system works...
This is the view in through the bottom cover of the transfer box
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/PICT4048.JPG[/img]
photo1 – Low Range
Here the transfer box is in low range.
Drive would come in from the main gearbox
HTML http://ollr.10.forumer.com/viewtopic.php?t=3133&highlight=bit+gearbox<br
/>on the far right of this picture and is transmitted via the
intermediate gears in the middle to the output gears on the
left.
The following photo shows the transfer box in high range
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/PICT4049.JPG[/img]<br
/>
photo 2 - High Range
Sticking out of the front of the transfer box are 3 shafts
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/images/PICT4036_(Small).jpg
photo 3
The thickest one, at the bottom of the photo, is the front
output shaft, which transmits drive to the front axle when 4wd
is selected, at its left hand end you can see the dog teeth, and
the silver ring of the dog clutch that slides over them to
engage 4wd ( see photos 4&5 below. The one in the middle with
nut on the end is the high low selector shaft; this is connected
to the red lever. The top one is the 4wd selector. The bronze
coloured piece attached to it is the 4wd selector fork.
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/images/PICT4032_(Small).jpg
Photo 4 - 2wd
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/images/PICT4042_(Small).jpg
Photo 5 - 4wd
In between the hi/low selector shaft and the 4wd selector shaft
there is another short shaft
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/images/PICT4044_(Small).jpg<br
/>
photo 6
This is the shaft that allows 4wd in high range to be selected.
(the photo shows it in low range 4wd)
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma's%20gear%20box/transferbox/images/PICT4046_(Small).jpg
Photo7
The ‘L’ shaped piece you can see is connected via a lever to the
yellow knob. As you push the yellow knob down it pulls the ‘L’
shaped peg in the direction towards the camera. This disengages
it from the short shaft and allows the shaft to move forwards,
pushed by the spring on either the hi/lo selector shaft or the
4wd selector shaft (can’t quite work out which), engaging 4wd.
When low range is selected the short shaft is pinned in place by
the 'L' shaped peg, so as the hi/low selector is pushed back, by
you pulling back on the red lever, the piece that is attached to
the short shaft by a pivot and runs between the hi/lo selector
and the 4wd selector pivots and pulls the 4wd selector forwards
engaging 4wd. This is illustrated in photos 4 and 5.
I think that's how it works. HOpefully it wasn't too boring and
anyone who knows better will be along to correct my errors and
clear up any unclear bits.
#Post#: 7791--------------------------------------------------
Re: A bit about Gearboxes
By: Lucy Date: January 26, 2012, 2:54 pm
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and a bit more to keep it in one place...
Rich was asking questions about gearboxes at the WWW yesterday,
and as I'm never one to stifel the urge to learn here's a bit
more about series 3 gearboxes. It's mostly applicable to series
2 boxes as well. I think the main differences (and please
someone who knows, correct me if I'm wrong) are that the series
2 box has square cut gears on 1st and 2nd and no syncros on
those gears.
Anyways, here's some piccies...
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4775%20%28Small%29.JPG[/img]
Photo 1 - Primary Pinion
This is the back of the input shaft (Primary Pinion) that is
driven by the clutch drive plate and goes through the Primary
Pinion bearing in the bell housing and has the Primary Pinion
gear on the back. Inside this gear sits the front bearing for
the mainshaft, the yellow cage of which you can see above.
Next on the inside of this gear you can see the dog teeth that
engage with the 3rd/4th syncro hub to take drive directly from
the Primary Pinion to the mainshaft resulting in a 1:1 straight
through drive for 4th gear.
Finally around the outside of the back of the gear is the syncro
cone that the 4th gear syncro hub sits over. You can see this
more clearly in the photo below.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4776%20%28Small%29.JPG[/img]
Photo 2 - Primary Pinion and Constant Gear
The gear on the left of the photo is the Primary Pinion, the
gear on the Right is the Constant Gear that transmits drive from
the Primary Pinion to the Layshaft.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4779%20%28Small%29.JPG[/img]
Photo 3 - 3rd/4th Syncro Hub (4th gear end)
This is the 4th gear end of the 3rd/4th gear Syncro Hub.
The brass coloured part sits over the Primary Pinion Syncro Cone
and the teeth around the outside of the middle part, engage in
the dog teeth in the back of the Primary Pinion gear as per
photo 4 below.
The splines in the middle of the unit engage with the splines on
the Mainshaft and transmit drive from either the Primary pinion
(4th gear) or, via the layshaft and 3rd gear, as per photo 5
below.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4781%20%28Small%29.JPG[/img]
Photo 4 - Dog Teeth, Primary Pinion and 3rd/4th Syncro
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4795%20%28Small%29.JPG[/img]
Photo 5 - 3rd/4th Syncro Splines Engage on Mainshaft
This is the 3rd gear end of the 3rd/4th Syncro Hub, it has a
slight recess in the centre before the splined section (that
engages on the mainshaft) starts to allow for the 3rd gear
spring retaining clip to sit in.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4784%20%28Small%29.JPG[/img]
Photo 6 - 3rd/4th Syncro (3rd Gear End)
Below shows the layshaft, 3rd gear and the 3rd/4th syncro hub in
place.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4786%20%28Small%29.JPG[/img]
Photo 7 - Layshaft, 3rd/4th Syncro, 3rd Gear and Primary Pinion
This shows the layshaft in place and the mainshaft with all the
gears removed.
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4789%20%28Small%29.JPG[/img]
Photo 8 - Layshaft and Mainshaft, (Gears Removed)
next we have...
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4799%20%28Small%29.JPG[/img]
Photo 9 - Layshaft, 2nd Gear, 3rd Gear, 3rd/4th Syncro, on
Mainshaft, and Primary pinion
On top, the Layshaft with the Constant Gear on the right next to
the bell housing. On the bottom from right to left we have, the
primary pinion, then the 3rd/4th syncro hub, then 3rd gear, then
2nd gear. (there should be a brass coloured spacer which is part
of the bush that 2nd gear runs on between 3rd and 2nd, but it's
broken)
The shiney, smooth part of 2nd gear far left is the syncro cone
for 2nd (series 2 boxes will have -I think- a square cut 2nd
gear with no syncro cone on it)
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4800%20%28Small%29.JPG[/img]
Photo 10 - Layshaft, 1st gear, 1st/2nd selector/reverse gear
(square cut), 2nd Gear, 3rd Gear, 3rd/4th Syncro, on Mainshaft,
and Primary pinion
Now I've added the 1st/2nd selector unit (the part with a square
cut gear on it) and 1st gear. The square cut gear I mentioned
is the reverse gear, this engages with the square gear on the
layshaft via the Reverse Idler, which sits on a small shaft in
the back of the gearbox casing.
All of the gears that sit on the mainshaft (1st, 2nd and 3rd),
with the exception of the square cut reverse gear are free to
rotate on the mainshaft, and are constantly rotating whilst the
vehicle is in motion as they are turned by the layshaft. The
drive from all these gears is transmitted to the mainshaft, and
then on to the transfer box by dog teeth engaging with the
selector units (1st/2nd and 3rd/4th) which engage with the
splined sections of the mainshaft that you can see in photo 8.
In reality the layshaft sits underneath the Mainshaft, I just
turned the camera round the wrong way)
See also this thread
HTML http://ollr.10.forumer.com/viewtopic.php?t=3133&highlight=bit+gearbox
and this one
HTML http://ollr.10.forumer.com/viewtopic.php?t=3778&highlight=bit+gearbox
Sorry for the repetition of threads.
Now for jumping out of 4th gear...
It seems that the most common cause is broken detent springs on
the 3rd/4th syncro hub
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4801%20%28Small%29.JPG[/img]<br
/>
[img]
HTML http://www.climbingchris.f9.co.uk/wilma/Wilma%27s%20gear%20box/gearboxagain/PICT4802%20%28Small%29.JPG[/img]
The top photo has one spring present, on the left and next to
the post on the right the spring is missing, the second photo is
a close up of the detent spring insitu. (If your syncro hub
looks like this one though, you've got bigger problems than just
a broken spring)
There are 3 of these springs, one for each of the posts on the
syncro hub.
The part number for the springs is RTC1956.
hth Rich
Any questions, corrections or clarifications required let me
know.
Luce
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