Question on Drive Train

[Lost Horizon]

I recently purchased a Series 2 California Car with 45,000 original miles that runs well and is about to go in for a frame off mostly cosmetic update rotisserie redo. In advance, I've put several hundred miles on it in the last few weeks to sort out what I like and don't about it. It runs very well, needs what you'd expect for 45K and elapsed time. The car is matching numbers, all original (including all the glass) except for paint and top at the moment.

My question is related to the overall gear ratios and the fact that it's around 3500 rpm @ 60 mph. Seems high and could get old quickly on my planned trip across Canada next year, which includes a stint across the rocky mountains.

Given that the car is original, I'm reluctant to drop in one of the after market 5 speeds, but am wondering if I take the rear end down a step with some other originally available ratio from the day how that might work out. The VIN is 2R14414, built in August 1970, so it's likely one of the last Series 2's around. As I understand what I've researched on the internet (!!), the California cars came with a 3.54 but the European versions had a 3.31.

Feedback on next steps is welcomed. Thx.

[mgcjag]

Hi Dana...common in the UK is 3.07 so you looking at approx 2750rpm at 70mph....but some are useing 2.88 so even less revs... Steve

[Lost Horizon]

Hi Dana...common in the UK is 3.07 so you looking at approx 2750rpm at 70mph....but some are useing 2.88 so even less revs... Steve

3.07 sounds about right, considering the Rockies are in the playground. 2.88 might be a bridge a bit too far.
Thx,

[christopher storey]

It is most likely that your tacho is out of trim. This is very common - although the circuit is fairly simple , the capacitors, resistors and the thermistor are now nearly 50 years old and probably well away from original parameters. There is a potentiometer inside the case which can be used to alter the reading although the real solution is to replace the resitors and capacitors etc . Your first step should be to check it against a calibrated instrument which any garage which does tune-ups will have

I would expect that your car has 3.54 final drive in which case the true reading at 60 mph will be about 2800 rpm

[mgcjag]

Well spotted Christopher.....didnt take much notice of the speed/revs that were quoted ......Steve

[Lost Horizon]

It is most likely that your tacho is out of trim. ...
I would expect that your car has 3.54 final drive in which case the true reading at 60 mph will be about 2800 rpm

Thx for that, and it could very well be the case..

Based on what you've provided in this thread, I did a quick comparative spreadsheet for 3.54 and 3.07. The speedo is correct, so the only other suspect would be the tach. Regardless, I'll still probably swap it out for the 3.07 for the trip since the car will be fully apart anyhow in the refresh process. It's a long way between gas stations thru the Rockies and parts of the country for the 3000 + miles, so any gains in mpg will be welcomed. I have no intention of drag racing off the line from stoplights.

[mgcjag]

Hi Dane.....the figures are in the Jaguar service manual.....Steve

[Lost Horizon]

Hi Dana.....the figures are in the Jaguar service manual.....Steve

That would be too easy Steve..

There it is! Page xiv !
Wow.. nice to know they agree with the spreadsheet. You guys gave me good data points to start. All good.
Now we have more data points than the manual.

[mgcjag]

Page A.5........General information...there is a lot of info in this section but gets overlooked...Ps one of our members James (Politeperson) has the 2.88 from an xjs....he loves it...2550rpm at 70 mph approx.. Steve

[Lost Horizon]

thx.

[Lost Horizon]

Having gathered the options from the discussion here and elsewhere, for my own decision process I put together spreadsheets based on the data for 4th and 3rd gears for the various ratios. I was thinking that the 2.88 *might* work, but for where I live, the 3.07 seems to be the right mix.

[Nickleback]

Dana,

My S2 coupe is a May 70 XKE car so close to yours in build date and came with a 3.54 diff.
As you say the revs were too high and car always felt like is was overworking.

After various recommendations and seeking advice, I have just had my IRS fully rebuilt with a 3.07 diff and kept the original casings and LSD etc and the difference is just great.

The car feels way more relaxed, pulls well through the rev range and feels a lot more comfortable at higher speed.
I just need to cover a few miles now to see how the fuel consumption has improved.

My recommendation is to go with the 3.07 as the 2.88 will be going too far.
The E and the rockies - great combination

[Lost Horizon]

Dana,
My S2 coupe is a May 70 XKE car so close to yours in build date and came with a 3.54 diff.
As you say the revs were too high and car always felt like is was overworking ...

My recommendation is to go with the 3.07 as the 2.88 will be going too far.
The E and the rockies - great combination

Yeah.. we think alike there. Based on my napkin scribblings, the 3.07 looks Goldilocks right. Other than that, this Project car is in excellent nic. I can't believe how solid it is given the nearly 50 years. California Cars are worth the extra as the starting point. Before giving it to the restorer this week, I ran it pretty hard to see where the leaks might show up, what vibration there might be in the drive line etc. To my surprise, the garage floor where it was parked over that period had no oil puddles at all in spite of my efforts.

Thx for the feedback.

[Herzeg]

Dana

I agree with Mike. Mine had the 3.54 fitted to US cars and I had it replaced with a 3.07 when I did the RHD conversion. 70MPH in top was teeth rattling and first gear was drag racing territory. Now its more relaxed and easier to live with whilst still keeping the torque that makes it so easy to drive in top. If you are doing the Rockies I think 2.88 is too much. I am so jealous of that route, the highest point where I live is about 300ft above sea level

John

[mgcjag]

Hi John....the Rockies sound great.....but nothing like a non stop sprint around M25

[Lost Horizon]

Dana
... I am so jealous of that route, the highest point where I live is about 300ft above sea level
John

You gotta work with what you got.. I'll try and take a GoPro with me for an XKE view of the passes on the way to Calgary from Victoria, and post it on my website with links here. I've done the trip a number of times, but always with a BMW.

It'll be far more engaging in the fully analog, normally aspitated ragtop than it is in the 400 HP turbo'd totally digital bimmer with adaptive cruise control and satellite radio. As a matter of fact, I'm trying to get a custom plate for it - 'ANA LOG'. Bucket List Check: Priceless!

[ETTony]

HI John, hi Mike,

I am intending to have my Diff rebuilt this winter currently its 3.54 i need it 3.07
Who did you have do the work, I am looking at Ward

Thanks Tony

[Herzeg]

Hi Tony

I had mine done by Angus Moss as part of my RHD conversion but don't know who actually did the rebuild

John

[Gfhug]

It might be Alan Slawson of AJS Engineering http://www.ajsengineering.com/index.html that Angus uses.

Geoff

[Heuer]

Don't go for the 2.88 unless you have a modified engine with lots of torque but even then 1st is too high especially if you are going into mountain roads. I have the 2.88 and regret it - great for high speed touring in France but compromised in town and the congested roads of the UK.