Great Lakes 4x4. The largest offroad forum in the Midwest - View Single Post - 4.7 stroker or 5.3
View Single Post
Old June 25th, 2013, 04:11 PM   #232
brewmenn
Grumpy old man.
 
brewmenn's Avatar
 
Join Date: 11-05-05
Location: Inkster, MI
Posts: 10,466
iTrader: (9)
Mentioned: 1 Post(s)
Default

Quote:
Originally Posted by Haggar View Post
While the second paragraph talked about an auto, the first is not auto specific. I was specifically thinking of my 1975 CJ5, when I wrote it.

One of those things that, on paper, looks like piss-poor gearing. 3.73 gears, T15 3 speed with a 3:1 first gear, and a Dana 20 t-case with 2:1 low range, with 34" tires. About 1/2 the overall gearing of my TJ before it. Buuut, it was extremely well matched.

One, the CJ5 was much lighter than the TJ. I suspect that the 304 made around similar horsepower to the 4.0, but more like 250-275 ft-lbs.

Two, and more important, was that first gear gave me a gear with about 200-230 rpm per MPH, which is something of a sweet spot for most Jeep engines. Basically, you want a high of gearing as possible that you can still lug.

With that setup, I could lug down to 300rpm or so, but still spin the tires up when in mud, if I needed to. I never needed to shift. Put it in 1st gear when you got to a climb/mud hole/snow pile, and leave it alone.

Had I put in something like 4.10 or 4.56 gears, I'd have helped low rpm crawling, but hurt the performance in those most common 'michigan' wheeling situations, where I needed RPM. I'd need to shift 3/4 of the way up hills, which sucks.

So, yeah, a well shifting transmission helps, in momentum scenarios. But if you are doing that very often, you should be asking why you've set up a Jeep that requires a shift at that point.
I've never analysed it all that closely. My 4.0L/NV3550/NP231/8.8w/4.10/33inch tires seems to work reasonably well, but I still like that I have a short throw shifter for quicker shifts.
brewmenn is offline   Reply With Quote
 
Page generated in 0.06418 seconds with 20 queries