I wonder if there is a definitive and accurate list of all
ratios used for the XK 140 Moss box ? I have recently
bought a 1956 car—originally sold to New York in LHD form
but now converted to RHD—which currently has a Getrag 5
speed box fitted. I actually do not like this and am
thinking of re-converting back to Moss and perhaps adding
an overdrive. I have the original box (good condition) with
a load of spares but it is only 4 speed—Number: JL 35925
CR which according to a previous post tabulating all types
should have 2.980, 1.740, 1.210, 1. However, I have
measured the ratios on the bench which turn out to be 3.53,
1.92, 1.34, 1 which is most confusing. Were gearboxes sent
to USA different or is the list inaccurate please ?–
Leofrik
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Leofrik,
There are no secrets with Gear Ratios for XK era Gearboxes’, whether made by
Moss or made by Jaguar, and the Gearbox Serial Number tells you what was
ORIGINALLY fitted within.
OSLxxxxB (Moss made) and JLxxxx (Jaguar made) gearboxes are considered
‘standard ratios’ and are:- 3.375, 1.982, 1.367 and 1.000 (use 26 and 39
tooth Constant Gears.)
JLxxxxCR are ‘close ratio’ as per the suffix, and have:- 2.980, 1.740,
1.210 and 1.000. (use 28 and 37 tooth constant gears)
JLExxxx denotes ‘Overdrive is fitted’ but ratios of gearbox are unchanged
A later JLSxxxxJS has slightly changed 3.378, 1.860, 1.283 and 1.000. (use
27 and 38 tooth constant gears)
The number of teeth on the gears remains constant for all Moss and Jaguar
Gearboxes - count them
The difference is with the number of teeth on the CONSTANT GEARS as shown
above, which must be fitted/interchangeable as a matched pair.
There are of course other differences, but nothing that impacts on your
question regarding ratios.
If your JL35929CR has much wider ratios, 3.53, 1.92, 1.34 and 1.00, then
either you have counted/calculated incorrectly, or at some time past in
Gearbox history it may have been rebuilt with custom ‘Constant gears’ , do
the arithmetic (maths).
Moss gearboxes were made for customers other than Jaguar and could well have
had different constant-gears, certainly your 3.53:1 first gear is a real
stump-puller.
But a JL prefix gearbox is Jaguar made, but no rules that stop non-Jaguar
Moss gears being sourced and fitted at some time in past 50 years.
Roger Payne
XK140MC OTS; 4.2E OTS; DaimlerSV8
Canberra, Australia
.-----Original Message-----
From: owner-xk@jag-lovers.org [mailto:owner-xk@jag-lovers.org] On Behalf Of
Leofrik
Sent: Saturday, 23 May 2015 8:15 PM
To: xk@jag-lovers.org
Subject: [xk] Moss gear ratios.
I wonder if there is a definitive and accurate list of all ratios used for
the XK 140 Moss box ? I have recently bought a 1956 car—originally sold to
New York in LHD form but now converted to RHD—which currently has a Getrag
5 speed box fitted. I actually do not like this and am thinking of
re-converting back to Moss and perhaps adding an overdrive. I have the
original box (good condition) with a load of spares but it is only 4
speed—Number: JL 35925 CR which according to a previous post tabulating
all types should have 2.980, 1.740, 1.210, 1. However, I have measured the
ratios on the bench which turn out to be 3.53, 1.92, 1.34, 1 which is most
confusing. Were gearboxes sent to USA different or is the list inaccurate
please ?
Leofrik
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Roger Payne sent Sat 23 May 2015:
http://www.jag-lovers.org/xk-lovers/library/gear_ratios.html
http://www.jag-lovers.org/xk-lovers/library/gearbox_reilly/moss_gearbox_identification.html
http://www.jag-lovers.org/xk-lovers/library.html#Gearbox--
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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Leo,
Are you in you in the UK? As it happens, I am looking for a close ratio non-od box for an SS. There are two numbers on the boxes one on the cast Iron case and another on the ali top. They should both be the same. It would be interesting to know if they are on yours. It doesn’t sound like a CR box.
You might be interested to know that the UK JDC XK Register, in conjunction with JLR Heritage, have just done a test of four different five speed boxes and a Moss OD box at the JLR Fen End testing facility. The results were rather surprising. I won’t steal the Register’s thunder by revealing the results prematurely but I can tell you that the Moss came last.
Roger L
I wonder if there is a definitive and accurate list of all
ratios used for the XK 140 Moss box ? I have recently
bought a 1956 car—originally sold to New York in LHD form
but now converted to RHD—which currently has a Getrag 5
speed box fitted. I actually do not like this and am
thinking of re-converting back to Moss and perhaps adding
an overdrive. I have the original box (good condition) with
a load of spares but it is only 4 speed—Number: JL 35925
CR which according to a previous post tabulating all types
should have 2.980, 1.740, 1.210, 1. However, I have
measured the ratios on the bench which turn out to be 3.53,
1.92, 1.34, 1 which is most confusing. Were gearboxes sent
to USA different or is the list inaccurate please ?–
Leofrik
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Leo,
A few inconsistencies with your question?
You say you are looking for a ‘Moss Box’ for your SS, then you ask about XK140 ‘Moss’ Gearbox ratios?
What is generically called a ‘Moss Gearbox’ is not necessarily the same in the SS period of the 1930/40s, nor the same as used post-war in XK140 and all other Jaguar sports/sedans fitted with a ‘Moss Box’
Indeed the ‘Moss’ box was a Moss Gears Design initially made by Moss and supplied to SS and post-war Jaguars, but this was quickly subsumed by Jaguar made gearboxes of the same ‘Moss design’ but then evolved to Jaguars own improvements/changes.
So what exactly do you want to do?
Fit a post-war Jaguar Made XK140 gearbox into an SS that was originally fitted with a Moss made/supplied gearbox?
There is a lot involved in doing that, but it is a common modification, but I think more easily done by sourcing an immediate post-war Mark IV ‘Moss Gearbox’, with more and more things to consider depending on origin of Gerabox you want to fit.
I am sure Ed Nantes can add first-hand-experience re what works easily and what doesn’t.
For a start - an SS Gearbox had DOUBLE-HELICAL GEARS.
A post-war Moss made or Jaguar made ‘Moss Gearbox’ has SINGLE-HELICAL GEARS, and you cannot mix and match if you goal is to fit a close-ratio gearbox.
By the way, the sole difference in a standard-ratio gearbox and a close-ratio gearbox, all else being the same - is the pair-of-CONSTANT-gears.
Indeed there is a 1950s SERVICE BULLETIN that tells XK120 owners if they want to change their ‘standard gearbox’ to a ‘close-ratio gearbox’ then they need to purchase by part number, the two CONSTANT-GEARS (close ratio) and exchange them for the existing pair of standard-ratio CONSTANT GEARS, but the advice after doing that was to then stamp in a CR suffix at end of the Gearbox Number, so the gearbox was now identified as being ‘Close Ratio’.
Later Gearboxes (as in XK140 era) were identified by Gearbox Number with the CR already stamped if ex-factory Close-Ratio, and no suffix if ex-factory with standard gears, but it gets more complex later on.
So bottom line is WHAT EXACTLY are you trying to do.
And remember, any gearbox you are looking at buying/have can be fully identified by its FULL gearbox number.
Roger
Roger Payne
XK140MC OTS; 4.2E OTS; DaimlerSV8
Canberra, Australia
.-----Original Message-----
From: owner-xk@jag-lovers.org [mailto:owner-xk@jag-lovers.org] On Behalf Of R LEARMONTH
Sent: Wednesday, 3 June 2015 7:35 AM
To: xk@jag-lovers.org
Subject: Re: [xk] Moss gear ratios.
Leo,
Are you in you in the UK? As it happens, I am looking for a close ratio non-od box for an SS. There are two numbers on the boxes one on the cast Iron case and another on the ali top. They should both be the same. It would be interesting to know if they are on yours. It doesn’t sound like a CR box.
You might be interested to know that the UK JDC XK Register, in conjunction with JLR Heritage, have just done a test of four different five speed boxes and a Moss OD box at the JLR Fen End testing facility. The results were rather surprising. I won’t steal the Register’s thunder by revealing the results prematurely but I can tell you that the Moss came last.
Roger L
I wonder if there is a definitive and accurate list of all ratios used for the XK 140 Moss box ? I have recently bought a 1956 car—originally sold to New York in LHD form but now converted to RHD—which currently has a Getrag 5 speed box fitted. I actually do not like this and am thinking of re-converting back to Moss and perhaps adding an overdrive. I have the original box (good condition) with a load of spares but it is only 4 speed—Number: JL 35925 CR which according to a previous post tabulating all types should have 2.980, 1.740, 1.210, 1. However, I have measured the ratios on the bench which turn out to be 3.53, 1.92, 1.34, 1 which is most confusing. Were gearboxes sent to USA different or is the list inaccurate please ?
Leofrik
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Roger Payne sent Tue 2 Jun 2015:
Roger, I missed the post but ‘‘later moss boxes in SS’’
xK typeboxes will generally interchange the whole box with
an SS.
That being said , all these boxes have either a short
extension or a long rear extention.
SS 1 and SS 100 had the short extension ,I’d guess on the
100 because the shorter wheelbase meant the shoter gear
box meant less of. A change of angle on the universals.
So a Late Mk 7 or XK140 box is a reasonably easy swap .
The main difference is the speedo cable exits at a
different angle. The SS has it coming directly up through
the gesr box cover.
It’s generally considered that the post war single
helical boxes are stronger… One could probably put the
post war internals into an SS box , but they look
virtually identical externally so it’shardly worth the
effort.
The SS boxes had a nicer ball joint gear change top, which
was nice and notchy and sporting.
But the whole top will interchane on boxes from about
1936.–
The original message included these comments:
What is generically called a ‘Moss Gearbox’ is not necessarily the same in the SS period of the 1930/40s, nor the same as used post-war in XK140 and all other Jaguar sports/sedans fitted with a ‘Moss Box’
Indeed the ‘Moss’ box was a Moss Gears Design initially made by Moss and supplied to SS and post-war Jaguars, but this was quickly subsumed by Jaguar made gearboxes of the same ‘Moss design’ but then evolved to Jaguars own improvements/changes.
So what exactly do you want to do?
Fit a post-war Jaguar Made XK140 gearbox into an SS that was originally fitted with a Moss made/supplied gearbox?
There is a lot involved in doing that, but it is a common modification, but I think more easily done by sourcing an immediate post-war Mark IV ‘Moss Gearbox’, with more and more things to consider depending on origin of Gerabox you want to fit.
I am sure Ed Nantes can add first-hand-experience re what works easily and what doesn’t.
–
Ed Nantes SS
Melbourne, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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