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05 1500 cc with vibration on stop w/new 20s


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I have a new 2005 GMC Sierra 1500 crew cab 2wd. It now has 2000 miles on it, and i just had a set of 20s with goodyear tires installed, mounted balanced..everything. NOW..every time you touch the brake pedal, there is what feels like an ABS vibration through the brake pedal. It was NEvEr there before. Has anyone had this problem? Something was said about a VCI number and reprogramming the ECBM? Can anyone tell me they have had this problem and that doing this fixed it? ANY help would be GREATLY appreciated.

THANKS

TONY

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I pulled this from another post on a different forum. GM stopped putting 20's on the CC trucks because it could cause damage to the suspension bracket. The vibration seems to be a different issue. Maybe this link will shed some light. Read GM-Tech's posts.

 

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Could be you had weak rotors from the factory, and the 20's were enough extra strain to kill them. Take it to the dealer and see what they'll do for you as far as warranty goes. I would insist on new rotors over simply having the existing ones turned, turning them would just make the matter worse, if that were the issue at all.

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Could be you had weak rotors from the factory, and the 20's were enough extra strain to kill them. Take it to the dealer and see what they'll do for you as far as warranty goes. I would insist on new rotors over simply having the existing ones turned, turning them would just make the matter worse, if that were the issue at all.

 

 

 

 

The problem with this is if GM did actualy insist on no more 20s on Crew Cabs the dealer isn't gonna help him He's gonna have to get an aftermarket set of rotors. I'd try Bear or Lingenfelter. Both make rotor kits for GM pickups.

 

Problem number 2 has to do with the suspensinon compenents. GM claims it is unique to crew cab. Rotors might not resolve the issue at all.

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I know this has been touched on before. I have an '05 2wd Crew Cab that I installed 20's on. I didn't know about this forum until after I had the new wheels. I got PARANOID when I rear the thread here about the 20's on an '05 Crew Cab so I called GM about the issue. It seemed that it was entirely dependant on WHO you talked to as to whether it was really an issue. I have a documented phone conversation, complete with operator's name, date and time of call to GM Customer Service saying that the 20's are fine. I also have an email sent to me from GM. While I don't doubt the validity of the warning about the 20's on crew cabs, GM DID NOT recall the trucks that had already been sold with 20's on it. They simply didn't sell anymore with 20's. As far as the vibration, I had one when I leveled the rear of my truck with shackles. A pinion angle kit from Bell Tech solved the problem. Anyway, hope this helps!!!!

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Just an update, and MORE information about my problem. I have installed the 2" drop shackles, and had no problems with that. It was done at less than 100 miles. EVERYTHING started the very second I installed the 20's. Driving down the road, there is virtually NO vibration, the truck seems to ride almost as smooth as it did before the wheel/tire change, with the only noticable difference is the ride quality is slightly stiffer than before due to the tires I am sure. The problem i have is that when you go to brake..stop at a red light or stop sign, or anywhere for that matter, there is a brake (abs?) pulsation that you can feel in the pedal. It seems to be 100% due to a braking or abs pulse. The rotors are NOT warped (yet..lol), and it is a very consistent feel in the pedal. Nothing happens weird or anything, its always the same thing consistently depending on how hard you are braking. I put the stock wheels/tires back on...problem goes away. I am at a loss....GM says i need to put in a new VCI number and reprogram my EBCM. I am worried that this will not fix anything. I checked the tire/wheel weight even. The new wheels weight is 34.6lbs.....stock are 35.2. Tires are within a pound of each other. Any more suggestions?

THANKS

TONY

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Just an update, and MORE information about my problem.  I have installed the 2" drop shackles, and had no problems with that.  It was done at less than 100 miles.  EVERYTHING started the very second I installed the 20's.  Driving down the road, there is virtually NO vibration, the truck seems to ride almost as smooth as it did before the wheel/tire change, with the only noticable difference is the ride quality is slightly stiffer than before due to the tires I am sure.  The problem i have is that when you go to brake..stop at a red light or stop sign, or anywhere for that matter, there is a brake (abs?) pulsation that you can feel in the pedal.  It seems to be 100% due to a braking or abs pulse.  The rotors are NOT warped (yet..lol), and it is a very consistent feel in the pedal.  Nothing happens weird or anything, its always the same thing consistently depending on how hard you are braking.  I put the stock wheels/tires back on...problem goes away.  I am at a loss....GM says i need to put in a new VCI number and reprogram my EBCM.  I am worried that this will not fix anything.  I checked the tire/wheel weight even.  The new wheels weight is 34.6lbs.....stock are 35.2.  Tires are within a pound of each other.  Any more suggestions?

THANKS

TONY

 

 

 

 

Did you check to see how tight the lug-nuts are torqued to? Want to get rid of your stock 17's?

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Tony,

You definetly need the VCI number and need to reproggram your PCM,Your GM dealer must do this for you,Trust me,I work at a GM dealership and a couple guys have tried to put on the 20's and not do the reproggram,It didn't work them!

Get that done first,Then if you still have the problem you can rule that out as being the cause of your problems.

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Can you explain to me what this VCI number can do to fix this? The overall diameter of the wheels and tires are less than 4 tenths of an inch...the overall weight is less than 3lbs. How can this make that much difference?

TONY

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Like you, I had checked EVERYTHING that I could so I took it in to the dealer. They checked the pinion angle and it was off. Just like you, my vibration was when the vehicle was stopping. My worst point was at about 12 MPH but this will vary according to each particular trruck. I put the pinion angle shim kit in and BOOM!!! No more problems. Anyway, hope this helps!!!!

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Oh yeah, I forgot to mention. . . one way to check this before installing the kit is to simply start braking and when you feel the vibration, shift your truck into neutral. If the vibration stops, it's your pinion angle and the kit should take care of it! Any further, please advise.

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Why would it start at EXACTLY the same time i put on the 20's? That is what i cant understand? The pinion angle should have been the same regardless of the wheel/tire combo i had, and i experienced absolutely NO vibration with the stock wheel/tire combo. An explanation of this would be super..lol...

TONY

 

P.S. No matter what...you guys have been very helpful....this is the best website i could ask for info on my sierra...thanks everyone

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Just got off the phone with bell tech (1 800 445 3767) tech support. They say they do not recommend a pinion angle kit with only a 2" rear shackle drop, as that the 2" should not have an effect on the pinion angle enough to make any difference (only saying what i was told!)....Can someone PLEASE tell me what their truck was doing (compared to mine) exactly and how this fixed it....and also, what degree kit did you use.

THANKS

TONY

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I, like you, went through this when I put the 20's on my truck. However, I put the 2'' drop on within a few days so I can't tell you it was just related to my wheels. However, I was told two different things when I lowered my truck. I was told that I didn't need them when I rordered my shackles then when the dealership told my the pinion angle was off, I called Bell Tech again and they said that with a 2'', not ALL trucks would need one but some would. Like I said, the vibration you describe is exactly the same as what I had. Just try shifting into neutral when the vibration starts. If it doesn't fix it, tell me I'm mistaken!!!!

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