Need Some Input on Brakes

I searched and found some info so if this is covered elsewhere please let me know. Not much seemed to fit this scenario. So here goes:

I am getting a shudder AFTER driving for a few minutes. Felt mainly in the seat, but hard to tell because it feels like the truck is shaking.

I took it to a brake shop and they said that their tech felt it in the seat and pedal a little bit but not much (likely because things were cold) so they asked me the symptoms. Their option was to replace all the brakes on the truck (not surprising). I told them the rotors on the front are new and if they could check to see if they are warped from the factory. Not likely but anything is possible. Shop said they cannot because they are slotted rotors.

Then the shop said they could start with just the rear brakes. I said "so basically you are guessing" and they said yes. I passed.

I popped the rear drums off to see if I could find anything obvious but the only thing I noticed is that the passenger rear had more dust come off the inside than the driver rear. Pad wear seemed to be the same and nothing obvious on the drums.

Anyone else had this?
I'm debating buying new drums and rear pads but don't want to be chasing this forever.
Any recommendations for a shop that doesn't wanna just start replacing things on a "guess"

2019 OR with 3 inch lift by State 48 about 2 years ago (great guys)
New Stoptech rotors and pads in front 2 weeks ago
New tires installed and balanced
No shudder at speed until truck is driven for a few and braking

Thanks everyone!!

 

It's hard to tell as heat is causing the runout.

What I do is if I can feel it in my butt while lightly braking while hot it's usually drums, I'll just cut them to see.

If its in the front you'll feel it by letting go of any pressure on the steering and watching the wheel while lightly braking.

I'd suspect the rotors as they are the new piece of the equation, sometimes they are dropped during shipping, who knows.

 

I debated getting them re-surfaced but new drums aren't much more...

 

Easy way to tell if its drums (rear) or rotors(front) is to apply the parking brake while moving. If its the drums you'll feel it then, if not, it's probably the front rotors

 

I put a set of aftermarket rotors on my tacoma and they warped in about 3 months. Bought a set of OEM rotors and they have been fine for over a year now.

Also next time you have the rims/rotors off, spend lots of time cleaning the Axle face, rotor, and rim bore with wire brushes to make sure you have no rust or dirt to cause runout.

I bought one of these years ago and it was money well spent, Check runout and play on all sorts of things:

$85 Fowler - 72-520-757 Economy Disc Brake Rotor and Ball Joint Gauge Set

https://www.amazon.com/Fowler-72-52...82481795&sprefix=clamp+on+dial,aps,166&sr=8-8

 

Thanks to everyone for the input.

Sun Devil Replaced front rotors and pads and that did it. I was at a loss since it only happened after driving for a bit, but oh well....

Glad to have the issue figured out but unfortunately they said they can't even check the rotors for warping because they are slotted but I got them back. I waited for a while to install them so I can't return them if they are warped,,,I ordered them online.

Now I just have to try and figure out why my mpg dropped