2005 DeVille

[skyman]

Just purchased a 2005 DeVille. 44k miles. Has an annoying shaky,jiggly ride that I have never had in any other Caddy I have owned. Just drove it down to N.C. from upstate N.Y. Had it checked out by a great dealer in the Raleigh area. They road tested the car with me in it which I thought was great as I got immediate feedback from the tech.They spent an hr going over the whole car, put little sensors around the car that picked up vibrations and drove it again. They replaced the rear air shocks, force balanced the tires. Definatley an improvement but.........there is definatley still something there. My gut tells me it's up front....Suspension or drivetrain. Just feels like there is movement up there. I can feel some movement"feedback" through the gas pedalsometimes when it shifts from 1st to second gear. Sometimes feels like it's too hard a shift in to second.

Wondering if this is just the nature of the beast or if there is some component that needs attention. A motor or tranny mount? The tech in N.C. there was one engine mount that had a small amount of movement and could be suspect.

Just wondering if any anyone else has hade this experience with this year,model Caddy.

I've only had the car for 4 days. I traded my 91 Eldo in on this car. The DeVille has lots more creature comforts..but as far as performance goes, the 91 eldo kncks the socks off the DeVille. I find the DeVille with the 4.6 Northstar to be really underpowered compared to the Eldorado.

[KHE]

I bought an '05 Deville last October with 39,000 miles on it. It has been a great car - sometimes, there is a very slight vibration in the 68-72 mph range but it is very slight an only someone like me notices it. I know it is in the tires and when it needs tires, the issue will be resolved.

It sounds like there is something else going on - it could be an engine or trans mount. Have they checked the ignition system (modules). Are there any trouble codes stored in the system?

My experience on the Northstar vs. the 4.9 engine is just the opposite of yours though.

[Texas Jim]

I bought an '05 Deville last October with 39,000 miles on it. It has been a great car - sometimes, there is a very slight vibration in the 68-72 mph range but it is very slight an only someone like me notices it. I know it is in the tires and when it needs tires, the issue will be resolved.

It sounds like there is something else going on - it could be an engine or trans mount. Have they checked the ignition system (modules). Are there any trouble codes stored in the system?

My experience on the Northstar vs. the 4.9 engine is just the opposite of yours though.

Same here...my Mom has an Eldo with the 4.9.

There is "NO WAY" it will run with a NorthStar.

[Cadillac Jim]

You're talking 200 hp with the 4.9 vs. 270 hp or 295 hp Northstar for the Deville, depending on model. Sometimes the seat-of-the-pants can be deceptive. For the real truth, use a stopwatch and some measured distances and speeds.

The 4.9 does have a great kick at lower RPM than the Northstar. But, have you given the Northstar a real opportunity to show itself? For a good time, when you are in a 60+ mph zone from a standing start, put the shifter in "2" and nail it AND HOLD IT DOWN TO THE FLOOR, moving the shifter to "3" after the transmission shifts to second gear. I will warn you that it won't come out of second gear until at least 80 mph, so watch your speed.

[mike27513]

My 03 Deville DHS initially had vibrations at highway speeds but alignments/balancing have solved it, smooth all the way past 100.

Car now has 86K miles.

Are the tires relatively new or original? What Brand?

If original they are 5 years old and may be having deterioration issues due to age [but the Dealer tech should have caught it if they rode with you].

[BodybyFisher]

As I was reading this, and when you said, first to second did not feel right, I said, engine mount

I would replace the engine mount the tech picked up was not right...

By the way, I had a 91 Seville and while it never embarrised itself, it was no Northstar

[ted tcb]

I'm with BBF, first thought was engine mount, especially when

you said you felt movement up front on the 1st to 2nd shift.

Do you feel a vibration at idle?

Following that, best success I've found to cure shimmying was going to Cooper CS4 touring

tires. I just came back from a long hwy drive, and my car is smooth as silk with the new tires.

I do find that the tires need to "run out" for a mile or two on the hwy, then they tend to settle in.

Some have said that just sitting overnight can affect the roundness, and these sensitive platforms need

to be run for a few miles to settle in.

Strangely enough, old fashioned outside wheel weights have given me superior balancing on two

different fwd STS', compared to balancing with the stick on inside weights.

[Cadillac Jim]

If there is any looseness in the wishbones or front motor mount then a WOT 1-2 shift with the selector in "2" or "3" will likely elicit a rattle in the exhaust or under the hood. The only motor mount that ever gives trouble with the transverse Northstars is the front one, although I had a wishbone go out once because I let the front mount go too long. Since you already know that it is suspect, I would go ahead and let them change it.

Nylon cord tires are known to take a "set" while the car sits, even overnight, and the "flat spot" goes away when the tires warm up when the car is driven. Nearly all tire cord is nylon these days. With steel-belted radials, the steel belts may make this less obvious in some tires.

[skyman]

Thanks for all the replies. I have to say that on my trip to N.C. I've driven on all types of pavment down and back. I have found that at highway speeds, I get a smooth ride on about 10 percent of the road surfaces with little or no feedback thru the gas pedal or the seats. I would have to clasify my problem more as road feedback then shimmy. When I initially test drove the car there WAS a front end shake and we examined the tires and found the rears to be good but the fronts were suspect so the dealer put brand new Michelin Symetrys on that matched the rear and this made a big difference but did not clear up the basic jiggly ride that I'm experiencing. Let me be clear that I do not feel this at lower speeds but mostly at faster speeds on the highway. It seems like The suspension is not absorbing enough of the deviations in the road surface. I have also noticed that when negotiating a bend on an interstate smooth road if I just put a little pressure on the steering wheel left or right I can feel a little feedback and sense something is not quite right maybe the CV joints or the Macferson struts. I have only owned one other car in my life with Macfersons and I remember I could always tell when they were starting to go by a shimmy at certain speeds but....I would not classify my present problem as an actual shimmy. It's more like the suspension is not handling the smaller roads abnormalities..it just jiggles and I feel all the tiny divits in the road. When I'm on the road, it does not have a "solid" feel....more of a delicate flimsy feel....and as for the power issue, when on the highway say 55-60 and I push down on the gas I don't really feel much aceleration unless I push down far enough to drop it into a lower gear. With my 91 Eldo, you could feel the acceleration immediatly without having to mash the pedal down hard.

Bruce

[MAC]

You're talking 200 hp with the 4.9 vs. 270 hp or 295 hp Northstar for the Deville, depending on model. Sometimes the seat-of-the-pants can be deceptive. For the real truth, use a stopwatch and some measured distances and speeds.

The 4.9 does have a great kick at lower RPM than the Northstar. But, have you given the Northstar a real opportunity to show itself? For a good time, when you are in a 60+ mph zone from a standing start, put the shifter in "2" and nail it AND HOLD IT DOWN TO THE FLOOR, moving the shifter to "3" after the transmission shifts to second gear. I will warn you that it won't come out of second gear until at least 80 mph, so watch your speed.

Exactly, Jim! The first generation Northstar not only has good pull from 0-60 (6.7 sec.), but from 60+ it pulls well for a 270/295 hp engine. It will easily accelerate by 100 mph. I have never driven a 4.9L, but, like you said, use a stopwatch. The Northstar may not be able to keep up with a 4.9L off the line, but after 40, it's basically over--the Northstar will win every time.

BTW, the '05 DeVille with the Northstar is rated at about 7.0 sec. 0-60. Not bad for a heavier car. The 1991 DeVille with the 4.9L is rated at 0-60 in 8.4 and the 1/4 mile in 16.5.

[KHE]

I have the Michelin Symmetry tires on my '05 Deville and they seem to be a smooth, quiet tire. It's possible you may have a bad tire.

[skyman]

Had the car to the dealer where I bought it. They checked the alignment. The car tracked straight no drifting so I was surprized when they said it was off. Apparentley it was off on the rear alignment by a tiny amount. They said there was a tech bulliten on this car refering to the rar alignment, which states that if the alignment is off by even a tiny amount it can manifest itself as a vibration at higher speeds. Apparently it involves installing a shim or shims someplace in the rear and pulling the wheel hubs. Well we'll see what happens. To me, The road feedback and vibes seem to come from the front.

I'll post the results.