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Pinion angle vibration
Are pinion angle vibrations speed/rpm dependent like tire vibrations or is it a go/no go proposition? My car is smooth as silk at 50 but at varying speeds up or down I have a driveline vibration I am chasing.
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In my experience it was similar to what you stated also. On my 71 GP SJ after rebuilding the entire car, I had that issue and did eliminate it after adjusting the pinion angle. The fully adjustable upper control arms helped make this easier. Tremec has a nifty app for phones that can help dial in the proper angle in reference to your driveshaft/transmission angle. Lots of other info on this out there. Hope this helps some.
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Definitely RPM or speed dependent. It's likely vibrating at lower shaft RPMs but you're just not detecting it in the car.
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Keep in mind the tremec app is a pass/fail app, and it's possible to do better. But, it still works.
There's youtube vids that can help too, pretty easy to accomplish. . |
If a driveshaft vibration is being caused by a pinion angle issue, much of the time it will present itself as a shudder typically at lower speeds between 15-30 mph and will reduce, or even completely eliminate after that. It will typically only be felt under a certain amount of load.
If the vibration increases with speed (not necessarily rpm) it's more indicative of a balance issue. You'd want to look at the shaft as well as the wheels and tires for an out of balance situation. On these cars, even with a stock type steel shaft, there's just not enough mass involved to create big vibrations from the shaft alone. If the vibration is RPM dependent where you can replicate it with the car sitting still, this indicates an out of balance situation with the engine, clutch, pressure plate, flywheel or even possibly something in the transmission. |
Can also be caused by accessory pulleys or accessories.
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We're pinion angles checked during install?
If not that's the first thing I'd check. It's simple and cost you nothing. Basically since this isnt a street strip application where you're looking for optimum angles at the track you'll be fine with a basic setup, which is the trans output shaft 1-3 degrees down and the rearend pinion yoke 1-3 degrees up. This works for all street vehicles. If that checks ok and you still have a vibration you can at least rest assure your vibration isn't caused by driveline angles and you have something else going on. Hope you don't have a driveshaft for your kit that came from inline shafts..... |
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If pinon angle checks out, it could be out of balance or bent drive shaft. Found a few that were out of balance.
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The Tremec app disappeared from my phone and is no longer in the app store
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iPhone or IOS? I still have mine on IOS, and still see it in the store.
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I still have it on my iOS device as well.
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TREMEC website shows it but error message when it transitions to App Store. And search on App Store doesn't show it. May have licensing issues.
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Sorry - took me a while to find these.
I wrote these as a development engineer for inclusion in the S truck service manual. Hopefully they are self explanatory. The only thing I would add is that imbalance is a first order of shaft revolution disturbance (ie, one "kick" per rev) and u joint working angle disturbances are a second order problem (two "kicks" per rev). They are totally unrelated even though they both affect the same component. K https://forums.maxperformanceinc.com...1&d=1706722141 https://forums.maxperformanceinc.com...1&d=1706722168 https://forums.maxperformanceinc.com...1&d=1706722168 https://forums.maxperformanceinc.com...1&d=1706722168 https://forums.maxperformanceinc.com...1&d=1706722168 |
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VERY NICE!!! ARCHIVED!!! THANK YOU!!!
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Thanks for posting!
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Thanks Keith!!
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