Diff ratios

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#1 Diff ratios

Post by Hugo » Sat Dec 16, 2017 9:51 pm

Two questions - was there a 2.88 diff fitted as standard to the E Type? And can a 2.88 XJ6 (or was it XJS?) diff be fitted to an E Type? And if not why not? Ok that's three I know ;)
Hugo Miller - rebuilding an imported Series II OTS & converting to RHD

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#2 Re: Diff ratios

Post by Nickleback » Sat Dec 16, 2017 10:37 pm

Hugo,
Why do you want a 2.88 diff in there ? Surely the best solution is for a 3.07 on an S2 which gives the best balance between power, torque & economy through the rev range ?
Just had mine converted from 3.56 lsd to 3.07 lsd by a local specialist to you & I and am really pleased with the result :mrgreen:
Mike,
1970 S2 FHC 2R28165

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#3 Re: Diff ratios

Post by Hugo » Sat Dec 16, 2017 10:46 pm

Yes, that would be my second choice. I have a 3.54 in there at the mo (it's a US import). I haven't entirely given up on my quest to squeeze an overdrive in there somehow, but if I concede defeat on that I will want to up the diff ratio. I was hoping to fit 5 speed but after doing lengthy research and settling on a JT5, I found out they were now unobtainable, and I've heard so many conflicting reports about the others I could not decide.
I want to just sit the engine & gearbox in the car before doing the final fitting of the bonnet (I'm told the extra weight won't alter the gaps, but my panel-beater friend who's doing it wants to play it safe). So all I can do for now is stick the existing KE gearbox in there & see how it drives. If it's good, I'll look for another diff; if it's no good I might start again on my quest for a 5 spd.
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#4 Re: Diff ratios

Post by Barry » Sat Dec 16, 2017 11:20 pm

I have an XJS 2.88 lsd diff on my 6.0 litre V12 E-type, mated to a standard Jaguar 4 speed gearbox, and 16”x7” wheels. It works really well, with 2850 revs @ 70mph in top. The combination is superb with the V12 engine because of all the extra torque. A 2.88 Diff with a 4.2, standard ‘box, and 185 x 15 tyres, I think you might find it too high. On the basis you don’t want a 5 speed gearbox, I would stick to a 3.07, which will give you the option of going to 5 cogs if you change your mind. A well trodden combination which many on this forum will testify to.

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#5 Re: Diff ratios

Post by Durango2k » Sun Dec 17, 2017 7:55 am

I did leave the 3.54 in mine, but fitted an OD. Hm, but it‘s a 2+2 so apart from minor metal bashing and cursing it did fit.

I am now very sure that auto 2+2s had wider tunnels then manual 2+2s.

Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650

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#6 Re: Diff ratios

Post by mgcjag » Sun Dec 17, 2017 9:32 am

Hugo....yes 2.88 were fitted to E types....2+2 auto (service manual page HYs1) 2.88 from an XJS can be fitted....James(politeperson) has lots of info on the forum, he fitted one to his 4.2 and rates it very well.....this long thread has details and videos of him driving with it viewtopic.php?f=9&t=7226&hilit=2.88+diff&start=100
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#7 Re: Diff ratios

Post by christopher storey » Sun Dec 17, 2017 10:20 am

The 2.88 is just about feasible with a later all synchro box, ( KJ/KJS etc as fitted to S2 ) which has shorter intermediate ratios, but is not suitable for use with the EJ series box which has closer ratios and thus requires much clutch slipping for hill starts etc , not to mention use of 1st gear round town . With the EJ box , even the 3.07 ratio can render the clutch a bit marginal for hill starts

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#8 Re: Diff ratios

Post by Hugo » Sun Dec 17, 2017 10:25 am

Very interesting - thank you. While watching the video I found myself squinting into the shadows to look out for oncoming traffic or obstructions in the road! From the comments I gather my reactions are not unique. At least my right foot wasn't reaching for the brake pedal!
Two questions, if you're listening James, does your car have power steering? It seems to turn with no effort at low speed despite that titchy steering wheel. Or are you just very strong? And why is your gear lever so far back? I've heard tales of people banging their knuckles on the radio engaging first, but yours is nowhere near it.
I've been scratching my head for a while over this five-speed business. Having explored every option, it looks like I'm back where I came in. I was assuming you would need five gears to get from zero to 150mph (-ish). No other car does it with four, not as far as I'm aware anyway. I was also assuming that the only reason they didn't fit o/d was that it wouldn't fit, as the longer 2+2's do have it. But I think those assumptions were unreliable, as assumptions generally are. I have a Corvair (four of them in fact!) in Florida, and that manages ok with just two speeds in its auto box, which will take it to well over 100mph (I think).
And I like that subtle whine in the intermediate gears in James' car.

Anyway, this is on eBay.com; "REBUILT JAGUAR DIFFERENTIAL 2:88 POWER LOCK FITS 1988-1989 XJ6 PN:JLM1292/28R" Item no. 162742033700. A mere $350 - no mention of a core charge. It's in Georgia, so I need to figure out how to get it back to the UK - in my luggage on a 747 I guess!
If anybody can tell me this won't fit, or can't be made to fit, please tell me sooner rather than later. And does anybody know what these things weigh? More than the 50lb luggage allowance on Virgin I'll bet!
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#9 Re: Diff ratios

Post by Hugo » Sun Dec 17, 2017 10:36 am

christopher storey wrote:The 2.88 is just about feasible with a later all synchro box, ( KJ/KJS etc as fitted to S2 ) which has shorter intermediate ratios, but is not suitable for use with the EJ series box which has closer ratios and thus requires much clutch slipping for hill starts etc , not to mention use of 1st gear round town . With the EJ box , even the 3.07 ratio can render the clutch a bit marginal for hill starts
Thanks - my last post overlapped yours incidentally, so I was replying to the previous one. According to my back-of-an-envelope calculations, my KE box will give the following speeds per 1,000 rpm in each gear: - With a 2.88 diff; 9.2,14.2, 19.5 and 27 in top. With a 3.07 I would get 8.6, 13.3, 18.3 and 25.3 in top. With the existing 3.54 diff I will get 7.5, 11.5, 15.8 and 22 in top.

I think the 25.3 per 1,000 rpm in top I would find a bit low, so I'd rather take my chances with a high first gear. It's a trade off, isn't it, and I always prefer higher (taller) gearing if poss. Most cars I pull away in 2nd gear anyway.
PS I just did another calculation, & the EJ box would give you 10 mph per 1,000 rpm in first gear. That would be pushing it (literally, perhaps!) but you could go from 0-50 without changing gear!
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#10 Re: Diff ratios

Post by malcolm » Sun Dec 17, 2017 11:52 am

Hugo, apologies in advance if my ignorance shows here, but I have a standard 1969 2+2.
I have the standard 3.07 diff on a manual box. I get 70 mph at 2850 revs as per the handbook I have, and as checked by sat nav (my speedo reads more)
I'm quite happy on the motorway, with 80 mph at about 3200 revs. However, it could easily handle higher gears. I have no troubles in steep hill starting in first - even 2nd sometimes. So I don't think the 2.88 would make my car more difficult to drive particularly.
Nonetheless, I'm a bit of a sucker for originality so I'll stick with what I've got.
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S

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#11 Re: Diff ratios

Post by Hugo » Sun Dec 17, 2017 1:57 pm

Thanks for you input - my book gives 2,780 rpm @ 70mph with a 3.07 diff, and 3,150 @ 80mph. I reckon that a 2.88 diff will run 70mph at 2,430, and 80 @ 2,590. And 80 in 3rd is a comfortable 4,000-and-a-bit. All this theorising is of little value compared to the actual driving experience, of course, but the good news is that it's a lot easier to change the diff if I don't like it than it is to change the gearbox.
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#12 Re: Diff ratios

Post by Moeregaard » Sun Dec 17, 2017 3:05 pm

Christopher makes some good points regarding gearbox compatibility with the 2.88 ratio. I think anything taller than the 3.07 would be a pain in the neck with the EJ-series 'box, and only marginal with the later gearboxes with their lower first gears. The 3.07 gears are probably the best compromise for most, and it is what Jaguar fitted to E-Types not destined for North America. When Denis Jenkinson was running his '65 FHC all over Europe in the 1960s, he felt that the 3.07 gears were a perfect match.
Mark (Moe) Shipley
Former owner '66FHC, #1E32208
Former owner '65FHC, #1E30036

Planning on getting E-Type No. 3 as soon as possible....

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#13 Re: Diff ratios

Post by Hugo » Sun Dec 17, 2017 4:19 pm

You're probably right - the 3.07 is the best compromise; but I have a preference for lazy engines and higher gearing where possible. Others may prefer a quick take-off. It's all subjective really.
What would transform the Jag engine - ant engine - is variable inlet cam timing. I have that on my little Rover 200 Vi that I use as a runabout, and it is just lovely. Best of both worlds - low-end torque and top-end power when you want it.
Mind you, I've just been looking at the latest crop of electric cars such as the Rimec, made in Croatia of all places - 1250 bhp and 3,000-odd lb/ft! The irony is that this high-tec stuff is ultimately powered by chopping down American trees, shipping them across the Atlantic and burning them to boil water, which then drives a steam turbine to produce 'low-carbon' power.
Sorry I'm drifting again ;)
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#14 Re: Diff ratios

Post by politeperson » Sun Dec 17, 2017 8:15 pm

Hello Hugo,

I am sure some of the 5 speed options are marvelous. However, I think £3k or £5k is better in my pocket!

I have now done a few thousand miles with the 2.88 diff. No complaints. You can pick up a good LSD XJS unit in the UK for a few hundred quid. Fit it with your old shims and dog bones and its job done as far as I am concerned.

Importing one from the US to the UK would be like exporting Champagne to Champagne.

My advice would be try to buy a nice dirty diff that is not too oily on the outside. Then you know the oil seals are probably ok and you can leave them alone. New oil seals fitted on these units can leak from day one.

My car accelerates very well and cruises on the motorway at 90mph beautifully if you want it to.

I bought one from these guys

http://www.justxjs.com

With the 3.54 the car was very fussy up to 80mph, first gear lasted for a millisecond and was basically useless.

You want the Salisbury unit not the Dana.

http://www.coventrywest.com/jaguar-diff ... tification

Whilst I appreciate the driving experience of these cars is subjective, Jim Patten did a 5 page article on my S2 in Jaguar World (Nov 17'), and liked it. He has driven a few E-types. I think he owns 2 nice ones. He especially commented on the acceleration and the 2.88 axle.

My car has no power steering and uses the original steering wheel. I have however replaced the bearings, ujs and rack and ball joints. It even has slightly wider Michelin 205 XWX tyres.

I find the steering light and lovely. Dont think my muscles are that big!

I say have a go.
Last edited by politeperson on Mon Dec 18, 2017 10:33 am, edited 1 time in total.
Its true, but Enzo never said it
Too many E types
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#15 Re: Diff ratios

Post by Hugo » Sun Dec 17, 2017 9:15 pm

Well, that is all very useful indeed - thank you. Coventry West, to whom you sent a link, are the people who have one on eBay.com right now. Doesn't seem to be anything in the UK at the mo, but I'll have a word with the XJS people in your link. But I'm in no rush - that's another job for another day. I am under slight pressure to make a decision on the gearbox / diff combination as I want to fit the engine & box, if only temporarily, to make sure the bonnet fit doesn't alter with the weight of the engine/box when we do the final the fitting. But I'm in no rush to actually change the diff - there are plenty of more pressing jobs right now.

That steering wheel in your car is never original, is it? Maybe it's the GoPro that makes it look small, but the spokes are all wrong. I have a nice four-spoke wood-rimmed wheel for mine, one inch smaller than stock.
Whilst reviewing your video to take another look at your steering wheel, I noticed something - when you accelerate in first gear, your gear lever seems to move backwards a lot under acceleration, then go forwards again when you lift off. That might suggest a bit of end-float in the mainshaft. Not that it would be worth taking the gearbox out, even if my observations are correct! Pity Jaguar didn't do what Astons did and have a detachable tunnel - you can get the gearbox out of a DB 4/5/6 in five minutes from inside the car (like a Triumph Herald!).
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#16 Re: Diff ratios

Post by politeperson » Mon Dec 18, 2017 11:03 am

Morning Hugo,

My steering wheel is a standard 15 inch 3 spoke steering wheel.

There is a thing beyond the forum called the internet. Have a look.

https://www.google.co.uk/search?rlz=1C1 ... Na1A0nSuBE

I think you will find movement in the gearbox lever is designed by Jaguar. It is as a result of the gearbox being supported by a spring at the rear.
Its true, but Enzo never said it
Too many E types
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#17 Re: Diff ratios

Post by Hugo » Mon Dec 18, 2017 12:00 pm

Ok, lots of nice pics of steering wheels, but they all have holes in the spokes. Yours has slots, doesn't it? Never seen that on an E Type? Not that it's any of my business - I have a four-spoke wheel after all ;)
Anyway, me and my big mouth - after suggesting you might have some end-float on your gearbox mainshaft, what do I find? Mine has exactly that problem - about twenty thou end-float on the output flange! Karma or what?
Unfortunately, I only discovered this as I was tightening the rear flange after replacing the oil seal, and that was after I had replaced the front oil seal and stuck the gearbox on the back of the engine. Those are seriously heavy lumps of metal when you're working alone.
The reason I left the rear seal till after the gearbox was mated to the engine was to make it easier to tighten and release the rear flange nut.
So now, do I strip the whole damn lot down again or pretend I haven't seen it?
I was never able to drive the car before I stripped it, because the clutch was slipping so badly it would not drive the car. No idea why, and I don't really care, but when you lay the pressure plate face-up and sit the centre plate in there, you can lay a straight edge across both surfaces - there's no clamping force at all. But it went through all the gears 0k with the car on jacks, so I decided to leave well alone. Or so I thought.
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#18 Re: Diff ratios

Post by Hugo » Mon Dec 18, 2017 4:13 pm

politeperson wrote:
Mon Dec 18, 2017 11:03 am
I think you will find movement in the gearbox lever is designed by Jaguar. It is as a result of the gearbox being supported by a spring at the rear.
I dunno about that - what would make the gearbox drop at the back under acceleration? I can't think of anything. The end-thrust on the mainshaft gears, on the other hand, would push the selectors backwards & forwards as the load reversed.
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#19 Re: Diff ratios

Post by Series1 Stu » Mon Dec 18, 2017 5:57 pm

" The end-thrust on the mainshaft gears, on the other hand, would push the selectors backwards & forwards as the load reversed."

I can't see that at all, Hugo. The selectors should be nowhere near the gear clusters during normal running. Only during gear changes. Unless there's an awful lot of wear in the gearbox, of course.

Regards
Stuart

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#20 Re: Diff ratios

Post by Hugo » Mon Dec 18, 2017 7:47 pm

Well, the selector forks will be sitting in the hubs, and one hub will always be in contact with a gear. In first gear the 1st/2nd hub will be pushed backwards against first gear; if the gear moves forward under load because of excessive end-float, it will push the hub forward and the lever backwards. N'est-ce pas?
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