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Discussion Starter · #21 ·
To isolate it you might want to see if it does it only under acceleration through that speed,at steady speed or if it does it slowing down. Also you can get it to do it and pop it in neutral and see if it quits ( being careful of course) that will let you know if it is a issue under load or not. I would find a safe place get It where it smooths out and decelerate in and out of gear and see If it shimmies.
(y)Always on a straight-a-way and only under acceleration from 30ish to 40ish, once I shoot past 40, it all clears up. I'll definitely try the neutral approach. I look forward to spending the day tomorrow (no joke) with all the good advice. Once I try to do what I can by driving it and if nothing comes of it, I'll hopefully have time to get it in for a "road force balance." Cheers all!
 

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Where are you located? You may be able to find someone local here that can help you as well for a couple of beers and swap stories. I know if you are around me I’d be more than happy to help try to identify the issue if you are in the PA/MD area.
 

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Regarding the mileage change, does your region change fuel formulations going into late fall? Winter fuel formulated for higher vapor pressure can have about 2% less energy than summer fuel. That wouldn't account for your entire change but may be some of it.
 

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Certainly could be rear driveshaft universal joints.
(y)Always on a straight-a-way and only under acceleration from 30ish to 40ish, once I shoot past 40, it all clears up. I'll definitely try the neutral approach. I look forward to spending the day tomorrow (no joke) with all the good advice. Once I try to do what I can by driving it and if nothing comes of it, I'll hopefully have time to get it in for a "road force balance." Cheers all!
Get underneath and grab the rear driveshaft and shake it and twist it. It might move a little but shouldn't make any clunking etc. type of noise. Also make it happen under load then abruptly let off of the gas and see if you hear any clunking or other noise. If this happens just under load it certainly can be this universal joint. I used to have to change them monthly on my lifted 1984 GMC Jimmy!

If you are local to Northern New Jersey I can help take a look at it.
 

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Greetings- Since owning my jeep for about 4 months now, I was averaging about 17 miles per gallon and it's now getting less than 16 (about 15.9). I really just drive it to work and back home which is around 16 miles RT so my driving speed and route are always the same and I use the same gas station for all fill-ups. Any ideas on that drop in mpg?

The biggest issue- which I've tried to fix per a "jeep guru's" advice, hasn't worked. At a specific range in speed, 30-40 mph, there's a feeling in the wheel and pedal as best described as a shudder or a shimmy. It happens all the time but it goes away once I move past 40. At the advice of the supposed jeep guru, I got new tires (which were necessary) and replaced the rear drive-shaft. Sadly, none of that has solved this issue. It's really annoying- I haven't had a "smooth" ride in the jeep since I've owned it. There isn't a noise, doesn't pull when braking, nothing to do with a balance or alignment. I've read about "misfiring" which would mean new spark plugs but I'm not sure how that relates to the shimmy at those specific speeds. I'm not a mechanical guy at all so any thoughts about this would be really helpful. I'm open to looking at anything but I don't want to keep throwing money at an issue that doesn't resolve the issue- like the expensive rear drive shaft. By the way, it's a 2010 Sport 2-door, auto transmission. Cheers!
Maybe I'm slow, I've yet to have my coffee, but


1 - what size tires are you running? Bigger tire = sucky gas mileage, unless you play with your gearing
2 - What "extra's" have been installed? Wight = Poor gas mileage.
3 - What type of wheel weights did they use on your last rotation and balance? Some suck, and if the rims are not properly cleans before application will become lose and fly off.
4 - Have you checked your tires for "weird" wear patterns? This will indicate tire damage, or an alignment issue.
What you're describing sounds like you have a tire out of balance.
 

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Greetings- Since owning my jeep for about 4 months now, I was averaging about 17 miles per gallon and it's now getting less than 16 (about 15.9). I really just drive it to work and back home which is around 16 miles RT so my driving speed and route are always the same and I use the same gas station for all fill-ups. Any ideas on that drop in mpg?

The biggest issue- which I've tried to fix per a "jeep guru's" advice, hasn't worked. At a specific range in speed, 30-40 mph, there's a feeling in the wheel and pedal as best described as a shudder or a shimmy. It happens all the time but it goes away once I move past 40. At the advice of the supposed jeep guru, I got new tires (which were necessary) and replaced the rear drive-shaft. Sadly, none of that has solved this issue. It's really annoying- I haven't had a "smooth" ride in the jeep since I've owned it. There isn't a noise, doesn't pull when braking, nothing to do with a balance or alignment. I've read about "misfiring" which would mean new spark plugs but I'm not sure how that relates to the shimmy at those specific speeds. I'm not a mechanical guy at all so any thoughts about this would be really helpful. I'm open to looking at anything but I don't want to keep throwing money at an issue that doesn't resolve the issue- like the expensive rear drive shaft. By the way, it's a 2010 Sport 2-door, auto transmission. Cheers!

I was experiencing the exact same issue with my 2011 JKU. After months of research and troubleshooting, I finally ended up changing the torque converter, and have had no issues since, and have put over 100k miles on the new converter. The torque converter chatters as it starts to engage into full lockup between 30 and 40 mph and is felt as a vibration. Once full lockup occurs the vibration stops. Your Jeep should have the 42RLE transmission, and the "61-1A torque converter" (from Florida) is the one you need.
 

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Discussion Starter · #28 ·
Hello all and a HUGE thanks for all the comments/suggestions. I really appreciate those offers of helping me diagnose the problem in person if we were close by. After a lot of driving around and my wife taking notes/observations, the "shudder" seems to be triggered when going over rough patches in the road- not pothole severe, just not smooth. When I go through a rough area and the road becomes smooth again, and I'm approaching the 30-40 mph range, the shudder begins. And, once I scoot past 40, it stops. Also, per "Digger84"'s suggestion, the shudder appeared to have gone away in 2nd gear. I don't know what that will lead to but it's a start I suppose.

As to some other inquires, a reminder; the Jeep is totally stock, no lift, no oversized tires, nothing aftermarket. The tires are brand new (2 months old) and were balanced by "Discount Tire". The rear driveshaft is brand new, about 1 month old. There are zero noises that go along with this shudder whether I'm gassing through it, or letting off the gas in the middle of the shudder.

Sorry for repetitiveness, just wanted to try and respond to everybody's questions/comments.
 

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After a lot of driving around and my wife taking notes/observations, the "shudder" seems to be triggered when going over rough patches in the road- not pothole severe, just not smooth.
Are you sure this isn't a very mild death wobble issue?
There are a lot of different reasons for death wobble, but it is extremely common on solid front axle designs. Sometimes it is brought on by worn front end parts. Sometimes it is brought on because it's just a solid axle. Sometimes it's brought on by a worn steering stabilizer.

Really mild death wobble can go away on its own a few seconds after trigger, and the more serious DW can only be stopped by slowing down..... and it's usually triggered by a mild bump or uneven road.... and it is quite repeatable over the same bump at the same speed.

My jeep is 4 years old now and the front end parts are a bit worn and there are two specific bumps in the road on the way to our cabin which now trigger a MILD version of DW. After I hit these bumps I can feel the steering wheel shudder back and forth. Now it will calm down on its own in about 10 seconds without me doing anything.... but it will at some point get worse and I will start going into full blown death wobble episodes where I have to slow down to get it to stop.

Anyway.... I wonder if that is what you are feeling.... a very mild version of DW and it's still early enough so it corrects on its own.

Search youtube for "death wobble". it's pretty common.... and not just on jeeps.
 

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Discussion Starter · #31 ·
Are you sure this isn't a very mild death wobble issue?
There are a lot of different reasons for death wobble, but it is extremely common on solid front axle designs. Sometimes it is brought on by worn front end parts. Sometimes it is brought on because it's just a solid axle. Sometimes it's brought on by a worn steering stabilizer.

Really mild death wobble can go away on its own a few seconds after trigger, and the more serious DW can only be stopped by slowing down..... and it's usually triggered by a mild bump or uneven road.... and it is quite repeatable over the same bump at the same speed.

My jeep is 4 years old now and the front end parts are a bit worn and there are two specific bumps in the road on the way to our cabin which now trigger a MILD version of DW. After I hit these bumps I can feel the steering wheel shudder back and forth. Now it will calm down on its own in about 10 seconds without me doing anything.... but it will at some point get worse and I will start going into full blown death wobble episodes where I have to slow down to get it to stop.

Anyway.... I wonder if that is what you are feeling.... a very mild version of DW and it's still early enough so it corrects on its own.

Search youtube for "death wobble". it's pretty common.... and not just on jeeps.
Think we've ruled out DW BUT, I don't know for certain, all the front end parts appear to be in good shape. Another way to try and describe it is like a minor/quick "skid" or drag? So hard to describe in words.
 

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All it takes is for the bolts on the track bar to be little loose. Have the front end gone over by a good front end shop that knows what they are doing. Have an alignment done.
 

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How fast do you drive? Are you using ethanol gas? (california) What is the rating and psi of your tires? You should have no problem in seeing 20 MPG. Mabey the EGR valve is dirty.
 

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Discussion Starter · #34 ·
So..after digging deep online, on the way home last night and driving into work this morning, I turned O/D "off" and I didn't feel the shudder at all. That was promising to say the least. I just don't know what that means- what does O/D off have to do with it all? I just use the Jeep as a commuter; lots of stops and goes for about 8 miles one way. Will turning O/D off be okay, long term?
 

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Post number two told you to shut off overdrive. I was going to post that too but someone already did. Then you stated it was off. Most of shudder problems is the torque converter locking in overdrive. Now that it's out of overdrive the shock is not so noticable.
 

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Discussion Starter · #36 ·
Post number two told you to shut off overdrive. I was going to post that too but someone already did. Then you stated it was off. Most of shudder problems is the torque converter locking in overdrive. Now that it's out of overdrive the shock is not so noticable.
Yes, I've been all over the place trying to figure this out and forgot about post 2- thanks for reminding me. I was also wrong about leaving O/D off, my bad- certainly wasn't meant to mislead etc.
 

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Yes, I've been all over the place trying to figure this out and forgot about post 2- thanks for reminding me. I was also wrong about leaving O/D off, my bad- certainly wasn't meant to mislead etc.
Oh i know you are not. Post a pic of your Jeep. You say you are on stock tires. What is happening is the trans is going into overdrive and lugging down the motor and then the torque converter locks, basically locking the engine to the trans. The 3.8 and the 4 speed auto are not great for the Jeep. You probably have 3.21 gears and while great for highway, in town sucks.
 

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Nice. But for the aluminum rimmed sport, stock tire size is 255/75r17. More narrow tire. About the same diameter. Not like you are running 35's. On your shudder. Could be dirty injectors in motor. But sounds like you are having problems lugging the motor. Spark or fuel messes with running. Now to figure out which one....
 

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Discussion Starter · #40 ·
Wow- just went with what was on it when I replaced the tires. Should’ve paid more attention. Wonder if that’s contributing to the noticeable drop in mpgs- slightly bigger tires? As for the shudder, spark plugs were just change about a month ago. If that’s what you’re referring to when you mentioned “spark”. Thanks for the comments.
 
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