H151 Transmission

[ArmyFJ]

I like how my H151 with the 1FZ drives. I have never needed to down shift to keep speed up hill or pass. I don’t have any experience with an H55 so I cannot compare. The shifts in the H151 have to be a little slow but nothing crazy. If you shift too quick it is a little notchy. I have 5.29s on 37s and it’s a little over geared for high speed and long distances. I’m pretty confident that probably contributes to how slow my shifts need to be. If I did it over again I probably would stay stock at 4.11s or maybe 4.56s. Not sure where you’re sitting right now with your diffs but something to consider.

 

[SoTexCruiserDoc]

I like how my H151 with the 1FZ drives. I have never needed to down shift to keep speed up hill or pass. I don’t have any experience with an H55 so I cannot compare. The shifts in the H151 have to be a little slow but nothing crazy. If you shift too quick it is a little notchy. I have 5.29s on 37s and it’s a little over geared for high speed and long distances. I’m pretty confident that probably contributes to how slow my shifts need to be. If I did it over again I probably would stay stock at 4.11s or maybe 4.56s. Not sure where you’re sitting right now with your diffs but something to consider.

I really appreciate the input. Diff gearing was going to be my next internal debate. I definitely feel like the stock 4.11s running 35’s leaves a lot to be desired on and off asphalt. Planning to stay on 35’s. Initially thought to take drivetrain in stages, starting with transmission and see how I liked it. Now thinking while it’s on the lift to go ahead and do it all, including part time. 4.56 vs 4.88 gears? I want the truck to remain “comfortable” on the asphalt at 70mph or so to get from TX to the mountain trails. Thanks again!

 

[ArmyFJ]

I really appreciate the input. Diff gearing was going to be my next internal debate. I definitely feel like the stock 4.11s running 35’s leaves a lot to be desired on and off asphalt. Planning to stay on 35’s. Initially thought to take drivetrain in stages, starting with transmission and see how I liked it. Now thinking while it’s on the lift to go ahead and do it all, including part time. 4.56 vs 4.88 gears? I want the truck to remain “comfortable” on the asphalt at 70mph or so to get from TX to the mountain trails. Thanks again!

I would highly recommend taking it in stages and see how you like it on stock gears with the transmission first. I wish I had spent more time on the stock gears on and off road before I swapped them to feel it out. I needed to get into both axles to fix some things when I first picked up my vehicle and figured I should swap the diffs at that time - that was a mistake.

I think the general rule of thumb I have seen somewhere on this forum or another is for a manual transmissions go with one less step in ratio than with an automatic - so I suppose in your case on 35s go with 4.56s instead of 4.88s. Again I would really recommend waiting to regear until you drive with the manual transmission installed.

 

[chenderson572]

View attachment 1364230
100 series with rear shift and full time case

note, the viscous clutch transfer case is not shown in any images above

Is this a stock photo... someone on Facebook is using the same Pic