leversole Posted October 19, 2011 Share Posted October 19, 2011 I drive my truck around prolly 20-30 miles a day...it is a pleasure to drive if I stay away from 24-25 and 48-50 mph. The truck bounces so bad it seems like it going to break something...There are a few ideas I want to try...I thought about chaining the rears up one at a time to see if that changes anything, but it doesnt look like there is any easy way to do it without tearing something upAlso thought about getting four wheels (no tires) and run the rears 4 tires at a time till I find the answer...thoughts?With the original crapped out mis matched tires, I believe it bounced real bad at 38-40 mph only...I bought new steer tires and 8 used drive tires 6 of the 8 match each other, all have lots of tread and "appear" to be good tires.Since the first time I left the tire dealer it has bounced at the two speeds really bad.The kings pins have been replaced. The steering box has a little slop, but when it bounces, it doesn't feel like it is coming through the steering wheel.I jacked the entire rear of the truck off the ground and ran the rears at all speeds and cound not detect any movement or bounciness. I video'd each set of duals and found one a little wobbly, but retightned and got those straight. My guess is that a serious tire problem would not present itself unless the trucks weight was on the tires. After this, still no change...the bounce is completely predictable and appears at the SAME speed every time, whether I am in a curve, going straight, or what.I guess I will have to change out tires till I either find the problem or eliminate tires as the issue. I am at my wits end... Quote Link to comment Share on other sites More sharing options...
jaysm35a2 Posted October 19, 2011 Share Posted October 19, 2011 Are all the lugs tightend down the same on each rim? Quote Link to comment Share on other sites More sharing options...
Rob Posted October 19, 2011 Share Posted October 19, 2011 If you take the weight off of one drive axle such as "chaining it up", or removing the drive tires, the truck is not going to move. This is because all wheels have to provide some traction or the power divider will apply 100% power to the undriven axle.If you can, jack the truck up again and place on stands, then indicate the driveline for a bent, or twisted driveshaft, worn slips and splines, tight universal joint etc.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
leversole Posted October 19, 2011 Author Share Posted October 19, 2011 I use a torque wrench when I tighten them...the untouched ones were put on at the tire dealer, but I will recheck them just to be sure...Thanks Quote Link to comment Share on other sites More sharing options...
David Posted October 19, 2011 Share Posted October 19, 2011 Try letting the air out of one tire at a time and driving it. It won't solve the problem but may help you find which tire is the problem and a lot less work than changing tires. Quote Link to comment Share on other sites More sharing options...
dirtywhiteboy Posted October 19, 2011 Share Posted October 19, 2011 were the steer tires balanced??? could be that famous wonderful camel back smooth ride!! Quote Link to comment Share on other sites More sharing options...
leversole Posted October 19, 2011 Author Share Posted October 19, 2011 Try letting the air out of one tire at a time and driving it. It won't solve the problem but may help you find which tire is the problem and a lot less work than changing tires.It is funny you mentioned that, as I was walking into work this morning, that thought "popped" into my head!Will definitely try that! Quote Link to comment Share on other sites More sharing options...
yarnall Posted October 19, 2011 Share Posted October 19, 2011 I have a 1950 Autocar which has a very similar problem. My father thinks the steer tires/wheels are not balanced. Mine is definitely coming from the front. The steering wheel wobbles too. I don't drive it very often. I just avoid that speed. I have not found someone who can balance a 12x24 wheel. How is the seat working out?Mike Quote Link to comment Share on other sites More sharing options...
jaysm35a2 Posted October 19, 2011 Share Posted October 19, 2011 I had the wobble in the steering wheel and it felt like you couldnt keep it on the road around 45-50ish but whoever put the new front tires on didnt tighten the lug nuts evenly. But it doesnt takem uch to check that though. Quote Link to comment Share on other sites More sharing options...
DCR Posted October 19, 2011 Share Posted October 19, 2011 Have you tried using Equal or a like material inside the tires to balance them? Myself, and many other bus owners, use it in all tires. When I put new tires on the B I had it put in all of the tires. I do not have any shimmy or wobble in my truck.Denny Quote Denny330-550-6020A "Mack Pack" Charter Member Link to comment Share on other sites More sharing options...
leversole Posted October 20, 2011 Author Share Posted October 20, 2011 I have a 1950 Autocar which has a very similar problem. My father thinks the steer tires/wheels are not balanced. Mine is definitely coming from the front. The steering wheel wobbles too. I don't drive it very often. I just avoid that speed. I have not found someone who can balance a 12x24 wheel.How is the seat working out?MikeOn the shelf for now...I am too big for it! Without modifying it, the seat does not come back far enough for me to fit my big a$$ on it! I did use the frame an made an adapter to mount the seat bottom I had before. I do not use a seat back...lean on a pc of plywood! Quote Link to comment Share on other sites More sharing options...
leversole Posted October 20, 2011 Author Share Posted October 20, 2011 were the steer tires balanced??? could be that famous wonderful camel back smooth ride!!Going to the Mack dealer Friday, I hear they have an "on the chassis" balancer... Quote Link to comment Share on other sites More sharing options...
leversole Posted October 20, 2011 Author Share Posted October 20, 2011 It is funny you mentioned that, as I was walking into work this morning, that thought "popped" into my head!Will definitely try that!I let all of the air out of the outside tires...the speed the bounce happens at changed! Now 19 and 39 mph! It sure was nice to ride around at 50! ANyway, like a dumba$$ I let ALL of the air out of the tires...tried to be carefull, but I broke the bead on all four! I got two of them seated and aired up...gonna try the fourth in a few, the first one may have to go to the tire shop...will take the schrader out and try to hit it with air quickly as I wrestle the tire around...I do not know what it means by the speed change though, I am baffled! Quote Link to comment Share on other sites More sharing options...
dkv411 Posted October 20, 2011 Share Posted October 20, 2011 are the rears aligned? my shop is telling me i have bushings out in the rear suspension and i can see that the alignment is out and that is creating a shake and almost uncontrollable shimmy thru the whole truck Quote Link to comment Share on other sites More sharing options...
leversole Posted October 20, 2011 Author Share Posted October 20, 2011 are the rears aligned? my shop is telling me i have bushings out in the rear suspension and i can see that the alignment is out and that is creating a shake and almost uncontrollable shimmy thru the whole truckI will have the alignment shop take a peek....mine doesnt shimmy, it bounces up and down! I cannot tell whter it is starting in the front or back! May get a video camera setup going and video each wheel to see if I can spot anything! Quote Link to comment Share on other sites More sharing options...
Rob Posted October 20, 2011 Share Posted October 20, 2011 That is what I've strapped the kids to the back of the cab for. They can report back any vibrations noted after the fear subsides. I tried it once with "Momma", but she was too heavy and the truck didn't bounce at all.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
leversole Posted October 20, 2011 Author Share Posted October 20, 2011 Maybe I could strap my "ol' lady" to the back! She doesnt like to ride in the cab, says it's "too noisy"! It WOULD be much quiter back there with the tires! Which works better, bungees, rope, or chain? Quote Link to comment Share on other sites More sharing options...
Rob Posted October 20, 2011 Share Posted October 20, 2011 Gawd, don't use no fiberous rope. "Momma" chewed through those restraints less than 1/2 mile down the road. She was really pissed too cause the wind was blowing her hair so bad it was revealing her bald spot and that may have contributed; (you know she does have pride).Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
miro Posted October 20, 2011 Share Posted October 20, 2011 Aw reminds of the days of the 866, low power complaint on an F model, they would put the cab down on me, the service manager would drive with a loaded set of trains and I would adjust the rack until it pulled good. A little warm but it got the job done when you don't have a dyno Quote Link to comment Share on other sites More sharing options...
fifth wheel Posted October 20, 2011 Share Posted October 20, 2011 I would say the problem is with the power divider.FW Quote Link to comment Share on other sites More sharing options...
leversole Posted October 22, 2011 Author Share Posted October 22, 2011 Played around with tire air pressures today...the lower the pressure, the lower the speed that the bounce starts...right now I have 80psi in the steers and 70 in the drives...bounce now starts at 43 and is gone by 46...gonna hang with these pressures for a while...One thing is becoming clear...I changed all ten tires and the only difference was the speed at which the bouncing starts...I am hoping when get it on the balancer that the problem presents itself...I do not see how a drum or something like that cause that big an issue and not show itself in tire movement...maybe the front end is creating an issue and the worn rear suspension is answering the call and back and forth...Anyway, I am done testing for now... Quote Link to comment Share on other sites More sharing options...
dirtywhiteboy Posted October 22, 2011 Share Posted October 22, 2011 are you bobtailing or you pulling sumtin??? Quote Link to comment Share on other sites More sharing options...
macksmoke Posted October 22, 2011 Share Posted October 22, 2011 Just to throw a few things out there:Could it be a rear brake drum balance issue?Driveshaft weight missing?If it is side to side in steering wheel, check tie rod ends.Maybe a Mexican put a kilo in your tire.Maybe you need some dead weight in the rear, I hear the white house has some. Quote Link to comment Share on other sites More sharing options...
maxidyne237 Posted October 22, 2011 Share Posted October 22, 2011 I agree with Fifthwheel. Check powerdivider and driveshaft for wear Quote Link to comment Share on other sites More sharing options...
leversole Posted October 22, 2011 Author Share Posted October 22, 2011 I am running with no load...I have jacked the entire rear off the ground and it does not shake shimmy or nuthin! I would think that if it werre something in the drive train, it would make the truck shake when in the air...though I am not ruling anything out! The bounce seems in time with wheel rotation...I am thinking maybe when I had the back end up, not all of the wheels were rotating the same speed...it only bounces between a 2 mph range....maybe the "culprit" never got going that fast because of differential action....hmmmmmmmm.I may use the brake adjsutment to get one wheel at a time going and see if I can identify the culprit! Quote Link to comment Share on other sites More sharing options...
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