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Discussion Starter · #1 ·
With the ice and snow on the east coast of the US, I put the new G into SA. There is a distinct vibration that occurs relative to the speed of the vehicle. It is worse in 2nd gear (of the automatic 4 -speed), but gets progressively worse at higher speeds to 50 MPH. Vehicle is a 1986 280 GEL with 86,000 miles. In two week drive "S" it is very smooth and without much vibration. My thoughts were the drive shaft balance.

Anyone have any thoughts and what I should do?

Thanks
 

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1984 280GE
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Are the roads that you are driving on dry? That would be the only thing I could think of. When I had trouble with the front drive shaft the vibration was there all the time. If you are driving on dry roads with the fronts engaged its going to feel real weird. I made it thru this storm without doing anything
 

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weberdocs - 1/26/2005 6:38 AM

With the ice and snow on the east coast of the US, I put the new G into SA. There is a distinct vibration that occurs relative to the speed of the vehicle. It is worse in 2nd gear (of the automatic 4 -speed), but gets progressively worse at higher speeds to 50 MPH. Vehicle is a 1986 280 GEL with 86,000 miles. In two week drive "S" it is very smooth and without much vibration. My thoughts were the drive shaft balance.

Anyone have any thoughts and what I should do?

Thanks
I hope you're not using "SA" on dry pavement! That could certainly cause vibration and serious damage to the drive train.

Vibrations are tough to track down, but the drive shafts are turning at all times - both in "S" and "SA"; so an unbalance would be there all the time.
 

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Discussion Starter · #4 ·
Thanks for the input. Regarding the conditions, I am only utilizing the SA on Snow/Ice and wet pavements. When dry pavements occur, I stopped and shifted to the S mode.

Thanks for the input regarding the constant spinning shafts. Not sure where to look next. The whole differential seams to shake and vibrate excessively when the SA is engaged...and less so with the S mode.

Thanks for the input, any other thoughts?
 

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Dave,

No need to stop when shifting in between S and SA. I would recommend to use SA only to get going and the switch on the fly back to S. http://4x4abc.com/jeep101/engage.html

By the way, SA is not AWD - it is part time 4WD. AWD is defined as a system of full time 4WD without low range.

About the vibrations. In S the entire axle assembly and the front driveshaft are rotating without any torque load = little or no vibration. When in SA the transfer case applies torque towards the front drive shaft and any accumulated play in areas where wear has occured over time (transfer case bearings, U-joints, slip joint, diff bearings, wheel bearings, rotor run out) will cause vibrations. Only replacing all parts that can have accumulated wear, including the drive shaft, will get rid of the vibrations.

Also, even slight differences in wheel diameter front to rear will cause tension. And tension combined with a lose/worn out system will cause vibrations.

It is difficult to achieve equal wheel diameters. Mark the center of a front wheel where it hits the ground - drive for 10 revolutions and measure the distance. Then do the same with one of the rear wheels. If distance is longer, reduce rear tire pressure step by step until you get an equal distance. Increase rear pressure when rear distance is shorter.

I had a client some time ago who had front tires of equal nominal size but by different manufacturers and that caused horrible vibrations (in 4WD only)since the two tires had different diameters.

Harald
 

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somebody correct me if i'm wrong but i really don't think you should be locking your transfer case when the groung is just wet (in rain). You still have way too much traction.
 

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In response to Mr 4x4 abc Sure a 460 transfer config is selectable 4wd but the AS means Street all wheel and is therefore all wheel drive for street use, I would however qualify that only with a loose surface street of either sand gravel mud or loose snow, it is wholy unneccesary on any compacted surface and could be damaging to the transmission over all.
I think theterm all wheel youare refering to is as in a Landrover PERMANENT All wheel drive. but once you have selected all wheel drive or 4 wheel or any some vehicles 6 wheel or even 8, you are in an all wheel drive vehicle
However a tecnique taught in the military, unique to the G Wagen was its ability to move extremely heavy loads using low ratio GA and 1st gear to move the load (up to 8 Tons) and then progressing up to high ratio SA then into 2nd gear main box before selecting 2wd not exceeding 50 kmh and selecting 4wd AS to bring load to a halt using engine and brakes.
So I would from experience excert that perhaps the G transmission is tougher than you think.
 

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AS is not all wheel drive and it is not recommended for use on pavement, except maybe when the surface is very slippery.
http://www.4x4abc.com/4WD101/defsystems.html

Granted, the G is tough and it won't immediately fall apart - by why cause stress that will lead to component failure later?

Here is my JGC transfer case after it remained accidentally in 4WD:
 

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weberdocs - 1/26/2005 9:14 AM
Thanks for the input regarding the constant spinning shafts. Not sure where to look next. The whole differential seams to shake and vibrate excessively when the SA is engaged...and less so with the S mode.
do you mean the t-case vibrates? vibes are tricky to troubleshoot without driving the vehicle. i know reisterstown is a long drive for you, but my friend trevor griffiths runs a shop up there called treasured motorcar service. they are a bit expensive, but most of the technicians drive land rovers and are EXTREMELY knowledgable about 4 wheel drive vehicles. i never suggest shops, but trevor has a guy that has been setting up diffs and gearboxes longer than i've been alive.

http://treasuredmotorcars.com
 

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Response to ABC. Harald isn't it. you are right it is not AS it is SA on the transfer selection lever which the German user manual refers to as "Strasse Alrad" and GA as " Gaelande Alrad" and unless German has changed that is still Street All wheel and Land All wheel.
I did qualify street as loose surface. I see no harm in driving all wheel on a 460 in a straight line and for short periods and torque wind up is easily unwound.
Having driven many miles in military permanent all wheel 6X6 "Alvis Stalwart" "Saracen" "Salladin" etc I am sure the technique is the same, bump it up the kerb now and again or reverse it.
 

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Sorry weberdoc. back to your original question, your vibration is likley either a worn spicer or input bearing in the transfer.
In two wheel the front axle is diving the transfer motion in 4 wheel the transfer is driving the front axle so drive surfaces are reversed and any wear will show, mild vibration is not unheard off in all 4 wd part time or full time and on a 460 this can be often put down to the fact that the drive shafts rotate in opposite directions and are unharmonised.
 

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You are right - they all unwind somehow. Just take a good look at my transfer case.

Harald
 

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Harald I have had a close look at the picture of your transfer box, I would have expected damage to the chain had the box failed as a result of wind up, a more likley cause of this kind of damage is impact at some time causing cracking of the casing which eventualy failed in use,
As was the case with this box from a Stonefield.
 

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Oh the humanity!

Stop already with the horrible pictures of mechanical destruction! Don't you know this is a family show? How am I to answer my 3 year old son who says, "Gee daddy, that looks just like the one in the garage!"
[:p]

Seriously though, the full synchro 4wd of the 460 is a gift from heaven. Especially when combined with the ingeniously perfect placement of the transfer case shifting lever. The detail of that lever placement speaks volumes to me about the suitability of this vehicle for it's intended use versus the other makes who want you diving under the front dash, or across to the other side of the trans tunnel into the passenger footwell to make the change to/from 4wd.

I'm off the subject again! What I meant to say is that I face a lot of mixed roads in winter. Two miles of harpack and ice, half a mile of dry pavement, more snow, more ice, more dry, etc. Day in and day out over my commute. So that transfer case gets a workout. The only time I ever had a wind-up issue I was actually able to clear it by just changing down into 2nd gear and letting the clutch out smartly, but only brifly. That little bit of engine braking was enough to reverse the drive line torque enough to let the t-case pop back out of 4wd (I held the lever to maintain the spring bias while letting the clutch out). Oh yeah, and I did this on a straight dry section. Goes without saying that it's courting disaster to ask that kind of traction on suboptimal surfaces - ask Serpe's wife.

Just thought I'd throw another one into the pot. If I'm flat wrong, or incurring undue risk of damage this way, let me know or I'll continue to try it when it sticks in 4wd. It's much more convenient than stopping to reverse or find a way to lift a wheel.

-Dave
 

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translation

I have the manual in various languages. The original German issue talks about
"SA" = Straßenfahrstellung (Allradantrieb) and makes the important destinction that this setting is only intended for slippery or icy road surfaces. Unfortunately they don't warn you not to use it on dry paved surfaces and don't say its OK for dry gravel roads. A serious mistake. Maybe they assumed that buyers of the Geländewagen had basic knowledge of 4WD use.

Now, the English version is a translation by dictionary (as there have been many by Mercedes that make your toe nails curl) and not by knowledge of the 4x4 arena. Yes, all-wheel-drive is the correct translation of Allradantrieb by the book - however, the term all wheel drive is commonly only used for full time 4WD systems without low range. http://4x4abc.com/4WD101/defsystems.html

So, everyone reading all-wheel-drive and assuming that this car has the capability of being used on dry pavement without serious side effects is making an expensive mistake.

The load created by the faster rotating front axle wears out all moving parts between the front diff and the transfer case (front U-joint, slip joint, rear U-joint, bearings of the front output shaft of the t-case and the bearings of the main shaft).
Wearing out these particular parts (aside from breaking them) will be one of the causes for the vibrations the G is so famous for.

Harald
 
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