'69 E-type 3.54 to 2.88 Differential Conversion

Bruce:

Yes, that should be 1312, not 1321 ...... finger/user error. The arithmetic is 32x41, which is 1312, so your speedo is marked correctly, and the correct one for the 3.07:1 should be 1120.

Cheers, Mark R.

Mark Roberts notes the speedo turns per mile for various ratios in Series 1 E-Types. I'm about to send my Series 2 (1970) E-Type 2+2 speedo to Nisonger for re-calibration. I'm in the process of changing the ratio in my differential from its original (3.54 to 1, I believe) to the European standard for the car (3.07 to 1). According to Mark's calculations my original speedo should have a 1321 marked on it for the 3.54:1 ratio. However my speedo has 1312 marked on it. Close but not exactly what Mark predicted.

I was wondering if Mark or anyone else out there knows whether the Series 2 cars had a slightly different setup in the speedo. The difference is certainly small (about 0.7%) and I know I can do the rolling 52.8 feet test but I doubt that I can be accurate enough from that to see whether the new rear end is 11.2 turns per 1/100 of a mile or something slightly different.

Bruce,
I had a worn 3.07 gear set replaced with a Dans 44 R & P and the shop included a new pinion shaft yoke. You'll receive the rebuilt diff with the a new pinion shaft yoke that is the correct length to bolt up to the U joint in the normal fashion. Any GOOD axle shop can explain and show you what I'm talking about as they've most likely have done this conversion on many Jag diff's that are going into Cobra kit cars,street rods etc.

Robert and Thomas,
I appreciate all your great advice. I've been researching the Dana 44 and have found a couple of things that I'd like to understand better.
One has to do with the pinion input shaft. I found this note "The other bad news is that in the mid 1960's, Spicer changed from a coarse, 10 spline pinion input shaft to a fine, 26 spline shaft. And new gearsets with the old 10 spline input shaft have not been available for some years now!" The author went on the say that the solution he found was a new 26 spline companion flange. "The Dana Spicer part number for the new 26 spline companion flange, which replaces the old 10 spline flange perfectly, is: DANA Spicer 2 - 1 - 2391.
Another article (that I have miss placed) indicated that an "installation kit" was required to fit the Dana 44 gear set to the Jag differential. The article said that the Jag differential was manufactured by Salisbury, a U.K. Division of Dana Corporation, therefore some adaptation was necessary.
I'm just trying to understand everything that is involved with using the Dana 44 gear set.

Thomas,
You list 875053 & 875093 or maybe it's 885---- as your cars. If that is indeed the case I would appreciate you contacting me at bobanddarlcomcast.net
Bob

Bruce, Robert is correct. The Dana 44 rear carrier is used in many vehicles. I bought mine from Advance Drive Line in Orlando. Any shop that handles axle work will be able to get whatever axle ratio you want. Would not go to the Dodge dealer.
Cheers Tom

Bruce,
The gear set is a Dana 44 that fit's a bunch of vehicles including some light duty trucks. Any GOOD ring and pinion shop can get the gear set and the shop in Waterford Mi. has changed a half dozen or more Jags from a 3.54 to a 3.07. If the Viper does use this gear set you can bet it'll be much more expensive then from other sources

WE'RE WAITING BRUCE! i HAVE TWO NEW SETS THAT ARE 46/13, 3.51;1 WHAT WOULD THEY BE OUT OFF?

Tom, thanks for the info. Are you saying that I can get Dodge Viper gear set at my local Dodge dealer and it will work in the E-Type? That would be fantastic. Do you know what the ratio is of the Viper gear set. I've been pretty frustrated looking for places to buy Jaguar gear sets.

You can buy a new gear set, not that bad $$$ for new. Ask for a gear set for a Dodge Viper, they use the same set. As for the speedo, there is an app for your cell phone that is free and works great.(Ulysse speedometer).
Cheers Tom

I have a '70 Series II 2+2 and I would like to change diff ratio for longer highway legs as discussed in this thread. Can anyone provide sources for the 3:07:1, 2.94:1 or 2.88:1 ratios? I have a good shop that can do the job assuming I can find the parts. All the speedometer info should save a lot of time.

Thanks,
Bruce McGeoch
Burlington, VT

A few years ago I picked up a basket case E-type which just happened to have a modified diff ratio, to 2.88:1 (49/17). This car also had a re-calibrated speedometer for that diff. I kept the diff and the speedometer.

Looking inside the speed head, the gears for the odometer are: 20 teeth- gear 1, 55 teeth - gear on each of the odometer "barrels". This gives a "turns per mile" of 1100.

From the markings on the speedo face plates, the standard differential ratios offered for Series I E-types had the following gear sets inside the speedo:

2.94:1
32x34 = 1088

3.07:1
32x35 = 1120

3.31:1
32x38 = 1216

3.54:1
32x41 = 1321

Following that system, the gear set that could/should be used for the 2.88:1 differential ratio is:

2.88:1
32x33 = 1056

Thus, the gear set within the re-calibrated speedo I have for the 2.88:1 differential is off a bit, meaning the speedo will be reading about 4% fast/too far from the actual. Not too bad, but it could be better with the 32x33 gears.

Now, getting the needle to swing right, that takes someone who understands how the magnet and spring really work. That is why you need to send the speedo off to Nisonger, Palo Alto, APT, or someone else to re-calibrate ..... with the number 10.56 for speedo cable turns over the 52.8 feet.

Cheers, Mark R.

Neither Palo Alto Speedometer nor Nisonger offer a replacement speedometer cable angle drive or other converter to correct for changes to rear axle changes. Both want me to perform the "rolling test" to count speedometer cable revolutions over a course of 52' 9?¢" (i.e. 1/100 of a mile) and then send in the speedo head for recalibration for ~$200-250.

APT Instruments offers straight through and offset ratio adapters for $95 and "custom ratio adapters built to almost any ratio". But when I presented my situation, they did not offer a ratio adapter as a solution. Instead, they wanted me to perform the same "rolling test" as above and, too, send in the speedo head for recalibration for $245.

Perhaps a "plug and play" option is not feasible.

Neither Palo Alto Speedometer nor Nisonger offer a replacement speedometer cable angle drive or other converter to correct for changes to rear axle changes. Both want me to perform the "rolling test" to count speedometer cable revolutions over a course of 52' 9?¢" (i.e. 1/100 of a mile) and then send in the speedo head for recalibration for ~$200-250.

APT Instruments offers straight through and offset ratio adapters for $95 and "custom ratio adapters built to almost any ratio". But when I presented my situation, they did not offer a ratio adapter as a solution. Instead, they wanted me to perform the same "rolling test" as above and, too, send in the speedo head for recalibration for $245.

Perhaps a "plug and play" option is not feasible.

I also installed a 2.88 differential and then sent my speedometer to Nisonger to be modified for the new ratio. Contact them for the procedure to determine the correct gears for your new setup.