5 speed trans. v. higher geared differential

Catching up on this thread:

I have a JT5 from Medtronics in my '69 2+2. It's proven to be a reliable box, and a perfect match to the 3.54 rear. As to whether this is "better" than keeping the four speed and going to a 3.07 rear, it's a matter of what else you're doing to the car. I needed a clutch, so it was an opportune moment to replace the transmission.

E-Type rear axles are variations of the Dana 44. Gearsets for the Dana are readily available in any ratio from 3.07 up to stump puller rears meant for farm trucks. Anything numerically higher than 3.54 will require a spacer on the ring carrier, but 3.07's are a pretty much drop in. The only minor changes will be sleeves on the ring bolts, and a new input flange.

I don't know about the modern S-type, but it wouldn't surprise me if Jaguar kept to a variation of the Dana 44. Take out the ring and pinion, and bring them to a drivetrain supplier. They may be able to find a match.

This is a bit off topic, but since there seems to be a knowledgeable group here, I hope you don't mind me asking.

I'm trying to understand the current S-Type Rear Axle gear ratio's. I'm trying to turn an S-Type into an Electric Vehicle and would really like to change the Axle ratio from the production 3.55 into something between 4.56 and 5.98.

Two questions for the group.
Does anyone, at any price machine Ring & Pinions for the 8.0inch axle?
Does the XJ6 from 2007, or any other Jaguar, use the same 8.0L IRS?

OTS Series 2, Frankfurt, Germany

In early 2005 I had installed a 5 Speed box from Classic Jaguar in my Series 2 Roadster & retained the 3.54 differential. It cost (I think) about $3,500.Subsequently I have driven about 8000 miles & it has (famous last words!) performed perfectly. Oil consumption has probabyl halved & petrol consumption improved. It is not quieter than the old box (probably due to the alloy bellhousing as against the old iron one)& as a broad generalisation I do not really think it was worth the money.This is not a criticism of Classic Jaguar (who provide an excellent service)- I just do not think that ANY 5 speed box is worth it in terms of improved ride, quieteness or whatever.

Over 5 years ago, I had my 3.54 in my 71 Series II car replaced with a Series I or II XJ6 differential, not sure which, but it fit using the XJ6 brakes. Believe I lost limited slip, but 70 MPH went from 3100+ RPM to 2700.

Could not tell much of an acceleration difference with the Strombergs. A set of K&N air cleaners more than compensated for the rear end ratio.

Later, after driving a friend's Series III, had to have more, so went to a triple SU and some headers, and life is good.

Still using the standard 4 speed transmission. From pricing new kit parts, going to a 5 speed would be almost as expensive as all of the above combined, and you would still have twin Strombergs.

Wow! I'm overwhelmed with authoritative responses. I want to profusely thank each of you who responded, this is exactly the type of information that I needed. Now its decision time. Cordial regards, Grant

The problem here is that that damn Bob knows EVERYTHING about E-types, and he just needs to be tweaked every so often. To get back to the subject of this thread, since Grant has done something to increase his power, he just needs to find a 3.31 or 3.07 to get 7 seconds to 60 and 150 mph. (I assume he's adding more air and gas)

Heh heh. And R&T says says my XJR should have a 3.58 diff when in fact they were built with a 3.27.

I'm thinking car magazines get all that data from the manufacturer's marketing/press departments and may not always reflect actual production specs.

I've never seen any manufactuer's spec sheets or brochures that didn't say "specifications subject to change without notice" :-)

That being said I always thought that the only USA E-types with the 3.07 were some of the 2+2 cars. But I'm a million miles away from being an E-type authority so I'll shut up now :-)

Cheers

Doug Dwyer
Longview Washington USA
1995 XJR

Put not your trust in parts books or service bulletins. From R&T road tests of actual cars:

Sep 61 OTS 3.31
Apr 64 FHC 3.31
Oct 66 2+2 3.31 (automatic)
Jun 69 FHC 3.54
Aug 69 FHC 3.54

All S I's were capable of 150 mph except the automatics. With a 3.54 it just can't do it. The Stromberg cars could make 120 mph on a good day.

Hey John, You're part way right which isn't half bad for an old fighter pilot who inhaled jet fuel fumes for 30 or so years! From the various Jaguar parts books we find with no dates,

J30 August 1961 3.31 standard with 2.93, 3.07 & 3,54 as options

J30 A.L.1 June 1963 3.07 standard with 3.31 & 3.54 as options The 2.93
complete final drive was no longer available.

J37 November 1965 3.07 standard except for Canada , & Newfoundl and USA
3.31 as an option and 3.54 required on cars shipped to the above
countries

Service Bulletin H.5 October 1962 Also lists the 3.07 as standard except USA & Canada which
had a 3.31

Service Bulletin H.11 September 1963 lists 3.31 for home market 3.07 for a list of countries and
3.54 for the USA, Canada and Newfoundland

As service bulletins could possibily be issued after the change took place all we know, I think, from the above, which wore out my one typing finger is:
3.07 axle was only standard in the USA until late summer early fall of 1962
3.31 until late summer of 1963 and then 3.54.
Are you going to be at the CC?
Bob

Now Bob, the E started with 3.31, went to 3.07 in 1965 and to 3.54 with the advent of the Strombergs. My '69 won't go faster than my 120, all the others went well over 140...

Grant, Actually Jaguar installed the 3.54 rear axle on USA E-Types at least 4-5 years before the US emmissions went into effect. I have a 3.07 axle in my 64 with a 68 transmission, not the close ratio one, and with an aluminum flywheel and hotter cams there is absolutely no need to slip the clutch
etc to get moving nor should there be as a 3.07 was standard for a number of years in many parts of the world. Jaguar went to the 3.54 gear mainly for more punch during "Stop Light Gran Prix's" that was so popular in the US.
Bob

Thanks, John, for your insight, it is much appreciated. I am curious, however, to see if going to the higher rear end ratio is problematic with needing to slip the clutch, for example, when starting off. I have had some modifications made to the engine to increase the power so I do not think that acceleration would otherwise be a problem.

When Jaguar slapped together its solution to US emission requirements, they also ruined the performance of the engine. To regain a semblance of sports car verve they put in the new rear end ratio so that 0 to 60 times would look better. You can change the ratio and enjoy reduced revs after you finally make it to 70 mph, or install a 5-speed and enjoy life. I only wish I could afford a 5-speed...