Just saw these words posted by cbcharley10, re tranny maintenance...

I had mine fully serviced at 75K and I have never run her hard or J-gated her much over the years..

I had always thought that not only was J-gating the best way to get optimal performance, but was also easier on the tranny pumps. Am I wrong?

 

Only during steep down grades do I use the J-Gate.

 

Same here, if I wanted a car I had to shift would have bought a manual.

 

My STR with a manual would've been my dream car. In the meantime, I will have to continue to make-do with the j-gate.
In my opinion, real cars should have 3 pedals.

 

Unfortunately, manual transmissions are becoming a thing of the past. They don't shift as fast, gas mileage isn't really any better nowadays, people aren't learning how to drive them, and a lot of new cars are being built with transmissions and engines designed to make each other better (such as the e60 M5: the 7-speed auto was designed for that engine, the manual wasn't and therefore wasn't as effective in delivering power), manuals can't handle the torque of newer cars without wearing out clutches (manufacturers don't want to warranty them), CVTs are becoming common-place, etc. I think the best compromise from a performance perspective is something like the dual-clutch systems in BMW or VW or Ferrari (I'm not even sure if Ferrari offers a manual in any of their new cars), etc. You still get to shift and control the transmission without the "hassle" of a clutch pedal, yet still can use it as an automatic.

 

I drive in sports mode 90% of the time.
In traffic I use the gears just as I would with a manual transmission, just no clutch.
Saves on brakes!
When I'm touring. I try to stay off freeways and always use the less traveled roads. If I happen to be in a place where I do have the opportunity to really drive the car I certainly do and I find the J Gate is totally adequate.
Yea its not a manual but I knew that when I bought the car.
After a few tickets I have also taken to using the speed limiter
The journey is the best part of getting to your destination when you are driving a Jaguar.
I find the J Gate a great compromise to a manual transmission.

Happy New Year from Western Canada

 

Yep, I do believe the automatic GTI with the DSG gearbox is faster than the manual.

I use the J-gate for anticipated acceleration, such as joining a major highway or grabbing an opportunity to overtake. Don't take eyes off road, just change down till rpm's sound like range 3000 - 4000 and GO. Does that cause more stress in the tranny than just using D?

 

It's probably conservatively engineered and just works.

There must be every imaginable driving style among the number of members on here and we're not seeing "I broke it" messages for the 6HP26, so heck just do what works for you.

The 5R55N on the earlier models seems quite good, too, with the odd spring going bad but then they're older and something's gonna give eventually. Plus it's a well-known box so easily fixed.

 

Makes no difference no matter how it's done. The computer decides which gear you can have, not you.

 

Not quite. You can lock out gears using the J-gate and many times (all?) that's why it's used. The computer (TCM for 6HP26, PCM for 5R55N) will stop instant damage, I expect, if the valves/springs/etc don't do that (which they may do).
The result is usually higher revs, perhaps much higher revs, due to not being in the gear the computer would have chosen.

 

If that were true, what is the point of the J-gate?

Surely using the J-gate to change down and raise engine revs prior to anticipated acceleration would be better than putting those massive pressures through the tranny's decision-making valves.

 

Well I don't think it would do that (because it will always defend itself), but it does mean you're already in a gear you think's more appropriate.

 

The ZF's TCM and valve body are programmed to not allow gear selections that are out of the rpm range for that particular gear.

 

I do much the same as well. It seems to me it's easier on the trans than just mashing the accelerator pedal. Most of the time I use the Sport Mode and use Normal as an overdrive once I hit 50 mph or so.

 

I use the J-gate cuz it's fun. Sometimes for a little engine braking under certain circumstances, but mostly just because it's fun. I wish i had a manual but obviously not an option with the STR. Is it slow to react? Sometimes (mostly) yes. Does it always to exactly what you want? Not every time. Am I worried about breaking anything? No.

Is it still fun - to me, yes!

 

Well since (in a round about way I started this thread) I thought I would chime in.

I personally dont think using the J-Gate will cause any actual harm to the car, however I was advised by the guys that did my gearbox rebuild that due to the intricate nature of the ZF it should primarily be used as it was engineered for optimal life expectancy.

As with everything else you have to observe this statement with some temperance. I for one dont feel that we should give up on the "fun aspect" we all get when J-gatting but rather use it wisely and maybe not drive the car as an auto-manual on a daily basis.

I think taking that SPIRITED Sunday drive down a long and winding country road is more than acceptable, I would even go as far as to say a necessity! Afterall why buy such a car if you just plan on lunkering it from point A to point B for work or groceries on a daily basis if thats where you are in life go buy a nice Chevy Cobalt.

The real important thing to watch whether you are using the auto-manual or the straight up auto is PLEASE PLEASE PLEASE be sure that you completely stop the car prior to the shift from Drive to Reverse and vice versa. This is the single and biggest issue I was cautioned about by the rebuilder (who sees hundreds of these not just Jags but BMW Merc etc).

These ZFs dont take well to that slam into drive whilst still rolling backwards. I dont do this and never have but my ex-wife used to do this all the time which I think was part of the reason my valve body failed. (well that and several engineering faults / issues with the early HP26 valve body designs)...

Bottom line: Use the car, enjoy the car, pay attention to the little things but DONT pay any attention to that man behind the Jaguar service counter - Definitely service your ZF gearbox on a regular basis!!

 

Exactly. You can put the J gate into '2' at 150 mph you want- but the transmission will not shift into that gear until the car has slowed enough to avoid over revving the engine. Conversely, selecting '5' while at low speed will not cause it to shift to 5.

At best the J gate gives only semi automatic control over the gearbox.

The 'massive pressures' you're talking about are the same whether in full automatic mode or J gate. No difference.

Not that I'd recommend it, but a person could select reverse while going at full throttle forward in drive. The transmission will NOT go into reverse until the car is almost stopped and the engine at low speed.

 

Interesting, but...

If, prior to acceleration, I manually choose an rpm setting which the computer would have selected in any case, will that not relieve the tranny pumps and valves of some stress and strain - or is the opposite true?

 

If I understand your question and concept of how auto transmissions work, neither. Makes no difference.

 

I doubt it changes the stress etc but it raises the revs sooner so any slight acceleration lag is reduced or removed. I can't see anything wrong other than very slight extra fuel usage. (This is not about braking using the J-gate, of course.)

Now, braking using the J-gate is different and puts very different stresses etc on the driveline than just using the brakes. Probably also tries to raise the trans temperature, too. I expect it's more than rated for it but I say that only based on what good engineers do...