[jcastag]

I am hoping this is not a ridiculous question.

I believe my car has the TC shuuder, and the dealer says that is does and they are going to replace the TC for me.

I know that the shudder usually happens between 40-70MPH on my car. And as we all know, it feels alot like rumble strips, bent wheel, bad balance, etc.

If you shift your car into neutral at those speeds does or would the shutter go away?

What does the dealer do exactly to diagnose the issue? Does the ECM or TCM show different readings than a "normal" fuctioning TC?

Just curious.....

[zr1chris]

I would think that it should definitely go away in neutral but I could be wrong.

[Mark114]

The transmission shudder is generally caused when the torque converter is trying to allow slip between the engine speed and the car speed and instead of slipping smoothly the TC shudders. People seem to notice it most commonly when driving on the highway on a road with a slight incline. I would not expect you to feel shudder when the transmission is in neutral as there wouldn't be any force on the TC.

There is a GM Technical Service Bulletin that gives a service tech specific steps to perform and specific results to look for to diagnose the shudder. The procedure is done by a service tech driving the car with a laptop running diagnostic software connected to the OBD port.

[urirx98]

i have been getting that same shutter aswell. i Couldnt tell if it was the road, my tires or the transmission but im glad someone else posted about it. I would say its also in the 40-60mph area and its deff not alignment!

[urirx98]

Just made appointment to have my car checked out for the shuttering feeling, Ill keep you all updated!

[crosive]

the shudder is caused by the tc going from the low pressure pump, allowing slip, and seeing it, to locking it down with the high pressure pump. The process repeats several times. doing this causes the shudder.

you will not feel it in neutral because that whole mechanism is disengaged.

[urirx98]

Originally Posted by crosive

the shudder is caused by the tc going from the low pressure pump, allowing slip, and seeing it, to locking it down with the high pressure pump. The process repeats several times. doing this causes the shudder.

you will not feel it in neutral because that whole mechanism is disengaged.

It is quite annoying, it really feels like your constantly driving over rumble strips. I was thinkin it was my tires or alignment but ill let them diagnosis it.

[crosive]

Originally Posted by urirx98

It is quite annoying, it really feels like your constantly driving over rumble strips. I was thinkin it was my tires or alignment but ill let them diagnosis it.

ok so here's the fun part. I had the rumble. I've had it flushed twice, and the tc replaced.

Having said that, I have a vibration that is tire related, but feels similar to the shudder.

my tires are out of spec according to the road force balancer, and when that vibration syncs, it causes a pulsing vibration that I can completely see how you'd think it's a part of the tc issue, but is not. I do believe the only way to truly see if it's the tc shudder or not, is to log and watch the slip when it happens, and/or put a pico scope on the transmission and listen for 20/40 hz (I forget which) coming from it when it slips.

[urirx98]

Originally Posted by crosive

ok so here's the fun part. I had the rumble. I've had it flushed twice, and the tc replaced.

Having said that, I have a vibration that is tire related, but feels similar to the shudder.

my tires are out of spec according to the road force balancer, and when that vibration syncs, it causes a pulsing vibration that I can completely see how you'd think it's a part of the tc issue, but is not.

Im deff not saying its not tire related, my front tires have 12k plus on them over technically almost 2 years. I bought car used in January with 3800 miles but the car was originally bought and returned in 2016, then sold again in March of 17. It sat at dealer from like Oct 17 til Jan 18 when i bought it. The tires look good but since they are RUN FLATS which are deff harder on the road, it could be them. If they tell me its tire related without doing testing ill be pissed lol

[crosive]

Originally Posted by urirx98

Im deff not saying its not tire related, my front tires have 12k plus on them over technically almost 2 years. I bought car used in January with 3800 miles but the car was originally bought and returned in 2016, then sold again in March of 17. It sat at dealer from like Oct 17 til Jan 18 when i bought it. The tires look good but since they are RUN FLATS which are deff harder on the road, it could be them. If they tell me its tire related without doing testing ill be pissed lol

well as I said, I'm not saying it's either or, it's just something to think about. my tires started pulsing at around 15k. I had them tested at 18k and had them fixed, to the best they could. they're at 20k now and I can still feel them, but nothing like what they were. they're also cupping because the stock alignment sucks.

[jcastag]

So good news and bad news.

Brought the car in for TC replacement and it took a full day. Picked up the car today and it is like a totally different car. There was definitely shudder. Between about 40-60 and that is gone. Yay!!

Unfortunately I get a little wheel vibration at 55 now so it seems I also need a wheel balance.

It's like I can't win. Lol

[urirx98]

Originally Posted by crosive

well as I said, I'm not saying it's either or, it's just something to think about. my tires started pulsing at around 15k. I had them tested at 18k and had them fixed, to the best they could. they're at 20k now and I can still feel them, but nothing like what they were. they're also cupping because the stock alignment sucks.

What size tires and rims do you have? I have the 20s with run flats that are so hard, you feel everything in the road. I sort of wish i had the magnetic ride control but unfort there wasnt many 2ss's on market when i was looking for a car. And considering i got this with 3800 miles and a cert preowned, it was pretty much a steal. Hopefully all issues get cleared

[crosive]

Originally Posted by urirx98

What size tires and rims do you have? I have the 20s with run flats that are so hard, you feel everything in the road. I sort of wish i had the magnetic ride control but unfort there wasnt many 2ss's on market when i was looking for a car. And considering i got this with 3800 miles and a cert preowned, it was pretty much a steal. Hopefully all issues get cleared

I have the stock tires/rims still, but I do have mrc. the pulsing is a tad more prominent in sport and touring mode, but only if you're looking for it.

I'm going with a non runflat tire after these, I do not like them.

[urirx98]

yeah i totally feel ya on the run flats, they are deff way to hard, but the pulsing for me is during touring mode and it seems everytime i slowly go from 40 to 60. hoping they can fix it. A friend was saying i should disconnect the battery and that could reset things also. I will mention that at the checkup tuesday