Harmonic vibrations in Jeeps: A new theory (please read!)

It seems a bit far fetched to me, but at least you are doing your part to make America great again. :)
I mean to really break it down, who would you put your money on at making the best gears for a Dana axle? Dana or an aftermarket company?

It dont think its a stretch to say that aftermarket gears are not on the same level as genuine Dana Spicer gears.

Its like buying Mopar sensors for the engine. OEM is USUALLY far superior to aftermarket.
 
I mean to really break it down, who would you put your money on at making the best gears for a Dana axle? Dana or an aftermarket company?

It dont think its a stretch to say that aftermarket gears are not on the same level as genuine Dana Spicer gears.

Its like buying Mopar sensors for the engine. OEM is USUALLY far superior to aftermarket.


Got anything to back any of your opinions up on the gears? Your screen name should be “madeintheusa”
I would think(my opinion) that aftermarket may be better than oem in some cases. I’ve personally put an oem Dana gear and a AM gear set next to one another and couldn’t see any differences.
 
I mean to really break it down, who would you put your money on at making the best gears for a Dana axle? Dana or an aftermarket company?

It dont think its a stretch to say that aftermarket gears are not on the same level as genuine Dana Spicer gears.

Its like buying Mopar sensors for the engine. OEM is USUALLY far superior to aftermarket.
If the aftermarket sensors were as good as most of the aftermarket gear sets, I'd have zero issues using them. There are plenty of good gear sets out there to do anything you want ratio wise and most of them are not Dana. I will concede that they make probably the best in certain ratios, I do not concede that it makes much difference nor will you be able to point to any aspect that will actually matter long term.
 
Got anything to back any of your opinions up on the gears? Your screen name should be “madeintheusa”
I would think(my opinion) that aftermarket may be better than oem in some cases. I’ve personally put an oem Dana gear and a AM gear set next to one another and couldn’t see any differences.
I would never say any aftermarket gear is better than a Dana gear set. I will say that it doesn't matter.
 
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I’ve personally put an oem Dana gear and a AM gear set next to one another and couldn’t see any differences.
Not trying to fuel an argument and I doubt anyone could change your mind (not necessarily a bad thing). I could put a slightly bent wheel and a true straight wheel in front you and you wouldn't “see” the difference. But put it on a vehicle and I bet you feel the bent/warped wheel

I set two brake rotors in front of you. One warped and one that isnt. I doubt you would “see” the difference. But I bet you would feel it once on a vehicle.

A cheap off road tire that mimics a Goodyear MTR looks the same but rides different. And sounds differenent going down the road. Will wear different too. But could you “see” quality or lack of it if the tires were next to one another with no branding on them? (Not saying I could)

Setting two different gear sets next to one another and comparing them isn't exactly fool proof is it?

My bottom line on my theory is Dana makes their gears here (SVL/blue box is the exception) and meets/exceeds OEM requirements for reliability/drivability. Makes more sense to me to run Dana gears in a Dana axle if given the choice.

A common pattern on most vibe issues are gears made in China/Korea/India. Thats all I got to go off of right now.
 
🤔 I am serious. I dont expect people to change their mind. If some people believe AM gears are just as good or better than OEM, thats cool. I can understand that. Im just going with Dana genuine parts if given the choice.
One of my all time favorite threads on Pirate was from a builder down in Australia. They had built a very specialized set of differentials for IFS/IRS. They were having trouble breaking gear sets and were cutting them apart, polishing the faces and doing some hardness tests. (standard method for checking the depth of case hardening) The issue as they related it had to do with (in their opinion) the fact that none of them were through hardened and all the teeth they examined showed to have a hard outer layer with a softer core.

The funny thing about that? All steel alloys used for making gear sets for the vast majority of automotive use are case hardening alloys of some type which can be easily carburized. They spent a bunch of time and effort finding out something that would have been fairly common knowledge at any of the gear makers had they thought to ask first.
 
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. . . I'm just going with Dana genuine parts if given the choice.

You had me with that. You should have stopped there.

If you wrote only the excerpt I quoted your position would be unassailable. Who could reasonably argue that replacing a factory installed part with a similar part from the same manufacturer would be a downgrade in quality? Country of origin is irrelevant to the ultimate conclusion.

There is also a non-technical and non-political argument for consistency.

When Yukon manual hubs were installed in my jeep I had the option of upgrading the factory inner axle shafts. The Yukon kit included the hub assembly, bearings, seals, u-joints and 4340 chromoly outer stub shafts, but it did not include inner axle shafts. I chose Yukon brand inner axle shafts, purchased separately.

Did I pick Yukon inner axle shafts because they were better in some way than the alternatives? Not at all. Did it concern me that Yukon branded axle shafts might not be as good as some other company's? Not really - every vendor's warranty is about the same. I bought Yukon inner axle shafts simply for consistency and to eliminate any argument that a warranty claim involves some other company's part.

There you have it. Yukon brand axle shafts were best for me and Dana brand gears will be best for you. No matter where they are made.

Its a perfect world. :giggle:
 
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How do you explain all the ones that don't vibe with Korean gears by the 100's of 1000's?
My first thought is obviously to defend my theory. To be devil’s advocate, my thought is many folks either dont notice, “its a Jeep, it’s supposed to drive and ride like this..” others may not care.

On the other side of the coin, Im sure the gears made overseas by aftermarket companies could be just as good as Dana gears. Maybe that’s the key, maybe they can make really good quality gears for Dana axles but are they consistent?
 
My first thought is obviously to defend my theory. To be devil’s advocate, my thought is many folks either dont notice, “its a Jeep, it’s supposed to drive and ride like this..” others may not care.

On the other side of the coin, Im sure the gears made overseas by aftermarket companies could be just as good as Dana gears. Maybe that’s the key, maybe they can make really good quality gears for Dana axles but are they consistent?
Are all oem tj wrangler gear sets made in America?
 
My first thought is obviously to defend my theory. To be devil’s advocate, my thought is many folks either dont notice, “its a Jeep, it’s supposed to drive and ride like this..” others may not care.

On the other side of the coin, Im sure the gears made overseas by aftermarket companies could be just as good as Dana gears. Maybe that’s the key, maybe they can make really good quality gears for Dana axles but are they consistent?
From my perspective, this is very similar to a lot of discussions about certain things like springs, control arm joints, steering, and material selection.
You are making the assumption that gears are causing the vibes and in your mind, the new RPM levels are not the problem, the quality of the gear set is. All he would have to do is swap in a set of Dana gears in the same ratio and all the problems would disappear.

If that were true, then this harmonic problem would have been around and prevalent a lot longer than before the introduction of the 5.13's and 5.38's because folks have been re-gearing Dana axles with non Dana gears for a very long time.
 
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My vibe started when I regeared my 00 with a 32RH to 4.10 in a HP30. It would start at around 62 or 64 mph and go to about 70 mph. I did all of the normal stuff, such as pull the rear shaft and still had the vibe. I pulled the front and it went away totally. Now the front gears were still spinning, just not under load. So thought the factory front shaft needed to be rebuilt. Did that installed and still had the vibe. Pulled the front and inspected, had it balanced, installed and still had the vibe. Ordered a new front shaft from Tom Wood and still had the vibe. Adjusted the pinion up down and every way that I could and still had the vibe. I searched and looked and could not find the answer. I finally found a thread on JF that Mrblaine commented that in some cases the only way to solve the front shaft vibe was to install the warn hub kit. So I found one local from a guy who pulled it before selling his TJ and I installed it. I have had no issues at all ever since. Now I do not think it has anything to do with the gears in my case. We are hitting a resonant frequency on some jeeps caused by the front shaft turning. I dont know if it is in the tcase or what but in a lot of cases it is caused by the front shaft being in the loop. I now when we would run a dynamics test and wanted to find a resonant frequency we would do a sine sweep on the shaker and us a strobe light that was adjustable and you could see the resonant wave going through the product. If we could do something like that I bet we could find the cause. Then we could find the fix. The hub kit works great but it is a band aid fix.
 
. . . The hub kit works great but it is a band aid fix.

I agree with the exception of the characterization "band aid."

A hub kit doesn't just mask the vibration issue as a band aid temporarily covers a wound, it cures it. Simply because we haven't been able to isolate the specific root cause of the vibration doesn't negate the effectiveness or the permanence of the fix.

Would it be helpful if we knew the actual cause? Absolutely, because it may lead to another fix that is less expensive and less involved than converting to manual hubs. But I'm going to leave that for those with engineering minds who stay awake at night thinking about such things. I'm just happy that the vibrations in my jeep disappeared when manual hubs were installed so that I can drive it without ever thinking about the vibrations again.
 
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I agree with the exception of the characterization "band aid."

A hub kit doesn't just mask the vibration issue as a band aid temporarily covers a wound, it cures it. Simply because we haven't been able to isolate the specific root cause of the vibration doesn't negate the effectiveness or the permanence of the fix.

Would it be helpful if we knew the actual cause? Absolutely, because it may lead to another fix that is less expensive and less involved than converting to manual hubs. But I'm going to leave that for those with engineering minds who stay awake at night thinking about such things. I'm just happy that the vibrations in my jeep disappeared when manual hubs were installed so that I can drive it without ever thinking about the vibrations again.
A band-aid repair can have more than one meaning depending on the user of the word. I call it a band-aid because we shouldn't have to resort to an expensive mod to solve this particular problem. Maybe crutch is more palatable?
 
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I wonder how a HP vs low pinion would have affected your vibrations? I am going to use spicer gears and lockouts on my HP44 build, I also live about a mile from Tom Wood's shop, so I will have the best IMHO of all worlds. Tim
 
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A band-aid repair can have more than one meaning depending on the user of the word. I call it a band-aid because we shouldn't have to resort to an expensive mod to solve this particular problem. Maybe crutch is more palatable?

What if you are able to determine the root cause of the vibration and based upon that determination conclude that the issue can only be resolved with manual hubs and there is no less expensive resolution? Wouldn't that mean that manual hubs were the fix all along and never a band aid at all?
 
What if you are able to determine the root cause of the vibration and based upon that determination conclude that the issue can only be resolved with manual hubs and there is no less expensive resolution? Wouldn't that mean that manual hubs were the fix all along and never a band aid at all?
What if unicorns farted rainbows and we could use them to patch holes in soft tops?

I have too many rigs running around on 5.38s with no vibes and no hub kit for the hypothetical to be anything more than that, hypothetical. We can derive as many scenarios as we like to prove or attempt to prove a point but until that is the ONLY answer that has worked, then it is a crutch, band-aid, what have you that shouldn't be required. It is a solution, it hasn't historically been the only solution.