Well, I’ve finally got the Mark V running like it should. I’ve got
about 300 miles on the rebuilt engine, and am still breaking it in. I
did notice that the gearing is all wrong for this area. First gear is a
stump puller, and I rarely use it except on very steep hills. Second
gear start-up works fine without hardly any wearing and slipping of the
clutch. Similarly, fourth gear is way to low to maintain a comfortable
60-65 mph. Third gear is also too low for the hills of New England. On
back country roads I find I am either screaming in third or lugging in
fourth up the hills, usually with a line of cars behind me.
The answer is simple, put higher gearing in the rear end. First gear
would become usable, third would climb hills at 50, and fourth would be
suited to the highway, all without excessive revs. My question to the
list is, has anybody done it and if so, where did you find the gears,
how did you do it and how did it work out?
In reply to a message from jagmkv@aol.com sent Mon 24 Oct 2005:
Craig,
Firstly does the car have an ENV or a Salibury rear end?
And is it a 2 1/2 or 3 1/2 litre?
Could it be a 3 1/2 that has had a 2 1/2 diff inserted? or V V.
I would say that my Mk4 3 1/2, while it would be nice with a
slightly higher ratio, seems not to have a lot of problems on hills.
Mk5’s of course with 16’’ wheels have a lower overall ratio.
I’ve always felt a Mk5 would improved in appearance by 18’’ wires
but on a more pratical level…assuming the car has a 4.27 diff
already…
Salisbury CW&P’s were also listed as an optional 4.07 ratio for
Mk7;'s but I think these may be very hard to find.
3.77 ratios were used in XK120’s and the CW&P’s are a bolt-in
changeover. If it has an ENV diff the same ratio is available from
XK 120’s in ENV.Probably from overdrive FHC’s.
I don’t know how these would go with hills. They may be an
advantage for highway driving.
If it’s a 2 1/2 engine , then the 4.27 from a 3 1/2 may help.
A friend has a ‘3 litre’ Mk4 that has had a 3.54 diff grafted in,
and on the week end told me that while this while good on the
highway is leisurely in acceleration.
The alternative is a dyno tune to make sure that the car is giving
the best performance with the existing ratio. And probably cheaper
and certainly less work.–
Ed Nantes SS
Melbourne, Australia
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In reply to a message from @JagMkV sent Mon 24 Oct 2005:
Ed, thanks for the reply. My car is a 1950 3.5 liter car. It has
about 300 miles on a completely rebuilt engine. I have the carbs
set perfectly, but have not yet tweaked the timing (it’s set at the
factory default). On typical northwestern Connecticut hills,
fourth just doesn’t quite have the pull to get the car and two
passengers up them. Like I said, in third gear I have to run at
quite high revs to maintain speed. To answer your question about
the type of rear end, I don’t have an answer. Next time I have it
on a lift, I can check. Where is the ID located?
Craig Carragan–
Craig Carragan
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Craig,
The ENV axle has bolts around the front so the front casting drops out; on
the back it is just a smooth dome, no bolts.
The Salisbury has bolts on the back and the back cover plate comes off, no
bolts on the front.
There are pictures of both in the manual. There should be a metal tag
attached on one of the bolts with two numbers, which are the number of teeth
in the ring and pinion gears; divide the high number over the low number to
get the ratio.
Frankly I was surprised to read your original question because my Mark V
with Salisbury 4:27 never struck me as having a poor ratio, though around
Chicago we don’t have a lot of what you would call hills. Its not exactly
hot off the line but I’ve hit an indicated 90 mph. Maybe I’ve just gotten
used to shifting down for hills so I don’t think about it. Automatics do it
and we aren’t even aware of it.
Anyway, if you really need a different ratio, I believe Jeeps also used
Salisbury axles so there may be a lot to choose from.
Rob Reilly - 627933>On typical northwestern Connecticut hills,
fourth just doesn’t quite have the pull to get the car and two
passengers up them. Like I said, in third gear I have to run at
quite high revs to maintain speed. To answer your question about
the type of rear end, I don’t have an answer. Next time I have it
on a lift, I can check. Where is the ID located?
Craig Carragan
Craig,
I agree that the 3.5 litre Mark IVs and Vs are undergeared with the standard
gearing. However, I am very surprised that you say yours won’t go up hills
in top gear. How steep are the hills? The 3.5 engine has so much torque
that you should be able to drive almost everywhere in top gear, including
climbing quite serious gradients.
On the subject of gearing, you are looking at changing the axle ratio to get
higher gears. The other way of doing it, which is now quite common in the
UK, is to fit a 5-speed gearbox. The gearbox from a Ford Sierra (I don’t
know if there is a US equivalent) fits with no modification to the chassis,
but it does require a different propshaft. With this box, you get about
24mph per 1000rpm in 5th, which gives much more relaxed cruising. You also
get the advantage of a very slick all-synchro box. On my own 3.5 litre SS
saloon I have fitted a Jaguar all-synchro box with overdrive, which has an
even higher ratio. I did about 200 miles in it today, and a fair bit of
that was on a motorway doing 70mph at 2700rpm. It really transforms the car
(and it goes up hills in overdrive!)
Denis Foxley
In reply to a message from jagmkv@aol.com sent Mon 24 Oct 2005:
Craig:
I have a 1 1/2 liter MK IV and live in the Blue Ridge Mountains of
Virginia. When I bought my car I took it for a drive and did not
think I would be able to get back home. I had to go down to second
gear to pull the mountain.
I adjusted the valves, which were way out of adjustment, and now
the car pulls the mountain in third with no problem. She will even
take the mountain highway roads in fourth gear at 50 mph.
With your newly rebuilt engine and only 300 miles you will probably
soon be re-torquing the head. The valves should be adjusted at
that time too. Your 3 1/2 liter should pull the hills with ease.
In reply to a message from Denis Foxley sent Thu 27 Oct 2005:
Denis:
I just read your reply to Craig Carragan regarding the Ford Sierra
transmission. I am a little familiar with that tranny as the
restoration shop where I work part time has put a number of them in
MGB’s. It truely is a sweet transmission.
I have a 1946 1 1/2 liter MK IV. I would like to make the car more
driveable on the highway by reducing the rpm’s. Do you know if the
Sierra tranny will fit into the 1 1/2 liter car too? What
modifications are needed to bolt it up to the engine?
I have a 1946 1 1/2 liter MK IV. I would like to make the car more
driveable on the highway by reducing the rpm’s. Do you know if the
Sierra tranny will fit into the 1 1/2 liter car too? What
modifications are needed to bolt it up to the engine?
Hi Bob,
I would think that it would be the same work to fit the box to a 1� as to a
2� or 3� litre. However, I don’t know if the mounting holes for the
bellhousing or the diameter of the spigott for the first motion shaft are
the same in the 1.5. You will need a new propshaft, as the Ford box has a
sliding spline fit, not a flange. As to the details of the conversion, mine
was already done when I bought the car, so I don’t know exactly what is
involved. I do know that it is entirely reversible and no structural
changes are made to the car.
It’s possible that a Triumph box with overdrive might be an easier fit for
the 1.5, but again I do not have any details of what work would be involved.
Denis Foxley
In reply to a message from Denis Foxley sent Mon 14 Nov 2005:
I am told that a new longer spiggot bearing is needed for Toyota
boxes as the input shaft is shorter.
At least on 2 1/2 and 3 1/2 's.–
The original message included these comments:
bellhousing or the diameter of the spigott for the first motion shaft are
the same in the 1.5. You will need a new propshaft, as the Ford box has a
What type of Jaguar all-synchro box with what type / series of overdrive did you fit? Did you have to make any modifications to make it fit to the 3.5 litre engine and drive train?
Studebakers and Willys used Salisbury rear ends, albeit having the same name on the plate does not equal all details are interchangeable.
Maybe 300 miles is not quite enough to get comfortable with the gearing? My Mark V experience (all in Southern California) starting from 1972 has been a comfortable one in terms of gear ratios in the drivetrain. First gear is a stump puller, Jaguar advised that 2nd was fine for starting from stop on level. Fourth is pretty flexible for use over a wide range of speeds, including comfortable at 60 or even 65. 125 horsepower is adequate but not exciting.
If the gearing seems inadequate for hilly terrain you experience, perhaps a check on fuel mixture and feed is appropriate. A proper air/fuel mix at idle does not imply correct mix under load or higher rpm. Needle function at speed is not finished when doing jet adjustment. Inadequate fuel supply at speed due to a slightly clogged filter is another possibility.
Also, a full check of the distributor advance curve over full operating conditions is warranted. Distributor advance may deviate from specification under load and higher rpm while being just fine typical garage testing conditions. Distributor advance parts can be wrong for the application or worn out.
These are just some much easier issues to address before possibly changing differential gearing, prop shafts, or trannies. Good luck on finding a pleasant outcome.