On well paved highways, my 1999 F150 Extended Cab rides great. I love it. But on certain freeways, the back end bounces up and down SO BADLY that everything in the cab & bed rattles, including my teeth and the headlights go up and down on the road (usually at about 60-70 mph). Bought new rims and tires recently, because it needed them, so I know it's not a wheel balance problem. The tire shop suggests new KYB gas shocks, but I wonder if that's really all that is wrong because it doesn't "sway" in turns, bottom out, etc. as would be expected with worn out shocks. It seems to be getting worse. Could it be the leaf springs or something else? A friend suggested putting sand bags in the bed. Come on... it didn't need it before, in fact it used to ride as smoothe as a Lincoln Towncar. Not anymore! I replaced the rear shocks (stock replacements) about 30,000 ago. Would like a mechanic or suspension specialist to provide recommendations or anyone who has had to correct such a problem, before I pour money into trying to figure out what should be fixed. Any suggestions?

 

Bought my 2001 extracab earlier this year with brand new Falken rubber on 18" wheels, which had bee installed by the dealer. Took a few months before I realize that highway speeds were a problem for me. After trying everything else, I spent $20 to have the rear tires re-balanced at Les Schwab. Turns out they were WAY OUT OF BALANCE and I thought the same thing you did.

"Certainly these new tires/wheels can not be out of balance."

Yet I know...they can. Not sure about your tire shop, but try and go back there when the person who sold them to you is NOT there, so you might get a more open minded perspective on re-balancing. Or if you have the money, take your truck somewhere else and have it done. The original shop will not want to admit they flubbed the job.

 

Ive always been curious, how do you balence tires?

 

It is done on a machine in which the computer makes it balance. All the tech has to do is put the new weights on.

 

In the case of my tires, there was too much weight and it was not in the correctly placed on the wheels. The tech who did the re-balance showed me how bad one of them was...it was bad.

But I am not surprised. Not to knock tire places, but when a dealer sends cars to get new tires wheels, the installer knows that this vehicle is probably going to just go sit on the lot for a while. There is not much motivation, in my case, to make sure it is done right...just in a hurry.

 

It seems unlikely that the new tires and wheels would react the same as the previous ones. It's my guess that the problem isn't unbalanced tires. The shop where I bought the new ones is very reputable. Someone else recommended throwing sand bags in the back for weight, but it never needed it before about 50,000 miles. Another truck owner said he removed a leaf from his springs to bring down the back end. Curious if anyone else has encountered this situation.

 

I seem to remember a thread ways back on this subject with the extended cabs being at such a length that the front and back wheels hit the expansion joints built into the highway at the same time causing the trucks to jump such like you discribe. You say it only happens on certain roads this may be the problem, or not. I would try placing some weight in the rear of the bed and see if it makes a difference. It can't hurt and if it does help i would get heavy duty shocks installed in the rear. Hopes this helps, let us know how you make out.

buck.

 

Well, my ride isn't perfect since the re-balance of the rear tires, just greatly improved.

As for the flipping of the lower leaf in the rear...I tried that too. That definitely softened things up back there, actually dropped the rear end too around .75", but I didn't like it at all. Felt kinda like an old 70's Cadillac! I flipped it back over within 48 hours.

 

02 screw, same thing here, seems to be happen between 60 and 70 after 70 it goes away had the tire balanced and mad no difference, 35K now and still don’t know what to do shocks? The dealer told me my tires are to aggressive, Dunlop Rover T/A’s I don’t see how that is aggressive, (no my choice of tires, bought the truck with them)

Steering wheel shakes, Passenger seat vibrates, console rattles,

 

My '01 XLT SCab has bounced on certain freeways in SoCal from day one. Not a tire/wheel problem, but simply the dynamics of the wheelbase length/suspension on the Scab Vs. the expansion joint "jolt" input into the suspension system at a particular frequency (i.e. road speed) on concrete road surfaces. You'll notice that it doesn't do it on asphalt surfaces (no expansion joints).

The 101 through Ventura is really bad - scared the poop out of me the first time until I figured it out. Bounces so hard and fast it's funny - my teeth chatter, I'm bouncing up and down - I have to think everyone's looking at the truck and going "look at that idiot bouncing up and down - that's gotta hurt"

Northbound there's a spot where the road surface changes right before the Santa Clara River bridge and it's like throwing a switch - bouncing suddenly stops.

Many long wheelbase PU's do this - all makes.

On my SCab, if you put a load in the bed it dampens the bouncing a bit but doesn't eliminate it.

 

Menchar, thanks for the reassurance that it may not be a problem with my truck. The 101 (north and southbound) is exactly where my teeth chattered too. Also the 10 eastbound through Ontario/San Bern and the 118 westbound in Northridge to Simi Valley. I just purchased a full set of KYB heavy duty shocks and, although it seems to ride better on surface streets, it didn't seem to affect those hwys (I tested it). As for looking like an idiot to other drivers... I know what you mean, because I thought the same thing! Funny thing is that I don't notice other F150s doing it. Guess I'll try some weight in the bed before I drive that route again and see how it responds. Thanks for your advice, too, buckdropper.
CWBT

 

Interesting. My '99 Scab did the same exact thing. I couldn't drive it over 65-70 on certain freeways in So Cal. I never resolved it, now I drive a '01 Scab and it doesn't do the bouncy bounce on the fwy. Only major difference between the two trucks was the rear-end. The '99 had 3.55s and current truck has the next smaller size - I think its 3.23?

 

My brnd new 01 Scab bounced real bad on the 5 between San Diego and Irvine when I had an empty truck. ( felt like I had a bunch of circus clowns in the back jumping around) With a load or carrying/towing anything it was just fine. I lost the truck when I was broadsided by a guy blowing a red light. I got a 01 Lightning and love the ride compared to the Scab. Never quite figured out the bouncing thing though.

 

My brnd new 01 Scab bounced real bad on the 5 between San Diego and Irvine when I had an empty truck. ( felt like I had a bunch of circus clowns in the back jumping around) With a load or carrying/towing anything it was just fine. I lost the truck when I was broadsided by a guy blowing a red light. I got a 01 Lightning and love the ride compared to the Scab. Never quite figured out the bouncing thing though.

 

I also have a 199 F-150 Extended Cab. It is a Lairat Flareside 4wd. It rides well on the roads here in Kansas but I had similar problems going through Oklahoma on the way to Texas so I can say that CERTAIN roads do indeed lead a person to believe that something is wrong with the truck. I also hate those mornings where the portion of the tires that sit on the pavement get colder or hotter then the rest of the tire. This somehow makes the tires a little out of balance and can make for a bumpy ride until the tires achieve a uniform temperature.

My question is: Have you always driven your truck on these CERTAIN roads and did you always have the bumpy rides on those CERTAIN roads?

Larry