Posted by Clint Dixon [126.96.36.199] on Monday, September 18, 2023 at 19:52:36 :
In Reply to: Speedo Drive Gear for Transfer Case posted by Glenn in Maine [188.8.131.52] on Monday, September 18, 2023 at 16:07:50 :
Just a litle back story. Straight from the MoPAR Parts Lists:
The drive gear in the transfer case is referred to as the "Gear". The driven gear exiting the transfer case is referred to as the "Pinion".
There were two different gears used - one with 5 teeth and one with 4 teeth. There were three pinions used - one with 14 teeth, one with 15 teeth, and one with 16 teeth.
It depended upon which tire size the truck was delivered with as well as the differential gearing that was used in the particular truck.
The normal combination for the (somewhat rare) small 7.50x16 tires would be to have 4.89:1 differential gearing. This would require a 5 tooth gear and a 16 tooth pinion for the speedometer to read correctly. The normal combination for the (more often found) 9.00x16 tires would be to have 5.83:1 differential gearing. This would require a tooth gear and a 14 tooth pinion for the speedometer to read correctly.
Then there were two additional oddball possibilities that are quite rare as most trucks used the tire size and differential gearing mentioned above.
The first oddball combination was found on trucks equipped with 7.50x16 tires and the 5.83:1 differential ratio. Why anyone would have ordered this option is beyond me unless they wanted to drive the truck VERY slowly working in a salt mine or something. This combination required a gear with 4 teeth and a pinion with 15 teeth.
The second oddball combination was found on trucks equipped with 9:00x16 tires and the 4.89:1 differential ratio. I doubt you will find very many trucks equipped this way as originally delivered from the factory. This combination required a gear with 5 teeth and a pinion with 14 teeth.
This description was mainly meant for the benefit of others as you apparently already know that you have a 4 tooth gear and a 14 tooth pinion, and replacing the 4 tooth gear with a 5 tooth will correct the problem.
Yes, the gear you found, part number 561 816 is the 5 tooth gear you need to swap in place of your existing 4 tooth original. The parts manuals show that that this gear was used for many years on both transmissions and transfer cases.
I have never tried this, but I have spoke to individuals who have and they report good results. However John's method is probably the easiest way to go, if you can find the correct adapter, and if you are not already thinking about rebuilding the transfer case. However you can't beat the $32.00 price tag. I am sure the adapter costs a lot more.
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