I have a 1999 F-150 V-8, 4.2 (i believe). I have started to experience a bouncing in the back of the truck when braking. I am not sure of what is causing the problem. I have change out both of the rotors and brakes on the rear wheels but that didn't help the problem. I have a long weekend coming up and so I would love to have some advice to where to start looking for this problem.

Any advice would be extremely helpful.

Thanks,

Davis

 

Are you sure it's the rear? Is it only when you brake? Have you changed the front rotors?

 

Also have you ever replaced shocks? Worn shocks will cause all kinds of handling problems.

 

Also, are you sure its a 4.2L V8? Either you have a 4.6L V8 or a 4.2L V6. I experience bouncing when slowing through 40 mph on mine, but I'm getting new pads soon.

 

Didn't even think about that. If it's still got factory shocks, it's probably time for new ones anyway.

 

If they are OE, they have probably been bad or going since about 2001. I never keep OE shocks past 30k.

 

I changed the front rotors and brakes a little over a year ago and I had all new shock put on the truck about 4 years ago.

The truck is a 4.6L, I couldn't remember off hand last post.

I will start will seeing if I can get the front rotors turned or see if they are wharped.

Myren: It feels like it is the back of the truck but it is hard to verify that fact for me.

I only have that bouncing effect when braking not under regular driving. Would that still be caused by faulty shocks?

Thanks!

 

It is possible it would still be shocks.When braking a lot of weight comes off the rear. May be enough with bad shocks that any little change in the road would cause bounce with a bad shock. Is there any oil on the outside of the shock.
As the rear springs are so stiff, it is very difficult to use the bounce test to see if the shocks are bad. You may want to unbolt the lower mount and see how much resistance you get when trying to compress the shock. 4 years can be a long time for shocks, depending on how many miles a year you put on them and how cheap you go with the replacements.

 

If the valving inside the shock(s) is messed up that may cause the problem or the front rotors could be a little warped........Have you had a buddy drive beside you to see if there is a visible shake when you brake? Kinda feel like I'm grasping at straws now.

 

Been there
Have the front torsion bar checked.
loose rubber will give a shimmie effect on stopping.
the harder the break the harder the vibrations, and faster,
big very fast vibrations, depending on the break force.

wrong 100