fozzi58
Full Access Member
TL;DR I have an intermittent shake (front to back) when I hit the brakes. Feels like a bent rotor but its not the brakes.
Full Story
Back in September I did a bunch of work to the truck - supercharger, torque converter, new driveshaft, Wilwood BBK up front, all the supporting mods etc. For a couple of months the truck just ran with no issues, like it was supposed to. Around November I started getting a front to back shake when I hit the brakes. It feels like a certain part or the brake pad is grabbing the rotor harder than the rest as it rotates. Didn't happen all the time but you could feel it. I thought at the time it was the back brakes. The pads were really low (62k on the truck) and there was some scoring on the rotors. Figured it was a simple fix.
Swapped out the OEM parts with Stop Tech rotors and new pads. Same issue. Kinda odd. Drove on them for about a month and then took it to the mechanic that's been handling all the mods on my truck. He wanted me to get replacement calipers and start over with everything new to make sure, and he also suggested I get steel lines for the rear as well. He let me order whatever I wanted. I went with the PowerStop rear kit which included calipers rotors pads and I ordered the steel brake line kit also just for the rear lines since the Wilwoods came with braided lines.
All that work was done and she is still doing the shake. The connecting ties on the front sway bar were also replaced with poly cause they were looking worn. Lastly, replaced the rear tires with a brand new set (05/13/22) cause the ones out back looked to be dry rotting. Front tires were done 6 months ago so all 4 tires have less than 7000 miles on them.
Its still shaking. *sigh* Again its intermittent. I can cruise the highway at 80mph, smooth as glass and as soon as I touch the brake pedal the shaking hits in. The harder I press the more violent it gets. Other times I can be diving into a corner on an off ramp, jump on the pedal and she slows down without any feedback in the truck. It comes and goes on the same drive and its driving me insane cause I am not seeing any issues otherwise. Obviously there is something going on but neither me nor my mechanic want to keep throwing money at parts that aren't going to solve the issue.
Mechanic checked the new PowerStop calipers to make sure they weren't seized, he mic'd the rotors and make sure they where perfectly flat. There's no slack in the drive train; the new driveshaft was done by a very reputable speed shop who my mechanic has used for a long time with never an issue. The wheels are true; high speed balance on the tires; no bends in the wheels; hubs checked to make sure they were true also. I also bought a heat gun, did some very spirited braking, and took the temps of the rotors. Did this a few times. I'm averaging 120 degrees up front and about 90 degrees out back. So the brakes are doing their jobs and dissipating the heat as expected. The calipers are clocking in at lower temps than the rotors which is to be expected so I have to believe the brakes are NOT the cause of the issue.
This shaking isn't coming through the brake pedal or through the steering wheel like ABS feedback or a bad front rotor - you feel it in the seat and the truck reverberates throughout - dash, steering wheel, and the passengers feel it too. We are both leaning towards a possible suspension issue. However there are so many other possibilities. Speed sensors on the wheels? ABS? Suspension? Could I need an adjustable proportioning valve? Wheel bearing? Possible issue in the carrier? We keep thinking suspension because maybe the "intermittent-ness" depends on the load of the truck on the suspension. I tried testing this theory by making shaper turns while braking, trying to shift the load of the truck by hitting pot holes (I know...), jerking the wheel and then braking etc. Again, its no rhyme or reason, right hand turn at high speed - sometimes the shake, and other times not. Then again, this is seat of the pants and its hard to replicate turns and braking pedal pressure.
I don't want to throw good money after bad but I need this resolved and I'm at wits end on this one. I know we just had a thread from a Yukon owner with a similar issue, but everything that was throwing his truck off, I've already replaced with new parts, plus a full brake fluid flush. Any suggestion from someone smarter than me would certainly be appreciated. Thanks everyone.
Full Story
Back in September I did a bunch of work to the truck - supercharger, torque converter, new driveshaft, Wilwood BBK up front, all the supporting mods etc. For a couple of months the truck just ran with no issues, like it was supposed to. Around November I started getting a front to back shake when I hit the brakes. It feels like a certain part or the brake pad is grabbing the rotor harder than the rest as it rotates. Didn't happen all the time but you could feel it. I thought at the time it was the back brakes. The pads were really low (62k on the truck) and there was some scoring on the rotors. Figured it was a simple fix.
Swapped out the OEM parts with Stop Tech rotors and new pads. Same issue. Kinda odd. Drove on them for about a month and then took it to the mechanic that's been handling all the mods on my truck. He wanted me to get replacement calipers and start over with everything new to make sure, and he also suggested I get steel lines for the rear as well. He let me order whatever I wanted. I went with the PowerStop rear kit which included calipers rotors pads and I ordered the steel brake line kit also just for the rear lines since the Wilwoods came with braided lines.
All that work was done and she is still doing the shake. The connecting ties on the front sway bar were also replaced with poly cause they were looking worn. Lastly, replaced the rear tires with a brand new set (05/13/22) cause the ones out back looked to be dry rotting. Front tires were done 6 months ago so all 4 tires have less than 7000 miles on them.
Its still shaking. *sigh* Again its intermittent. I can cruise the highway at 80mph, smooth as glass and as soon as I touch the brake pedal the shaking hits in. The harder I press the more violent it gets. Other times I can be diving into a corner on an off ramp, jump on the pedal and she slows down without any feedback in the truck. It comes and goes on the same drive and its driving me insane cause I am not seeing any issues otherwise. Obviously there is something going on but neither me nor my mechanic want to keep throwing money at parts that aren't going to solve the issue.
Mechanic checked the new PowerStop calipers to make sure they weren't seized, he mic'd the rotors and make sure they where perfectly flat. There's no slack in the drive train; the new driveshaft was done by a very reputable speed shop who my mechanic has used for a long time with never an issue. The wheels are true; high speed balance on the tires; no bends in the wheels; hubs checked to make sure they were true also. I also bought a heat gun, did some very spirited braking, and took the temps of the rotors. Did this a few times. I'm averaging 120 degrees up front and about 90 degrees out back. So the brakes are doing their jobs and dissipating the heat as expected. The calipers are clocking in at lower temps than the rotors which is to be expected so I have to believe the brakes are NOT the cause of the issue.
This shaking isn't coming through the brake pedal or through the steering wheel like ABS feedback or a bad front rotor - you feel it in the seat and the truck reverberates throughout - dash, steering wheel, and the passengers feel it too. We are both leaning towards a possible suspension issue. However there are so many other possibilities. Speed sensors on the wheels? ABS? Suspension? Could I need an adjustable proportioning valve? Wheel bearing? Possible issue in the carrier? We keep thinking suspension because maybe the "intermittent-ness" depends on the load of the truck on the suspension. I tried testing this theory by making shaper turns while braking, trying to shift the load of the truck by hitting pot holes (I know...), jerking the wheel and then braking etc. Again, its no rhyme or reason, right hand turn at high speed - sometimes the shake, and other times not. Then again, this is seat of the pants and its hard to replicate turns and braking pedal pressure.
I don't want to throw good money after bad but I need this resolved and I'm at wits end on this one. I know we just had a thread from a Yukon owner with a similar issue, but everything that was throwing his truck off, I've already replaced with new parts, plus a full brake fluid flush. Any suggestion from someone smarter than me would certainly be appreciated. Thanks everyone.