Brake Drag and Vibration Question...

Hello,

New to the forum. I searched around 5 pages and didn't find my answer, so I thought I would post a question.

I have a 99 Jeep Cherokee Sport and my gas mileage has been poor lately. Admittedly, I haven't kept up on checking my mileage until gas price hikes recently. But, before I would get 16-17 MPG in town now I'm barely making 13 MPG. I put in new Bosch 4+ Platinum plugs, K&N Air Filter, New Spark Plug Wires, and also got a Fuel Injection System Cleaning at a local lube shop. All of these seem to have little or no effect on my end result. I have noticed a metal on metal sound coming from my front end, a friend thought it sounded like my brakes were "dragging." Further inspection leads me to believe that is why my MPG are so low. Does anyone know how to adjust for this, or is it something a brake shop would have to tackle?

Second question related to same Jeep. I just put on new tires, new shocks (and Steering Stabilizer), and had the tires rebalanced and watched for out of round rims/tires (Which were all perfect) and had my alignment checked. Now, between 55MPH and 75MPH I get a vibration in the front end (feel it in the steering wheel, not seat). It somewhat goes away if I am coasting, but while accelerating or maintaining speed is when I feel it most prominent. Anyone have any ideas what would cause this?

Thanks,
Matt (NUKE)

For the vibration problem, check your u-joints. Grab your drive shafts and push, pull and twist in both directions to see if you have slop at the joints. I just fixed my vibe problem with a new u-joint on my rear drive shaft.

Good luck.

Jason

Actually, I thought that might be the prob too. I took my driveshaft down to a mechanic and he said that it was tight, no need to mess with it, but as he said "If you want, I CAN charge you to fix whats not broken!!!" Not the greatest salesman!

Matt

Check your front wheel bearings, I just had a similar problem (both the dragging and front-end vibe) that was traced to a bad unit bearing on the passenger side. Replaced it and all is much better now

How many miles? Could you need a new O2 sensor or two? Also check you brake pads for wear. If one side is worn a lot more than the other, you calipher on that side might be sticking. Usually its the drivers side.
Tom

Just an update.

I replaced the O2 sensor closer to the rear, and my MPH jumped from 13 to 20MPG. Huge!!! Vehicle still feels like its being "Held back." I checked with a Technician Friend of mine and he said that my brakes are not dragging. He thought that maybe my front driveshaft may not be disengaging completely. I lubed up the slip yoke really good, also checked U-joints...seemed OK. He said that more than likely I had bad vacuum somewhere. But, said I should bring it in to be sure. Since I have no money for such diagnosis, I was wondering if anyone on this forum has had this same issue.

Matt

I think I have the same symptoms as you do. About two weeks ago I replaced the front ujoints in my 2000. Since then I have had a strange grinding/vibration feeling just under my feet. It does not happen at acceleration, or at higher speeds. If I am doing a constant speed around 30 then I feel it. It seems like this only happened after I did this work but it may just be psycosymatic. The brakes sound and work fine, no noise whatsoever.

Eric