leversole Posted November 30, 2011 Share Posted November 30, 2011 Well it is definitely the front causing the issue! Don't know which side yet, but it looks like I will be buying replacement drums!Video looking at the rears is smooth with no bounce at all!Will try to get a cleaner video, but the first bounce starts at about 20 seconds in and ends abruptly at about 2:32... Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/ Share on other sites More sharing options...
MACKS Posted November 30, 2011 Share Posted November 30, 2011 That's some bounce alright,something definitely out of round.. Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-92534 Share on other sites More sharing options...
41chevy Posted November 30, 2011 Share Posted November 30, 2011 With a bounce that bad, I'd think if you jacked the front wheels off the ground and spun them you see which one . Than I'd start at the tire and move in from there. Your suspension has been checked? Paul Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-92540 Share on other sites More sharing options...
leversole Posted December 1, 2011 Author Share Posted December 1, 2011 With a bounce that bad, I'd think if you jacked the front wheels off the ground and spun them you see which one . Than I'd start at the tire and move in from there. Your suspension has been checked? PaulBalanced at the Mack Dealer! It only does it at 22 mph and 44 mph...no trace at other speeds! New king pins...wheel bearings tight...Everything that rotates on the front is new with the exception of wheel hubs and brake drums... Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-92553 Share on other sites More sharing options...
slpwlker Posted December 1, 2011 Share Posted December 1, 2011 Glad you secured that camera securely and didn't shake it off Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-92559 Share on other sites More sharing options...
leversole Posted December 8, 2011 Author Share Posted December 8, 2011 Removed the drum on the pass side today, as it was the one that has a heavy spot...with the rim/tire off, that one always rolls heavy side down...Took the drum off, everything "looks" okay...reinstalled the wheel and tire...no change in the bounce! Dammit! Before I pull the other side, I am goin to temporarily put the steers on the back and air them down...if it is a front rim or tire problem, it should be evident,,, Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93328 Share on other sites More sharing options...
MACKS Posted December 8, 2011 Share Posted December 8, 2011 Removed the drum on the pass side today, as it was the one that has a heavy spot...with the rim/tire off, that one always rolls heavy side down...Took the drum off, everything "looks" okay...reinstalled the wheel and tire...no change in the bounce! Dammit! Before I pull the other side, I am goin to temporarily put the steers on the back and air them down...if it is a front rim or tire problem, it should be evident,,,I think that's your best bet,swap the tires and rims and see what happens.. Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93337 Share on other sites More sharing options...
leversole Posted December 8, 2011 Author Share Posted December 8, 2011 Dammit!...Dammit!...Dammit! Talk about frustrating! I'm in the mood right now to park it and make it a lawn ornament! Swapped the drivers side steer and front rear tire/rim...NO CHANGE AT ALL! Tomorrow I will do the same thing on the other side, and when that doesnt do anything, I will remove the drum on the drivers side, and when that doesnt make any difference, I might drive it off a cliff with me in it! Maybe the SOB is possessed! Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93338 Share on other sites More sharing options...
mack mhe9 Posted December 8, 2011 Share Posted December 8, 2011 when i bought my superliner it had sat for a couple years tires looked good werent out of round and balanced but they had flat spoted from sitting a couple years drove them for a month put on new ones bounce went away. not saying its your problem just something different, Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93339 Share on other sites More sharing options...
Speed Posted December 9, 2011 Share Posted December 9, 2011 You said something about a drum with a heavy spot,but without the drum it still does it? I'd think THAT'S your problem.Maybe if you find the place that hub and drum settles to,re-install the wheel and add a few ounces of wheel weights to that wheel at the top,opposite the "heavy side",and try it-see if anything changes. Might have to adjust the amount of weight to counterbalance the heavy side. Or,If you could borrow a different hub to try for a couple of miles that might tell you if the hub is the problem-maybe it's machined wrong or has a casting flaw that upsets the balance. Speed Quote "Remember-ANY Gun Control is Unconstitutional!"<!--sizeo:3--><span style="font-size:12pt;line-height:100%"><!--/sizeo--><i><b>MACK-E Model Registry # 36</b></i><!--sizec--></span><!--/sizec--><a href="http://www.nvabatetravel.com/"target="_blank">http://www.nvabatetravel.com/</a> Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93384 Share on other sites More sharing options...
Rob Posted December 9, 2011 Share Posted December 9, 2011 You said something about a drum with a heavy spot,but without the drum it still does it? I'd think THAT'S your problem.Maybe if you find the place that hub and drum settles to,re-install the wheel and add a few ounces of wheel weights to that wheel at the top,opposite the "heavy side",and try it-see if anything changes. Might have to adjust the amount of weight to counterbalance the heavy side. Or,If you could borrow a different hub to try for a couple of miles that might tell you if the hub is the problem-maybe it's machined wrong or has a casting flaw that upsets the balance. Speed Look at the back side of the spokes. They rust badly and eventually start to "chip off" internally. You could have lost a few ounces due to this and the unbalance rotating mass could be the problem.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93391 Share on other sites More sharing options...
miro Posted December 9, 2011 Share Posted December 9, 2011 I don't think that you have a Balance problem as the tire is not really bouncing the chassis is. Has the frame been stretched or modified in any way?How are the crossmembers and motor mounts? Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93392 Share on other sites More sharing options...
Rob Posted December 9, 2011 Share Posted December 9, 2011 Look at the back side of the spokes. They rust badly and eventually start to "chip off" internally. You could have lost a few ounces due to this and the unbalance rotating mass could be the problem.Have you had the tire spin balanced while mounted to the hub? This would readily reveal this problem.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93393 Share on other sites More sharing options...
leversole Posted December 9, 2011 Author Share Posted December 9, 2011 The Mack Dealer spin balanced both steers on the truck...on the pass side, there are two pcs of flat steel welded to the back side of the hub presumably for balance...The drum wheel combo (pass side) has a heavy spot, when I took the drum off and mounted just the wheel, there was no heavy spot.When it warms up a little, I will remove the drivers side drum, and swap front rear tire on the passenger side... Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93396 Share on other sites More sharing options...
Rob Posted December 9, 2011 Share Posted December 9, 2011 The Mack Dealer spin balanced both steers on the truck...on the pass side, there are two pcs of flat steel welded to the back side of the hub presumably for balance...The drum wheel combo (pass side) has a heavy spot, when I took the drum off and mounted just the wheel, there was no heavy spot.When it warms up a little, I will remove the drivers side drum, and swap front rear tire on the passenger side...I've seen old drums present the problem also. Some of those can be difficult to acquire new. You might have that hub assembly balanced while it is apart by welding, and grinding for balance. This can't hurt.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93398 Share on other sites More sharing options...
miro Posted December 9, 2011 Share Posted December 9, 2011 I still think you're barking up the wrong tree. The front end is swaying in the sprung weight, the unsprung weight is reacting to it. I have seen this in brand new Superliners in the 70 and other trucks over the years. the only way to stop it on the Superliners was to put inside channel in the frame. The frame takes on harmonics at certain speeds and will not come out of it untill you get out of that speed. If the balance was that bad as in the Video the tire would actually lose contact with the road. I would like to see a happy outcome from all this. Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93401 Share on other sites More sharing options...
b61fred Posted December 9, 2011 Share Posted December 9, 2011 I have an idea, Maybe if you would mark the back of the tire in four spots and drove it down the road with your camera. You might see that if say mark number 3 is always on the ground when the hop starts then you might have idea where to start. If the position of the tire has no bearing on the hop then you know to try another area. If its a rotational out of balance problem it should have a cosistant mark hitting the ground. Quote 15 gears...no waiting! Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93402 Share on other sites More sharing options...
miro Posted December 9, 2011 Share Posted December 9, 2011 He's already had them spun balance and the passes, I think you,re looking for something that is not there Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93403 Share on other sites More sharing options...
Rob Posted December 9, 2011 Share Posted December 9, 2011 He's already had them spun balance and the passes, I think you,re looking for something that is not thereI can't watch the video. Are you stating the tire/wheel assembly is not "hopping" at the posted speeds? If the tire is not oscillating or hopping at any given speed an imbalance condition prolly doesn't exist. If the bounce is from an unsprung condition, this could start at many places through the truck and transfer forward.If you can, restrain one frame rail of the truck and use the engine to inch forward, and rearward noting the movement of the left frame rail with the right rail stationary, (you don't even need to come off of idle) then repeat with the left rail stationary. If you notice more than about a half inch of movement in either rail, start blowing the rivets retaining the xmembers, and replace with grade eight bolts very tight. Also make sure the 5th wheel plate, (if equipt) is very tight to the frame if not welded. Loose xmembers are bad about doing what you are experiencing; once a vibration starts anyplace on the truck, it can transfer anyplace else till it finds a place to freely oscillate.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93405 Share on other sites More sharing options...
MACKS Posted December 9, 2011 Share Posted December 9, 2011 This is getting complicated,I hope for your sake that the problem lies in the other tire or drum. Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93420 Share on other sites More sharing options...
Rob Posted December 9, 2011 Share Posted December 9, 2011 Finally was able to watch the video. Although unclear, I would not be looking at an unbalance condition. I do not see evidence of wheel tramp, or out of round to the tire/wheel assembly. That is somewhat of a linear oscillation to the frame rapidly unloading the spring and suspension. This is probably set up and amplified distant from the point of notice. What I cannot tell from the video is if the oscillation is linear from side to side, or more pronounced on a single side.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93421 Share on other sites More sharing options...
Rob Posted December 9, 2011 Share Posted December 9, 2011 This is getting complicated,I hope for your sake that the problem lies in the other tire or drum.The symptoms are indicative of loose crossmembers in a light duty full frame vehicle such as a pickup truck when the frame has been straightened from a "diamond" condition. If the retaining rivets are not replaced with bolts that retain the crossmembers, the vehicle usually suffers from symptoms such as Leslie is experiencing. Given a heavy truck has much stiffer springs and heavier components, this is easy to become violent once conditions are right.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93423 Share on other sites More sharing options...
leversole Posted December 10, 2011 Author Share Posted December 10, 2011 Last several post are very interesting...WIth the front tires on the rear, absolutley no change in the bounce...I am stil going to remove the left hand drum just so I can say I KNOW it is not the drums or the tires on the front...Anyhow...I took about ten videos today and though the truck is still bouncing, I cannot see it in the video, front or back at all...the rears have never moved...BUT...I took two videos with the camera mounted on the airtank (about mid frame under the battery box) and it looks like the camera was moving up and down, but not the front or rear axles! I was dumbfounded untill I read the last few posts...In the morning I will touch every bolt on all of the crossmembers, and also look for signs of any movement between the crossmembers and frame (if it is flexing, it should leave a mark)Still doesnt explain why it happens at one speed, and exactly twice that speed, and only a range of +- 1 or 2 mph....that is, 22 mph and 44 mph...If I air up the tires to 100 psi, all it does is raise the bounce mph to 25 mph and 50 mph...Thanks for all of the comments!(It takes a community to raise a truck) Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93445 Share on other sites More sharing options...
fxfymn Posted December 10, 2011 Share Posted December 10, 2011 Not to be too obvious, but the sure sign of a loose rivet is a rust streak coming from the hole. Quote Money, sex, and fire; everybody thinks everyone else is getting more than they are! Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93486 Share on other sites More sharing options...
MACKS Posted December 10, 2011 Share Posted December 10, 2011 I'm certain this is not your problem but one time I had a driver who kept complaining that there was something wrong with my truck,said it bounced like a bronco but only in the morning and then it would go away,I checked everything and couldn't find the problem,turned out to be the road he was taking to the job site.lol Quote Link to comment https://www.bigmacktrucks.com/topic/21884-bounce-slow-motion-video/#findComment-93489 Share on other sites More sharing options...
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