Engine/Transmission (1994 - 1998) transmission mount question

[trudydog]

I am getting a slight center console shimmy at 2000 RPM ... nothing in the wheel and no slips in the shifting . U-joints and center bearing all seem to be in solid condition. Has anyone experienced this phenomenon? I was wondering if maybe transmission mounts were failing or loose. A quick look underneath all appears fine but that don 't mean it is. Is there a top cross bar mount or rubber bushings I am missing? any suggestions on the shimmy given the specific location and RPM? I have heard ideas from rear springs to failing torque converter (yikes)



thanks for any related info and remedies in advance

 

[GAmes]

There isn't any mount other than the one on the bottom. Mine is the original, but that doesn't mean that yours hasn't came unbonded. They aren't very expensive, and are easy to replace. However, the first thing that came to mind was the damper. Is yours original? Inspection criteria is in the factory service manual.

 

[trudydog]

Thanks for the reply. Yes my dampener is original but I have a mere 122k on this truck... . or is that a false sense of security? Never thought of it but I guess yea it would transfer a frequency right through wouldn't it?

 

[radixr]

I had my dampener off recently and a close visual inspection turned up no obvious problems. I have over 140,000 miles on my odometer.

 

[GAmes]

Just to let you know, a dampener is a wet washcloth. Our engines have dampers.

 

[NIsaacs]

I am getting a slight center console shimmy at 2000 RPM ... U-joints and center bearing all seem to be in solid condition.



thanks for any related info and remedies in advance

A bad u-joint is not always loose, it can be dry and binding and seem okay. If the damper is bad you should be able to duplicate the console shimmy, stopped and in park or neutral with rpm's at 2000.



Nick

 

[trudydog]

GAames. . LOL nice... . yeah i realized i fat fingered the spelling, thanks for the correction... . brought a smile to my face this morning with that one.

 

[trudydog]

A bad u-joint is not always loose, it can be dry and binding and seem okay. If the damper is bad you should be able to duplicate the console shimmy, stopped and in park or neutral with rpm's at 2000.

Nick

Nick, solid troubleshooting tip there, should have thought of that... . exactly why this forum is so awesome. . getting tech tips others in the field. Will give it a "spin" and report back. thanks!

 

[trudydog]

Transmission in park I ran er up to 2000 rpm and set for 20 sec or so. no shimmy at all so,..... back to mb u-joints and/or center bearing???
Took it to a local transmission guy in town for an opinion. he drove it, agreed on the shimmy at 2000rpm and ruled out damper, torque converter , and even u joints. he also noted the trans mount was in good shape. Although not able to pin point the exact cause, based on the shimmy location he felt it was in the front end, mb axle. I should note: tires are brand new but on original rims. I dunno, it is drivable and not a real issue but frustrating cause it ain't right! I hate to just throw parts at it too.

A bad u-joint is not always loose, it can be dry and binding and seem okay. If the damper is bad you should be able to duplicate the console shimmy, stopped and in park or neutral with rpm's at 2000.

Nick

 

[NIsaacs]

I dunno, it is drivable and not a real issue but frustrating cause it ain't right! I hate to just throw parts at it too.

I agree, throwing parts is silly, yet I see it all the time. Troubleshooting until you pin point the issue is key. When I make a mistake I am mad at myself and kick dirt and stuff



Usually if you have a front end issue, the noise/vibration will transmitt to the steering wheel. However, with any noise/vibration associated with the drive train can be hard to track down, the noise can travel up or down the drive shaft. Did the old tires vibrate the console? Is this issue in any gear at 2000 rpm or just overdrive speeds? Any difference loaded or empty?



The next time you take it for a long drive, park on some clean pavement or parking lot and feel all the joints. The front joint should be the same temp as the transfer case, the rear joint the same temp as the rear diff and the center joint and center bearing should be cold.



Nick

 

[JMcCoy]

Is the vibration worse in 4wd? I might inspect the drive shafts to make sure they didn't throw a balance weight. I don't like throwing parts at a vehicle either, but if I were to, I would throw u-joints at it. The very worst that can happen is that you have new u-joints. Good luck

 

[trudydog]

I have never reached 2k rpm in 4 wheel drive \

I hear ya on the u-joints but... . there are also conflicting opinions on product quality on "newer u-joints". some old dogs say only replace those OEM joints when absolutely necessary... they just don't make em like htey used too... . remember when water heaters has 15 years warranties

 

[trudydog]

Yep, same condition with the old tires. Shimmy happens round 2k rpm all gears (i never use the O/D). no difference loaded or empty. Long drive coming up in a week will touch test the driveshaft and report back.

 

[trudydog]

update. new transmission mount installation seems to hae taken much of the shimmy out. solid through 2000 RPM now. $29. 99 at Autozone with lifetime warranty. East remove/install. I suspect the joints and center bearing are coming due.....

thanks all