My car has the 3.54 US spec diff, it’s a 4.2 and has been
converted to 3 x SUs. I’m always searching for a non
existant 5th gear cos it’s presently like my Healey was when
the OD didn’t work. I want to change the diff but what is
the concensus as to the best ratio to go with, 3.07 as per
Europe spec or a 2.88 from an XJS? I have a 3.07 LSD already
but am undecided whether to put that in or go all the way
and find a 2.88:1.
Any and all experience and advice welcome.
In reply to a message from riv944 sent Tue 16 Jul 2013:
The 3.07 is the best allround compromise, but it will pull a
2.88 without any difficulty provided it has a KE or KJ series
gearbox . The one thing to avoid is putting a 2.88 on a car
with the close ratio EJ series box, which makes 1st and 2nd
gears uncomfortably high with maxima of over 50 mph and 80
mph respectively . This can make hill starts produce quite a
nasty smell of overheating clutch linings . Since you have a
3.07 to hand, I would go for that–
christopher storey
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from riv944 sent Tue 16 Jul 2013:
You won’t be disappointed if you go with the 3.07. I changed out
my 3.54 to a 3.31 and am very happy with it, figure a 3.07 would be
even better.–
The original message included these comments:
the OD didn’t work. I want to change the diff but what is
the concensus as to the best ratio to go with, 3.07 as per
Europe spec or a 2.88 from an XJS? I have a 3.07 LSD already
but am undecided whether to put that in or go all the way
and find a 2.88:1.
Any and all experience and advice welcome.
–
Jack Terrick 66 FHC
Greensburg, PA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from riv944 sent Tue 16 Jul 2013:
Hi Ian
I have a 4.2 series 2 with triple SUs, and I swapped my 3.54 for an
XJS 2.88.
First gear is a tad tall, but overall I’m happy. I would think that
a 3.07 would be ideal, especially if you have one on hand.
cheers
Doug–
69 E type FHC 1R25901, 91 Miata Turbo, Locost 7,
Edmonton, Alberta, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from riv944 sent Tue 16 Jul 2013:
I put a 3:07 in my Series 1, and I have a friend with a 2:88
in his Series 11. We took a 3000 mile trip together 2 years
ago, and his mileage was about 1 to 2 MPG better than mine.
We opened them up on the highway to see how the acceleration
differed, and after 8 to 10 seconds he was just a dot in my
rear view mirror. I would go with the 3:07. Comfortable
highway cruising, and sufficient acceleration. JMTCW.
Joel–
ex jag, '66 E-type S1 4.2, '56 XK140dhc, '97 XJ-6
Denison, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from riv944 sent Tue 16 Jul 2013:
Ian, the XK engine is so torquey I look for a fifth with a 3.07. I
can let the clutch out at idle in first w/o stalling (or excessive
slippage). It can easily handle a 2.88 if you have a first gear
ratio that you can live with.
I think your decision should be based on what Christopher said, as
well as your intended use, AND the tires you plan to use.
I am using modern (lower circumference) 65 tires and wind up with
an effective 3.3 ratio with a 3.07 rear gear. This compared to a
stock 75 series tire. Its a nice combo but the car can pull more
gear easily. If I was doing more highway, my tire combo with 2.88
would be ideal.
My 2 cents.
Dave–
1969 BRG OTS
Skaneateles, NY, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from riv944 sent Tue 16 Jul 2013:
A note: (warning, I am a dyed-in-the-wool 3.54 and Moss box fan!)
Your acceleration will be significantly less with a 3.07 based on
my experience driving E-Types. I could seriously feel the
difference from my car (stock) to a 3.31 '64 FHC I drove a long
distance recently. I guess the 3.07 was the target for the car
originally though. I like the acceleration, myself.
Jerry–
The original message included these comments:
My car has the 3.54 US spec diff, it’s a 4.2 and has been
converted to 3 x SUs. I’m always searching for a non
existant 5th gear cos it’s presently like my Healey was when
the OD didn’t work. I want to change the diff but what is
Any and all experience and advice welcome.
–
Jerry Mouton '64 FHC 889791 ‘MIK Jaguar’
Palo Alto, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from mouton sent Tue 16 Jul 2013:
Go for the 3.07. First gear carries a lot longer so you
aren’t looking for second in 60ft. And, my rpm at 70 mph is
2350. It’s a comfortable and quiet car at that speed/rpm.
The wind noise increases faster than the engine noise. Yes,
I can no longer burn rubber from a dead stop without putting
a lot of stress on the clutch. BUT, I never did that anyway!
And, since you have it in a LS version, Definitely go for it.–
Jim Ashworth 1970 S2 OTS, 74 Triumph TR-6
Tampa Bay, Florida, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from mouton sent Tue 16 Jul 2013:
Go for the 3.07. First gear carries a lot longer so you
aren’t looking for second in 60ft. And, my rpm at 70 mph is
2350. It’s a comfortable and quiet car at that speed/rpm.
I believe the book states 25mph/1000rpm for the 3.07. In my car
(converted many years ago from the 3.54 to the 3.07) I I get almost
exactly what the book says…3000rpm at 75mph.
I agree with Jim and all the others that have talked about going for
the 3.07. Great way to go. The only other, and far more expensive
way to go is to keep the 3.54 and go for a 5spd conversion.On Tue, Jul 16, 2013 at 6:13 PM, Jim Ashworth jaglotus@gmail.com wrote:
In reply to a message from Les Halls sent Tue 16 Jul 2013:
Another vote for the 3.07.
I replaced the 3.54 in my series 1.5 with the full syncro
box.
Generally I am pretty happy with the results. I can’t get
wheelspin with a freshly rebuilt 4.2l engine and 205/65/15
tyres but it cruises comfortably at 70 mph. Most of my
driving is done on windy roads between 30 and 60mph and
third gear with the 3.07 is perfect for this.
There’s no doubt that the 4.2l will pull the 2.88 but for me
I reckon first would be just too long.
For my series 1 3.8 which I am currently rebuilding I’m
sticking with the 3.54 diff but instead putting in a JT5
gearbox to replace the Moss box. This is a mroe costly
option but I want the shorter first as well as having 5th
for highway cruising.–
The original message included these comments:
Go for the 3.07. First gear carries a lot longer so you
In reply to a message from mouton sent Tue 16 Jul 2013:
Hi Ian,
It all really depends on what you want to use your car for? If you
want to drag race it everywhere, go with the 3.54, you will cruise
better with a 3.07 with lower revs on top. It is a little scary
trying to work out what is right for you, as everybody has a
different opinion? I spent ages pondering my latest creation, I run
diffs in a number of 60’s & 70’s Jags I have, fromm 2.88 to 3.77 in
a 67 S Type MOD (an original matching numbers car). I decided at
the last moment to stick to the 2.88 diff in my 67 auto Series 1 E
Type. I have fitted a 340 h.p. 4.2 coupled to a 67 Jag MOD box,
original motor & BW box saved. Yes a tad slow off the mark, still
pulls away no trouble, but once we hit a little over 2000rpm, the
car hauls on a very lively free reving motor, acceleration above 30-
40 m.p.h. is amazing. The punch line for me, is a car cruising
around 1800r.p.m. at 60m.p.h. The speed limit in Western Australia
is 110 k.p.h. on our very long straight uninhabited roads and an
occasional 1600km journey north, it is not about corners here, but
passing road trains. The acceleration in third & fourth is
exciting, but the usual torquey 4.2 motor at lower revs is still
there in overdrive. If you want an econimical cruiser and not so
worried about a rapid wheel spinning take off, consider the 2.88. I
have a few spare diffs, but I am now looking for a spare 2.88 just
incase.
Regards,
Rob–
The original message included these comments:
It’s not the stoplight dragstrip that is enjoyable, it’s the
ability to explode out of a corner in second gear. Wouldn’t want
to lose that!
–
Gumnuts: 2 x E’s, Mk2, S type, XJ Ser 2 & others
Perth, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Gumnuts sent Wed 17 Jul 2013:
Thanks for all the input, concensus seems to be the 3.07 is
ok. I do lots of miles but mainly on twisty bendy roads in
rural France and Spain so not really interested in the
standing start acceleration. Since I have the 3.07 I’ll go
with that. Looking forward to having it done and dusted.
Thanks again
In reply to a message from Gumnuts sent Wed 17 Jul 2013:
Thanks for all the input, concensus seems to be the 3.07 is
ok. I do lots of miles but mainly on twisty bendy roads in
rural France and Spain so not really interested in the
standing start acceleration. Since I have the 3.07 I’ll go
with that. Looking forward to having it done and dusted.
Thanks again
Be assured, you will not regret it!On Wed, Jul 17, 2013 at 12:40 PM, riv944 we3@vanuatu.com.vu wrote:
You’ll love the 3.07 but will lose that nose up acceleration at
25-3000 RPM’s in high gear. I have a 3.07 with a syncro box in the 64
and a 3.54 in the 69 and I much prefer the 3.07.
Bob
889076
Plymouth, Mi.On Jul 17, 2013, at 12:40 PM, riv944 wrote:
In reply to a message from Gumnuts sent Wed 17 Jul 2013:
Thanks for all the input, concensus seems to be the 3.07 is
ok. I do lots of miles but mainly on twisty bendy roads in
rural France and Spain so not really interested in the
standing start acceleration. Since I have the 3.07 I’ll go
with that. Looking forward to having it done and dusted.
Thanks again
In reply to a message from riv944 sent Wed 17 Jul 2013:
As for rural roads in France, I got the IRS smoking one time doing
a spirited ascent of L’Alpe d’Huez. I felt quite pleased with
myself at the top, listening to the ticking of the cooling engine
and seeing wisps of smoke curling up from under the wheel arches,
as I sat and watched the world go by.
Today I noticed that, unbelievably, the Tour riders will have to
climb it tomorrow TWICE!!! And that’s only a few days after
climbing the Mt Ventoux road that wore me out just driving up it. I
left a tubular draped over the Tommy Simpson memorial that time…
Looks like Froome for the win unless he crashes. Who’d have thought
a Brit team winning two years on the trot?
Pete–
The original message included these comments:
ok. I do lots of miles but mainly on twisty bendy roads in
rural France and Spain so not really interested in the
standing start acceleration. Since I have the 3.07 I’ll go
–
1E75339 66 D, 885958 62 FHC,1R27190+1R28009 70FHCs, 1960 Mk9
Gaithersburg, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–