Does anyone know the correct RPM/Speed(MPH) shift points for the XJR transmission, both in "Sport" and "Normal".

I have a suspicion mine is shifting early, but am curious what the spec is.

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At WOT mine always shifted at exactly 5500 RPM in sport or regular mode. That was about 50 mph in first, 75 mph in second, and over 100 in third.

At minimum throttle the shifts were more like 15, 20, and 35 mph in regular mode and maybe 20 30, and 40 in sport mode.

At anything between minimum throttle and WOT the shifts could fall anywhere between what I mentioned above, depending on load and throttle opening.

What is yours shifting at?

Cheers
DD

 

I haven't taken the time to look at WOT, but the light throttle points of 15, 25 and 35 at around 2-3000RPM align with your observations, so that's good news.

I currently have the "switch" unplugged with my console top apart. Not sure if that matters at all.

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Well, after some unscientific testing, I think all is well with the shift points based on Doug's comments above, along with some reading up on the 4L80E where some implementations show nearly 70MPH in first gear.

But I do wonder how smooth the shifts are for those with the 4L80E equipped XJR especially between 1st and 2nd under part throttle?

I seem to get a pretty noticeable drop in RPM/power, almost as if I've lifted off the throttle. It doesn't really seem normal, although now that I think about it..... I seem to remember a similar experience with my 1989 Suburban that had the same transmission..... so maybe this is typical for the 4L80E as I've also read some accounts of big RPM drops for 1-2 shifts in the 4L80E in other applications.

I do know that depending on my driving style I can minimize this RPM/power drop between 1-2, and to a lesser degree 2-3 gear shifts

But for slow speed part throttle pull away, the 1-2 power drop and perceived minor 'lurch' seems to exhibit what I think is un-Jaguar behavior I'd be surprised is by design.

What is your experience, completely smooth shifts as you pull away under part throttle, or moderate gaps/drops between 1st-2nd at times almost as if fuel is cut back?

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From time-to-time (no particular pattern) I would notice what seemed to be a drop of power on the 1-2 shift. It never happened enough to research or draw any conclusions. A little weird. Like hitting a sour spot on the power curve.

The timing is momentarily retarded at each upshift. That might play in. Some sort of glitch?

Also weird....don't laugh....but the engine sometimes felt much more power when making a right turn.

Cheers
DD

 

Mine... sport mode full throttle shifts at redline. 500 short in regular mode, again at full throttle. The shifts are typical older auto box soft drop in rpm to next gear at that rpm. Now oddly enough if mine is what is normal for a healthy example... then it's the lower range upshifts I prefer. But, they are probably nothing more than me "tricking" the shift points. If I accelerate with decent torque load but not full open and give it a little more at just the right moment, you get that paddle shift sequential style shift. Feels awesome and sounds really nice with the supercharger whine changing as well. Wish it shifted like that all the time. On the other hand every once in a while for no obvious reason the transmission fault light comes on and it doesnt have ANY "cushion" on upshifts at all. Really IS like a sequential racing box. I immediately stop the car and restart to clear. Because a heavy torque upshift like that would probably twist the rear end to pieces.