Vibration at 70 mph, Driveshaft in question

[Arsenal741]

Hi All,

I've got 121k on my 2020 XLT FX4 that I have owned since new. From day 1 it has had the Ford Performance Fox level kit installed and has been running the FP tune. At 60k miles I moved up to 33"s 285/70R17 on +35mm offset rims. I've had a hwy speed vibration that is very noticable at 70 mph which shakes the whole vehicle. I've had the wheels road force balanced, checked alignment and all show in spec. I'm leaning towards it being a driveshaft issue however when I look up part numbers there shows to be two Driveshafts available but neither fits the description to a T.

KB3Z-4R602-A is listed for 4wd application but without the LSD.
KB3Z-4R602-B is listed for 2wd application with LSD.

I have 4wd with LSD and wondering if anyone knows which would be the right driveshaft?

Any input on how others might have alleviated a hwy vibration would be appreciated!

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[RangerBill]

Hi All,

I've got 121k on my 2020 XLT FX4 that I have owned since new. From day 1 it has had the Ford Performance Fox level kit installed and has been running the FP tune. At 60k miles I moved up to 33"s 285/70R17 on +35mm offset rims. I've had a hwy speed vibration that is very noticable at 70 mph which shakes the whole vehicle. I've had the wheels road force balanced, checked alignment and all show in spec. I'm leaning towards it being a driveshaft issue however when I look up part numbers there shows to be two Driveshafts available but neither fits the description to a T.

KB3Z-4R602-A is listed for 4wd application but without the LSD.
KB3Z-4R602-B is listed for 2wd application with LSD.

I have 4wd with LSD and wondering if anyone knows which would be the right driveshaft?

Any input on how others might have alleviated a hwy vibration would be appreciated!

Are you sure that you have a limited slip differential? I haven't heard of 5G Rangers having it. Some have a locking differential.

 

[Arsenal741]

Are you sure that you have a limited slip differential? I haven't heard of 5G Rangers having it. Some have a locking differential.

Gah good catch Bill, I meant locker not LSD.

 

[TJC]

My truck is not raised, but I had severe shake at >=75mph. Bad enough to be seriously dangerous. I opted for a Tom Wood's single piece driveshaft. Silky smooth sailing since.... and I had it up towards 100mph and it was still silky smooth. And no slow speed startup vibration either.

 

[DukeCanBuildit]

I had a shimmy at 80 that went away at 85 - easy fix.

Actually, my issue turned out to be my Big ol’ General Grabbers and a road force balance took care of it. Before you buy a new driveshaft, maybe try lubing the existing slip joint just to rule it out and make sure it’s operating as smoothly as it can.

It’s super easy to do but if that’s not your thing, I get it.

 

[Frenchy]

When you say the alignment is in spec, what's the toe look like? If it is exactly at zero on both, then that is your problem. I ran into this with my 2019 Ranger and had to set the toe in by a few points to correct it.

 

[TJC]

I had a shimmy at 80 that went away at 85 - easy fix.

Actually, my issue turned out to be my Big ol’ General Grabbers and a road force balance took care of it. Before you buy a new driveshaft, maybe try lubing the existing slip joint just to rule it out and make sure it’s operating as smoothly as it can.

It’s super easy to do but if that’s not your thing, I get it.

I fixed it >=75mph I was still on stock tires too...

 

[fusseli]

You went to 33s and that added a vibration at high speed and you are blaming the drive shaft? How do you know it's the drive shaft and not your wheel/tire/alignment combo? You don't.

A single piece drive shaft would fix low speed shimmy and is technically WORSE at high speeds. I would not jump to that solution personally.

 

[TJC]

You went to 33s and that added a vibration at high speed and you are blaming the drive shaft? How do you know it's the drive shaft and not your wheel/tire/alignment combo? You don't.

A single piece drive shaft would fix low speed shimmy and is technically WORSE at high speeds. I would not jump to that solution personally.

You are speaking in generalizations.

My Tom Woods single piece drive shaft is substantially superior to the Ford stock 2 piece unit. Go over to the Dana/Spicer website, configure the driveshafts based upon the parts used and run the tests. The data speaks for itself. My Tom Woods Driveshaft had FAR superior limits over the Ford part. There is a long thread on this forum where I and others ran the tests to prove it.

The Ford driveshaft was sourced from Dana/Spicer. The Ford driveshft specs are far far worse than the Tom Woods parts, and all parts for both driveshafts were sourced from Dana/Spicer.

The Dana / Spicer Critical Speed Calculator can be found here.

 

[bostonburner]

I also had this issue and switched to the tom woods driveshaft, it's a night and day difference. The truck had a slight vibration since I picked it up with 17k on it but around 50k the carrier bearing on the factory driveshaft started to go and the vibration kept getting worse. If it's as bad as mine crawl under the truck and grab the driveshaft near the carrier bearing if you can shift it side to side and hear/feel clicking it's probably at the end of its life.

 

[Arsenal741]

You went to 33s and that added a vibration at high speed and you are blaming the drive shaft? How do you know it's the drive shaft and not your wheel/tire/alignment combo? You don't.

A single piece drive shaft would fix low speed shimmy and is technically WORSE at high speeds. I would not jump to that solution personally.

I'm suspecting the driveshaft. I noted I have road force balanced tires and checked alignment multiple times to try to rule those out. I haven't stated I know exactly what it is, if I did it would be fixed and I wouldn't have even created a thread...

 

[Arsenal741]

When you say the alignment is in spec, what's the toe look like? If it is exactly at zero on both, then that is your problem. I ran into this with my 2019 Ranger and had to set the toe in by a few points to correct it.

Good call-out, last check was showing total toe at -0.16 and based on this I might try to adjust to toe in to see how to affects things.

 

[Arsenal741]

I had a shimmy at 80 that went away at 85 - easy fix.

Actually, my issue turned out to be my Big ol’ General Grabbers and a road force balance took care of it. Before you buy a new driveshaft, maybe try lubing the existing slip joint just to rule it out and make sure it’s operating as smoothly as it can.

It’s super easy to do but if that’s not your thing, I get it.

Good call-out. I'll look into that as I think it would be beneficial regardless.

 

[JerryRange]

I'd try crawling under and checking that carrier bearing first like someone mentioned - if you can wiggle the driveshaft side to side at the carrier bearing and it clicks or clunks, that's probably your culprit.

 

[Frenchy]

Good call-out, last check was showing total toe at -0.16 and based on this I might try to adjust to toe in to see how to affects things.

That will do it. You will want a + toe. I found +0.05 on each to be just right

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