I've got a bounce in the passengers side front on my Mack from 45 MPH-50. I bought a new front tire and thought I got a bad one so I up graded to high end tire and still no change. Couple thoughts: I get a bang or sounds like in the front U Bolt when I hit the brakes hard? Also my tires are new except one set on the duelies. Tire guy said it might be traveling up to the front? My u bolts look tight - no sign of paint scrap from movement.? How does yours ride? Any thoughts on what it might be?

Try checkin the toe! Should be more than 1/8 " but less than a 1/4"

Whats the toe? The alignment? Or the plumbness?

Let someone step on it and you will shout get off my toe.

check your king pin and bushings grease

Bad shock maybe!

Tire out of balance or bent rim ? The noise I would guess is a rubber grommet somewhere in the front suspension.

Few things to check. front spring bushing, broken center bolt , cracked frame rail , if the front springs have rust between the leaves they will bind up and slap on  the rear hanger. If you do have shocks on it check for worn bushings. My guess is the front springs need to be replaced.

The toe refers to the a measurement from a fixed point in front and back of the axle Lift the truck where the tires can spin freely, spin the tire and make a mark all the way around the tire, next do the same on the outher tire, now let the truck down and get a tape and measure the scribes once in back of the axle mark that number down and do the same in front mark the number down, now take the two numbers and find the difference. This will be your toe. You want about 1/8 ", to much toe in will make the tires bounce at 45-50 mph and ware your tires fast, toe out will let the truck wonder allover the road

Toe

That was a good explanation Rockhard..

What kind of wheels do you have on the steer axle ???????? Bud or dayton ?????

Noise could be cab jack and hook,or a novel idea the rear hook of main leaf,leaf bushing on front of spring.If one suspects a dynamic inbalance jack front axle and use a dial indicator for tire runout.I wouldn't overlook steering gearbox and related parts,mack did have issues.You had these issues some time back.

Here's some thoughts

http://www.thedieselgarage.com/forums/archive/index.php/t-5968.html

I don't have shocks (wish I did). Many, the issues with this truck y I think was a small seal leak on the steering box. It fixed its self! As far as the bam it could be a spring bussing but.. Its a pretty new truck 02 with 129k. The DOT inspector said it was very tight and all looked great. It sounds like a U bolt is loose. The tires are Michelin XZY 3. Rock thanks for the toe advice I'll check it. Getting ready to drive to I- Falls tomorrow, 160 miles for a 5:15 AfuckingM pour.( 2 AM departure). Is 2 AM considered morning or still night?

I checked the toe: It seems if my measurements are right, i'm 1/2" out from the front to the back? I put a pencil line around the two front tires, then measured across the front and rear of the tires and the back is 1/2" wider than the front.

I wonder if when I adjust the tie rod will i need to hammer out the ball joints or if i can just spin the center rod? Being that it has threads on both ends. Yes i'm sure its going to be very tight and it'll need to be cherry red to spin.

B. With a couple of pipe wrenches and some help from one of your buddys, spray wd40 in around the threads and the clamps " liberaly" let it soak, losen the clamps good n lose, something eals that helps is to lift the truck off the tires, takes the bind out. It takes a couple of tries to get the toe just right patience is key. Lol @ many man you crack me up

Sorry forgot mention, under no sircumstances do not use heat on any part of the steering. The heat will brittle the steel and the part could fail. Just thought you like to know

Haven't had the chance to crawl under for the undertaking yet. I'll keep you all informed on the out come.. Thanks for the great advice!