expedition vibes only when towing??

Didn't realize this year Expedition was IRS. That does change things as far as my initial thoughts.

But diagnosing based on what is/has changed, I still say it has something to do with ride height and it's relation to driveling angles/issues.
 
I don't know what year his his. I know irs began on the 2nd gens in 03.
If he has a 98-02 then my point is null.
 
Ron said:
Don't do this. You don't understand how irs works. You will button hook into a ditch at speed
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im confused now, it has struts so i was thinking it would keep the strut from compressing "as much" when a load is on it. I'm not arguing just trying to learn i guess how that's not good for IRS setup.
So I suppose if this is the case, just save up for a set of air shocks in the rear only?
Jody Treadway said:
I still say it has something to do with ride height and it's relation to driveling angles/issues.
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if it comes down to this all being the issue, should I not load with the "squat the rear couple inches" theory then? load with maybe 1" squat rather than several?
It's a 2003 btw, and it is IRS rear
btw, i wanted to mention the trip before last, it towed without the vibes but very weird "no power pulling hills" like in the drivetrain not the motor. Motor has been running great very strong for while now. This seemed to be like the TOD in the Tcase distributing power weirdly (if I'm making sense). Then the last trip few weeks ago, it towed with regular power up inclines (actually hardly downshifted) and that trip I just had the vibes real bad at 60. So I still really think it had at least something to do with the TOD mechanism inside Tcase (very possible it was in 4HI since they do that when GEM modules go bad) and a week later it shifted into 4Lo on it's own going 45mph. So theres a little more recent history that might help, nontheless it was weird towing between those 2 trips and even driving to work would act funny (lack of take off) until Tcase went and now just being in 2wd, has had full throttle ever since.
 
Mines a 03 guys, it does have the IRS. it's the first year they came out with them. It sucks cause it costs more to do gear swap than normal lol. The only good part of mine I like is that it has full locking diff
 
Well aside from struts being little soft and just a hair movement in control arm bushings everything is tight as I expected.
Didn't get a chance to load and test but I'm bout 99% sure it's in the loading too far forward on trailer. Thanks everyone for advise.

Am I better of to buy rear air shock kit and leave the struts alone or replace struts with oem/better
 
marty79 said:
Well aside from struts being little soft and just a hair movement in control arm bushings everything is tight as I expected.
Didn't get a chance to load and test but I'm bout 99% sure it's in the loading too far forward on trailer. Thanks everyone for advise.

Am I better of to buy rear air shock kit and leave the struts alone or replace struts with oem/better
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So let's think about this for a second.
What effect will too much tongue weight have on pinion angle? How would that cause vibes?

Assuming that is the cause, what can you do to combat in a safe manner?

That's your answer
 
Jody Treadway said:
Assuming that is the cause, what can you do to combat in a safe manner?
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Guess you're referring to don't put the Jeep so far up on trailer..or add traction bars?
 
marty79 said:
I've seen those..are they really worth it, they're kinda pricey
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Yes they actually do what they are intended, since you have such a lightweight vehicle (in towing terms) and your suspension is designed more for comfort (soft) the weight distribution hitch will help to keep your steering and front suspension loaded so the front dosent get light while on the road. All that assuming you set it up right. You can find used hitches on Craigslist or let go or Facebook market place all the time.
 
Stuntman Autoworks said:
Yes they actually do what they are intended, since you have such a lightweight vehicle (in towing terms) and your suspension is designed more for comfort (soft) the weight distribution hitch will help to keep your steering and front suspension loaded so the front dosent get light while on the road. All that assuming you set it up right. You can find used hitches on Craigslist or let go or Facebook market place all the time.
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Alright thanks. I'll start keeping eye out for one.
 
Jody Treadway said:
So let's think about this for a second.
What effect will too much tongue weight have on pinion angle? How would that cause vibes?

Assuming that is the cause, what can you do to combat in a safe manner?

That's your answer
Click to expand...

There is no pinion angle change with tongue weight. It's IRS, remember?

I have an 03 and have never had these issues towing. I do like a WD hitch though and have started using one when loaded. It drives much nicer.
 
justjeepin86 said:
There is no pinion angle change with tongue weight. It's IRS, remember?

I have an 03 and have never had these issues towing. I do like a WD hitch though and have started using one when loaded. It drives much nicer.
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A well supported IRS shouldn't have any movement. But again, this is Fuller we're talking about. Originally it was in the front, then he felt it in his butt, then God knows what.

Maybe I should say driveshaft angle as opposed to pinion angle. I say that due to the proposed overloading of tongue weight causing the rear suspension to sag to a point where the driveshaft angle is no beuno for the road speed.

I mean, if you lower an IRS car to look cool, that doesn't mean you may face driveline vibes as a result.

I may be wrong. I once sat down all broken hearted. Thought I had to crap but only farted. It happens.
 
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Jody Treadway said:
A well supported IRS shouldn't have any movement. But again, this is Fuller we're talking about. Originally it was in the front, then he felt it in his butt, then God knows what.

Maybe I should say driveshaft angle as opposed to pinion angle. I say that due to the proposed overloading of tongue weight causing the rear suspension to sag to a point where the driveshaft angle is no beuno for the road speed.

I mean, if you lower an IRS car to look cool, that doesn't mean you may not face driveline vibes as a result.

I may be wrong. I once sat down all broken hearted. Thought I had to crap but only farted. It happens.
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Agreed on the op.

Not to nit pick, but you still won't see a driveshaft angle change. Axleshafts and CV's, definitely.

Sent from my XT1635-01 using Tapatalk
 
DSM Turbos said:
Didn't you blow up the tcase or something and change something inside of it after? Did the vibes start after that?
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No this was 2trips before so nothing to do with that
 
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