Well hopefully christo or someone as smart will chime in.....adding weight for brian and i obviously cures our problem. But what does this mean, we need DC driveshaft?
Front Drive Shaft grrrrrrrrr findings so far. .
- Thread starter concretejungle
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sleeoffroad
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I would still do the test of running on the front with no rear. Passengers in the truck, then the noise goes away points to the rear. Also, CM05 does not have a rear bumper with heavy springs. Not sure about Concrete. You might think it comes from the rear, look at where the transfercase is in relation to the seats and you will see that one could easily be mistaken.
christo,
Will do.....but im still curious, lets say we pin the problem to either the rear or the front driveshaft, what exactly is the cure? or is there more one thing that can be done?
Will do.....but im still curious, lets say we pin the problem to either the rear or the front driveshaft, what exactly is the cure? or is there more one thing that can be done?
sleeoffroad
Supporting Vendor
If you are running the heavy spring with no additional weight in the rear, that is the problem.
We never have these issues if the components are in good shape and the suspension is chosen correctly. How to solve it, either lower the truck, add weight, get adjustable arms and try to adjust and/or buy a rear cv shaft.
We never have these issues if the components are in good shape and the suspension is chosen correctly. How to solve it, either lower the truck, add weight, get adjustable arms and try to adjust and/or buy a rear cv shaft.
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For the rear you need longer lower and/or shorter upper links to correct the drive line geometry. On the front maybe a CV shaft or change the castor/axle angle to correct the drive line geometry. Have you tried running the front shaft in phase?
On my truck there is a slight grr from both shafts, when one shaft is removed the other one delivers all the drive force, so the dynamics are changed and the sound changes. When only one axle is driving the suspension bushings flex more to carry the additional load changing the loaded pinion angle, by adding weight you are also changing the loaded pinion angle, not definitive tests but will give you an idea what's going on. I find measuring the drive line angles helpful, you can only measure the static angles, so some fudging of the numbers needs to be done to determine loaded angles.
On my truck there is a slight grr from both shafts, when one shaft is removed the other one delivers all the drive force, so the dynamics are changed and the sound changes. When only one axle is driving the suspension bushings flex more to carry the additional load changing the loaded pinion angle, by adding weight you are also changing the loaded pinion angle, not definitive tests but will give you an idea what's going on. I find measuring the drive line angles helpful, you can only measure the static angles, so some fudging of the numbers needs to be done to determine loaded angles.
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sleeoffroad said:
With J's and no weight my rear pinion end joint runs at 6 degrees, too steep for a CV. My pinion is only about 2 degrees high static, so I am making slightly longer lower arms that will make it about 1 degree low static, that should allow the stock shaft to be happy?
The front with J's and 1.5" spacers, the pinion end joint is about 3 degrees high from pointing at the transfer flange. Going to roll a couple of degrees more caster into the axle and add a CV shaft?
Busted!!! You got me there. Maybe I need a lighter spring 'til I get some lbs back there.sleeoffroad said:
Does this mean pulling the shaft apart and reassembling w/ a 90 degree twist? If this were to make noise go away, are there potential neg. repercussions of running "in-phase"?Tools R Us said:
sleeoffroad said:
Me too,
So the real way to fix all my issues would be to get a nice heavy rear bumper. Sounds good to me.
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brianinaustin said:
Correct.
Most all shafts run in phase, the 80 series front is the only one I can think of that runs out of phase, the stock broken back geometry is also unique. If changing it to in phase smoothes it out the only downside I can see is it my need balancing for the new configuration. Mark where it's at, drop one end, put it in phase and try it, what do you have to lose, a few minutes? If it doesn't improve, change it back.
brianinaustin said:
Romer, christo,
I've just done some reading in the medium vs. heavy thread that romer referred to.
I'm running heavies all around with only a front ARB and no winch. Obviously my setup is not how it is truely supposed to be run, i should have a winch and rear bumper....So b/c i have the wrong setup im getting this GRR.
Now, lets say i add a winch, a rear bumper and my rides improves alot, but then i decide i want a little more lift and add mr gasket spacers in the front, my grr comes back.....at this point what should i do?
Go with a double cardan?
Lastly, i added 90 lbs up front last night and grr was gone. Next time i get a chance i will through some weight in the rear and see how she rides.
BTW, thanks for keeping up with this thread.
I've just done some reading in the medium vs. heavy thread that romer referred to.
I'm running heavies all around with only a front ARB and no winch. Obviously my setup is not how it is truely supposed to be run, i should have a winch and rear bumper....So b/c i have the wrong setup im getting this GRR.
Now, lets say i add a winch, a rear bumper and my rides improves alot, but then i decide i want a little more lift and add mr gasket spacers in the front, my grr comes back.....at this point what should i do?
Go with a double cardan?
Lastly, i added 90 lbs up front last night and grr was gone. Next time i get a chance i will through some weight in the rear and see how she rides.
BTW, thanks for keeping up with this thread.
- Thread starter
- #92
B, the grrrrr is not caused by running the wrong spring combo. There is an issue somewhere causing that grrrr. For me, i really feel it's the contact between the tie rod and the leading arms. If you have had your shaft balanced and put new ujoints in it then perhaps you do need a double cardan shaft.
I'm no pro at this for sure, but the way your statement above is worded, you make it sound as if the spring package is causing the grrrr when infact it is something actually creating the grrrrr sound.
I'm no pro at this for sure, but the way your statement above is worded, you make it sound as if the spring package is causing the grrrr when infact it is something actually creating the grrrrr sound.
sleeoffroad
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The spring package used incorrectly lifted the truck to much. The u-joints in the driveshafts does not like to operate at the new angles, hence the GRRR sounds.
However loading the vehicle with weight causes less lift and the u-joints are happy again.
It is a geometry thing. So you have to correct it. How you do it is up to you.
However loading the vehicle with weight causes less lift and the u-joints are happy again.
It is a geometry thing. So you have to correct it. How you do it is up to you.
The nice thing about the Mr. Gaskets is they can be removed in 20 minutes if the grrr comes back.
Like I said, I am running mediums all around and have spacers on the front and am fully loaded. Even with the front spacers, the rear is still slightly higher than the front. This probably doesn't help your delima much, but I thought it was worth mentioning
Like I said, I am running mediums all around and have spacers on the front and am fully loaded. Even with the front spacers, the rear is still slightly higher than the front. This probably doesn't help your delima much, but I thought it was worth mentioning
Cruiserhead05 said:
Ok,
Sorry i made it sound like the lift was causing the grr. Its more like the lift has brought about the sound instead of actually causing it.
For the short term, it sounds like i need to lower the truck somehow until im ready to through down for a double cardan or other suspension component to fix the geometry and i will probably wait to do all this at once when i go to a larger lift. 4 inch is what i really want but it may be a little while till i can do that.
Sorry i made it sound like the lift was causing the grr. Its more like the lift has brought about the sound instead of actually causing it.
For the short term, it sounds like i need to lower the truck somehow until im ready to through down for a double cardan or other suspension component to fix the geometry and i will probably wait to do all this at once when i go to a larger lift. 4 inch is what i really want but it may be a little while till i can do that.
sleeoffroad
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You have to remember that the double cardan shaft will not fix the problem if the geometry of the pinion flange vs transfercase flange are not setup for a double cardan shaft. It seems on the front that after 2.5" you start getting issues. In between 2.5" and 4" you seem to have issues, then after 4" you sometime are vibration free or you need the shaft. As for the rear, you need to turn the pinion up. In order to do this you have to change the length of the links.
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sleeoffroad said:
Turn the pinion up for a CV shaft or down slightly to make the stock shaft happy.
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Tools R Us said:
but not too far or you will make the tie rod and leading arms unhappy
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concretejungle said:but not too far or you will make the tie rod and leading arms unhappy
True, for the front, I was replying to Mr Slee about the rear.
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here's what i did today. Only did one of the two arms. I took my time, took some breaks to watch the race in Martinsville. Anyways, hopefully some time in the week i'll do the other arm. Hopefully that will keep my tie rod off the arms. Then i'll put the front drive shaft back in and see if i still get the grrrrrrrrrr we all are getting tired of hearing about.
