Increased vibration on my 2008 Lincoln Mark LT Truck between 45 and 60 mph

I have a 2008 Lincoln Mark LT with 212k miles on it. It serves me very well.

I have a problem that I need some advice with.

While driving between speeds of 45mph and 60 mph there is a perceptible vibration increase that goes away if I am driving at speeds greater than 60 miles per hour. It seems like the engine is revving unusually. The engine RPM seems to remain consistent with the speed I’m travelling at. There is no wobble and I have my tires properly inflated (last week) and aligned (about 5000 miles ago). Is there something i need to look at or consider before I take it to the shop?

At 200k miles I changed the belts, plugs, hoses, exchanged all the fluids and a bunch of other regular maintenance items.

Any advice is much appreciated. If I have posted in the incorrect forum, my apologies, and do let me know the right place to post.

Where do you feel the vibration? Steering wheel or pedals? Other place? At 212,000 miles, I wouldn’t be surprised if you need new bushings for your suspension.

This sounds like it might be a driveline vibration, especially due to the mileage. Failing U-joints, center bearing and/or mounting rubber and maybe even differential pinion bearings.

Since you asked this…

I’d say No.

The symptoms are there and from the post I’d say you aren’t a DIY’er so off to the shop it goes. Tell them what you told us, don’t tell them WHAT to look at, let them diagnose it.

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Torque converter?

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Second. If it’s mild, it might just indicate that the U-joints need to be greased. Get it looked at ASAP, though, because waiting means whatever is causing the vibration is tearing up other stuff that will end up needing replacement.

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A tire may have thrown a wheel weight, or the struts/shocks may be worn.

Either one can cause a tire/wheel to start to do this when driving at certain speeds.

Tester

Has the transmission ever been serviced? Aged fluid can cause a torque converter shudder around those speeds.

A U-joint is also a consideration’; especially the front one. If the shaft feels tight on the joints that does not mean the joints are good. With age the grease dries and the needle bearings take on square sides which means they’re sliding instead of rolling.

And if by chance this does turn out to be a U-joint problem I would strongly suggest using Spicer joints only. There have been some fitment issues with store brand joints and the Spicers are worth the extra cost.