Transmission Ratio - calculating

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M

Mother

Guest
Grumble is (probably) going Auto...

So, I have in mind - to place between the 4.6 V8 and the wheels, a
standard 4 speed auto box, but cannot decide upon transfer box. My
thinking is as follows: A Borg Warner box has fixed ratio and
although quieter, has the disadvantage of chain stretch...

So, looking at an LT230 (as it also has the diff lock) as an
alternative, but cannot get my head around the ratio to go for.
Having standard 101 front and read diffs (which are fairly low ratio)
but bigger wheels 28.5" - I want to try to avoid having too high a
ratio (cruising at 70 doing 1,500rpm is not good for a V8 and makes
for frustrations for the driver).

Anyone care to shed their light on this?


--
Some Land Roveresque (101 biased), links available
from: http://links.solis.co.uk/Geek/X4_Land_Rover/
I also have a little Land Rover site biased toward
my beloved 101 "Grumble", at: http://www.101fc.net


Reading this in 'alt.fan.landrover'? Did you know
there's a group FAQ: http://www.aflfaq.dyndns.info
 

"Mother" <"@ {mother} @"@101fc.net> wrote in message
news:[email protected]...
> Grumble is (probably) going Auto...
>
> So, I have in mind - to place between the 4.6 V8 and the wheels, a
> standard 4 speed auto box, but cannot decide upon transfer box. My
> thinking is as follows: A Borg Warner box has fixed ratio and
> although quieter, has the disadvantage of chain stretch...
>
> So, looking at an LT230 (as it also has the diff lock) as an
> alternative, but cannot get my head around the ratio to go for.
> Having standard 101 front and read diffs (which are fairly low ratio)
> but bigger wheels 28.5" - I want to try to avoid having too high a
> ratio (cruising at 70 doing 1,500rpm is not good for a V8 and makes
> for frustrations for the driver).
>
> Anyone care to shed their light on this?


You sure about 70mph at 1500rpm? By my calculations, all else being as
expected, you should be hitting 4000rpm at 70mph.

If the gearbox, transfer box & diffs are standard, and only the engine &
wheels have changed....

Engine Speed (rpm) * 1/1 * 1/1.174 * 1/5.57 = Wheel Speed (rpm)
| | |
Top Gear ratio -------+ | |
| |
Transfer Box ---------------+ |
|
Diff Ratio ---------------------------+

So - 4,000rpm Engine speed = 611.69rpm Wheel speed

With 38" dia. wheels & tyres, 1 rpm = pi * 38 inch/min, or pi * 38 * 60 /
63360 miles/hr

so 611.69rpm = 69.15 miles/hr at the aforementioned 4,000rpm engine speed.

If you specify what engine rpm you want at 70mph (or 611.69 wheel rpm), you
should be
able to plug numbers into the above and work out what transfer ratio you
want.

From what I've seen, the final drive on an auto box is probably 0.7:1 or
thereabouts.
Sticking 0.7/1 into the top gear ratio indicates that you'd need to swap to
Range Rover
diffs (at 3.54:1) in order to see 70mph at about 3700, otherwise you'll only
get 48mph @
4000 rpm.


I hope all that's of some use - if anyone can see anything wrong with what
I've done, feel
free to chip in...

- Andrew

PS. Useful links :
http://www.lrfaq.org/FC/FAQ.FC.101tech.html For 101 gearing ratios
http://www.cruzers.com/~twakeman/LR/gear_ratio.htm For General L.R. Gearing
info


 

"Andrew" <[email protected]> wrote in message
news:[email protected]...
>


<snip stuff that was probably mostly right>

> From what I've seen, the final drive on an auto box is probably 0.7:1 or
> thereabouts.
> Sticking 0.7/1 into the top gear ratio indicates that you'd need to swap

to
> Range Rover
> diffs (at 3.54:1) in order to see 70mph at about 3700, otherwise you'll

only
> get 48mph @
> 4000 rpm.


Sorry - it's 1/0.7 that you stick into the top gear ratio, and that means
that
you'll get 70mph at about 2800 rpm with the 101 diffs and all else remaining
the same.

- Andrew


 
On Thu, 29 Jul 2004 12:59:51 +0100, Mother <"@ {mother} @"@101fc.net>
wrote:

>Grumble is (probably) going Auto...
>
>So, I have in mind - to place between the 4.6 V8 and the wheels, a
>standard 4 speed auto box, but cannot decide upon transfer box. My
>thinking is as follows: A Borg Warner box has fixed ratio and
>although quieter, has the disadvantage of chain stretch...
>
>So, looking at an LT230 (as it also has the diff lock) as an
>alternative, but cannot get my head around the ratio to go for.
>Having standard 101 front and read diffs (which are fairly low ratio)
>but bigger wheels 28.5" - I want to try to avoid having too high a
>ratio (cruising at 70 doing 1,500rpm is not good for a V8 and makes
>for frustrations for the driver).
>
>Anyone care to shed their light on this?


You have mail. A spreadsheet that calculates road speed for given RPM
and gear ratios.


--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'95 Discovery V8i aka "The Disco" (FOR SALE)
'03 Volvo V70

My Landies? http://www.seriesii.co.uk
Barcoding? http://www.bartec-systems.com
Tony Luckwill web archive at http://www.luckwill.com
 
Tim Hi,

I would be extremely obliged if you could also send me this calculator.

Thanks in advance

Take care
Pantelis

"Tim Hobbs" <[email protected]> wrote in message
news:[email protected]...
> On Thu, 29 Jul 2004 12:59:51 +0100, Mother <"@ {mother} @"@101fc.net>
> wrote:
>
> >Grumble is (probably) going Auto...
> >
> >So, I have in mind - to place between the 4.6 V8 and the wheels, a
> >standard 4 speed auto box, but cannot decide upon transfer box. My
> >thinking is as follows: A Borg Warner box has fixed ratio and
> >although quieter, has the disadvantage of chain stretch...
> >
> >So, looking at an LT230 (as it also has the diff lock) as an
> >alternative, but cannot get my head around the ratio to go for.
> >Having standard 101 front and read diffs (which are fairly low ratio)
> >but bigger wheels 28.5" - I want to try to avoid having too high a
> >ratio (cruising at 70 doing 1,500rpm is not good for a V8 and makes
> >for frustrations for the driver).
> >
> >Anyone care to shed their light on this?

>
> You have mail. A spreadsheet that calculates road speed for given RPM
> and gear ratios.
>
>
> --
>
> Tim Hobbs
>
> '58 Series 2 88" aka "Stig"
> '77 101FC Ambulance aka "Burrt"
> '95 Discovery V8i aka "The Disco" (FOR SALE)
> '03 Volvo V70
>
> My Landies? http://www.seriesii.co.uk
> Barcoding? http://www.bartec-systems.com
> Tony Luckwill web archive at http://www.luckwill.com



 
On Thu, 29 Jul 2004 14:52:36 +0100, "Andrew" <[email protected]>
wrote:

>I hope all that's of some use


Yup - this and Tims Spreadsheet have me sorted, TVM

BTW, the wheels are 38.5 (not 28.5 - that was my typo). I was using
the 70mph @ 1,500 RPM as a demonstration - not what I'd get - as
that'd be very scary! :)


--
Some Land Roveresque (101 biased), links available
from: http://links.solis.co.uk/Geek/X4_Land_Rover/
I also have a little Land Rover site biased toward
my beloved 101 "Grumble", at: http://www.101fc.net


Reading this in 'alt.fan.landrover'? Did you know
there's a group FAQ: http://www.aflfaq.dyndns.info
 
On Thu, 29 Jul 2004 15:03:06 +0100, Tim Hobbs
<[email protected]> wrote:

>You have mail. A spreadsheet that calculates road speed for given RPM
>and gear ratios.


Top notch - many thanks!

I've modded it for a 101 (with credit) and placed it here in case
anyone wants to play:

http://www.101fc.net/files/gearratios.xls



--
Some Land Roveresque (101 biased), links available
from: http://links.solis.co.uk/Geek/X4_Land_Rover/
I also have a little Land Rover site biased toward
my beloved 101 "Grumble", at: http://www.101fc.net


Reading this in 'alt.fan.landrover'? Did you know
there's a group FAQ: http://www.aflfaq.dyndns.info
 
On Thu, 29 Jul 2004 12:59:51 +0100, I wrote:

>So, I have in mind - to place between the 4.6 V8 and the wheels, a
>standard 4 speed auto box, but cannot decide upon transfer box.


OK, here's the plan - not too cunning and a bit of a soft option...

Standard ZF 4 speed box - ratios as per spreadsheet mentioned in reply
to Tims post. Also standard Rangie transfer ratios - geared box so as
to avoid chain stretch in Borg Warner. Essentially the unders of
Grumble will be the same as when it was built, but upgraded Range
Rover parts rather than older ones ;-)

Now... Cross drilled input gears anyone? I'll assume that later
boxes will already have them - when were they added?

Also, what's the score with the hanging in 1st gear problem associated
with these boxes? Again, would a later box have overcome this?

Initially - as this is an experiment and I want to limit my financial
exposure, I'm going to go get a s/h box - if this works out alright,
I'll put an Ashcroft box in next year. Otherwise it'll be back to the
LT95... Hmm...

Finally, Charlotte and I both - at the same time - last night
mentioned to each other that we'd never (ever) driven an Automatic!


--
Some Land Roveresque (101 biased), links available
from: http://links.solis.co.uk/Geek/X4_Land_Rover/
I also have a little Land Rover site biased toward
my beloved 101 "Grumble", at: http://www.101fc.net


Reading this in 'alt.fan.landrover'? Did you know
there's a group FAQ: http://www.aflfaq.dyndns.info
 
On Fri, 30 Jul 2004 11:28:07 +0100, Mother <"@ {mother} @"@101fc.net>
wrote:

>
>BTW, the wheels are 38.5 (not 28.5 - that was my typo). I was using
>the 70mph @ 1,500 RPM as a demonstration - not what I'd get - as
>that'd be very scary! :)


Do you remember that Rolls Royce engined special that RR cars insisted
not be called a RR or have a flying lady, built by someone called
Dodd?

Geared at 100mph per 1000rpm and rev limited at 2900rpm!

AJH

 
On or around Fri, 30 Jul 2004 11:49:08 +0100, Mother <"@ {mother}
@"@101fc.net> enlightened us thusly:

>On Thu, 29 Jul 2004 12:59:51 +0100, I wrote:
>
>>So, I have in mind - to place between the 4.6 V8 and the wheels, a
>>standard 4 speed auto box, but cannot decide upon transfer box.

>
>OK, here's the plan - not too cunning and a bit of a soft option...
>
>Standard ZF 4 speed box - ratios as per spreadsheet mentioned in reply
>to Tims post. Also standard Rangie transfer ratios - geared box so as
>to avoid chain stretch in Borg Warner. Essentially the unders of
>Grumble will be the same as when it was built, but upgraded Range
>Rover parts rather than older ones ;-)
>
>Now... Cross drilled input gears anyone? I'll assume that later
>boxes will already have them - when were they added?


never heard mention of it on the ZF... they date from about 96 on manual
boxes. Maybe the ZF output shaft is better quality?

If you want to hunt an LT230-type setup, you're looking at an ex-disco one.
I suspect the BW transfer box arrived at the same time as the ZF in the RRs,
although I'm open to correction on that.

>Also, what's the score with the hanging in 1st gear problem associated
>with these boxes? Again, would a later box have overcome this?


neither of the SH ones I had suffered that. I think it's more liekly to be
down to crappy maintenance.

if buying a secondhander, I'd go the whole hog, buy a filter (about 25
notes) and lots of ATF and make some attempt to drain the TC as well as the
box, which you can only do when it's out, so as to get a decent oil change
etc done before installing it. Unless you know the history... sump off to
change the filter, but it's got a big rubberoid seal which should be OK to
refit.

>Initially - as this is an experiment and I want to limit my financial
>exposure, I'm going to go get a s/h box - if this works out alright,
>I'll put an Ashcroft box in next year. Otherwise it'll be back to the
>LT95... Hmm...
>
>Finally, Charlotte and I both - at the same time - last night
>mentioned to each other that we'd never (ever) driven an Automatic!


auto in the 110 was great. You can make it play tunes, by applying more or
less boot. You can also force it down into low gears with the shifter.
generally, I really liked it, if the engine hadn't been ****e I'd still be
running it. I wouldn't have gone back to a manual. almost tempted to hunt
an auto for the current disco, rather than hunting a better manual box.
Almost...


--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
In Touch: Get in touch with yourself by touching yourself.
If somebody is watching, stop touching yourself.
from the Little Book of Complete B***ocks by Alistair Beaton.
 
On Fri, 30 Jul 2004 11:49:08 +0100, Mother <"@ {mother} @"@101fc.net>
wrote:

>On Thu, 29 Jul 2004 12:59:51 +0100, I wrote:
>
>>So, I have in mind - to place between the 4.6 V8 and the wheels, a
>>standard 4 speed auto box, but cannot decide upon transfer box.

>
>OK, here's the plan - not too cunning and a bit of a soft option...
>
>Standard ZF 4 speed box - ratios as per spreadsheet mentioned in reply
>to Tims post. Also standard Rangie transfer ratios - geared box so as
>to avoid chain stretch in Borg Warner. Essentially the unders of
>Grumble will be the same as when it was built, but upgraded Range
>Rover parts rather than older ones ;-)
>
>Now... Cross drilled input gears anyone? I'll assume that later
>boxes will already have them - when were they added?
>


Does the cross-drilled gear problem apply to the autos?

>Also, what's the score with the hanging in 1st gear problem associated
>with these boxes? Again, would a later box have overcome this?
>
>Initially - as this is an experiment and I want to limit my financial
>exposure, I'm going to go get a s/h box - if this works out alright,
>I'll put an Ashcroft box in next year. Otherwise it'll be back to the
>LT95... Hmm...
>


If it's OK I might buy it off you! Seems fair as I'm letting Warren
practice on yours before doing mine!

>Finally, Charlotte and I both - at the same time - last night
>mentioned to each other that we'd never (ever) driven an Automatic!


Do you want to practice in my Volvo? Mandy hadn't either, but it's
easy as pie. Tuck your left leg under for a few miles otherwise the
emergency stops can get tedious as you try to bang the clutch in.

Hardest bit is driving a manual again afterwards. I keep driving the
Merc 10 yards down the road on the starter motor....


--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'95 Discovery V8i aka "The Disco" (FOR SALE)
'03 Volvo V70

My Landies? http://www.seriesii.co.uk
Barcoding? http://www.bartec-systems.com
Tony Luckwill web archive at http://www.luckwill.com
 
On Fri, 30 Jul 2004 11:30:29 +0100, Mother <"@ {mother} @"@101fc.net>
wrote:

>On Thu, 29 Jul 2004 15:03:06 +0100, Tim Hobbs
><[email protected]> wrote:
>
>>You have mail. A spreadsheet that calculates road speed for given RPM
>>and gear ratios.

>
>Top notch - many thanks!
>
>I've modded it for a 101 (with credit) and placed it here in case
>anyone wants to play:
>
>http://www.101fc.net/files/gearratios.xls


A big improvement I'd say!



--

Tim Hobbs

'58 Series 2 88" aka "Stig"
'77 101FC Ambulance aka "Burrt"
'95 Discovery V8i aka "The Disco" (FOR SALE)
'03 Volvo V70

My Landies? http://www.seriesii.co.uk
Barcoding? http://www.bartec-systems.com
Tony Luckwill web archive at http://www.luckwill.com
 
In <[email protected]> Mother wrote:
> On Thu, 29 Jul 2004 12:59:51 +0100, I wrote:
> Now... Cross drilled input gears anyone? I'll assume that later
> boxes will already have them - when were they added?


I'm not certain this is an issue with the ZF, I've never known anyone
have a problem... certainly haven't done anything to any of mine.

> Also, what's the score with the hanging in 1st gear problem associated
> with these boxes? Again, would a later box have overcome this?


This is a problem with all the ZF boxes and is usually caused by the O
rings inside the governor housing. They are easy to replace/inspect with
the transfer box removed. Sometimes the governor itself gets scored and
cuts the O rings in which case a new governor will set you back about 30
quid. It takes about 10 minutes to fix once the xfer box is off.

> Initially - as this is an experiment and I want to limit my financial
> exposure, I'm going to go get a s/h box - if this works out alright,
> I'll put an Ashcroft box in next year. Otherwise it'll be back to the
> LT95... Hmm...


Check the oil colour in the box - a nice clear pink and all is well (
probably), a brown colour could mean trouble. If there is no oil in it
then pull the sump plug out and take a look. Brown sludge or lots of
metal on the magnet (built in to the plug) could mean trouble.

While I remember, if you get the ZF and the xfer box seperately, make
sure that you can get hold of a suitable output shaft. The ZF to BW
output shaft splines stop about half way down the shaft. The LT230 needs
full length splines.... Discos and early 4 speed classic RR were factory
fitted with LT230s.

Watch out for (maybe avoid) the electronic ZF version from later models
as you will need an ECU to control them. You can make your own
controller for them but it can be a bit of a pain, particularly the
speed control which uses a pulse width modulated input signal.

>
> Finally, Charlotte and I both - at the same time - last night
> mentioned to each other that we'd never (ever) driven an Automatic!


Go on, you know you want to :)

cheers

Dave W.
http://www.yorkshireoffroadclub.net/
 
In <[email protected]> Austin Shackles wrote:
> If you want to hunt an LT230-type setup, you're looking at an ex-disco
> one. I suspect the BW transfer box arrived at the same time as the ZF
> in the RRs, although I'm open to correction on that.


Yep, you're right, it does need correcting :)

There were some classic RR fitted with the LT230. The BW Xfre box wasn't
fitted until the 1989 model year. The ZF was fitted from 1986.

cheers

Dave W.
http://www.yorkshireoffroadclub.net/
 
On Fri, 30 Jul 2004 15:27:57 +0000 (UTC), Dave White
<[email protected]> wrote:

>In <[email protected]> Mother wrote:
>> On Thu, 29 Jul 2004 12:59:51 +0100, I wrote:
>> Now... Cross drilled input gears anyone? I'll assume that later
>> boxes will already have them - when were they added?

>
>I'm not certain this is an issue with the ZF, I've never known anyone
>have a problem... certainly haven't done anything to any of mine.


Smashing answer - feel a bit better now :)

>> Also, what's the score with the hanging in 1st gear problem associated
>> with these boxes? Again, would a later box have overcome this?

>
>This is a problem with all the ZF boxes and is usually caused by the O
>rings inside the governor housing. They are easy to replace/inspect with
>the transfer box removed. Sometimes the governor itself gets scored and
>cuts the O rings in which case a new governor will set you back about 30
>quid. It takes about 10 minutes to fix once the xfer box is off.


So it's probably worth doing this anyway, whilst out of the vehicle?

>> Initially - as this is an experiment and I want to limit my financial
>> exposure, I'm going to go get a s/h box - if this works out alright,
>> I'll put an Ashcroft box in next year. Otherwise it'll be back to the
>> LT95... Hmm...

>
>Check the oil colour in the box - a nice clear pink and all is well (
>probably), a brown colour could mean trouble. If there is no oil in it
>then pull the sump plug out and take a look. Brown sludge or lots of
>metal on the magnet (built in to the plug) could mean trouble.


Good idea. I'll mention this to Warren when he goes looking. I'll be
flushing and refilling anyway but a neb before buying is a very good
idea.

>While I remember, if you get the ZF and the xfer box seperately, make
>sure that you can get hold of a suitable output shaft. The ZF to BW
>output shaft splines stop about half way down the shaft. The LT230 needs
>full length splines.... Discos and early 4 speed classic RR were factory
>fitted with LT230s.


Ah, yes - came upon this somewhere else. I'm going to try and get a
complete gear and transfer box out of a Disco or Rangie (did they both
have the same transfer ratio?).

>> Finally, Charlotte and I both - at the same time - last night
>> mentioned to each other that we'd never (ever) driven an Automatic!

>
>Go on, you know you want to :)


Just have - albeit not very far. I can see two things happening;

1. My left foot will kick through the front of Grumble until I'm used
to not having a clutch.

2. My left leg will lose weight and wither away once I get used to
not having a clutch.

:)



--
Some Land Roveresque (101 biased), links available
from: http://links.solis.co.uk/Geek/X4_Land_Rover/
I also have a little Land Rover site biased toward
my beloved 101 "Grumble", at: http://www.101fc.net


Reading this in 'alt.fan.landrover'? Did you know
there's a group FAQ: http://www.aflfaq.dyndns.info
 
In <[email protected]> Mother wrote:

> Initially - as this is an experiment and I want to limit my financial
> exposure, I'm going to go get a s/h box - if this works out alright,
> I'll put an Ashcroft box in next year. Otherwise it'll be back to the
> LT95... Hmm...


Oh, and another thing :) I guess for the 101 you'll be creating your
own transfer box lever (a lot easier with the Borg Warner BTW !). But if
you are thinking of utilising an LT230 lever assembly make sure you get
the mounting plate for the auto box.

On some manual boxes the xfer lever bolts onto the top of the gearbox
directly. On a ZF you need a mounting plate and these cost around 60
quid new so best to get one with the ZF if you can.

cheers

Dave W.
http://www.yorkshireoffroadclub.net/
 
In <[email protected]> Mother wrote:
> On Fri, 30 Jul 2004 15:27:57 +0000 (UTC), Dave White
> <[email protected]> wrote:
>>This is a problem with all the ZF boxes and is usually caused by the O
>>rings inside the governor housing. They are easy to replace/inspect
>>with the transfer box removed. Sometimes the governor itself gets
>>scored and cuts the O rings in which case a new governor will set you
>>back about 30 quid. It takes about 10 minutes to fix once the xfer
>>box is off.

>
> So it's probably worth doing this anyway, whilst out of the vehicle?


Definately worth a quick look. While you're in there, check the parking
pawl as well (the governor is actually bolted to the disk the pawl
locates into.

> Ah, yes - came upon this somewhere else. I'm going to try and get a
> complete gear and transfer box out of a Disco or Rangie (did they both
> have the same transfer ratio?).


Yes, they both used 1.222, only the Defender used 1.4 and 1.6 AFAIK.

LT230's that came from the back of a 3 speed RR auto are almost 1:1
ratio BTW.

> 1. My left foot will kick through the front of Grumble until I'm used
> to not having a clutch.
>
> 2. My left leg will lose weight and wither away once I get used to
> not having a clutch.


REAL auto drivers use left foot braking, essential when you need to get
away from the lights fast or your engine tickover isn't what it ought to
be. It can also be used for high speed cornering and to allow a quick
exit from a slow corner. All this is going to be relative with Grumble
though :)

cheers

Dave W.
http://www.yorkshireoffroadclub.net/
 
<[email protected]> wrote in message
news:[email protected]...
> On Fri, 30 Jul 2004 11:28:07 +0100, Mother <"@ {mother} @"@101fc.net>
> wrote:
>
> >
> >BTW, the wheels are 38.5 (not 28.5 - that was my typo). I was using
> >the 70mph @ 1,500 RPM as a demonstration - not what I'd get - as
> >that'd be very scary! :)

>
> Do you remember that Rolls Royce engined special that RR cars insisted
> not be called a RR or have a flying lady, built by someone called
> Dodd?
>
> Geared at 100mph per 1000rpm and rev limited at 2900rpm!
>
> AJH
>


I remember, from years and years ago, reading about a guy who had installed
a Spitfire engine into his car (the V-12 aeroplane Spitfire, not the piffly
little Triumph 1500cc Briggs & Stratton affair) - had to use a lorry clutch
as I recall, but it was good for about mach 17 at 2200 rpm apparently.
Possibly the car you're referring to? It might have been one of those
drag-racers now I think about it.

Hmmm. I wonder if I could squeeze the engine from one of Her Majesty's
warships into my S-IIa....... ;)

Steve


 
I remember this one. The engine, although originally designed for the
Spitfire, was actually out of an Air Sea Rescue launch. The owner was an
insurance broker. The whole issue came to light when a polite letter was
received by Rolls Royce asking that they not road test their new models on
the German autobahn as the high speeds were causing the traffic monitoring
equipment (some sort of measure of density I think) to fail

Alan


> Do you remember that Rolls Royce engined special that RR cars insisted
> not be called a RR or have a flying lady, built by someone called
> Dodd?
>
> Geared at 100mph per 1000rpm and rev limited at 2900rpm!
>
> AJH
>



 
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