Alberto_YJ Posted March 9, 2015 Share Posted March 9, 2015 Hi, I'm getting a noise from my YJ 3-speed TF999 transmission. It starts when the transmission shifts to 2nd gear, then it comes louder and faster when shifts to 3rd gear. When I release the gas pedal it will be more noticeable as the Engine sound is not at the background. I've removed the tunnel cover plate and recorded this video to see if anyone of you can help me out to identify which will be a possible source of that noise. I'm thinking it can be the planetary gears. There is also another noise that I think it can be coming from the Transmission Oil Pump. Let me know what can be causing that pump to emit that noise if you know. Any comment is wellcome. Thanks. IMG_3531.MOV Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted March 9, 2015 Administrators Share Posted March 9, 2015 Hi, Alberto! If there is no noise in 1st gear or reverse, this does sound transmission related. If you can get someone to drive the Jeep YJ while you hold a piece of tubing (copper or even PVC plastic) against the transmission case, you may be able to pinpoint the noise. Use the tubing as a "sounding" tube, it will amplify the sound. Protect yourself from the open tube end, the tubing will dance around with a moving vehicle and transmission! Move the tubing around, toward the torque converter (front of transmission housing) and toward the rear of the housing and transfer case. Try to narrow down the source of the sound. The tubing will simulate an automotive stethoscope, which would also work here. Let us know what you hear and where... Moses Quote Link to comment Share on other sites More sharing options...
Alberto_YJ Posted August 28, 2015 Author Share Posted August 28, 2015 Hello Moses, I`ve taken the YJ to a workshop so we can try to identify the noise. The noise is coming from the rear end. We have tested the tranny without the transfer case to discard the transfer case as a source of the noise. The noise is only present after the tranny shifts to 3rd gear and remains if you shift to neutral until the inertia keeps the shaft turning, But if you shift manually to 2nd gear the noise stops. We have tried with another planetary gear set but the noise is still present, tomorrow we will try the complete annular and center pinion and shell set to see if it is an excess of wear on those components, we can found them used only. Another technician says that the sprag could be the source of the noise. We have replaced the bearing on the rear end as well. I just need to know which is the part that turns in 3rd gear only. This is taking me gray. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted August 28, 2015 Administrators Share Posted August 28, 2015 Alberto...As the tech suggests, the overrunning or "sprag" clutch could be defective. The other two parts I would target are the planetary gear set (damaged or broken) or the output shaft bearing. The noise sounds speed related. I would first inspect the output shaft bearing for damage. Since the noise is present with the transfer case removed, you can rule out problems at the transfer case input assembly. A defective output shaft bearing could be the reason for a misdiagnosed "rear end" noise. The 999 output bearing noise could be transmitting or resonating through the transfer case to the rear driveline. This could sound like a "rear end" noise. I would drive to a loose traction surface area, stop and shift the transfer case to low range. Drive through the three speeds and see what kind of noise occurs and the pitch. If your trouble is within the transmission (defective sprag or planetary), the noise should be similar to the high range noises. If the noise is the output shaft bearing, it will sound less intense when in 3rd gear, low range. Output shaft bearing noise is vehicle speed related. Let me know what you find... Moses Quote Link to comment Share on other sites More sharing options...
Alberto_YJ Posted August 28, 2015 Author Share Posted August 28, 2015 Moses, thanks for your input. I've done the test you describe in low range, the pitch and noise is barely the same. The output shaft bearing has been replaced yesterday with no improvement. Tomorrow we will replace the sprag and see how does it go. I will keep you all posted. Regards. Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted August 28, 2015 Administrators Share Posted August 28, 2015 Alberto...The noise sounds like grating more than "whirring", it's more apt to be the sprag. Inspect the planetary gears carefully at the same time. Please update...You and the shop have this narrowed down. Interesting that parts must be used ones. The 999 and 30/32RH are getting older here in the 'States, too. There are upgrades available from Sonnax, see the catalog online: www.sonnax.com. There may be pieces you want to consider now or in the future. I did upgrades on my Ram 48RE transmission with Sonnax pieces, you can see some of the trouble-prone RWD Chrysler transmission issues at my article: http://www.4wdmechanix.com/Survival-Upgrades-for-Jeep-and-Dodge-Ram-Automatic-Transmissions.html. Your local shop would find these fixes of interest if they do a lot of RWD Chrysler 727/904/999 and RE/RH transmission work. Moses Quote Link to comment Share on other sites More sharing options...
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