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-   -   Vibration at 50 mph (http://www.wranglerforum.com/f282/vibration-at-50-mph-81603.html)

anthonyrini 02-22-2011 10:53 PM

Vibration at 50 mph
 
Ok when I drive my jeep and hit 50 mph it starts to hum like "whom whom whom" it does this till like 55 but if i turn overdrive off it dosent to it. also i can avoid it if I race past 50. Anyone know what it is?.....:banghead:

anthonyrini 02-22-2011 10:54 PM

also let me add this is an automatic transmition

InfernoGirl 02-23-2011 07:41 AM

Idk, but the easiest thing to check first is the torque on the lugs. Star pattern, 100 ftlbs... If they're mistorqued then they will shimmy bad at certain speeds.

anthonyrini 02-23-2011 10:26 AM

Thanks i checked that they all are working good. I think I'm going to have to bring it in.

TexasT 02-23-2011 10:30 AM

I would get the tires rotated too. See if it changes.

DString 02-23-2011 10:31 AM

could just be the harmonic balance point

anthonyrini 02-23-2011 08:52 PM

ok so i just took to the local transmition shop and the guy there says that its is not pronounced enoughf when he took it on a test drive . he then put it on stand and got it up to the same mph and there was no problem. on the drive home i coasted do the grade at 50mph there was not sound or vibration

Steve Loves Jeeps 02-23-2011 10:53 PM

Same thing happens with mine. It happens at around 40ish mph with OD turned off. I think its just because of the low rpm of the gear you are in. It's right above the previous gear so the rpms are lower than usual. Thats just my opinion, I am not sure if it is right

anthonyrini 02-24-2011 01:38 AM

ok well i found out that trans that we have is just geared like shit they say the only way to fix that is to gear the shit out the diff to compensate for the shift points.

Steve Loves Jeeps 02-25-2011 12:44 AM

Yeah it isn't on the top of my to do list lol

Jerry Bransford 02-25-2011 12:54 AM

If you're feeling that rhythmic hum/vibration up through the seat of your pants, it could be that your rear pinion angle is just a tad off. Is your Jeep modded so the rear pinion angle has ever been adjusted?

JDsDream 02-25-2011 05:00 AM

It took me a while to find out what year TJ you had. I have an 06 and it has been doing this since the day it rolled off the lot. The problem is that these transmissions will shift into OD at around 45. If you level out around 45-50 or start an incline, the trans does not shift down automatically and the rpms drop too low for the gear. Chrysler came up with this nifty little idea of giving you an OD Off switch rather than gearing it properly. When you feel the vibe, simply switch it off.

anthonyrini 02-25-2011 11:49 PM

Quote:

Originally Posted by Jerry Bransford (Post 1080984)
If you're feeling that rhythmic hum/vibration up through the seat of your pants, it could be that your rear pinion angle is just a tad off. Is your Jeep modded so the rear pinion angle has ever been adjusted?

I have a zone 4" lift on the jeep I got a transfer case drop also just took it to a trans shop and they said everything looks good trans dif and drive line angels

anthonyrini 02-25-2011 11:51 PM

Quote:

Originally Posted by JDsDream (Post 1081076)
It took me a while to find out what year TJ you had. I have an 06 and it has been doing this since the day it rolled off the lot. The problem is that these transmissions will shift into OD at around 45. If you level out around 45-50 or start an incline, the trans does not shift down automatically and the rpms drop too low for the gear. Chrysler came up with this nifty little idea of giving you an OD Off switch rather than gearing it properly. When you feel the vibe, simply switch it off.

Yep been doin that it's so lame though

kjeeper10 02-26-2011 07:25 AM

Mine has been doing the same thing thanks for the description, I really could not put it to words. Problem is a vibration can be caused by a million different things. I just figured it was because of my new tires (31" MT/R) I actually had them rebalanced and it seemed to help but soon came back. Mine starts at about 45-50. I heard about what I think is called road force balancing and I might find a shop that does so and give it a shot. so many people start threads about vibrations and they are so hard to pinpoint because everbodys jeep is different (tires,mods,mileage,etc ) my vibe is not all that bad, I just learned to deal with it..

Sent from my iPhone 4 using WF Access

Steve Loves Jeeps 02-26-2011 11:24 AM

Quote:

Originally Posted by JDsDream (Post 1081076)
It took me a while to find out what year TJ you had. I have an 06 and it has been doing this since the day it rolled off the lot. The problem is that these transmissions will shift into OD at around 45. If you level out around 45-50 or start an incline, the trans does not shift down automatically and the rpms drop too low for the gear. Chrysler came up with this nifty little idea of giving you an OD Off switch rather than gearing it properly. When you feel the vibe, simply switch it off.

Thats usually what I do, or I just accelerate to about 55 then it stops.


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