Tahoe front end noise
 

Hi all
I've got a front end noise/vibration that i'm having trouble diagnosing.
I'll try and keep it brief.
I was going to DIY the front brakes on my Tahoe. I tried removing the guide pin on the lf caliper. It wouldn't budge (Canadian winters). I tried heat still no go. I gave up put the tire back on. From that moment now I have a vibration around 45 mph and higher. When the brake is applied the noise increases.
I took the vehicle to my mechanic, he replaced pads, rotors. The noise is still there.
I took it back and he said the front diff is the culprit and installed used one from salvage yard. The noise is still there.
I still think it's something with the caliper but he says it can't be.
I've used this shop for 20 years and this is the first time I've had an issue with them.
Any ideas from the GM brain trust?

Thanks in advance
Brian

You worked on the brakes. Something major changed then.
It's the brakes, and not the diff.

The caliper might be stuck sideways with the brakes dragging and bouncing?
Or a tire way out of balance from weights falling off?
What else could have changed?

One of the biggest bummers when doing a brake job is finding a frozen slider pin because you told the customer it would probably just be pads.

You do everything to free it including putting that pig in a vice and laying heat to it with the dust boot removed.

If nothing budges or it breaks you have to make the phone call.

If it does move you clean the bore and the pin and re-grease.

When I had the brakes done I also bought new winter tires using steel rims for winter. I thought the noise may have been the tires. I even re-installed the summer tires, same sound.
I keep thinking it's the caliper.
Thanks John

When I re-installed my new winter tires I looked at the guide pin, it looks like it was never touched, they did replace the pads.
The shop recently expanded from 2 techs to 5 so I'm thinking someone less experienced did the brakes.
I'll have to see what they say.

Thanks Bob

That car loves to eat front wheel bearings. Just another thought.

Gary

Replace the front calipers. They’re cheap.
Tony

That was my first thought . Did he get the pin free, or replace the bracket ? I do tons of wheel bearings on Gm trucks

^^^^agree^^^^

You never really said what it sounded like. Mine sounded like a plane getting ready to take off. It will usually change when turning one direction or the other. You've got one of the most dependable vehicles on the road. Congratulations.

I worked in GM service for about 9 years and was Service Manager for the last three of those. Most of us in service drove that same generation of truck. My shop foreman was over 300k on his and it still looked new.

LF hub replaced this past March
RF hub replaced in 2017
I removed the LF wheel yesterday when I installed winter tires. Aside from new pads/rotors the caliper looks like nothing was done. I couldn't budge one pin. I'm going to call them out on this tomorrow.
In 20 yrs. this is the first time I've had an issue with this shop. They've expanded from 3 (including the 2 owners) mechanics to 6.

It sort of sounds like noisy tires. It starts at 45mph, it will make the noise in gear or neutral.
It gets louder when applying the brakes heavily.
I'm going tomorrow and see what they found. I'm going to see if they'll replace the caliper.

update
 

Spoke to my mechanic today. He still can't locate cause of noise. This what he did today.

1 Removed drive shafts from transfer case and front diff.
2 Swapped front hub bearings
3 Removed rear diff. cover and checked rear diff
4 Checked main driveshaft
Every time he tried something he road tested, the noise is always there.
He's replacing he front caliper tomorrow, the poor guy is pulling what hairs he has left.

Do you have fancy wheels? Some of them have a small alum. or plastic hub cover. My duramax came with these after market rims and I had the some noise issue at speed of over 60. My wrench pulled his hair out too and couldn't find anything. A few weeks later, I went to rotate these old tires, ha, the tire guy found the front hub cover a little loose. A turn of an Allen key, fixed the issue. Worth a look?

Nope, both sets of rims are stock. I just purchased new snow tires on steel rims. At first I thought the noise was from the tires. I re-installed my summer tires on the aluminum rims. The noise is still there.
Both front hubs axles have been checked and one swapped out.
My mechanic is running out of ideas

Transfercase pump rub? Long shot but it shoun't only do it at speed?

The drive shaft input to the transfer case was removed and output shaft to front diff were removed. He road tested it and the noise was still there, it gets worse under heavy braking that's why I suspected the front caliper. All this started when I was trying to remove the guide pins for a brake job. Canadian winters are tough on calipers/rotors. That's when the noise appeared. I gave up and took the vehicle to my mechanic.
He or one of the other mechanics changed the rotors and pads. At the time I questioned the caliper
I'll know more tomorrow.

What else can it be? Let us know what he finds.

Caliper hardware. Always replace the hardware with new pads. Apply grease or other to the pad backing to mitigate squealing. CRC is what I use.

I'm guessing you have one warped rotor.