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-   -   325i Gearbox Issue? Jerk to stop and accelerate (http://www.bimmerfest.com/forums/showthread.php?t=654329)

kmbaczynski 10-26-2012 03:17 PM

325i Gearbox Issue? Jerk to stop and accelerate
 
Picked up my 325i last weekend, great car. It's got the Steptronic transmission.

I've done a little bit of searching on this problem and there seem to be conflicting answers.

When I take my foot off the brake of my car it jerks forward and seems to really want to go, and when I stop I'm really having some difficulty doing it smoothly.

I've seen people say that something needs to be reprogrammed? Taking it in to an indy shop down the street next weekend for an oil change so if I can get that done at the same time if it needs to be changed.

I've also seen people indicate that the stock pads are really "sticky" (what? isn't that what they're supposed to do). Or that there may be a problem in the differential.

Any advice? Thanks!

CALWATERBOY 10-26-2012 05:48 PM

Quote:

Originally Posted by kmbaczynski (Post 7159824)
Any advice? Thanks!

Test drive before you buy.

Do a PPI.

Negotiate a warranty.

Discover why it's on the market. Arguably you've today done this.

kmbaczynski 10-26-2012 09:30 PM

Quote:

Originally Posted by CALWATERBOY (Post 7160098)
Test drive before you buy.

Do a PPI.

Negotiate a warranty.

Discover why it's on the market. Arguably you've today done this.

Thanks for your response. I did test drive the car; the issue wasn't bad enough for me to notice at the time and still isn't *terrible*, but it's slightly annoying that the car lurches forward when I take my foot off the brake.

I was more curious if anyone had any suggestions as to what it might be (or is it normal behavior?). It is within my means to pay to have my car repaired, please don't mistake this for buyer's remorse. I got an awesome deal on it.

aleks001 10-27-2012 12:46 AM

Quote:

Originally Posted by kmbaczynski (Post 7159824)
Picked up my 325i last weekend, great car. It's got the Steptronic transmission.

I've done a little bit of searching on this problem and there seem to be conflicting answers.

When I take my foot off the brake of my car it jerks forward and seems to really want to go, and when I stop I'm really having some difficulty doing it smoothly.

I've seen people say that something needs to be reprogrammed? Taking it in to an indy shop down the street next weekend for an oil change so if I can get that done at the same time if it needs to be changed.

I've also seen people indicate that the stock pads are really "sticky" (what? isn't that what they're supposed to do). Or that there may be a problem in the differential.

Any advice? Thanks!

I have a feeling that you're brake booster valve needs replacing. It's such a small annoying thing that causes so many random issues with the car. Also have a look at using a gasket sealer to seal the new one properly, it's pretty much faulty brand new in terms of keeping pressure on a lot of cars.

dallas70 10-27-2012 04:54 AM

If it makes you feel any better, I bought my 325i almost 4 yrs ago as a CPO w/23k miles on it and it has always done what you describe (definitely just a brake pad issue; not differential or brake booster). The brakes are "sticky" just as I come to that last couple of inches to stop or take off from a stop, making it difficult to be completely smooth. I mentioned it to the service guys the first time I took it in for service and was told they're working as designed. I'm still on the original front pads w/about 60k miles and just changed the rear pads and flushed the brake fluid several weeks ago; no difference in braking (changed the fluid a couple of years ago also with no noted performance difference). Great brakes so I can deal with the minor stickiness at a stop. I may consider switching to different front pads (non-OEM) when they're due as you'll find some great recommendations here, but I've been satisfied with the performance.

A longwinded response but in a nutshell - I wouldn't worry about it.

BTW, I've driven a couple of newer 3's as loaners over the years - slightly less brake stickiness than mine but very little difference. It's a design thing. Search the forum for good pad recommendations.

kmbaczynski 10-27-2012 07:23 AM

Quote:

Originally Posted by aleks001 (Post 7160606)
I have a feeling that you're brake booster valve needs replacing. It's such a small annoying thing that causes so many random issues with the car. Also have a look at using a gasket sealer to seal the new one properly, it's pretty much faulty brand new in terms of keeping pressure on a lot of cars.

Thanks for your response. I feel like the brake pedal would be hard if this was the issue. While it's certainly much harder than my old Grand Prix, it doesn't feel any harder than other cars I've driven. This is provided you're talking about the check valve, not a different one. Might throw a vacuum code too???

Quote:

Originally Posted by dallas70 (Post 7160660)
If it makes you feel any better, I bought my 325i almost 4 yrs ago as a CPO w/23k miles on it and it has always done what you describe (definitely just a brake pad issue; not differential or brake booster). The brakes are "sticky" just as I come to that last couple of inches to stop or take off from a stop, making it difficult to be completely smooth. I mentioned it to the service guys the first time I took it in for service and was told they're working as designed. I'm still on the original front pads w/about 60k miles and just changed the rear pads and flushed the brake fluid several weeks ago; no difference in braking (changed the fluid a couple of years ago also with no noted performance difference). Great brakes so I can deal with the minor stickiness at a stop. I may consider switching to different front pads (non-OEM) when they're due as you'll find some great recommendations here, but I've been satisfied with the performance.

A longwinded response but in a nutshell - I wouldn't worry about it.

BTW, I've driven a couple of newer 3's as loaners over the years - slightly less brake stickiness than mine but very little difference. It's a design thing. Search the forum for good pad recommendations.

Thanks for your response. This does put my mind at ease a bit; I haven't driven another 3 before but 5's and 6's and they behave rather differently it seems. The OEM brakes do seem stellar so I probably wouldn't look for aftermarket ones; it's just unexpected. I'm coming from a car that's got +120HP/lbft torque and so it's a little strange so have the 325i "launch" itself when I take my foot off the brake.

CALWATERBOY 10-27-2012 09:59 AM

Quote:

Originally Posted by kmbaczynski (Post 7159824)
Picked up my 325i last weekend, great car. It's got the Steptronic transmission.

I've done a little bit of searching on this problem and there seem to be conflicting answers.

When I take my foot off the brake of my car it jerks forward and seems to really want to go, and when I stop I'm really having some difficulty doing it smoothly.

I've seen people say that something needs to be reprogrammed? Taking it in to an indy shop down the street next weekend for an oil change so if I can get that done at the same time if it needs to be changed.

I've also seen people indicate that the stock pads are really "sticky" (what? isn't that what they're supposed to do). Or that there may be a problem in the differential.

Any advice? Thanks!


Jerk from standing stop isn't normal - that needs attention.

Smooth stop is really elusive in these cars. If you can do the golf tee mod, it'll help.

Real finesse and foot feel's needed to stop smoothly - it can be done.

bramp 11-12-2012 07:00 PM

Shifting
 
I have the same problem and my service advisor told me since the car was purchased used they may need to reset the computer or memory something to that effect. I am going to get my car back tomorrow so I will let you know if it works, also can let you know exactly what they did if it is fixed.
Thanks,

kmorgan_260 11-12-2012 07:08 PM

I went with ceramic pads when I did my brake job and they are smoother than the OEM pads. Also much less dust.

aleks001 11-12-2012 08:05 PM

Quote:

Originally Posted by kmbaczynski (Post 7160776)
Thanks for your response. I feel like the brake pedal would be hard if this was the issue. While it's certainly much harder than my old Grand Prix, it doesn't feel any harder than other cars I've driven. This is provided you're talking about the check valve, not a different one. Might throw a vacuum code too???

Hey, yes this is the valve and no it won't throw any codes. When you get into your car after say a longer period of standing is your brake pedal hard ?

The only reason I throw this out there is because this bloody valve caused so many little annoying issues for me. I finally resolved it by replacing the valve.

The main two issues i had was feeling a little push when i was at the lights, after releasing the brake pedal even on level ground it would take 3-5 seconds for the brakes to let go and finally, a hard brake pedal in the morning when I went to start the car.

The sticking issue was resolved with a new valve, but the other issues were resolved by using a gasket maker sealent, now after 3 days stationary my brake pedal is still soft to press when I go to start the car.

Once your car is running I don't believe the brake booster valve makes any difference to your braking.

Squidget 11-12-2012 11:51 PM

Quote:

Originally Posted by kmbaczynski (Post 7159824)
When I take my foot off the brake of my car it jerks forward and seems to really want to go, and when I stop I'm really having some difficulty doing it smoothly.

Define "difficulty stopping smoothly." Is does it feel like the transmission is fighting you?

Because a common problem is that transmissions can be really jerky sometimes. It's actually not the brakes, it's the transmission hunting for the wrong gear at the wrong time, and upsetting the car's motion.

It's relatively easy to test brakes. Get up to short speed, force the transmission into Neutral, then apply braking. With the transmission out of the picture, you should better be able to tell if the brakes are actually sticky.

For what it's worth, I'm not buying the "by design" explanation. Dealers always say that. Brakes should be smooth and progressive; they definitely are in my BMW.

dallas70 11-13-2012 06:14 PM

Quote:

Originally Posted by aleks001 (Post 7191410)
Hey, yes this is the valve and no it won't throw any codes. When you get into your car after say a longer period of standing is your brake pedal hard ?

The only reason I throw this out there is because this bloody valve caused so many little annoying issues for me. I finally resolved it by replacing the valve.

The main two issues i had was feeling a little push when i was at the lights, after releasing the brake pedal even on level ground it would take 3-5 seconds for the brakes to let go and finally, a hard brake pedal in the morning when I went to start the car.

The sticking issue was resolved with a new valve, but the other issues were resolved by using a gasket maker sealent, now after 3 days stationary my brake pedal is still soft to press when I go to start the car.

Once your car is running I don't believe the brake booster valve makes any difference to your braking.

Great info - thanks for the details. Since you added the detail about the symptoms related to that valve I'm guessing that has been the cause of my brake "stickiness" since I bought the car and just assumed that's the way it's supposed to be (though my symptoms are a little less severe than what you mentioned).


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