Scared to re-gear 42RLE after reading through the "vibration" thread

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TLDR: Looking for successful regears to at least 4.88 on the 4 speed 42rle. I don't need to hear from 3 peed, 5 speed, or 6 speed, nor anyone with giant tires. The vibration thread got me scared to just go 4.56. Please include tire size, and transmission. I know the non 4 speed guys will still chime in. Not being mean it seems to just be a 4 speed problem though. Thanks all!

Hey all. I'm looking for success stories on going 4.88 or deeper with 33" tires and the 42RLE. I'm dead set on that being the right ratio for me. I made the mistake of going down the rabbit hole of that phantom vibrations thread and I'm scared of getting the drivetrain vibrations now. I know it is easier to find people with problems than success stories, so I'm asking for some "I did it and it worked!". Just the 42RLE 4-speed please, I don't care about the 3 speed, 5 speed, 6 speed, or giant tires that wouldn't see the drivetrain spinning that fast. I'm on 31's and will be for the next 30,000 miles-ish. I'm not worried about the RPMs. This thing ends up running 3200 rpm+ most of the trip anyway since it can't stay in overdrive. The regear puts it down around 2850, so that would still be an improvement until the 31's wear out. Yes, I know I can install a manual hub up front. No I really don't want to do that.
 
My 05 Rubicon was regeared about 10 years ago and could not be happier with the 33's it has on it . My son has owned it for the last 8 years or so and still won't part with it . Never had a vibe . It also has a Tom wood drive shaft I think I bought at Savvy Offroad
 
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My 05 Rubicon was regeared about 10 years ago and could not be happier with the 33's it has on it . My son has owned it for the last 8 years or so and still won't part with it . Never had a vibe . It also has a Tom wood drive shaft I think I bought at Savvy Offroad
Nice! What gear ratio?
 
I made the mistake of going down the rabbit hole of that phantom vibrations thread and I'm scared of getting the drivetrain vibrations now. I know it is easier to find people with problems than success stories, so I'm asking for some "I did it and it worked!".
I don't think it's a mistake at all. Now you know what could happen. It's like wearing a seat belt, no matter how many successful trips to the supermarket you make you prepare for when things go wrong. Now you know what can go wrong and what people did to fix it. Regear and be happy, if you happen to get vibes you know the solution. Nobody can tell you if you are going to get in the accident on the way to the supermarket no matter how many safe trips they've had.
 
A few iterations ago I ran 4.88's on 35's. No issues at all - other than at that time I could only run the 4.88's in the Dana 30 and I would have preferred the 5.13's that you can do today. So, I think 4.88's on 33's would be fine.
 
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42RLE, 5.13's, 35's, no vibes, only improvements across the board (mpg increase, improved acceleration, increased engine rpm for better throttle response).
 
For 33s and the 42RLE, go to at least 5.13. You’ll be left wanting more with 4.88. I went to 5.13 on my previous TJR with the 42RLE/33s and while it was drastically better, I sometimes wished I had gone all the way to 5.38.

To simulate the driveshaft RPM after a 5.13 regear and 33” tires at say 70 mph, you could drive your current setup at 90 mph.

Current setup speed = New setup speed * (new gear ratio/new tire size) / (current gear ratio/current tire size)

Speed = 70 * (5.13/32) / (3.73/30) = 90.2
 
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To simulate the driveshaft RPM after a 5.13 regear and 33” tires at say 70 mph, you could drive your current setup at 90 mph.
Or the OP could simply hit the O/D button and drive on his 31" tires at about 63 mph. Pretty much the exact same RPM as 5.13 gears with O/D engaged at 70 mph (with the new 33" tires). You can always simulate highway RPM pretty well just hitting that O/D button and going a little slower or faster to get a general idea.

Edit: I missed the driveshaft part, you are correct on that one, sorry
 
Or the OP could simply hit the O/D button and drive on his 31" tires at about 63 mph. Pretty much the exact same RPM as 5.13 gears with O/D engaged at 70 mph (with the new 33" tires). You can always simulate highway RPM pretty well just hitting that O/D button and going a little slower or faster to get a general idea.
That won’t work since the gear reduction (turning the od off) is before the driveshaft. Driveshaft speed would remain the same whether in od or not.
 
This is pretty much a bullshit thread. The reason is because no polling of other rigs has a single fucking thing to do with what any other rig will experience or how it will respond.

Based on our experiences working with 100's of TJ owners, adapting big brake kits to hub kits, installing hub kits, and solving gearing related vibrations, the chances of a rig not getting them is right at 50/50.

The way this should work is every single person who tells you they don't have vibes and to go for it, if you regear and get unsolvable vibes unless the front driveshaft is out, then all those folks who told you they don't have vibes get to chip in and buy you a hub kit.
 
I'm running 4.88s with the 42RLE with a slight lift in the rear with no drop or SYE. I have a cyclical harmonic noise 70+mph. That kind of stuff normally annoys me but the interior of the Jeep is loud enough that I hardly notice. It seems to be more obvious when the soft top is on versus the hard top - possible difference in ride height?
 
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In case I wasn't clear, we are adapting our brake kits to hub conversions at a rate of 1-6 per month. Sometimes 2-3 in a week. Reports from the owners are always related to being unable to dial out the vibes or getting it dialed out by raising the front pinion so much that the steering is now crap.
 
I'm curious what I should be expecting to pay for a regear is southern california. I was quoted 1350. Is this a good deal?

I ask you Jerry, because I know you are a local.
Man. The "reputable" shop here was $2200. That was a full master kit with new axel bearings and everything though.