Y'all have me scared to do my re-gear


JFace

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I'm the type of guy that delves into a subject and reads intensely to better understand it. How are you supposed to get better at something if you don't understand it? With that said though, after reading 15 pages of @bobthetj03 thread on driveline vibes, I'm a little wary of regearing for larger tires.

Is this a very common issue when it comes to gearing? After seeing his thread and countless others on this forum and others, it's making me reconsider my choice to go to 5.13 from my 3.73.

So, is this something I should be worried about? Or does the internet just amplify unicorn cases?
 

Chris

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It is indeed a common issue, yes.

Be prepared to go to manual locking hubs in the event you get the dreaded vibrations after re-gear.
 

Chris

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It exists. I'm not sure if it's common.
I couldn’t say, but I can say I seem to hear about it very frequently these days. Just within the last few months I’ve heard of 3 people who had it happen after a re-gear.
 

rasband

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I wouldn’t let it scare you off, the big thing is finding the right place or person to do it. I’ll be doing mine in the next month or so and can’t wait for it.
 
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Goatman

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More common around me than I would have thought. The key is to find a shop that has a lot of experience at it. I think the best places are the 1 or 2 man shops that have a small 1 or 2 bay building and have been doing it forever. I don't hear many complaints when buying a new complete axle as much. Those places have a ton of equipment to ensure things are right normally. But in the end I think it may be the new gears going into an old and slightly tweaked axle that may be the culprit. But that is just a guess.
 
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Hopper

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I have heard of it as well. I didnt experience anything after my 3:07 to 4:10 regear. I wonder if their is any correlation to higher gears or certain axles and higher gears creating vibes. Someone mentioned locking hubs, how and why does this help?
 

Alex01

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I wouldn't let it scare you. Many of us have regeared without any vibration issues.

Someone mentioned locking hubs, how and why does this help?
With the hubs unlocked the front DS will not spin when driving. No spin = no vib.
 

mrblaine

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I couldn’t say, but I can say I seem to hear about it very frequently these days. Just within the last few months I’ve heard of 3 people who had it happen after a re-gear.
I'd put the number at about 1 in 10. I'd also put the vocal intensity of the 1 at very high which tends to drown out the 9.

We've narrowed it down to spending the least amount of time possible to get them dialed in. We pull the front, drive it to dial in the rear pinion. Then we install the front driveshaft and see what happens. We do the known good methodology to dial it in and test drive it at the driver's requested common highest speed and it is pretty easy to tell if it is going to respond well or be a little bitch about it. At that point we stop, spend no more time on it and put further efforts into a hub kit.

I can usually throw a couple of hours at it and figure out if it is going to behave or not. There is another consequence of not running a hub kit if needed. Some rigs will let you dial out the vibe up to about 65-70 by raising the pinion. The problem is you lose good steering because the caster angle is fucked.
 

Hopper

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I wouldn't let it scare you. Many of us have regeared without any vibration issues.


With the hubs unlocked the front DS will not spin when driving. No spin = no vib.
Ok thanks, so the vibes are concentrated to the front driveshaft?
 

Vulture

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Went from the dreaded 3.07 to 4.10 in my 01 and no vibe trouble so far. You won't know until you make the change. I think that most people don't have trouble so you never hear from them.
 

jjvw

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I have heard of it as well. I didnt experience anything after my 3:07 to 4:10 regear. I wonder if their is any correlation to higher gears or certain axles and higher gears creating vibes. Someone mentioned locking hubs, how and why does this help?
The harmonic vibes typically show up with the 42rle geared deeper than 4.88 on 35s.
 

Hopper

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No, they are a consequence of a cyclical harmonic created when both shafts turn. You can pull the rear shaft and drive only on the front one generally without the vibe.
Thanks. So their are two cures? Spend time creating the absolute proper angle or manual hubs?
 

mrblaine

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Went from the dreaded 3.07 to 4.10 in my 01 and no vibe trouble so far. You won't know until you make the change. I think that most people don't have trouble so you never hear from them.
Most with the pre-03 are likely not going to be in the higher probability group. The problem generally happens with the Rubi case, 42RLE, and the lower gear ratios that spin the driveshafts faster.

Note the prodigious lack of definitive terms.
 
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