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Piggysims
Date registered: Dec 1899
Location:
Vehicle(s):
| Propshaft Vibrations
Hi All, I've just lifted my G400 swb 40mm and now have small vibration between 20 and 60 mph. I took it to a prop shaft guy the other day and he said that the knuckle alignment need changing.
Has anyone has experience of this?
Thanks In Advance |
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Brent
Expert
Date registered: Apr 2006
Location: SW Colorado USA
Vehicle(s): '13 Wolfsburg GTI
Posts: 1754
| RE: Propshaft Vibrations
You have changed the driveshaft angles with the lift. I would be very interested to hear how the shop proposes to change the alignment. There is no adjustment to be made. To get the angle back to the old you either need to drop the drivetrain by 40mm or you can get part way there by using custom trailing arm bushings to rotate the axles.
The swb trucks are most prone to this because the angles are already sharp. My suggestion, before you get too carried away, is to just drive it for a while. The u-joints should wear in a little better at the new angles and the vibes should lessen. If it is bad, you need to address it. If it is minor, just drive it for a while and see. You could also spend the money on new shafts that would wear in from new at the angles present. |
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Piggysims
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Propshaft Vibrations
Hi Brent, thanks for the reply so quickly.
When I mentioned the knuckles being aligned I meant the phasing of the 2 ends rather than to change the angles of the UJ's, this involves pulling the prop apart and turning it round on the spline's (only one or two splines). Both the yokes on my shafts are already out of alignment by a couple of spline's from new so it will only be a slight variation.
As is was only a tiny lift the angles of the props have only moved by a couple of degrees it more to do with the balancing. |
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Brent
Expert
Date registered: Apr 2006
Location: SW Colorado USA
Vehicle(s): '13 Wolfsburg GTI
Posts: 1754
| RE: Propshaft Vibrations
Why would the shafts be out of alignment? Have they been apart before and not correctly re-assembled? If not, I would be leery of changing the way they came from the factory. I would be interested to see if a machine spin balance cures the vibes though. I am sticking with my "new angle" diagnosis though. It takes very little change to cause the vibration. I had the same problem on nearly new shafts, with a small lift, on my old lwb. |
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dai
Expert
Date registered: Apr 2006
Location: Oregon USA
Vehicle(s): 300GD 300TD BMW R100RS Landini 80F
Posts: 2110
| Re: Propshaft Vibrations
I agree with Brent. I have a pretty big (70mm) lift on my SWB. Vibration is an issue. It is however a 460 series and your machine must be a 463. The driveshafts have some 'on purpose' out of phase assembly in some of the shafts. If you go to the clubgwagen site there is an article in the Tech section about them. Also Harald's 4x4abc.com site has a lot of great information.
If you have the patience you can experiment with the phasing. First determine what is correct with the alignment arrows and then pull them apart and go a spline or two off and install it and give it a try. This is a big pain because the little bolts and nuts that mate the flanges are an open end wrench, one flat at a time, slow to remove and slow to install adventure. G wagens teach Zen patience. I would recommend using 4 bolts instead of the 8 on each flange (every other hole) to test them until you get the result you want and then fill all the holes. Be methodical and you might find a sweet spot. Driveline people want to "correct" the phasing before balancing them and make the yokes aligned. Some of the shafts are set up 0 degrees like that but the front shafts often have 70 degrees offset. Try to find out what is correct for your vehicle and how the shafts are set up with the alignment arrows pointing at each other. The websites will show you where the arrows should be and provide some info on phasing for some models.
It is critical to mark the flanges where they meet before removing anything because my understanding is they have been balanced at the factory connected with each other. Use an automatic center punch or something permanent to provide a reference before you go for it so you can put things back to stock position.
-Dai |
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ewalberg
Expert
Date registered: Apr 2006
Location: Past: San Francisco. Present: Germany
Vehicle(s): 2000 g500
Posts: 1887
| RE: Propshaft Vibrations
i want to focus on something. If you know your drive haven't been toyed with, you need to educate your mechanic that they are delivered to factory spec with offset/out of phase becuase as he seems them so that in the stock ride height they will provide the least vibration, so if he wants to mess with it based on the new height, then he can, but make damn sure he doesn't lose the original orientation, becuase if he does, and you decide you want to go back to factory height you could have a fair amount of time and trouble before he finds the right orientation by trial and error. I would be very explicit about this.
You may also want to consider using body lift instead of spring lift, or going with 20cm spring and 20cm body lift to address your issue. No personal experience, but from being reading posts for 3 years, i'd say 40cm lift is a fair game for some new vibrations especially on a SWB.
How many miles on the truck? If you don't have many miles on it anyway, then i think the vibes should get any better, only worse, becuase the shafts are still tight. |
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mb230s
Date registered: Apr 2006
Location: SWFL
Vehicle(s): G-less for now, vintage MBs, FJ40
| Re: Propshaft Vibrations
2006 G400 SWB! Can you post some pics (engine and interior also)?
Edited by mb230s 4/28/2006 2:54 PM
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Braingears
Expert
Date registered: Apr 2006
Location: St Petersburg, FL
Vehicle(s): G320 & ML320
Posts: 1450
| Re: Propshaft Vibrations
This sounds like what my guy told me...
Remember that the two arrows MUST LINE UP. The Mercedes "Knuckles" are not meant to be aligned. The arrows must line up!
Do not let them "Straighten" the driveshaft. They can rebalance it with weights, but do not let them heat-treat and/or straighten the shaft.
Chuck |
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