Gm Brembo upgrade added...sluggish acceleration and much lower mpg.

[steiny93]

The weight difference between the Brembo's and stock are negligible; the mpg didn't change due to rotational weight difference.

If you have brakes dragging enough to impact mileage you will be getting heat out of the rotor(s). Drive it for 10 miles, come to a stop without using any brake, if they are dragging that much, if you hit neutral it will stop. If they are hot you have an issue.

Changing the rotors doesn't involve setting any tension on say the wheel bearings or anything like that, so that isn't an issue.

 

[Rocket Man]

Hint: it’s not the brakes.

 

[RST_FRED22]

Hi guys. Need some advice. A couple of weeks ago I added the GM - Brembo big brake kit on my 2022 RST 6.2. I only drive the vehicle in weekends and have placed roughly 100 miles on it since adding the brake package. Problem is, I can clearly sense a difference with drivability. I understand the larger rotors may weigh more and possibly even the larger caliper but My G-D!! My mpg is now at 12!!! My acceleration seems labored as if I am towing something. Never have I felt this in a car. Even the acceleration sound driving normally seems as if my engine is working harder. I ultimately went back to the dealer where it was installed. They placed it on lifts and stated they see nothing wrong because the wheels / rotors are spinning freely. After driving for an additional 30 miles with mpg plunging to 11, I have made an appointment and will not accept any other excuses from them. Not sure what the tech may have done. Dragging calipers, brakes not fully releasing? Is it possible he may have tightened something too much where my ebrake is slightly holding or something. Any ideas or thoughts would be greatly appreciated. My steering feels heavy also and it just seems as if more weight has been added. Really thinking of removing these things and getting my lively RST back to stock.

Maybe try lifting up the truck and see if the wheels spin freely, maybe bad calipers? Do you smell anything while driving?

 

[Rocket Man]

Maybe try lifting up the truck and see if the wheels spin freely, maybe bad calipers? Do you smell anything while driving?

Re-read the original post.

 

[Chad G 1979]

Re-read the original post.

What is it then? All he did was have the brembos installed and his acceleration is sluggish and mpg took a nosedive. Dealer claims they are fine, but did they really check?

 

[Rocket Man]

What is it then? All he did was have the brembos installed and his acceleration is sluggish and mpg took a nosedive. Dealer claims they are fine, but did they really check?

I don’t know what it is, I just can tell you it isn’t the brakes. And it was out on a lift and wheels spin freely like the first post stated. It’s an issue that will require an actual diagnosis which is hard to do over the internet. Rolling mass difference? Please. I’m running 16” Wilwoods on my 02 and like others have said it makes zero difference on a truck this heavy. If they were dragging enough to cause a drop in acceleration and mpg they would be getting so hot it would be obvious. So I can say with 100% confidence it isn’t the brakes. It’s something else.

 

[Doubeleive]

I don’t know what it is, I just can tell you it isn’t the brakes. And it was out on a lift and wheels spin freely like the first post stated. It’s an issue that will require an actual diagnosis which is hard to do over the internet. Rolling mass difference? Please. I’m running 16” Wilwoods on my 02 and like others have said it makes zero difference on a truck this heavy. If they were dragging enough to cause a drop in acceleration and mpg they would be getting so hot it would be obvious. So I can say with 100% confidence it isn’t the brakes. It’s something else.

that's why I asked if he was driving it differently, you know putting on performance brakes means you gotta test em out right? who spends a few grand on brakes and doesn't go out and see how they perform.....

 

[Rocket Man]

that's why I asked if he was driving it differently, you know putting on performance brakes means you gotta test em out right? who spends a few grand on brakes and doesn't go out and see how they perform.....

I know I test my brakes and supercharger out constantly.

 

[Tahoered]

Have an appointment for Thursday morning. No extra heat coming from any of the wheels or rotors that I can detect. No weird smells neither. Mpg plummeted beyond belief! I drive like I'm driving Daisy on Sundays. 6.2 and I would easily average above 18 or 19 mpg. Since change, I am at 12! I literally just went and boosted psi up to 42, 43 in each tire to raise this horrid mpg. It helped alot but not quite sure if I really want to be rolling like that. I used to keep it 37. Is there anyway possible may e the ebrake would've been adjusted or torqued differently where the car can feel sluggish accelerating? I'm scratching my head here. I regret not weighing the rotors and brakes vs stock. I still have all of the stock parts so worst case scenario I'll go back to stock set up. One thing I can say is there is a nice big increase in rotors size from about 13 to 16 inches up front.

 

[Tahoered]

Just had my buddy test drive it. I feel he gave a better description of what's going on. It feels as if I am driving with my emergency brakes on. Exactly what it feels like. I literally went into my beater 2014 Accord and drove down the block with ebrakes on and that's exactly what it feels like! Steering feels more weighted, acceleration seems a bit labored and even rolling on drive on a flat road the Tahoe is barely rolling. I just. Amt wait for Thursday. Smh.