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post #1 of (permalink) Old 05-27-2002, 06:47 AM Thread Starter
 
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CJ/(all) - Old transmissions and noise

Well, the T98 is in and working just fine. However, I can't help but notice that even though this is a fresh rebuild, the thing is a heck of a lot noisier than my grindy old T150 ever was. I chalked this up to the fact that it's a nearly 40-year-old transmission. However, I recently read where bad input and output bearings can cause such noises and this, of course, caused me to worry.

To characterize the noise, it's a noticeable whine when there's load on the transmission at 30mph+ in 3rd and 4th gear (I guess the only two gears capable of 30mph+ anyway). the whine ceases when coasting.
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post #2 of (permalink) Old 05-27-2002, 07:52 AM
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Re: CJ/(all) - Old transmissions and noise

The only indicator that I've had for a bad input bearing was a chatter at idle that went away when I pushed in the clutch. I've been told that the output bearing will evidence itself most when using the counter shaft (all gears except direct ..and in some cases overdrive) since the counter shaft puts additional helical and reactive loads on the bearing. The helical action causing them to want to go in opposite directions from each other(one shaft foward in direction - one rearward) and the reactive where they want to spread apart. This pretty much goes away in direct drive when the transmission turns into basically a straight shaft w/o helical or reactive loads on it. This is not to say that your condition is not a bad output bearing. Its just curious that it only happens in 3rd and 4th where you are using the input and counter shafts for one but not the other.

I take it that the rebuild did not include i/o bearings.
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post #3 of (permalink) Old 05-27-2002, 08:22 AM Thread Starter
 
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Re: CJ/(all) - Old transmissions and noise

yeah, I put in new bearings but this was my first tranny rebuild ever... never know when you might screw something up. Since I otherwise have none of these symptoms you mention, I guess I may just chalk it up to being an old, crotchety tranny which gives the CJ more "character."
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post #4 of (permalink) Old 05-27-2002, 03:17 PM
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Re: CJ/(all) - Old transmissions and noise

Do you have a dana 18 behind the T98? The sound may be from the Dana 18, because they are just loud transfercases, unless you get the expensive AA bull gear and shaft to quiet it down.

Dan Stewart 1963 CJ5 "Caloosa Jeepers" member
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post #5 of (permalink) Old 05-27-2002, 05:40 PM Thread Starter
 
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Re: CJ/(all) - Old transmissions and noise

AHA! I also lowered the gears in the Dana 20 using D18 parts... perhaps that's the source of the noise, then.
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post #6 of (permalink) Old 05-28-2002, 01:23 PM
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Re: CJ/(all) - Old transmissions and noise

Shortly after I purchased my new '69 with the Dana 18 33 years ago, I took it into the dealer complaining about "the whine". They told me it was characteristic of that particular model and was caused by the reverse idler gear. The Jeep now has 148K miles on it, transfer case has never been opened, and yes-it still whines.
post #7 of (permalink) Old 05-28-2002, 02:26 PM
 
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Re: CJ/(all) - Old transmissions and noise

I did the same thing with the 18guts in the 20 and have picked up a whine. Also check the rear transfercase bearing clearance. I had a wicked vibration until I corrected it.
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post #8 of (permalink) Old 05-28-2002, 02:30 PM
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Re: CJ/(all) - Old transmissions and noise

I recall an article I read about straight cut gears ans helically cut gears. straight cut being the older style and more noisy because you basically have the entiere flat surface of teh gear tooth hitting as opposed to a meshing of a helically cut gear tooth. this might attribute to the noise if the T-98 is straight cut.

Brent
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