Slight jolt/thump at stop lights

asiflicious · 05-03-2018, 11:53 AM

Hey everyone, over the last few weeks I've been noticing a slight jolt/thump from what feels like the rear end when at stop lights with my foot on the brake. It'll happen a few seconds after coming to a complete stop and only happens once. It's slight but enough to be felt and move the car a bit. Any ideas?

chris_flies · 05-04-2018, 08:36 AM

Quote:

Originally Posted by asiflicious

Hey everyone, over the last few weeks I've been noticing a slight jolt/thump from what feels like the rear end when at stop lights with my foot on the brake. It'll happen a few seconds after coming to a complete stop and only happens once. It's slight but enough to be felt and move the car a bit. Any ideas?

Could be the transmission shifting back into first, you do have an auto, right?

I don't know how these trannies are programmed, but a lot of very modern ones won't shift to first until you're stopped...

Esteban · 05-04-2018, 12:20 PM

I had an '08 with the Steptronic transmission and I never got any kind of jolt or thump when I came to a stop.

1and1 · 05-04-2018, 12:32 PM

Symptoms would change, if only slightly, by repeating in S and M modes.

If not gear change/trans, then it sounds like something is binding up a bit, and releasing after you come to a stop?

asiflicious · 05-04-2018, 12:34 PM

Quote:

Originally Posted by chris_flies

Quote:

Originally Posted by asiflicious

Hey everyone, over the last few weeks I've been noticing a slight jolt/thump from what feels like the rear end when at stop lights with my foot on the brake. It'll happen a few seconds after coming to a complete stop and only happens once. It's slight but enough to be felt and move the car a bit. Any ideas?

Could be the transmission shifting back into first, you do have an auto, right?

I don't know how these trannies are programmed, but a lot of very modern ones won't shift to first until you're stopped...

That's what I thought originally because that's exactly what it felt like but then I noticed it do it even after already being in first gear

asiflicious · 05-04-2018, 12:35 PM

Quote:

Originally Posted by 1and1

Symptoms would change, if only slightly, by repeating in S and M modes.

If not gear change/trans, then it sounds like something is binding up a bit, and releasing after you come to a stop?

Hm I haven't tried it in M or S but that is what it feels like

1and1 · 05-04-2018, 05:14 PM

Sorry for the lame question, but I really just don't pay enough attention....

Have you done any coding on the trans? Alpina, or xHP?

Really what I'm looking for is troubleshooting 101- split the problem in half, then see which half is screwed up. Keep doing it till you run out of stuff to cut in half and you're most likely looking at the culprit.

In this case, perhaps thirds- trans, driveshaft and it's stuff (guibo, center bearing etc) or diff & beyond (brakes).

Trans is easy- change something- From D mode to S or M modes, or if coding is involved, change the coding.

If symptoms remain then try with e-brake one click up (one click only please...).

Drop it in neutral as you roll up to a stop and learn what it does...

One at a time change anything, everything. Test for effect and learn what changes....

05-03-2018, 11:53 AM	#1
asiflicious Captain 711 Rep 971 Posts Drives: 2018 M2 Join Date: Aug 2017 Location: Winchester, CA iTrader: (0) Garage List 2018 BMW M2 [10.00]	Slight jolt/thump at stop lights Hey everyone, over the last few weeks I've been noticing a slight jolt/thump from what feels like the rear end when at stop lights with my foot on the brake. It'll happen a few seconds after coming to a complete stop and only happens once. It's slight but enough to be felt and move the car a bit. Any ideas?
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05-04-2018, 12:20 PM	#3
Esteban Major General 44454 Rep 7,227 Posts Drives: a slow car fast Join Date: Jun 2014 Location: SoCal iTrader: (0)	I had an '08 with the Steptronic transmission and I never got any kind of jolt or thump when I came to a stop. __________________
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05-04-2018, 12:32 PM	#4
1and1 Loves me some MHD! 1864 Rep 1,725 Posts Drives: faster than he should... Join Date: Jul 2016 Location: Tally, FL iTrader: (2) Garage List '09 135i [10.00]	Symptoms would change, if only slightly, by repeating in S and M modes. If not gear change/trans, then it sounds like something is binding up a bit, and releasing after you come to a stop? __________________ 1and1 135i - E82.N54 2009 BSM - MHD / xHP / DCI, PR CP & 7.5" Race IC / N55 mid & Borla . . WL RSFI, Koni, Eibach & Dinan CP's, M3 CA's / EBC Red's & Firehawk 500's X1 - E84.N20 2013 MGM - JB4 - The Wife's, now with new turbo & ewg
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05-04-2018, 05:14 PM	#7
1and1 Loves me some MHD! 1864 Rep 1,725 Posts Drives: faster than he should... Join Date: Jul 2016 Location: Tally, FL iTrader: (2) Garage List '09 135i [10.00]	Sorry for the lame question, but I really just don't pay enough attention.... Have you done any coding on the trans? Alpina, or xHP? Really what I'm looking for is troubleshooting 101- split the problem in half, then see which half is screwed up. Keep doing it till you run out of stuff to cut in half and you're most likely looking at the culprit. In this case, perhaps thirds- trans, driveshaft and it's stuff (guibo, center bearing etc) or diff & beyond (brakes). Trans is easy- change something- From D mode to S or M modes, or if coding is involved, change the coding. If symptoms remain then try with e-brake one click up (one click only please...). Drop it in neutral as you roll up to a stop and learn what it does... One at a time change anything, everything. Test for effect and learn what changes.... __________________ 1and1 135i - E82.N54 2009 BSM - MHD / xHP / DCI, PR CP & 7.5" Race IC / N55 mid & Borla . . WL RSFI, Koni, Eibach & Dinan CP's, M3 CA's / EBC Red's & Firehawk 500's X1 - E84.N20 2013 MGM - JB4 - The Wife's, now with new turbo & ewg
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