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On the pre 72 “Ford 3 litre” Marcos, by far the best mod you can carry out is to
alter the gearing, this being totally wrong for the engine installed, and not really
tough enough if the car is used to its full capability. An engine whose power is
starting to tail off at 4750 rpm needs far higher gearing for the road. |
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Volvo 3 litre models benefited from correct gearing, Ford motor company having introduced
the 3 litre Capri “heavy duty” axle, and now making it available to the likes of
Marcos, Volvo also gave the gearbox well spaced ratio’s unlike the MK4 Ford Zodiac
box which had 2nd not very well spaced between 1st & 3rd. |
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The benefits of this axle were obviously its strength, but more importantly raising
the gearing to 3.22-1 from the 3.77-1 in the original Cortina/Corsair axle, and
incorporating an increase in brake shoe width from 1.75” to 2.25”, with a brake
cylinder reduction in diameter from .75” to .70” to maintain brake balance between
front and rear. (Marcos/Triumph Vitesse/GT6 front brakes were similar in size to
the Capri already). |
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The original axle can have the diff fitted from Corsair 2000E (if you can find one)
or Escort RS 2000 raising the gearing to 3.54-1, which is a slight improvement,
(but no stronger). |
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This was the first modification I tried on my car, fine while the overdrive is working!
But hopeless when it doesn’t as it's still the “Top gear”, and not an overdrive!
It still also does nothing for the worst part of the gearing 1st & 2nd), great
for destroying the tyres, (you needed 3rd gear for 60mph!!) no need to wonder why the Volvo was quicker to 60 then! (Achieved in 2nd). |
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Tyre aspect ratio’s have also changed since the cars were new from 80% of tyre width
to 70%, when you do the maths it’s a surprise what a difference this makes alone.
To maintain original gearing you really need to change to 14” wheels with 185/70
or 195/65 tyres! |
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The next mod I tried was altering the gearbox ratios, by obtaining a “3 rail” Mk11/111
Capri / Mk1 Granada “3 litre type E”, 4 speed box. When stripped this will allow
you to use the complete lay gear and 2nd gear from the main shaft, and fit them
in the Zodiac / Overdrive box changing the ratio’s from: |
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While the 3 rail box is stripped you can also use any gears & syncros / shafts
& bearings that are worn, plus you could change the selector forks which are
steel in the 3 rail but bronze in the zodiac. |
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This has made 60 mph achievable at 6000rpm in 2nd with 185/70/13 tyres and 3.54
diff ratio instead of 53 mph, gearing was now far better spaced but overall still
not good enough, I had to “bite the bullet” and go for Mk 1 “3 Litre” Capri axle,
with 3.22-1 ratio.
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The original axle is a 48” casing and drum face to face 52”. The new axle is a 50”
casing, and 54”drum face to face, therefore an inch extra width each side, which
didn’t seem excessive at the time, so with new plasma cut “Marcos” brackets welded
on it was fitted to the car, the gearing was transformed and exactly what the car
needed, 66mph at 6000rpm in 2nd gear, a gain of 13mph from where I’d started!! |
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With the new set up the car was much better to drive, but my satisfaction was about
to come back to earth with a bump!! I had 7x13 Wolfrace type wheels with 185 tyres
stretched on and the car looked ok, but I wanted my “Marcos alloys” on the car.
I was doing concours competitions and these were the correct wheels which I loved
on the car, (what other manufacturer at the time had their own wheels produced!!) |
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From behind the car looked utterly ridiculous, I was absolutely gutted, it looked
like the body shop had not talked to the chassis dept when designing the car, surely
no one would seriously produce a car like that? Marcos perhaps had seen this when
they fitted the Volvo 3 litre with “Cosmic alloys” correcting the back, but leaving
the front like it was fitted with “space saver” spares!, but at least you could
space them out if you wanted to. |
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My car looked so horrible, and not wanting under any circumstances to fit add on
wheel arches I took the axle off and sold it, and refitted the original axle with
a 3.54 limited slip diff to strengthen it.
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All was ok for a while until the overdrive packed up again, was rebuilt, and packed
up yet again AAAARGH!!!! |
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The gearbox was exchanged for a 4 speed 3 rail with the lever fitted at 180 degrees
(perfect fit and gear change, and will take 300bhp). The type N “5 speed” Mk11 Granada
/Injection Capri could be adapted to fit but was weak, with 1st gear easily stripped
and so gradually I got fed up with the gearing, and the car got left for 10 years!! |
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I had purchased a new Mantis and after driving it for a while I questioned myself
like a number of us who’ve kept the old and bought the new “do I still want the
old banger in the garage”!! |
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Looking at the poor old thing it did look sorry for itself. I realised how much
I had neglected it and how much work it required, I heaved the drivers door open,
chased the spiders out, and sat in the seat remembering the good times we’d had
together, as I sat there I was astonished how much more room the Mantis had inside!
I could not move my legs, and my knees hit the tripometer extension & pedal
adjuster wheel, I thought, “how on earth did I drive this”! (You’ll do anything
with rose tinted specs on!!) |
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The cars seemed the same inside; in fact the Mantis should have less room with its
higher seats!! I was confused?? |
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The 3 litre, I decided had to go, but by the morning I’d changed my mind. I’ve owned
it 20 years and although not worth much now it would still be a wrench, another
look at the car, and then it dawned on me “it was the steering column that was so
much lower”!! |
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Out came the dash, up went the column, and bingo!! Someone could sit on my lap now!! |
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The trouble was I’d never really bothered, you’ll put up with anything as long as
it looks good!! I’d never really considered basic engineering solutions, that’s
it!!! the old girl is staying whatever work is needed. The work now underway “to
make the car enjoyable!!!” |
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The car had to have the Capri axle ratio but now with 3.09-1 that came with the
Mk11 onwards and I would stick with the 4 speed for now. Talking to people about
the width problem I was introduced to the world of “Ford rallye sport” who had manufactured
the “Narrow Atlas” axle, also known as “baby atlas”. This was a Capri axle strengthened
and shortened, now only available second hand, but you could build one yourself
using any Capri axle, and “Quaife Engineering” half shafts cut to the required lengths.
These are beautifully made in two pieces, with separate flange & shaft all stronger
than standard. |
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I obtained a Capri Mk1 axle from fellow member, Dave Parslow who was advertising
parts for sale, very useful with Marcos brackets already fitted and should be a
straight swap once shortened. |
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I took the axle to Gartrac Engineering in Surrey; they have been involved in rally
cars for years and still shorten Capri / Atlas axles for Mk1/11 Escorts which are
still very popular in club rallying. (When the work is completed, you simply cannot
tell.) |
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They agreed to shorten my axle to “Cortina width” at 48” and put different ends
on to accept the larger wheel bearings, (introduced in late 74 with the Mk11 Capri)
and supply cut down Quaife half shafts with blank flanges drilled to Triumph p.c.d.
(usually supplied drilled Ford pcd), the shafts are supplied with longer splines
at the diff end so when cut, enable any length to be chosen; shot blasting the axle
for ten quid was a bargain. They also supplied a new diff cover that had rusted
through, and a rear cover clamp, a very useful half moon shaped piece of metal ¼”
thick bolted over the diff cover to ensure that when the car is raised on a trolley
jack the diff doesn’t drip oil because you have distorted the cover. (In rallying,
when the car grounds.) |
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The only mistake made was the brakes, no one had realised there was a different
offset depending on which bearing is fitted, (because most people go for disc brakes).
Although I had a 48”axle casing I now had 52.5” once the half shafts were fitted
which has left it similar to the early Marcos 3 litre “Salisbury” axle which was
fitted to wooden chassis and early steel up to “H” reg , (can’t find anything written
on this axle, can the gearing be uprated ? - I believe parts are scarce?) |
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I had to use the original Cortina brakes and back plate with the Capri drums. This
allowed the 6m/m extra each side to be taken up i.e. 1.75” shoe in a 2.25” drum,
not perfect but will have to do till the car is on the road and perhaps I can obtain
the later brakes. So, if you wish to go down this route stick with small bearing/floating
brake cylinder, large bearing/fixed brake cylinder, but bear in mind small bearing/floating
cyl axles are now very rare with all brake parts unavailable from Fords. The wide
axle can be picked up for peanuts, although 2.8 lsd axles are now harder to find.
There were a few large bearing/floating brake cyl wide atlas axles from pre Dec
74 Mk 11 Capri’s (rare). |
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The wider large bearing/fixed brake cyl axle 52” casing 56.5” drum face to face
from 74 onwards was the reason Marcos widened the Mantula with wheel arches, the
2.8 injection axle being available new. All wide axles had 3.09-1 diffs, the narrower
axle came with a 3.22-1 (unless they’ve been modified). |
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The axle now is always referred to as the Atlas (although strictly not true) but
everyone knows what you mean by this term i.e. narrow atlas & wide atlas, it
is also usually described in casing width i.e. 50” 52” etc. (minus shafts) the differential
is removed from the back. (Shorten 52” casing to 47.5” with this axle, 52” when
shafts installed). The original axle is known as the “English axle”, also described
in casing width. |
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With the differential removed from the front in its own housing, fitting up in the
car was easy, every thing bolting back in the same place. Shot blasting was also
vital as I could now see cracks around the panhard rod locating bolt, this was renewed
and strengthened, (lose this, you’ll lose your car!!) |
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At last the car had the correct gearing and looked good!! (i.e. you’d never know).
Some cars will need the prop shaft flange changing but mine was the same. |
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For those wanting to up rate the “English axle” you can renew the diff side gears
from 22 spline standard to 16 spline Atlas gears and then use the “Quaife” atlas
16 spline half shafts cut to length. With a steel limited slip diff (lsd) fitted,
this would be a strong axle but the crown wheel and pinion would be the weak point,
speak to Gartrac. |
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For those wishing to uprate an “Atlas axle” (really for competition use) this time
you change the 16 spline side gears for 18 spline “Quaife Atlas”gears, this then
allows you to fit the larger Quaife 18 spline half shafts. With this set up you
can go to fully floating shafts, vented discs etc and you can spend £3000!!, for
an all bells & whistles axle capable of 500 bhp plus!!!
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This article has been written with the steel chassis in mind, but the “Atlas” can
be fitted to the wooden chassis cars with some wood work (Mike McCullough 3 litre
wood chassis). You should take some advice on strengthening where you have to relieve
the wood, perhaps from Rory at Marcos Heritage or maybe Richard Falconer (in club
directory) seems to be an expert in all things wooden, I’m sure its fairly straight
forward once you know what to do. |
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I would urge anyone with wood chassis car to go for a shortened axle and avoid wheel
arches, apart from the 1800’s you have the most valuable / desirable cars. In the
seventies / eighties it was fashionable to adorn the cars with deep offset wheels
and arches (mine included!!) but today the cars are proper classics and should now
be treated as like. |
COSTS
Atlas 16 spline shafts £90.00 each
Flange £62.00 each
Shaft bearing/plate £26.00 each
Shorten axle casing £160 total. (To any length)
Back cover plates £30.00 pair. (Strengtheners)
All plus vat
Atlas “new” back cover available from Marcos Heritage |
Telephone Nos
Gartrac Ltd 01428 682263/4 fax 01428 682265 Very helpful company; will
give you all sorts of advice
Quaife Engineering Ltd 01732 741144 Very busy!! Company; long wait if out of stock
but produce amazing kit for major car Manufacturers |
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Phil Ward |
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Anybody needing further advice just give me a ring. |