I am Chasing a vibration on a Mack Granite, and looking for some tooling to help in the diagnostic process. Inquired with the Snap-on man about tooling and came up with chasis ears. This seems like tool to find a noise, anyone have a clue if this tool would work on a vibration, or an alternative tool.
During my teaching career, the University I worked for hosted Chrysler Academy training for the local dealers. Their vibration & drivability class was very good. Probably the best of the big three. They showed us how to use an inexpensive Sirometer for analyzing frequency to revolution orders. Which works 95% as well as a $2,000 electric gizmo. My first reaction was, “ what sort of black magic is this?” But, was soon impressed with the accuracy of this goofy little thing for pin pointing harmonics.
I think they're sold by Briggs & Stratton. They are very accurate. There are also some that look like a bar graph. Wonder if an automotive stethoscope could work for you?
Is the vibration harmonic or dynamic? From my limited experience with mulcher rotors harmonic balancing won't cure dynamic imbalance.
vibration from road like the driveline clocked wrong or engine dead hole? Tape measure tandem drive hub to hub could be out of line
Vibration comes in on the highway 60 mph. Doesnt seem to bother with truck loaded, or pulling a grade steady throttle. 1) Entire driveline was pulled and sent to Gilbert driveline in Manchester, slip yokes replaced, carier bearings replaced, new U Joints and Balanced. 2) Front Carier Replaced with a ReMack 3) Rear Hubs replaced 4) Steer axle replaced, king pins replaced, new bearings and races. 5) Front motor mounts replaced. 6) Chalmers Suspension, all suspension bushings replaced, and walking beams.
6) tandems could be out of alignment. Center hub to center hub
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I havent thought of mis aligned drives as a vibration issue. I have not used wheel balancing equipment on drives, always ran equal in the steer tires. With 24.5 tires what speed does a vibration come in at, with my pickup truck it is more like 70 mph
crap. * 60 mph vibe issues lie in wheel ends, unbalanced drums, issues with tire casings and rims. 90% plus of the time it starts at 55 ends at 64 mph, 60 is most severe. Depending on type of tread pattern plus brand of casings can be the biggest factor, some as much as 24 oz out. Combine two like that on one wheel end clocked close on hub when mounted combined with out of balance drum. And if it has Dayton's, those wheel ends are tough to balance. * Suggest have all spun balanced and see how many pounds it takes to get in sync before going any further if you haven't done that already. * Equal is a poor balancing agent--it's more for casing life.
Interesting, All wheels are Hub Pilot.
What's it got for tires on it?
Doesn't matter, casings these days are a roll of the dice. Toyo is probably one of the worst right along with Double Coin. Only two casings I trust, Bridgestone/Firestone & Yokohama for minimal runout and balance.
Sure seems like a tire issue. Even if tires are skidded in an emergency stop or locked up they can get out of balance. Have heard the import tires can be way out of balance. Liquitube has pouches for semi tires that supposedly work for balancing as well as small leaks but might just just be marketing hype. Supposed to be really good for leaks as it coats the entire inside of the tire and rim. Cleans up easily with water and doesn't leave a sticky mess.
Ive used this https://truckvibration.com/pages/in...nimize-part-swapping-with-driveline-analyzers Works really good. Just put sensors on the seat, frame and engine, speed sensors on the engine and trans. Enter some engine/ trans/ driveline info and go for a drive. Based off where the vibration is/ frequency it will identify the area it comes from. Also the owners are very knowledgeable too. Used to do a truck a week when the spl250 driveline got introduced. Tires/wheel end vibration is slower then driveline. Checked driveline phasing and measured driveline angles? Felt in the steering wheel or seat/cab? Probably one of the worst things to help diagnose remotely.
Driveline--vibe range big or small high 30's to high 40's, has to do with rpm/gear ratio frequency, such as 6th/6th over roughly 35 to 40 mph with 3.73's under torque, anything above or below it phases away normally. In the case of op's range of noticeability, it seems under a low torque semi-coasting scenario from what I gather in post #6. * Just possibly the worst I had to find was transmission related, only happened in 7th/8th over, a buzzing vibe with gear sing. A reman transmission that was 5 months old that got progressively worse over time and most noticeable at 52 to 62 mph. Removed back section and as would have it nothing looked unremarkable until I looked over gears used in power flow for overdrive. A odd wear pattern on teeth plus wearing at a angle on front countershafts to auxiliary drive gear. The rear section case had been improperly bored off center for rear bearing housing bores causing shafts to not run straight with bad tooth contact. Replaced counters, auxiliary drive and entire case, no more issue. But in order for it to act up a certain rpm speed under a torque load had to be applied. * Agreed.
Front Steers 385 Bridgestones Front Drives Virgin Generals Rear Drives my Firestone casings capped The vibration tool is exactly what I need, looking at the website it may be worth reaching out to the sales guy to see who has one and pay them to run it on my truck. A buddy of mine from the dealer suggested jacking the truck up all wheels off the ground and running it up to speed, but that sounds dangerous, and thoughts of breaking something when slowing down. Yes these vibration issues are difficult to diagnose remotely, I have run out of the typical answers, but have a few avenues to persue after this conversation. 4:64 Ratio in the rears, Mack 9 speed
New rear suspension idea check over there work & if you can jack truck up hand spin tires.https://youtube.com/shorts/kPz5C2_vwqM?si=aRDSJN0T3FyFsfxC
I would probably be most suspicious of the caps, before a lot of the things that you already replaced.
Pull the axles and run it up to highway speed. No vibe tells you it’s a wheel, tire or something in the wheel end. Vibe tells you it’s motor/trans/driveline or diffs. If it still vibrates with axles pulled then pull the short shaft between diffs. No vibe tells you it’s the shaft or that diff. If vibe is still there keep pulling them until it stops telling you where to look, if you’re out of drivelines then you know it’s up front.
Check tires first, less time and expense involved. If engine related it will be there all the time. I seriously doubt the driveline shop screwed up. Could be a rear drive or axle. With all the work performed already most of it has been covered, normally metal will be found on drain/fill plugs if it's a carrier/side or pinion bearing destructing. But 60 mph vibe is road speed related, a very high percentage of the time.
Is it just me, or are the majority of new tires just crappy? The Goodyear, Michelin and Bridgestone National Account Reps must send me all the out-of-round ones. I think the Michelin steer tires are more likely to be round, than the others. “Yeah, send those egg shaped ones to Coaldust. The roads are so bad, they won’t even notice”.
Zero luck with Goodyears, Bridgestone 213's decent, Firestone 591's decent, Michelin has become a mediocre tire. Toyo and Continental both are lousy on steer. Yokohama 527's on drives are good.
You beat me to it! I used this tool in the seventies to set rpm on small engines. I still have it.
So a sirometer is $30 on Amazon. How am I using this to identify vibrations? Explain like I'm a child.
Someone else can probably explain it better. I’ll try. Put the gadget on the dash and have someone watch it. Measure the frequency of the vibration when it occurs and compare it to a known chart to roughly pinpoint the component. For example: driveshaft vibrations occur at 1x to 3x driveshaft speed, calculated by multiplying your wheel speed by your final drive gear ratio. Like this; Multiply the ratio by the first order tire frequency. Let’s say the ratio is 3.08. So, 3.08 x 11.5 Hz gives us 35.42 Hz. Therefore, at highway speed, an out-of-balance driveshaft on this vehicle will produce a reading between 35 Hz and 36 Hz at about 60 mph. You can do the math to more accurately determine first order tire frequency, or just use 11.5 hertz as an average. It’s going to be 11-14 on a 11R 22.5. If the driveshaft were bent in a way that produced a second order vibration, we would read between 70hz and 72hz.
They measure frequency and engine RPM by vibration. You could essentially put it or hold it on different places to see where there's a major difference in frequency. It uses a wire that vibrates back and forth and you extend the wire to where there's almost no vibration to get your RPM or frequency. Who ever designed it is a genius.
The downside is trying to get good measurements driving down the road. A chassis dyno works well.
Explain the "first order" vs "second order" part. Because I'm not following that. If I would have known how much math I was going to do later in life, I would have paid more attention in math class. Vs staring longingly at Stephanie, Becky, and Kendra's tight shirts. 7th grade was hard. But anyways - here we are.
I'm lucky because I went to a trade school. They taught math that you would actually use on a job. Coaldust's math is a little (or a lot) more complex though.
I stick to simple coffee over math,coffee jumping out of cup=bobtail,coffee cup dancing road vibration cup on its side tire blowout
There was a lot of good suggestions in this thread, his vibration was 50-60. HeavyEquipmentForums
Thank you guys for the thought process. I reached out to the Truck Vibration Technology Representative, the tool is 7K and they suggested some local dealers that have this technology, but also they rent the tooling by the month and will work up a vibration analysis for that rental. I have ordered some of the centering lugnuts for another truck so will use some on this truck also. Reading up on tire balance and resonance frequency, and will be having a look at balancing tires. Also ordering a tram guage for rear alignment check. I am suspicious of the transmission in this truck, time will tell.