Feeling like a Jerk when slowing to a halt

[556129]

I'm a happy owner of a used 2002 local 520i, with about 50,000km on the clock, which I picked up for vios money. Car's been running like clockwork since i picked it up several months ago. By my standards, I push the car pretty hard on outstation trips, running up to 200kmh off and on and its really a great drive.However, recently I've experienced occassional jerks when i come to a slowing halt, but is otherwise totally smooth when accelerating away. I have changed the gearbox fluids and filter, but it still persists. Its as if the gear box couldnt make up its mind when dropping from 5-4-3-2-bump...At this time, its more an annoyance rather than a problem. But its unfortunately a problem when you get used to the butterry smoothness of a flawless car. I'm a little worried the little jerks will become a big bang sometime in the future.Anyone having this problem and managed to solve it? I really hope its something other than the gearbox otherwise I'll just hv to drive till the gearbox gives up the ghost.

 

[bimmer73]

Bro

Get your Gear box reformatted/reprogrammed. Reseting only deletes the error codes which may still be in the ECU memory. Then if it still persist check your Precat O2 sensor, gear box selonoid and fuel and air intake system.....hope This helps

 

[bimmerholic]

Is there new versions of GB software just like the ECU?

 

[jarance]

6129, you mentioned that you change the ATF and filter.. Did your mechanic used the right ATF oil. Using the Wrong ATF will give you problem with your GB..

BTW, how much did you pay for the ATF oil and filter?

 

[astroboy]

Bimmer AT trany has 2 sets of pressure actuators, one for high pressure and one for low pressure.

Low pressure actuator is activated during gear shift allowing clutch packs to slip to remove the shift bumps/jerks.

High pressure actuator is only activated when gear shift has been secured and stopping the clutch pack from slipping.

That's why bimmer auto trany when shifting is so smooth because the clutch packs are allowed to slip, and this action will worn the clutch packs a lot faster than a conventional auto trany. Part of the notorious high wear & tear of bimmer parts, all in the name of smooth driving and passenger comfort.

Sounds like your low pressure actuator is not working for whatever the reason, electronically or mechanically, no slipping of clutch packs during shift and created the hesitation of shift, high pressure actuator running full time. Jerks are more obvious during downshift. Pickup and upshift must be damn power because no slipping of clutch..

 

[jaleeks23]

Can the low pressure actuator be changed/replaced? Cost of replacement? Are they also known as solenoids? I had a GB overhaul early this year year, then did a full reset...but I still have the jerk when slowing down however the jerk is not prominent when I use manual....Since overhaul, the GB has covered less than 30k mileage, with 1st service at 5k and 2nd service soon at 25k.
When I do hard braking to stop the car at a higher rate, the jerk is more prominent when compared to normal slowing down.
Thank you.

 

[bmw7833]

Bimmer AT trany has 2 sets of pressure actuators, one for high pressure and one for low pressure.

Low pressure actuator is activated during gear shift allowing clutch packs to slip to remove the shift bumps/jerks.

High pressure actuator is only activated when gear shift has been secured and stopping the clutch pack from slipping.

That's why bimmer auto trany when shifting is so smooth because the clutch packs are allowed to slip, and this action will worn the clutch packs a lot faster than a conventional auto trany. Part of the notorious high wear & tear of bimmer parts, all in the name of smooth driving and passenger comfort.

Sounds like your low pressure actuator is not working for whatever the reason, electronically or mechanically, no slipping of clutch packs during shift and created the hesitation of shift, high pressure actuator running full time. Jerks are more obvious during downshift. Pickup and upshift must be damn power because no slipping of clutch..

Good info..:top: But can only the low pressure actuator to be change?

 

[astroboy]

Can the low pressure actuator be changed/replaced? Cost of replacement? Are they also known as solenoids? I had a GB overhaul early this year year, then did a full reset...but I still have the jerk when slowing down however the jerk is not prominent when I use manual....Since overhaul, the GB has covered less than 30k mileage, with 1st service at 5k and 2nd service soon at 25k.
When I do hard braking to stop the car at a higher rate, the jerk is more prominent when compared to normal slowing down.
Thank you.

Yes! They are also called solenoids.. can be changed. But involving dismantling of GB le. But what triggered the solenoids need to be inspected too. Maybe just ECU programming or sensors which if not working correctly, replacing solenoids won't solve your problem.

Can be ATF wrong grade, can be clogged ATF veins, can be loose connectors... can be so many reasons la. Manual trany no such headaches..

 

[jarance]

Yes! They are also called solenoids.. can be changed. But involving dismantling of GB le. But what triggered the solenoids need to be inspected too. Maybe just ECU programming or sensors which if not working correctly, replacing solenoids won't solve your problem.

Can be ATF wrong grade, can be clogged ATF veins, can be loose connectors... can be so many reasons la. Manual trany no such headaches..

No need to dismantle GB to change solenoid. Once you remove the oil sump, you can access the filter and solenoid control module.:smokin:

 

[jarance]

Yes! They are also called solenoids.. can be changed. But involving dismantling of GB le. But what triggered the solenoids need to be inspected too. Maybe just ECU programming or sensors which if not working correctly, replacing solenoids won't solve your problem.

Can be ATF wrong grade, can be clogged ATF veins, can be loose connectors... can be so many reasons la. Manual trany no such headaches..

No need to dismantle GB to change solenoid. Once you remove the oil sump, you can access the filter and solenoid control module.:smokin:

 

[astroboy]

Ooo... but if the GB recently overhauled, how come solenoid not replaced? Or its not meant to be a wear&tear replacement item? I had a friend who buka the E34 AT trany and overhaul himself, he spent a good few grand just to buy parts.. end up after the job, sold the E34 lio... too complicated and costly to run an E34 by his standard. Made me worried for a while there..

 

[556129]

6129, you mentioned that you change the ATF and filter.. Did your mechanic used the right ATF oil. Using the Wrong ATF will give you problem with your GB..

BTW, how much did you pay for the ATF oil and filter?

Hi, I paid about RM500ish for the ATF and the filter. Got it done at Heritage, and I should think they used the right ATF since they only do bimmers.

Thanks for the replies guys. Its beginning to sound more like the solenoids or low pressure actuator. I did the atf change only after the jerky problems started to become more obvious.

Someone mentioned valve body as a potential problem as well, although i hv no idea what that means except that it costs $$$

 

[556129]

Can the low pressure actuator be changed/replaced? Cost of replacement? Are they also known as solenoids? I had a GB overhaul early this year year, then did a full reset...but I still have the jerk when slowing down however the jerk is not prominent when I use manual....Since overhaul, the GB has covered less than 30k mileage, with 1st service at 5k and 2nd service soon at 25k.
When I do hard braking to stop the car at a higher rate, the jerk is more prominent when compared to normal slowing down.
Thank you.

Dude, sounds like we have the exact same problem. In sports mode, I dont get the jerk when slowing down as well. I'm wondering how much these pressure actuators cost??

 

[jarance]

Hi, I paid about RM500ish for the ATF and the filter. Got it done at Heritage, and I should think they used the right ATF since they only do bimmers.

Thanks for the replies guys. Its beginning to sound more like the solenoids or low pressure actuator. I did the atf change only after the jerky problems started to become more obvious.

Someone mentioned valve body as a potential problem as well, although i hv no idea what that means except that it costs $$$

Yup, if you have the jerky problem prior to changing the ATF and filter and the problem still persist, then the cause is not the ATF.

Time to look at the solenoid. The solenoid can be test by a GT1 module. Alarm are registered and will tell you which solenoid is faulty.

Unfortunately, if you need to replace the solenoid, you will need to replace the ATF even though it have been replaced recently. Reason is that the ATF might be contaminate during the draining..

So another RM300+ for the ATF oil again. Normally, it is common practice all the 3 or 4 set of solenoids when 1 of them is faulty.

 

[jaleeks23]

I was told solenoids are not included in the GB overhaul...i hope i wasn't cheated....my GB is 5HP19...
Question, are the solenoids part of the valvebody or are they different parts in the GB?

 

[jaleeks23]

BTW, so far, there's no alarm shown that indicates solenoid issue......next question, what sends signals to the solenoid?

 

[XXX]

...oh! this thread abt Gearbox...I was wondering , how is it when slowing to a halt can make you Feel like a jerk.....:love:

 

[king82]

good one XXX

 

[bmw7833]

Damn, seems this is the common problem for old folk e39..

 

[Dan08]

Izit the jerk comes in when it is ABOUT to stop as if the GB downshift to 1st gear? Pls describe the jerk..