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

[Doubeleive]

Yes, sprung vs unsprung weight. Rotational vs static. https://www.linkedin.com/pulse/what-sprung-unsprung-weight-nikhil-jagdale#:~:text=Sprung weight includes anything supported,you're considering making modifications

It will be interesting to see what it ends up being. Hopefully he replies back with a quick fix.

Ok so then by your theory I should be able to downgrade my brakes to the old 13" and get the cheapest lightest pads I can find and some old aluminum Silverado wheels (light as hell) and some lightweight tires and gain 6-8mpg? Right, ain't gonna happen

 

[Doubeleive]

And how come when I went from 16" wheels to 22" wheels chrome and heavy I didn't go oh sh$t where did my mpg go? Because the effect is not that great on these big heavy bastard trucks, ya you might be able to see it in controlled conditions but it's not going to be much.

 

[Rocket Man]

Dude doesn’t know when to give up.
You know, he’s smarter than the rest of us…

 

[Rocket Man]

No one is blowing smoke. I showed you the link that goes in detail what rotational mass can do. It may not be a result of his total 8mpg decrease but it is no doubt attributing to it. Especially if he is pressing the gas more to overcome the heavier feel. Im willing to bet the truck feels 'heavier' to him and he is using the gas to compensate.

Rotational mass increase can make a vehicle feel very labored. Some less sensitive may not feel it. But many people will.

It could be a dragging brake but he mentions no heat. A single caliper dragging will also cause a pull. What's the likelie hood of a pair dragging ? Probably pretty slim. So next up would be a e brake dragging. Again he says no heat. So that may or may not be it. He doesn't mention any pulling so that rules out a single corner.

The one fact we do have is that he put giant brakes on his suv and complains that it is labored and struggling and low mpg.

To rule out what im saying as 'smoke' is ignorant.

You’re something. You’ve now called me ignorant, after first calling me stupid as in “It's basic physics. Heres a quick simple read to help you over come your lack of understanding” and so on. You’re wrong, again, if you think a BBK is contributing to a decrease in mpg by anything noticeable. AGAIN, I say prove it happens on a full size GM SUV. Let’s see your evidence. Not that article, real actual user experience where the mpg decreased due to installing a BBK on a FULL SIZE GM SUV which is what we are talking about.

 

[randeez]

sub'd

cause this keeps getting better and better

 

[George B]

sub'd

cause this keeps getting better and better

Right?!

 

[randeez]

You’re something. You’ve now called me ignorant, after first calling me stupid as in “It's basic physics. Heres a quick simple read to help you over come your lack of understanding” and so on. You’re wrong, again, if you think a BBK is contributing to a decrease in mpg by anything noticeable. AGAIN, I say prove it happens on a full size GM SUV. Let’s see your evidence. Not that article, real actual user experience where the mpg decreased due to installing a BBK on a FULL SIZE GM SUV which is what we are talking about.

i dont know man....when i fill my yukon up with gas my mpg goes down pretty quick. when its nearly out i get a lot better mpg. explain that genius, clearly its the extra weight of fuel

 

[Rocket Man]

i dont know man....when i fill my yukon up with gas my mpg goes down pretty quick. when its nearly out i get a lot better mpg. explain that genius, clearly its the extra weight of fuel

It’s basic physics. Need a link?

 

[Thrust]

Yes, sprung vs unsprung weight. Rotational vs static. https://www.linkedin.com/pulse/what-sprung-unsprung-weight-nikhil-jagdale#:~:text=Sprung weight includes anything supported,you're considering making modifications

It will be interesting to see what it ends up being. Hopefully he replies back with a quick fix.

I love when people link to articles that have ZERO equations or test data backing up what they say. Yes agreed, it's always better to reduce unsprung weight but since I don't see anything in the OPs post of how much the stock setup compared to the Brembo setup it's hard to say what that difference is. And coming from someone who did the Brembo brake upgrade myself, I didn't notice a change in MPGs, but when you have a supercharger on top of your engine you don't really care about MPGs.

 

[DuraYuk]

Loaded down vehicles getting the same mpg!? Heavier bigger wheels and tires getting same mpg!? Yeah we are at a crossroads here. Im gonna head out now and curiously await whatever OP finds. I put my 2 cents in as a former GM heavy line tech and current mech engineer. Was just trying to help and combat some misinformation.

Maybe my tone was misread. Idk. Hope everyone is having a good day.

Smh.

 

[Doubeleive]

Yes, sprung vs unsprung weight. Rotational vs static. https://www.linkedin.com/pulse/what-sprung-unsprung-weight-nikhil-jagdale#:~:text=Sprung weight includes anything supported,you're considering making modifications

It will be interesting to see what it ends up being. Hopefully he replies back with a quick fix.

and that article you linked does not mention one iota of MPG it has to do with moving a mass faster (1/10th) of a second is mentioned...wwoooooo no sh&t sherlock
one tenth....of a second wow that's going to kill my mpg. I would guess your going to burn up more gas getting that mass moving 1/10 of a second faster than you would with a nice controlled acceleration with 10X the weight.
there is a whole bunch of stuff involved in the MPG, brakes is one of the least of them.
your kicking a dead horse, now i'm waiting for "well the aerodynamics on the inner wheel well is affected by the size of the rotor" pfftt

 

[randeez]

yea im inclined to believe that there is something wrong with the install or the parts.

the upgrade is only the front? so they just remove the caliper and rotor, swap on the new, rebleed the brake system?

this guys talking about a ~30% reduction in mpg?

added weight - i cant see being more than 20lbs a side

any pictures of the install?

 

[Rocket Man]

yea im inclined to believe that there is something wrong with the install or the parts.

the upgrade is only the front? so they just remove the caliper and rotor, swap on the new, rebleed the brake system?

this guys talking about a ~30% reduction in mpg?

added weight - i cant see being more than 20lbs a side

any pictures of the install?

He also mentioned the engine sounds different driving normally, like it’s labored, the steering feels heavy, acceleration seems labored like he’s towing something, feels like the e brake is on all the time yet there’s no huge amount of heat coming from the rotors after driving. All this almost makes me think it might be something electronic that they messed up, like something got unplugged and it’s in limp mode in some way. Just shooting the breeze here, not sure what it could be.

 

[WalleyeMikeIII]

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

If your ebrake is dragging that could be the cause of the issue. It is possible that it had gotten out of whack when they did the brake change. Hopefully the driving you've done hasnt done much wear on the ebrake system, but if so, then the dealer who did the work can fix that as well. For...

www.tahoeyukonforum.com

Post 33 says he has scoring in one rotor. Hum...let's wait till the OP comes back and gives us the answer he gets when he takes it in.
My understanding on this kit is the only change to the rear should have been a red painted caliper, same as the factory...and stick w/ the factory rotor; so def seems like an install issue...but lets see what he says.

 

[randeez]

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

If your ebrake is dragging that could be the cause of the issue. It is possible that it had gotten out of whack when they did the brake change. Hopefully the driving you've done hasnt done much wear on the ebrake system, but if so, then the dealer who did the work can fix that as well. For...

www.tahoeyukonforum.com

Post 33 says he has scoring in one rotor. Hum...let's wait till the OP comes back and gives us the answer he gets when he takes it in.
My understanding on this kit is the only change to the rear should have been a red painted caliper, same as the factory...and stick w/ the factory rotor; so def seems like an install issue...but lets see what he says.

Yep, or something completely random that just so happened to coincide when this was done and has nothing at all to do with the brake upgrade

 

[slickbrave]

Dealerships have been known to perform a PCM flash without asking/telling the owner since it's factory recommended and done at no charge if still under warranty. Not sure how or why that would decrease MPG and performance unless they installed the wrong program, maybe for a 5.3? Just speculating here, but I'd check the paperwork from the brake upgrade and see if they performed such a "service."

 

[Doubeleive]

Dealerships have been known to perform a PCM flash without asking/telling the owner since it's factory recommended and done at no charge if still under warranty. Not sure how or why that would decrease MPG and performance unless they installed the wrong program, maybe for a 5.3? Just speculating here, but I'd check the paperwork from the brake upgrade and see if they performed such a "service."

mine wouldn't unless they are getting paid to do it, which means either under a recall or requested by the customer otherwise there not touching it, in the case of a recall I would be notified.

 

[89Suburban]

This is a good case for using a remote-reading infrared thermometer. You can drive a bit and then measure how hot your rotors and hubs are.

The one I have came from Radio Shack and is about 15 years old. Sorry I can't recommend any particular current one. Here is one example: https://www.summitracing.com/parts/wmr-w89722

This is the most logical simplest thing I have seen posted here, has it been done? Great tool for diagnosing dragging brakes.

 

[Kpwweb]

If it is not a dragging brake, it could be an ecm update. Any time the ecm is flashed or updated, it will lose the fuel trim. Your mileage will be horrible until the fuel trim relearn process is completed. Relearn can take up to 45 minutes or maybe 100 miles.

I’ve had to do it after bettery disconnect. I got down in the 12s, exacerbated by colder weather, until the fuel trim was relearned.

 

[Tahoered]

Hi guys! Just came back from dealership. Again, want to thank each and everyone of you for your input with this matter. Great info exchanged. So...trying to find a way to make this short. My visit to dealership was truly an experience. Will keep this as basic as possible and will answer questions whenever I log in. First service advisor drives car and definitely agrees something is wrong. Agreed with the symptoms I mentioned initially. We meet master tech and another adviser who requested to test drive the car. Both returned and said everything feels perfectly fine. I get extremely aggravated. Clearly the clowns have never driven a V8 to justify the way this driving. After arguing back and forth and not settling for my car to go back in the lift for them to just rotate rotor and say everything is OK, another "master tech" who seems to the most experience one at the dealership arrives. He is immediately notified to go on another test drive with me. We both remained quiet for whole test drove (awkward). Immediately after driving a few miles, we return to dealership and he requests that I exit the vehicle with him while he checks Temps. Both front rotors gave a reading within 4 degrees of eachother. Rear passenger rotors-breaks read 145 degrees. Rear drivers reads 210 degreese. Now, with these rear calipers-breaks...they actually contain the ebrake system right on it. It's either the installer jacked it up installing the things or the rear caliper or calipers are defective. He believes the ebrake somehow is somewhat active. The grooves on the rear driver side should have been a clear indication something was wrong but this damn dealership loves playing stupid games. He stated he can unplug the ebrake system and drive car but in uncertain what type of codes or nonsense he will have to reset after doing so. This part is on back order and will be hard to come around. Dealer will do a warranty claim - whatever that is with gm for a replacement. Tech is stating since steering is not swaying towards one direction, both sides may be dragging with one being worst. Will have to compare after new one is installed. The absolute weird thing is that non of us can feel the difference in heat by touch or scent. Only when we repeatedly put temp scanner to it we repeatedly get an avg of 60 degrees difference. No smell, fumes, irrgular hot wheels to the touch...just drastically difference Temboth sides. sides.