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Grinding When Coasting

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101stairborne View Drop Down
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    Posted: 29 June 2018 at 7:52pm
Hi guys,

I have a new noise that my 1948 Willys is making. It seemed to start doing it after I had the Transfer Case off to replace the gasket between the TC and Transmission. 

Here is what I am hearing:

When I am driving at any speed I don't hear a grinding noise, but when I coast at any speed it starts to make this noise. It stops making the noise when I press down the clutch while coasting or when I put it in neutral and coast. 

I had a similar noise occur when the rear drive shaft was out of phase, but I fixed that and put new U-joints in. The front drive shaft is not currently installed. 

I am not very mechanically inclined, so I have no idea what could be making this noise. Any ideas are appreciated!

Thanks,

Ryan
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Ol' Unreliable View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 29 June 2018 at 9:47pm
Transfer case intermediate shaft problem? 
There's a reason it's called Ol' Unreliable
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nick_ Quote  Post ReplyReply Direct Link To This Post Posted: 29 June 2018 at 10:25pm
My transfercase does this under load when I let off the gas. It started happening after I installed my overdrive, and it's been so long but I vaguely recall it once running low on oil.
'47 CJ2A/M151 Submarine Jeep
'49 CJ3A/MB - Daily Driver
'51 CJ3A APU Navy Jet Starter
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tufcj2a View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj2a Quote  Post ReplyReply Direct Link To This Post Posted: 29 June 2018 at 11:14pm
I have similar issue on my 47 CJ. Most folks, including myself, thought it was either the transmission or transfer case. Turned out to be the ring and pinion in the rear end.  We trouble shot it by removing the rear axle and driving it in 4-wheel (front-wheel) drive.  Magically the rattle went away. Remove the rear plate and found lots of play in the spider gear and pitted ring and pinion.  Just received the parts today so will let you know what happens. But I'd suggest at least checking that before you pull or rebuild the transmission and transfer case.

Edited by tufcj2a - 29 June 2018 at 11:40pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TERRY Quote  Post ReplyReply Direct Link To This Post Posted: 30 June 2018 at 10:36am
Check slop in rear driveshaft splines.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 101stairborne Quote  Post ReplyReply Direct Link To This Post Posted: 30 June 2018 at 2:44pm
I took the rear drive shaft out and drove in in 4WD and I didn't hear anymore grinding. There is a tiny bit of play in the rear drive shaft splines, but not much. If there is play in the rear differential is there an easy fix to it or does it require a complete overhaul? The gears look like they are in good shape. There is no pitting or chipped teeth.

Ryan
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TERRY Quote  Post ReplyReply Direct Link To This Post Posted: 30 June 2018 at 4:48pm
Rather than looking for rotational play in the splines, apply force perpendicular to the shaft and see if there is deflection. Sometimes pulling the spline joint apart and rotating the relationship 180 deg can help.
Otherwise new yokes and splined sections are available and a driveshaft repair guy can weld it together. That is what I finally had to do.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj2a Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2018 at 8:48pm
Not sure how far along you are with the troubleshooting or repair.

Something else we discovered when looking at mine, how many rear leaf springs do you have? The previous owner added a couple extra on my CJ. This changed the angle of the drive shaft to the transmission. The U-joints were tapping occasionally.  We lowered the transmission about 1/2" to get to an acceptable angle. Problem solved. We did also replace the axle bearings (they were also a contributor to the noise I'm sure), but the ring and pinions were in decent enough shape we didn't have to replace, in fact the ones we ordered were in worse shape than mine.





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Post Options Post Options   Thanks (0) Thanks(0)   Quote 101stairborne Quote  Post ReplyReply Direct Link To This Post Posted: 16 July 2018 at 9:27pm
I think it has the original leaf springs that look unmodified, so I don't think that's an issue. I think its most likely the play in the driveshaft splines and probably the play in the differential
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sierra Quote  Post ReplyReply Direct Link To This Post Posted: 17 July 2018 at 8:52am
I had a grinding noise 1948 cj2a at coast also, my rear ring and pinion was complete wore out!
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