Hi,
I have a 1999 F150 4x4 w/ 5.4l Triton, 71,xxx. 5 lug wheels with 12mm studs.

When applying my brakes, I get a relatively violent hop/shake around 40-45mph.
I pulled both wheels off and checked the roters and pads. Both seem to be in good shape.

Any thoughts as to what would be causing this problem?

Thanks and happy new year.

 

if you feel it in the back end, i would check aaxle mount bolts, and drive shaft universal joints. If you feel it in the steering wheel, start looking at the front ball joints and idler arm mount to the frame

 

Thanks Steve,
It is definately coming out of the back. I will check the U-Joints and axle mount bolts; I have also been reading that others have had a similar problem and new shocks were the solution.
Any thoughts on that?

 

I'll bet on shocks as long as you don't have a warped rotor or tire balance issue.

My 91 F250 needs rear shocks and hops pretty badly some times.....

 

Thanks guys.
I am going to try the shocks. I drove it around and hit the brakes and put the truck in neutral (taking the pressure of the shaft and u-joints) and I still got the hop.
I will change out the shocks and report back.

 

I'd be willing to bet you might have a warped rear disk. I would measure the thickness of the rotor, and if they were still thick enough I would go get them turned.

 

Ok,
I think it might be a combination of a few things. I removed all 4 wheels and looked at rotors and pads. I would say that the pads are 50% and the rear rotors look fine. The fronts look like the could be turned but I don't think they are all that bad. I have a pulsing in the pedal but no shake in the steering wheel when I hit the brakes.

If the rotors in the front were warped, wouldn't I feel it in the steering wheel and not just the pedal?

Could it be warped front rotors and bad rear shocks?

Thanks again everyone.

 

i just have a hard time believeing that shocks would cause this. you should be able to bounce on the bed and see if the back end keeps bouncing, then you need shocks. hard to believe they are causing vibration. --warped rotors, hard/ burnt pads, or sticking caliper slides , looks alxe mount shackles, are normally related to vibration when braking. if it does it when not braking, then you look more toward tires, wheels, drive shaft, universals

 

You said that you had rear disks, so I was saying to get them turned since you are feeling it in the back of the truck.

I doubt bad shocks are causing this. I know for a fact that my shocks are extremely worn out, they have over 240,000 miles on them and about 190,000 was used as a work truck hauling supplies. I have never noticed any shaking or any ill effects due to the worn out shocks.

 

Sounds good.
I tried one more thing. I drove the truck and applied the rear brakes only by using the parking brake. No bounce! When I applied the brakes using the pedal, it bounced! The fronts looked the worst of them all so, I will change the front brakes & rotors and report back. I would have them turned but new ones were almost the same cost as having them turned.....

 

Here is the same problem as reported on f150 online
http://www.f150online.com/forums/bra...g-braking.html


Looks like front rotors could be the issue.

 

If you applied the parking brake and you have rear disc brakes, it may not bounce for the parking brake is inside the rotor and acts like a drum brake rather than a disk brake. IMO that is the what's causing the problem, unless they're severely warped, you can't physically see the warping in the rotor, i mean you can but ya know what I'm saying.

 

Wow,
Good thing I can hide behind this computer. That way you guys can't put a face to this idiot!

Thanks for your help and putting up with the slow and idiotic like myself!

 

That's fine man, that's what this site's for, idiots like US. Start with your rear rotors, see if you can get them turned and if not a set is relatively cheap.

 

I have rotors and shoes for the front and rear axles sitting in my garage for the past 3 days. I am just too cheap to put them on if that isn't the problem.

I guess I should just replace everything and move on.

Thanks for your help.