First gears are not happy

[haigha]

Originally Posted by EODguy

I am by no means an expert transmission guy but, I'd guess you are leaking between the D and E channels in the valve body leading to that high reading and 0 refill time (cause it's already full?) I hope RRRPhil sees this thread and chimes in because he is an actual transmission expert.

My values before the reset were:

Pressure: -140, 185, -135, -92, 204
Rapid Refill: -2, 26, 19, 0, 0

I had a different problem and the values are quite different. However we both have 0, 0 for refill on D and E.

As you wrote, hopefully Rapid Refill Phil will chime in

[grounch]

I have a bit more info about that case.
Wrote to ZF and they told me that the 750 value might be a leaking E clutch.
Or a failing solenoid. Or a leaky/sticky valve.


I also found an old ISTA print from a year ago, and the values were quite similar to today so i don't think it's related to that recent continuous jerk at low speed.

But possible related to the bump from 2 to 1 which always been here.


Could it be a transfer box or read diff issue?

[andrewwynn]

You can disable the TC by pulling a particular fuse. If the symptom is easy to reproduce you can test if it's coming from the TC. (if your truck is new enough to have x-drive.)

Google for which fuse. When you pull it your wipers may run continuously like the E90 I was working on. You can maybe also pull the wiper fuse.

You can measure your exact rolling circumference: put a dab of something on the front and rear tire such as grease or peanut butter and drive fwd. Find the marks and measure to the nearest 16th inch.

BMW spec is tires within 3% of original size and 1% between axles.

87.6" is the expected rolling circumference most E53 tires.

87.6/100=7/8" must be less than 7/8" difference and actually I just saw that bmw says 2mm max tread depth difference which prob works out to even less.

2225/π= 708.26 mm

704.26*3.1415=2212.433

2212/2225=0.994 that's only 6/10 of 1% difference.

There are regular threads about jerky performance and even TC self destruct from a single tire being replaced.

[andrewwynn]

Low speed continuous jerk can be from CV or front drive prop. Just throwing that out.


Sent from my iPhone using Tapatalk Pro

[Squiggy]

Originally Posted by grounch

So you say i should be able to do such complicated operation on my parking lot?

I no longer work under my X5 in parking lots. It's a safety issue. Everything I'm doing might be safe but I can't predict when some driver might swing into the parking lot and hit my car while I am under it.

[grounch]

Originally Posted by Squiggy

I no longer work under my X5 in parking lots. It's a safety issue. Everything I'm doing might be safe but I can't predict when some driver might swing into the parking lot and hit my car while I am under it.

It's a private parking with a passing rate of 2 cars a day so safety wise I'm not really concerned. More about the accessibility to all the things down there

[grounch]

Narrowed down the issue cause. Unplugged the TC connector, jerking gone.
So i guess the tc did not liked the change of only 2 tires, even if the thread difference was bigger with the used rear ones.
I'll plan to do a tc oil change and reset (and ideally change the 2 remaining tires) meanwhile will drive in 2wd to avoid any extra wear.

Could a reset only make a difference in relearning to behave with new tires size?

[omodos]

Originally Posted by grounch

Narrowed down the issue cause. Unplugged the TC connector, jerking gone.
So i guess the tc did not liked the change of only 2 tires, even if the thread difference was bigger with the used rear ones.
I'll plan to do a tc oil change and reset (and ideally change the 2 remaining tires) meanwhile will drive in 2wd to avoid any extra wear.

Could a reset only make a difference in relearning to behave with new tires size?

Hi Grounch curious, I had reverse problem, replaced fronts and had this weird shudders behaviour, replaced all 4 tires with new ones and was ok, didn't do any resets relearing after new tires.....

[andrewwynn]

Originally Posted by grounch

Narrowed down the issue cause. Unplugged the TC connector, jerking gone.
So i guess the tc did not liked the change of only 2 tires, even if the thread difference was bigger with the used rear ones.
I'll plan to do a tc oil change and reset (and ideally change the 2 remaining tires) meanwhile will drive in 2wd to avoid any extra wear.

Could a reset only make a difference in relearning to behave with new tires size?

No, you can't train the TC to be happy when different size tires are front and back axle. It's not about tread depth if the tires are different models it's rolling circumference. You can measure this by putting a dot of grease or similar on all tires and driving then measure the distance between the dots.

7.3 ft is the baseline 2225mm the car expects. 87.6" ± 1% 86.7—88.5 should be the limits.