brake vibration

[chris989]

Hello all,

Over the past year i was developing a vibration when braking hard like with my empty dump trailer.

I thought it was just the pads/rotors so i finally change them with all new,even the pins, bolts etc. properly lubed along with new wheel bearing, and all the ball joints.

I still have the shimmy in my wheel when braking. I was thinking of adding dual steering stabilizers instead of the single skyjacker.

Also my rims are a little narrow (7")for the the 315/75 BFGs. I feel like the shimmy came about the same time as the new tires. When i had 33s i do not remember having any issues.

Has anyone had a vibration that turned out to be something other than the brakes?

Chris

[cadillac_al]

Maybe the shocks? A long time ago I got a bad set of rotors that vibrated form day 1. I had to turn them to fix them. That was 30 years ago and haven't really had that problem since. When I tried to run 12.50 tires on 7" rims I couldn't get the sides of my tread to touch the road unless I had about 20 lbs of air in them. I didn't want to see the center of my tread wear out so I changed the rims immediately. That's my .03.

[nonstop]

Focus on tires. I’ve chased shimmys and wobbles more than once that had me cursing. I replaced a steering box, pump, etc, to cure a wobble. At the end of the day, rotating the tires fixed it. Also got rid of the dual stabilizer and went back to stock on 315’s. By the way, one of the sets of tires that gave me a problem was bfg’s.

[chris989]

I am going to check the run out of the rotors with a dial indicator today. If that checks out i guess the next step is the 315s on the 7 inch rims. The tires look ok, no crown, but the sidewall does have a decent bulge.

I doubt it is the brakes because in my restore i used all new USA or OEM parts with new bearings, drums and rotors.

I will report back in a few days with an update

[chris989]

I just checked the run out on the front.

The rims have ~.010 runout. They are aluminum and old but I think that number is ok.

The rotors have a total runout of .002. I can't think that is causing it.

I guess i will pull the drums next.

[homemade87]

Something to think about . I had somewhat the same thing happen . If I read correctly it only happens when braking with trailer attached ( extra work for the brakes ). Its possible the front rotors are getting hot because they are doing all the work . Once they get hot they will start to vibrate . This may be because the rear brake are not doing there job and putting all the work load on the front . Mine never gave a problem until I had long or heavy braking to heat the rotors up . Once I got off the brakes and cooled they were fine ( so it seemed ) .

[chris989]

Originally Posted by homemade87

Something to think about . I had somewhat the same thing happen . If I read correctly it only happens when braking with trailer attached ( extra work for the brakes ). Its possible the front rotors are getting hot because they are doing all the work . Once they get hot they will start to vibrate . This may be because the rear brake are not doing there job and putting all the work load on the front . Mine never gave a problem until I had long or heavy braking to heat the rotors up . Once I got off the brakes and cooled they were fine ( so it seemed ) .

I should clarify,

It does it when ever i brake a little harder than easy driving. Like someone pulling out in front of me, but when my trailer is empty, i can not use my trailer brake or they lock up due to the lack of weight.

The rears are adjusted well,

I have been reading about "bedding" new pads and rotors. Honestly, I have never done it in 30 years of wrenching but maybe i should give it a try.

The new from pads are Centric posi-quiet extended wear. I thought i would buy a better pad for this build but maybe i will go back to the el cheapos and see if that solves my problems

[GRADYS Performance]

Does your trailer brake controller have any adjustment to change braking depending on trailer weight?

[chris989]

Originally Posted by GRADYS Performance

Does your trailer brake controller have any adjustment to change braking depending on trailer weight?

I have a nice brake controller, It is not trailer specific, It will do it without the trailer, just with the trailer it is more noticable.

I do have 315/75 on 7.5 rims which most likely do not help any but i think it is a pad issue.