2014 WK2 Hemi Driveshaft Vibration

[rpaoness]

So after replacing rear differential mounts that were visibly torn and motor mounts that had permitted inches of engine displacement under torque, I still have a low-speed, torque-related vibration. Further inspection it looks like the driveshaft has no visible issues and I don't feel anything odd, wrong, or any play in the cv joints or "rag" joint at the rear. I do however, find that the carrier bearing support in the middle of the two-piece rear driveshaft appears to be excessively "soft", which makes me think that the rubber isolator around the bearing is tired. The OEM strategy is to replace the entire driveshaft assembly as a unit, but that's $787 from RockAuto for Mopar, or $581 for Dorman.

I'm considering doing one of these, but I was hoping to find a similar product for a lot less $:
https://www.jxbperformance.com/products ... er-upgrade

[kevm14]

Those center isolators are normally pretty soft. Like you would be able to displace it almost an inch including the +/- direction on a properly functioning one. I have not found them to be super stiff. As I have said before, all I've ever heard (since my CTS-V days) is the center bearings can go. I've never really heard (or don't remember) an issue where that isolation fails before the bearing and causes your symptoms. Doesn't mean it isn't but it seems uncommon at least in my travels.

Check those giubos for fine cracks. They can cause issues long before there is an obvious chunk missing. But, everything would point to higher speed issues.

[rpaoness]

I've seen others that have built temporary molds/dams and injected RTV-type rubber in the space for things like differential mounts, like window installation urethane or similar. I think I have a tube from JCB window resealing kicking around. Might be worth experimenting with.

[rpaoness]

There are other options...
https://makodriveshafts.com/products/re ... -2010-2018

[rpaoness]

I guess this would be a candidate to try to attach a "sports" camera (GoPro?) to the undercarriage and watch it during a loaded take-off to see what's actually going on.

[rpaoness]

Subaru WRX guys and Mitsubishi 3000GT/Dodge Stealth guys seem to recommend RTV in lieu of something stiffer/harder. I do have some gray RTV in a caulk tube kicking around.

[rpaoness]

During a regular oil change I tried to look it over again. Internet wisdom says that the cold clunking is a driveshaft crv joint thing. Driveshaft replacement is/was the prescription. I’m planning on doing a fuel pump/check valve sometime in the next couple months and have to remove the exhaust and driveshaft. I guess I should just pony up the $ to replace.

[rpaoness]

I spoke with these guys about a replacement driveshaft assembly today. I had emailed a while back but they had never responded to the ticket they opened for me.

https://www.wellbuilt.com/product/431-05929/

They have an "outsourced" (I assume China off-brand) OEM replacement driveshaft assembly for $299 or their upgraded assembly for $599. There was no info on the differences on their website.

The upgraded one is a single-piece driveshaft with no carrier bearing. I asked about driveability/vibration issues with the one-piece vs the stock two piece with carrier bearing. They said they do once in a while have vibration complaints that are usually related to shipping damage, but they replace a second time and no issue. He indicated that at worst they would swap me out back to the OEM type they offer and credit me the difference if I was unhappy with the performance of the one-piece.

When I mentioned that I'm suspicious of carrier bearing over-travel/bounce during torque load up under acceleration, he said he has had customers send him go-pro video of the carrier bearing and has seen the shake/shudder that sounded similar to what I was describing.

He showed the MOPAR PN as 52123627AB which would be this one:
https://www.mopar-direct.com/oem-parts/ ... wtdjgtZ2Fz

[rpaoness]

Ah - here's a pic of it. He didn't mention that they also post on Amazon. Makes sense that it's about $80 more than the Wellbuilt site price w/ shipping ($599+$45 shipping vs $724 on Amazon)

https://www.amazon.com/Upgraded-Drivesh ... C99&sr=8-3

[rpaoness]

R&R'd the fuel tank last night to replace the fuel pump and still have the driveshaft out. Appears the rear driveshaft CV joint at the transfer case is the most likely culprit for my vibes. Seem to be relatively limited options for CV replacement. I found a late 2013 date code on the driveshaft, so it's original I think. PN's seem to have been updated to delete a rubber coupling at the rear diff that was found on earlier models, so I think the 2014 was less likely to have issues than earlier model years - looks like the newer design is backfit compatible based on PN listings on MOPAR sites.

Above I talked about a Wellbuilt driveshaft. They offer a $299 likely made in China cheapo that I wasn't really considering, and they offer their $599 upgraded shaft, 1-piece. I have a significant concern with the one-piece: the front of the driveshaft meets the transfer case at a somewhat-significant angle. Usually you match that angle with the rear diff, and if the u-joints are indexed correctly wind up with a "smooth" rotation/torque application at the rear diff. If the angles don't match, u-joints will wind up with a speed-up/slow-down indexing with every 1/2 revolution. Constant-velocity joints are just that - no speed pulsations with rotation even at off-angles. I think I want to stick with a CV joint at least at the front. The rear axle angle is so "flat" that I think it would cause problems from lack-of-u-joint indexing [and obviously doesn't match the angle at the x-fer case], which can wind up with the needle bearings brinelling or seizing due to corrosion from lack of moving in the grease. I specifically had that issue on my WJ which had a dead-flat driveshaft angle. U-joints are replaceable, but it was a PIA.

So the options for rear driveshaft (w/shipping) are:
1.) $375 - USA Standard Gear - this is a product of Randy's Ring and Pinion (which is known for their lifetime warrantied Yukon line in the 4x4 world). There are lots of claims that USA Standard Gear ring and pinions are Yukon parts that didn't meet QC. I'm not convinced that's true, but they may be made on parallel mfg lines and don't get some finishing. Most claim that they're "noisier" than Yukon parts in diffs. I can't seem to find any reviews of driveshaft longevity, nor does Randy's appear to have a comparable Yukon driveshaft. This is $650 on Randy's website. https://www.randysworldwide.com/shop/zds105929 1 Year Warranty

2.) $680 - Dorman - Claims are that all Dorman driveshafts are made in the US. Picture has a large US flag on it. Lifetime warranty.

3.) $817 - MOPAR - 2 year warranty