Background:
replaced front pads ~7k ago: turned rotors, new bearings, regreased caliper slide pins. All ~2 weeks before buying a boat. Ordered boat with brakes. Obviously have the boat, but the brake kit is still on order.

Current situation:
Been using the boat (18' alum, ~2klb). Have noticed a vibration when stopping; the harder I press the pedal, the worse it gets. Everything in a straight line; no pulling side to side. If I roll gently to a stop, I get no vibration. I do not notice the vibration when towing. The vibration is predominatly in the chassis; very little vibration is felt through the steering wheel.

Possible causes:
I know, since the boat trailer does not have brakes, I have to use the truck's brakes much more than I should. Is it possible that this has overheated and warped the rotors? Somehow, I don't think so.
Could a caliper piston be hanging up and causing the vibration?

Next Steps:
This weekend i will be pulling the wheels off to measure the runout of the rotor (both sides).
I am also thinking that I should check the drums too.

Any other thoughts?

Thnaks!

Tony

 

is the vibration in the wheel or the brake pedal?? if its the petal then most likely its the rotors, if its in the wheelm then you may need a supension part. lol

 

'Dropper,
Thanks for the info. Neither the pedal pulses nor the wheel vibrates(though very slightly)....The whole chassis vibrates.

Tony

 

Don't quote me but it sounds like a u-joint on the driveshaft.

 

I had this while towing my 3600 lb boat. It only did it while towing. I think its the ABS. When I don't tow it's fine. This tells me the brakes are fine it's just the ABS pulsating.

 

'Dropper & Laneman,
Thanks for the info. Will check the u-joints. I don't notice it as much when towing the boat, and don't notice it at all when towing the flatbed (electric brakes).

Haven't had a chance to check rotor runout...too much to do over the weekend. Will do tonight.

I have noticed something else...The vibration seems to be worse on rougher roads, coming to a stop. Need new shocks? 60K miles on originals!

Tony

 

If the combined weight of your truck and boat and trailer and beer is greater than the rated capacity for your truck (for example, my truck is rated for 7700# Gross Vehicle Weight Rating), then you've been using your brakes in excess of their rated capacity -- in which case you could have been generating enough heat at the pads/shoes to result in hot-spots or heat-checking or other deformation of the rotor/drum.

Lacking other descriptions from you, the most obvious suggestion is simply that the drums/rotors are no longer 'perfectly true' -- either meaning the sides of the rotor are not running parallel to each other -- or the drums are no longer perfectly round.

Neither of which is life or property-threatening per se.

The normal 'fix' is to machine the rotors and drums back to 'true' -- or simply get used to it as have many many other Ford F-150 owners.

Jim

 

I`ll bet it your rotors are warped. I had this happen too, by over use of the brakes. Turned them twice in 20,000 the last time had hard spots more than really being warped. I hope this helps!!!!
Lariat#1

 

after you check for runout on the rotors if its more than 2-3 thous get new rotors
then i would check the shocks like you said with 60k bad shocks can change the braking effecentes (sp) check wheel bearings for looseness and ft end wear tire rods idler ect look at the tire wear or broken steel belt in the tires but your on the right track good luck

 

All: Thanks for the info!

I haven't done anything to it yet...Figured that sine I STILL don't have brakes on the trailer, I don't want to warp a fresh set of rotors.

Also, thought I would use aftermarket (napa, etc.) rotors and Ford brake pads. I have Bendix on there now. The Bendix produce LOTS of dust. Have to was the truck weekly to keep the wheels clean.

The truck still stops fine, even with the boat, so I don't feel at risk, but I do want to get it taken are of ASAP.

Tony

 

my 97 4x4 does the same thing. I only have rear ABS, but I think it is too sensitive. It does not do it all the time, but if you stop around 45 you get this rythm to the truck. Really odd. Let off and apply again, it is gone. I am about read to unplug the ABS fuse to see if it makes a difference.

 

F150tony......I have a question. You said you replaced the wheel bearings on your truck.......which ones did you replace? When I bought my truck and sent it for an inspection, they failed me for a right front wheel bearing and wanted almost $500.00 to replace it. I researched the part and it was about $280.00 just for the wheel bearing, and then I called someone else for a price and they said "which one do you need...........I show 2"? Well of course I went somewhere else for the inspection and it passed with fyling colors and not one mention about a bad wheel bearing. I too have a 97 4x4 with the 5.4L
Any help would be appreciated.

 

JVangel,
I have a 4x2 & replaced the inner & outer wheel bearings.

Are you having a problem with a bearing? Has the boot split? Or was it just an inpection agency trying to make money?

Tony

 

Well...Finally pulled the rotors:

Drivers Side:
Inner Runout - .005" - .007"
Outer Runout - .005" - .010"
Bearing Condition: poor; brown line ~1/8" wide on all rollers of outer. Not going to bother to pull the inner.

Passenger side:
Inner runout - .003" - .007"
Outer runout - .003 - .007"
Bearing condition: Poor; ~80% of all rollers are scored on outer. Again, not going to bother to pull the inner.

Have 2 new rotors, new FORD pads ($120!), and new bearings. Just have to put it back together.

Can't find runout in the factory manuals: doesn't matter, I'm replacing the rotors anyway.

Also, I used Mobil synthetic grease. On one rotor the grease was discolored. Not sure if I will be using sta-lube or Valvoline.

I'll let everyone know how it goes.

Tony

 

Just to close out, so there's info for everyone:
Had a slight pull to the left after the brake job. Rotated tires last night: no more pull: Brakes are neutral.

Grease, Short term: Used Valvoline's Synpower (sp?). So far, it seems to be holding up fine. As I recall, within 1 week after the last brake job, the Mobil1 Synthetic started to separate & had oil spattering out of the dust caps. I'll probably check the outer bearings in ~5k miles, just to be sure.

Tony