Driveline upgrades

Got the parts to do some upgrades on the cj5. At the moment it has a t90c, d18 with overdrive and 5.38 gears in the d44 and d30. I spent up on t176 and adaptor to fit the d18, terralow gears for the d18, new bits to make the overdrive work with the new gears, 4.56 ring and pinions and front and rear air lockers. All the info I have read about the terralow gears say I need a large hole 18 or 20 case. Is this so you can unbolt the t/case without having to remove the gear off the gearbox out put shaft?

 

The reason is due to the diameter of the Teraflex 3.15 intermediate gear.
A Teraflex 3.15 intermediate gear is of larger diameter than a Spicer 2.46 intermediate gear.
If you try to install it, the 3.15 intermediate gear hits against the top inside of the small hole D18 case.
In theory you could grind a small hole D18 case to allow the 3.15 gear some clearance.
But in doing so the small hole case would become extremely thin from the clearance grinding.

The large hole D18 or D20 cases have a different casting shape than the small hole cases.
The large hole cases are increased in size in the area surrounding the intermediate gear.
The 3.15 intermadiate gear does not hit the inside top of a large hole case.

 

Any way I see that the Tremec T176 Narrow Ratio (NR ) 4 speed ranges from 3.82/1 to straight drive (1/1).
Including the 25% OD, the 3.15 Tereflex and the 3.56 final drive ratio (FDR ) your Gear Span (GS)
ranges from a "crawl ratio" (CR ) of 55/1 to a "hiway cruise ratio" (HCR ) of 3.42.

 

Thanks Oldtime, will have to look for another case. Removed the box and transfer today then fitted the t/case and overdrive up to the t176 to check the shifter and linkage for the overdrive would work with the 176. Need to do a little modifying but will all fit.

Geoff