Got a BMW 3 SERIES auto,the automobile jerks when a upon a reduce gears,the garage pronounced when a automobile is negligence down a rigging box is anticipating it formidable to tumble upon to a aloft gears as a result jerking,the mechanism indicates no faults upon a rigging box,the garage says rigging box needs to be transposed ,i have my doubts suspicion would get a experts opinion.Could it be injector oil or someting elementary similar to that,please help.Thank you.

I would start with a Complete Transmission Fluid Flush…and a filter change while you got them under the car…
You could be surprised at what fresh fluid can do for it, i know i though i needed to replace a trans once and was told to do a fluid flush and filter first to see if it helps… i wont ever forget to pass this on…
See if this helps, if not then get another opinion from a different transmission shop.
Best wishes,
“/JOe
Hi ya.
Well after spending 32yrs rebuilding automatic transmissions, i have always found it quite difficult in diagnosing over the phone. Only because a persons description isn’t always accurate. No fault of their own. Any way here goes.
If your computer memory doesn’t have any fault codes, you can bet that if it is the transmission, it will be a mechanical or a hydrolic problem. Computers only diagnose electronic faults. Now comes the hard part. LOL.
I have found that if a transmission has been over heated to a serious degree, sometimes a particular clutch pack can sometimes fues them selves together. This makes that clutch pack not want to disengage when slowing down. Then it will cause a symptom of what you describe.
The other problem you may have could be a valve body fault. The valve bodies have very small rubber balls in them that block of cirtain holes at a given time. This lets oil go to another part of the valve body alowing the trans to perform another task.
The last thing is that its not the transmission at all. I would sugest that you drive the car manualy and see if it still does it. It’s imperitive that you know what gear the car is in when it does it. And try another dealer. Hope this helps. Hope i didn’t complicate things to much. LOL
Laurie