I've been refurbishing an XJR I purchased as a project. It always seemed like there was a dronening noise on the freeway but I thought it might be tires or something. Anyway, I replaced the transmission fluid and have been really paying more attention to the shifts lately. The car is shifting perfectly but I don't think it's going into overdrive. When I'm doing 70 and I put the Jay gate into 4 it doesn't change. It's at about 2100RPM's when doing 70. Any thoughts?

 

I'm at 2100 at 70 as well and I'm pretty sure im in 5th.

 

Does the j gate work in other conditions, like lower speeds?

 

Yes the J gate shifts normally. Does the J gate go right into fourth in manual mode? When you're cruising at 70 and slide it to the left does it drop down?

 

so in doing some gear calculations....2100 in the .831 overdrive 5th with the standard 3.06 diff results in about 64mph.

2300rpm would put you right at 70mph.

2100rpm in 4th gear is 53mph

 

Great math. Thank you. I'll try and find a flat roadway to test again. Nothing changes though when I go into 4th on the J gate. Maybe it doesn't kick out of 5th until you put your foot into.

 

If you're counting shifts and thinking you're in 4th, be aware that when the trans is in normal (aka non-sport) mode, it starts in second gear.

Do any other gears on the manual side of the gate work? Like if you start in 2nd, does it holds second gear or does it upshift? The left side of the gate is electronically controlled, while the PRND side is a physical cable control...I'm wondering if your dual linear switch may be faulty or need a cleaning.

 

Good suggestions here. I was thinking the same thing, that the linear switch might need to be cleaned. Mine was gooey with what looked like old Coca Cola, and it had a ton of cat hair and grime all over it.

 

The Jay gate works fine in lower gears/manual mode. I think the drowning noise must be the diff or carrier bearing instead of being stuck in 4th. Thanks for the info.

 

Update. I took the car out and there is an issue with the J gate as mentioned. When shifted into 4th it doesn't illuminate red. There may be some coke or Red Bull in there. I haven't really messed around with it too much in sport mode. I decided to bury it tonight with it switched on and the car really took off. Scary fast. It always seems to hold 3rd or 4th in normal mode resulting in lackluster acceleration. Thanks again for all the input.
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what type fluid did you use? How did you check the level.

 

The sport mode switch will allow two reverse speeds depending on what position the switch is in.

 

I bought a dipstick off eBay and measured what came out and put that amount back. I used Maxlife fluid. I've got another gallon to run through, Just drain and fill at this point. Don't have to drop the pan again. I think it was the original fluid, It was pretty dark. Also did the connector housing.

1. 

 

The correct fluid is SHELL 134 type or equivalent.
Big discussion a few weeks/months ago on one of the forums.

No idea if MAXLIFE is compatible?(I use ATF 134 in both of my XKRs)

 

It Does exactly what it says on the tin (as the Brits say &#128514
Which is that it's compatable with the Nag1 transmission, which is good enough for me.