Bad caliper or U Joints (driveshaft)?

[jk333]

I replaced the front brakes on my Jeep (87 Laredo). The pads about 600 miles ago and rotors about 500 miles ago. Both brand new. I noticed that the old passenger side old rotor had some bad scarring and the drivers side wasnt as bad. The guy at the auto parts store said that my passenger side caliper could be sticking. As of this last week, I get a shaking when I hit about 60mph and it becomes more prominent at 65-70mph. I can feel it in the steering wheel. I have owned the Jeep since it had 112,000 miles and it now has 183,000 miles. In that time, I have never changed the drivehshaft u joints. I think my problem is one or the other. I would think that I would notice a dragging or the Jeep would pull one way if the caliper was sticking. Maybe? I have tried doing a sudden stop coming off the freeway and letting go of the wheel. It tracks straight. I dont get the sensation in the pedal of bad rotors . Is there a way to check if my driveshaft u joints are bad? Money is kind of tight right now, so Iwould really like to try and narrow the problem down, vs. throwing money at a couple different things.

 

[tommyr]

Try a search, but the 2nd post here is something I came up with a while ago. It may help

http://www.naxja.org/forum/showthread.php?t=950264

 

[joe_peters]

Tommyr's post in the link is a very good description of what to look for.

Push come to shove, and you aren't sure, pull the shaft and "flex" or "work" the joint by hand. Any problems will be obvious to you.

However, I think your problem could be related to other things. You could have a bad tire, you could have lost a wheel weight, or you could have some bad components in the steering/suspension.

At 183K, and 23 years young, a thorough inspection of the front end components is necessary.

Also--done any recent mud? Sometimes you will end up with mud packed behind a wheel(s) and it will throw the balance off. It doesn't take a whole lot.

EDIT: and when were the rubber brake lines replaced? They do break down over time, and a line can develop issues where loose pieces will act like one-way valves and hold pressure to a caliper or wheel cylinder after the service brake pedal is released.

 

[winterbeater]

I wouldn't think driveshaft u-joints myself, but you can check them for both failure modes. Worn out - get under and rotate them back and forth looking for free play. Frozen - pull driveshaft off (4 nuts or bolts) and bend joints to see if they move freely.

First - did you try moving front tires to the rear, etc. to see if the vibration moves?

I see Joe beat me to it...........listen to him first.

 

[jk333]

I checked the U Joints on the driveshaft today (rear) and I cant see any play in them at all. I dont think thats my problem. Im wondering if its a sticking caliper? As of yesterday, the Jeep drives ok ,and the brakes never smell hot after I get done driving it. I can feel vibrations in the pedal when I go to stop from 50 mph plus. I dont get it. Can a caliper(s) stick part way? Ive done a stop where I let go of the wheel again, and I get the same result, it tracks straight. I felt the rotors and they seem to me to be in good shape yet. I can see very faintly a ring starting in one spot on the passenger side rotor, but I dont know if thats normal to see on a brand new rotor?


I dont offroad in this Jeep, its just a daily driver, so mud doesnt really come into play.

 

[jk333]

for reference, when you change the drive shaft u joints (from vibrations), do you change the front shaft and rear shaft?

 

[joe_peters]

for reference, when you change the drive shaft u joints (from vibrations), do you change the front shaft and rear shaft?

My thoughts on this is if you are doing a job, and it is something that is easy to get to, probably won't leave me stranded, and I wouldn't mind doing it again like next week--then I would only do half of the job.

Things like replacing an internal clutch slave--usually going to do the clutch while I'm in there. Replacing a RMS--the oil pump and bearings are going to be inspected (more than checked). That is on my personal vehicles. On a customer's vehicle I would explain the situation to them, recommend that the complete job be done, and if they decide not to then they have to sign a statement on the work order or they can go down the street to another shop.

Seen too many "half-job" shops go under from law suits and eating warranty repairs.

 

[jk333]

My thoughts on this is if you are doing a job, and it is something that is easy to get to, probably won't leave me stranded, and I wouldn't mind doing it again like next week--then I would only do half of the job.

Things like replacing an internal clutch slave--usually going to do the clutch while I'm in there. Replacing a RMS--the oil pump and bearings are going to be inspected (more than checked). That is on my personal vehicles. On a customer's vehicle I would explain the situation to them, recommend that the complete job be done, and if they decide not to then they have to sign a statement on the work order or they can go down the street to another shop.

Seen too many "half-job" shops go under from law suits and eating warranty repairs.

then, front and rear, haha. Im with you, I like doing it once and being done with it. Just wanted some clarification. Thanks Joe.