Custom Driveshafts - A fix to driveline vibrations or a cause for their increase?

[noGreta!]

I never learn my lessons so...I am on my second manual GT (first a 2021 and now a 2023) that has the same driveline vibration (55mph to 75 mph, steering shimmy and slight vibration that is non tire/wheel related).

Since Ford dealers call it "within spec" and dismiss it, I have contacted a local shop in Houston that can make a custom, one piece driveshaft that they claim will fix the problem.

Having read so much about one-piece driveshafts actually increasing vibrations and noise and also considering that the issue in these cars many not necessarily be the two-piece driveshaft itself, I am at a loss on how to proceed.

What should I do?

Try my luck with a custom driveshaft?

Ignore the minor vibration and shimmy?

Get Ford Corp. involved? (I really don't have time for all that)

...or trade it in and curse my bad luck for buying two $45K vibrators in a row?

Thanks guys...

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[AZlb5.0]

Wow that’s crazy. Did you test drive the vehicle before purchase? Because I’m scratching my head on how you’d get two vehicles with the same problem. I would try a different stock driveshaft. That’s what I’d do first to make sure it’s not something else. If that doesn’t fix it, then I would take it to an independent mechanic. I know it sucks having to come out of pocket but I couldn’t drive like that all the time. I’d want to throw myself off a cliff.

 

[jmagnus87]

a good technician will have something called a Chassis Ear. it's these little boxes that they mount all over the underside of the car and they pick up frequencies of noise and i think vibration too, but don't quote me on that. perhaps before you waste even more money, it would be worth buying yourself one of those.

https://www.amazon.com/Steelman-Cha...ocphy=9002199&hvtargid=pla-1889215459913&th=1

looks like $279 on amazon if you're that paranoid about it to buy one yourself and not believe a technician. (i'm that paranoid about my car and technician's being after my wallet that i would buy the tool myself)

That being said, i can't believe you have any vibration at those speeds but there's a million factors on these things that allow stuff to shake shimmy and roll. namely, all the rubber bushings everywhere are a freakin nightmare. 10/10 would recommend replacing all of them or locking them out with kit's from Kelltrac/BMR/Steeda etc. Kelltracs look the best to me tho IMO.

 

[noGreta!]

Wow that’s crazy. Did you test drive the vehicle before purchase? Because I’m scratching my head on how you’d get two vehicles with the same problem. I would try a different stock driveshaft. That’s what I’d do first to make sure it’s not something else. If that doesn’t fix it, then I would take it to an independent mechanic. I know it sucks having to come out of pocket but I couldn’t drive like that all the time. I’d want to throw myself off a cliff.

I did test drive it... extensively too.

The problem showed up 2 or 3 days later just like last time.

I couldn't believe it

 

[noGreta!]

a good technician will have something called a Chassis Ear. it's these little boxes that they mount all over the underside of the car and they pick up frequencies of noise and i think vibration too, but don't quote me on that. perhaps before you waste even more money, it would be worth buying yourself one of those.

https://www.amazon.com/Steelman-Cha...ocphy=9002199&hvtargid=pla-1889215459913&th=1

looks like $279 on amazon if you're that paranoid about it to buy one yourself and not believe a technician. (i'm that paranoid about my car and technician's being after my wallet that i would buy the tool myself)

That being said, i can't believe you have any vibration at those speeds but there's a million factors on these things that allow stuff to shake shimmy and roll. namely, all the rubber bushings everywhere are a freakin nightmare. 10/10 would recommend replacing all of them or locking them out with kit's from Kelltrac/BMR/Steeda etc. Kelltracs look the best to me tho IMO.

Good idea on the bushings.

Should have thought of that especially since I am not experiencing the bad seat and rear view mirror vibration 2016 vehicles had. Mine is primarily on the steering wheel.

 

[jmagnus87]

Good idea on the bushings.

Should have thought of that especially since I am not experiencing the bad seat and rear view mirror vibration 2016 vehicles had. Mine is primarily on the steering wheel.

You could also check out a bump steer kit. You shouldn't have any issues stock but if you're lowered at all you definitely need it to correct steering angle
Also, i would like to point out I've had my car since 2015 on some pretty awful roads and the worst vibration i ever had came from the shifter with the trans mount bushing installed

 

[noGreta!]

The car is completely stock with less than 1,000 miles on it so that's not an issue.

I can't help but wonder if it is alignment related.

What's remarkable to me is that both cars had the exact same, totally identical behavior at the exact same speeds. What are the odds?

 

[jmagnus87]

The car is completely stock with less than 1,000 miles on it so that's not an issue.

I can't help but wonder if it is alignment related.

What's remarkable to me is that both cars had the exact same, totally identical behavior at the exact same speeds. What are the odds?

assuming that it's an 'as built' condition, based off the design, i would imagine the odds are quite high. can you have a passenger take a video of the steering wheel doing it at those speeds? it should come off the assembly line with an acceptable alignment, but due to all the rubber bushings, there's no way to keep that alignment true. that's why we have camber lockout plates and many other parts to address this issue.

if it's just the faintest of vibration and really it's only you that notice it, it could very well be a characteristic of the mustang. these cars aren't BMWs and they weren't ever truly intended to be 'smooth'. That being said, you shouldn't have a death wobble on a brand new car either.

Also, do you have steering wheel modes in yours? try putting it in different modes and see if you notice a difference. comfort mode should give you the least amount of feedback from the raod

 

[Turbolag87]

its prob all in ur head. Odds of both cars doing it ?????

 

[noGreta!]

its prob all in ur head. Odds of both cars doing it ?????

lol ... it wouldn't be the first time but I had friends drive both cars and they agree with me. The Ford service department agrees with you though that the problem is me

For what is worth, the shimmy/vibration is worse in very smooth roads.

I will try to take a video soon.

Thank you all for the replies.

 

[noGreta!]

Also, do you have steering wheel modes in yours? try putting it in different modes and see if you notice a difference. comfort mode should give you the least amount of feedback from the raod

I tried that and unfortunately there is no deviation among the steering modes.

 

[jmagnus87]

Yeah man keep us posted so we can help you figure out what it may be??

 

[SHOdaddy68]

If your tires are properly balanced and the wheels are true, and the vibration is in the steering wheel, then it shouldn't have anything to do with the driveline. My guess is a bad front tire that has a high spot or otherwise out of round.

 

[91gt331sc]

I had the exact same problem with my 21 when it was brand new. I ended up replacing the driveshaft and that totally cured the problem. The dealer wanted to perform a series of trials with hose clamps on the driveshaft and multiple road tests. I just ordered a new driveshaft and replaced it myself. I have very little trust in dealerships as I have worked in one for 15 years. What I found was that the factory driveshaft was not indexed correctly and simply repositioning on the rear flange probably would have fixed it. I have 6,000 miles since replaced and all is well. If you lay underneath and look at the rear differential flange it will have a yellow mark, make sure the weights do not align with that mark, you want the closest weight on the driveshaft to the rear diff flange to be 180 degrees off. I would start by checking that first.

 

[noGreta!]

If your tires are properly balanced and the wheels are true, and the vibration is in the steering wheel, then it shouldn't have anything to do with the driveline. My guess is a bad front tire that has a high spot or otherwise out of round.

In both cars I had multiple attempts at balancing and also completely new and different wheels and tires fitted. There was no chage at all...

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