Changing gear ratios

Does anyone have the instructions for changing the gears in the Gems? I have the two gears themselves and nothing else.

What is your current gear ratio?

What gears do you have in hand (number of teeth on each)

Reason for changing ratio?

Below are common ratios and gear combinations

RATIO… TOOTH COUNT…1ST RED…2ND REDUCTION
8.9 TO 1…27,53- 26,118…1.96…4.54
10.35 TO 1…27,53-,22,116…1.96…5.27
9.31 TO 1…27,53- 24,114,…1.96…4.75
12.44 TO 1…21,55-,24,114…2.62…4.75
11.89 TO 1…21,55- 26,118…2.62…4.54

I currently have the stock (for a 2005) 10:1 but have an 8:1 gear in hand. I live in a very flat area and my reason for wanting to change is to have just a bit more speed in my back pocket when needed.

Ok just to make sure you have the 26 and 118 gears in hand.

I’m just looking for a set of instructions on how to change them out.

Hmmm are you sure its not a 12.44 to 1 which was stock for 2005 carts?

Just to be clear on a 10.35 conversion to 8.9 you change the Secondary gears.

Just to make sure your unit is a 10.35 to 1 the input shaft will have 27 teeth. A 12.44 will have only 21. Pull the input shaft and verify the ratio before pulling the gear box.

If it turns out to be a 12.44 you have to change the PRIMARY gears and end up with a 9,3 to 1 ratio.

One more comment: If you have a 5 HP motor the advantage of going from a 10.5 to 1 to 8.9 (9 to 1)
to 1 are minimal. You can program to 30 MPH with stock tires and not damage the motor. However if You have the 12.44 you DO need to up grade.

I haven’t seen a manual for this unit but they are very simple. Off the top of my head:

  1. empty oil

  2. remove input seal (if Equipped) snap ring and input shaft assembly

  3. clamp unit in a vice upside down.

4 remove differential cover

5 drill a small hole in intermediate shaft hole covers and force covers out with a screw

6 remove snap rings on intermediate shaft and axle output shafts.

7 remove axle output shafts (these can be a ***** and may have to be pushed out from the inside) I use a long taper wood chisel and add 5/16 nuts to work them out if I cant pull them from the out side.

8 remove differential assembly

9 remove intermediate gear assembly

10 remove and replace differential gear and replace

11 press off intermediate shaft and press on new

12 put it back together in reverse order.

Note: If the gear box was quiet and not leaking you will only need to replace the covers on the intermediate shaft and the input shaft seal. However: The experts will tell you to change out all bearings and seals. Unless the unit has over 5000 miles on it ain’t broke and I don’t fix it.
It’s not necessary to clean off the old sealant just wash off the oil with gasoline and apply a heavy bead of blue PERMATEX. Lightly tighten the cover bolts and leave it set 24 hours before adding oil. You can tighten the bolts when you put it back in the car.

Keep us up to date.

Rodney

Old Houseboater you have been very helpful. Thanks. I just counted my teeth. The large ‘donut’ gear has 107 teeth. The smaller gear with the shafts on each end (one stepped shaft) has 33 teeth. My '05 is stock. I picked up the gears (only the 2 gears) new, no instructions. I sure wish that someone who has done one of these gear kits before would post or send the instructions. Your step by step instructions are very helpful, graphics would be even better!

I have never heard of that tooth combination for an H12 series gearbox. Thats about a 3.2 to 1 ratio. If they would fit you would really haul ass. However you would need a LOT more motor than 5HP. Where did you get the gears and are they for an H12 Series Spicer (DANA) gearbox?