So my X decided it was gonna developed a horrible driveline shake yesterday. I removed the rear driveshaft and found the rear u joint to be crunchy. I've always had a slight vibration that got worse at high speeds so I figured I'd get both u joints replaced and get the driveshaft balanced.
I took it to the local truck driveline shop and their specialist informed me that if they balance it with the factory dampener it will just go back out of balance in a few months. He said this is because with the age of the dampener, it's possible that the rubber is split and this allows the dampener to turn. He recommended i let them essentially build a new driveshaft without the dampener and then they could guarantee it would be balanced and stay that way.
So what say you guys? Anyone ran into this before? It's gonna cost $215 to replace the u joints and balance what I have or $360 for new joints and a new driveshaft without a dampener. It seems silly to drop over $200 on it just to have it go out of balance again shortly.

 

Mark the balancer and see if the ring truly slips. Generally they are there for noise. The factory doesn't put anything on that isn't necessary. The question is if removing it, what issues dos that cause you down the road.

 

Well I can't really do a trial with bad joints and it would be silly to install new joints and not balance it. I'm just having them build a new driveshaft today without the dampener

 

I was assuming you would press the new joint in yourself. The cost for that is minimal but sounds like you'll be back on the road soon!

Please post your findings. Thank you.

 

Normally I would have replaced the joints myself but these were extremely rusty. Anything I spent on the original driveshaft would have been money wasted if later it needed a the new driveshaft anyway due to an imbalanced which it most likely would have had just from installing new joints.
I'll let you know how it turns out

 

I've replaced u-joints before, didn't balance the driveline and had no vibration. So it's not necessarily "silly" to do so.

Honestly I would just change the u-joints and see if the vibration is there. To me it sounds like they are trying to sell you something you don't necessarily need.

 

Anytime ujoints are replaced there's a risk of throwing the driveshaft out of balance. Like I stated in my op, it seemed to always have some imbalance at high speed, wether that was in the driveshaft or a compromised u joint, I may never know.
What would be"silly" is to replace the u joints myself just to find it still had a vibration. At which point id have to get it balanced. Then considering what the guy at Inland Truck Parts said even if they balanced the factory driveshaft it could still go back out of balance later due to the dampener. That would them require them to make/ modify the driveshaft, which they are doing now, thus costing me more money in labor and possibly in u joints again. I don't want to be doing this more than once and/or costing myself more money than necessary.
I thought the scope of this situation was clear before without having to type this entire diatribe but that was silly of me to think that I guess.

As to what the dampener does, even the guys at ITP went sure. They said no ford engineer has been able to explain to them why it is there. Certainly they've dealt with a lot of driveshaft issues, certainly more than,I so i trust them. Unfortunately it's just a pricey repair, not unlike most on the excursion.

 

I've seen dampers added to diesel driveshafts to reduce gear rattle in manual transmissions...that said, perhaps the Excursion uses the same driveshaft as one of the SD diesel trucks with a manual trans. I can't see a purpose for it with an auto.

 

You may be correct but I thought all the trucks had 2 piece driveshafts.

 

Well we're about to find out how it responds to not having the dampener because the truck shop just called and said my drive shaft is done. On my way to get it now.
By the way this truck sure is smooth in front wheel drive mode

 

I didn't realize our Tcase had a lock-out enabling one to drive without a rear driveshaft. Good to know.

 

I dunno about a lockout but I just locked my front hubs and put the switch in 4x4hi.

So got the driveshaft back in today. The X has never been so smooth. Ran it up to 80mph and smooth as silk.
ITP said the old tube had tossed a weight, which I didn't notice. They also replaced both pieces of the rear yoke due to some wear, replaced the joints with the good spicer joints, lubed the slip joint and painted the whole assembly. It looks great. All that and it came in $50 under their estimate. I'm pleased.
I spoke to Anthony at Super Duty Service and he said he usually gets the dampener removed also.