I have a 2007 XKR and love it, minus 3 HUGE things.....the slow to respond transmission, the awful interface/head unit, and the lack of a limited slip diff. I know that from 2010 on, they put an E-LSD in the car, so that cures that issue.

I know that the interface is the same in the newer cars and I can live with that (somehow), but I don't know if I can deal with the slow transmission in manual mode again. It really drives me nuts, especially after having a DCT in the past.

I'm considering a 2012-2014 XKR soon, but I would like to know if Jag did anything with the transmission itself (or its computer), to make the shifts quicker. and react quicker than what I experience in my 2007.

Thanks in advance.

 

What transmission does the 2007 XKR have in it? Is it a Mercedes or ZF?

 

ZF

 

Its not apples to apples, there is one major thing.

You only need a good transmission if you have a bad engine. In the ideal world an engine would not even need a transmission. The 5l supercharged aj8gen3 comes fairly close to that ideal. Its power curve is such that a DTC is not even required as there are no shifts required.

Its been engineered around real world driving requirements. Such as doing 50 to 70 in 1.9 secs, without gear change. See video below of review against Aston with MT. Note how the xkr passes the Aston like it was standing still. Thats the real difference between having an engine that requires no gear shifts vs one that develops its power in a narrow band- you are constantly shifting to find that band.

But first, one needs to realize that this is a completely different animal than the typical modern German or Japanese engines. The pleasure here is the Long gratifying pull in each gear as opposed to bunch of short shifts, i.e. low dynamic range (the range of rpm each gear sees.

It develops its power at slightly above idle and keeps going to near redline. Very few engines can do that. Translated into real world driving, if you had a manual clutch that you could feather, you can keep the car in 3rd gear for most city driving.

Go to the 4:00 minute mark

 

A quaife diff installation will resolve the inability to get the power down.

In regards to shifting issues if your after faster/aggressive upshifts I can put you into contact with a fellow member that has the appropriate software updates for the zf6hp

 

Per the tranny, drive it like you stole it and the ECU will learn to shift more aggressively. I've noticed that mine is lazier on up shifts when I'm at part throttle but is instantaneous above 1/2 throttle. I've also found that the car shifts / runs harder in drive vs. sport mode. In fact I like manual shift better than sport because mine will hold doesn't like to up shift until 4500 even at part throttle which feels excessive.

No LSD is a real bummer. I know where four 1st gen Lincoln LS's are at the local junk yard and they have the correct rear to install an 8.8 traction lock unit in. It's on the 'list'.

 

[QUOTE=Ranchero50;1710877. I've also found that the car shifts / runs harder in drive vs. sport mode. In fact I like manual shift better than sport because mine will hold doesn't like to up shift until 4500 even at part throttle which feels excessive.
[/QUOTE]

Same even on 5liter xkr. I think Jaguar wants to give old farts a 'feeling' of spirited driving by keeping the revs needlessly up, even under zero throttle. You are exactly right, Drive gear gives the most satisfactory, accurate and non engine wearing results...especially after it learns how you drive.

One more video, Jaguar XKR vs PDK review. Spoiler alert Jag wins.

 

Can you elaborate on 8.8 I don't think that's going to work on our gen 2 diffs

 

Did you look at the S-Type forums and I believe some others where members attempted this but I believe they were not able to make it work in the end, too many mods to the pumpkin.

A Quaife LSD is indeed the solution here, I have one and love it.

The TCU is an adaptive one and the harder you drive it, the quicker it will become. Also there are 2 modes on the shifter D and DS with the S standing for Sport, with quicker shifts as well.

 

I've not noticed a difference in shifts when manual mode is engaged whether it is in DS or D. It just stays in manual when in DS.

What I find, is if I want to cross multiple gears as a downshift, it is much faster to go to DS than click it down. There is a delay between shifts in manual mode, probably to keep people with jittery fingers from shifting more gears than they intend to do.

I imagine this is the delay the OP is talking about? The actual shift times of the XK itself is quite fast, however, in manual mode, if you are wanting to go from 6th to 2nd, there is a pause between each shift that doesn't occur if you simply go D to DS and let it do it automatically.

 

Yeah, you just need a 1st gen LS / S type carrier and axles. Hopefully I can talk them into just flipping a car and dropping the assy out as a unit. Those LS's have been there forever. I figure I can do it for a fraction of the cost of a Quaife unit since i have a ton of 8.8 parts floating around.

 

Will the gen 1 carrier bolt up to our subframe

Are the ls/s type axles going to be the correct length to bolt up to the hubs or will they need to be modified

Will the tail shaft need to be replaced / modified

If in fact you are able to bolt up the gen 1 diff you have opened the door to put in shorter ratio gears (as it stands the shortest ratio currently avail for gen 2 is 3.58)

If your saying all this can in fact be done the x type awd rear diff would also be an option as it would be a lsd

 

I don't think the carrier is a direct swap and I'm not 100% sure on the prop shaft. Axles are supposed to be the same but offset because the gen 1 housing is to center the prop shaft in the tunnel. I figured if I get the whole rear LS sub frame for a decent price it's worth investigating. I read almost all of the LS vs Cadillac threads and the follow on S type threads on the subject. I'm also not adverse to modifying another 28 spline LSD to fit the gen 2 housing or machine my own. I'll go to extreme measures to get LSD.

 

hi guys, thanks for all the replies. what i'm referring to is the incredibly slow downshift response when using the paddles, not the upshifts. the upshifts aren't amazing, but i'm fie with them. if there is a software upgrade that can improve this, i'd be all over it.

I guess my main question hasn't been answered though...is there any difference in the transmission between my 2007 and a 2012-2014?

 

Naturally there is- its attached to a different engine- with different behavior, and software. I may have gone through too much effort to explain. Let me simplify:

There is no instance where you will need rapid downshifts beyond 2 gears- if that. Say you are approaching a light at 5mp and you were in 3rd gear as you should be, the light suddenly turns green, you are not going to drop it in 1st. You will blast away in 2nd- thanks to the different engine. Those downshifts are very fast.

I dont have your car so I dont have a reference, but I notice no lag in mine. The only thing that sucks in all these cars, Porsche included is that you have to go through all the gears to downshift...but the need to do that in the new engine-trans-software combo is significantly less- even than my friend's Porsche.

 

I think I covered already what his problem is, but I'll put it another way.

It isn't the transmission shift times, it is the delay between it shifting gears when in manual mode. Fast gear shift > pause in 5th > Fast gear shift > Pause in 4th > Fast gear shift > Pause in 3rd > Fast Gear Shift > You are now in second gear.

If you simply go from D to DS, it will drop from 6th to 3rd without the pauses, one tap of the paddle and you arrive at 2nd.

It isn't the transmission shift time, but a built in delay between the shifts activated with the click buttons on the steering wheel.

 

got it, tnx. yes, I understand the dymanics, as I raced cars for a living for 12 years, I just wasn't aware that there is a built-in delay on downshifts when in manual mode. it still shifts a bit slow on the upshift in manual mode, but no worse than a 2015 ZO6 auto that I drove. that was TERRIBLE! the newer XKR's seem to be quite a bit better overall than my 2007. the engine, the sound system, the ELSD, some damper and spring changes, the rotary shift knob, some exterior styling changes, some more creature comforts, etc. i'll probably pull the trigger on a 2012-2014 soon. any notable differences between the 2012-2014 model years? doesn't seem to be any.

 

2012 they changed to what I think is a much better looking side fender vent. The older style is more distinctive, the new style is more mature.

I think the 2012 fender change is much much better than the out going parts it replaced.

 

I think they both look good...a bit of a six of one...

 

Your 2007 has a ZF 6HP26 and the 5.0L cars have the 6HP28. One of the differences mentioned by others is that the gearbox is able to 'miss out' gears when changing down so will in theory change quicker. Not sure if this would make a difference to flappy paddle mode though.