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Discussion Starter #1
Help me ! T18 – Dana20 + Dana18 = Gear Noise

I have just finished rebuilding my CJ. I replaced AMC20 with offsetted Waggy44 and in order to solve the bad drive shaft angle, we decided to replace Dana20 with Dana18. I found the required “big hole” (4”bore) dana 18 case from an early Kaiser (unused military surplus :grinpimp: ), and an almost unused willys dana18.... I swap all the gears to Kaiser dana18 with the guidance of Novaks’ chart... install a new idler shaft..

http://www.novak-adapt.com/knowledge/transfer_case_gears_grid.htm

From Dana 18;

Intermediate Gear 18-5-7, 34t x 21t

Front Output Gear 18-8-18, 26t

Front Sliding Gear 18-8-17, 39t


From T18, the same gear used in Dana20;

Drive Gear 18-8-46, 26t x 6


Everything worked fine on the ground (as always), all the gears worked perfectly... but when we install it, in high speed 2h, there is a very high gear sound, especially when I release the throttle... Does anybody have an idea? or experience? My concern is in novaks’ chart, it is said that the helix angle of 18-8-46 17.5 degrees and dana18 gears are 20 degrees, can it be the problem…

Other problems I faced ;
- the front bearing shaft cap of dana18 was touching the side wall of T18, so I grind it around 5mm and it is broken during the installation of sticks… need to find a way.
- and front drive shaft needs to be shorten (if you call it a problem…..)

 

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make sure you are using the correct bull gear for the 18. Not all D20 gears are interchangable with the 18, I had the same issue a long time ago when I built my Willys.
 

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Back in ’92 on my first Jeep build, I ran a SM465, 205, 9”, and 44 SOA with 4” rancho springs. The rear pinion was pointed up at the T-case to reduce the drive shaft angle, and it made a similar noise….sounded like gears grinding or rattling when I let off the gas….really bad. I could never find out what the noise was. Latter I went with Wrangler flat leafs, and cut out my fenders….noise got less. So I installed a CV on the T-case….noise went away. I talked to Pewe at Republic at the time, and we came to the concussion that the noise was caused by the upper joint??????
 

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Ford Bigot
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I rebuilt my Dana 18 because I heard that sound and it made that noise afterwards. I went up the street and talked to an old guy who restores WWII Army Jeeps and he said they all made that noise. Mine is all within spec, I set the preload on the lower shaft, and I checked the lash in the gears. All was good.

Mine is a Scout case, with the Novak hardened 1.250" shaft. I've beat the shit out of it and it doesn't seem to mind much. No problems to speak of other than the damned thing leaks like a siv. I've done a full gasket kit and it still leaks. I magnafluxed the case when I had it apart so I know it's not cracked.
 

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You already answered your own question. You need to take the bull gear off the T18 and replace it with 18-8-19 or 18-8-31 before you really mess the case up running 2 different gear pitches.
 

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Discussion Starter #7
I am running 37s with SOA...The rear drive shaft angle was very bad, the vibration on the highway was like an earthquake.. but with dana 18 I have a much much better angle. I am afraid of breaking the gears I could not try it long on the highway....
Sure I am expecting some noise from dana 18, I remember it from my M38A1 but it is the sound of old style gears....But now it sounds wrong.
I will try to find the right gear and replace it.. I will post the result on the list...

thanks for sparing time...
 

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I am running 37s with SOA...The rear drive shaft angle was very bad, the vibration on the highway was like an earthquake.. but with dana 18 I have a much much better angle. I am afraid of breaking the gears I could not try it long on the highway....
Sure I am expecting some noise from dana 18, I remember it from my M38A1 but it is the sound of old style gears....But now it sounds wrong.
I will try to find the right gear and replace it.. I will post the result on the list...

thanks for sparing time...
My old cj ran 37" IROKs with a D18 behind a T18 and later behind a TH400. It's a pretty tough case, although if you like bouncing up and down you will break the output shafts.
 

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]2eDeYe
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Thanks guys,

I just put together a Dana 20 with 18 gears and this was a timesaver. Checked the chart and I have to pick up a 18-8-33 or -23.
 
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