Re-gear or tranny/TC swap

[paddyp]

My Wag has the TH400/QT combo w/ 3.07s in the diffs. Would it be better to swap the TH400/QT for a T18/D20 combo, and keep the stock gearing, or keep the drivetrain and re-gear the D44s? My TH400/QT is in good shape, and I realize it is a strong setup, but I am tired of having to use momentum to get over things when wheeling. This is not my DD, nor will it be a hardcore rockcrawler. I just want a capable, go anywhere type of rig, without a lot of fabrication and expensive adapters. Would appreciate any input.

[Cecil14]

I'm gonna have to say that at LEAST 3.73s would be a good thing. I don't think the tranny is really the problem. A granny gear would only be a band-aid fix I think.

Anthony

[goldhammer]

Prob looking at 3.73's. I don't remember where the cut off is on carriers, might be 3.90. You might look at 3.73 and keep the T400 and put in an 80's @300 out of a CJ7 that came with the T400, just get the adapter and shifter stuff. D300=2.62 low, iron case, gear driven. Should work out alright, depending on tire size. Going to a stick means hanging all the clutch stuff as well.

[ November 08, 2004, 04:22 PM: Message edited by: goldhammer ]

[Cecil14]

CJ's never came with a TH400 and a D300. Don't believe anything did from the factory. Keeping the D20 would be a much better option in that case. Either that or swap in a TF727 and a D300 from a few 80's vehicles. smile.gif

Anthony

[Stuka]

I dont see tire size mentioned. A TH400 with a QT in low range should give more then enough crawl with stock size tires with the 3.07's. Heck my J10 with a 258/T176/208 with 2.73's and 31's still crawls pretty good. Never need to use momentum, although it does mild stuff comparably, still has seem some steep hills.

[goldhammer]

Cecil- was thinking about a CJ7 with auto from around 80 or so, but don't know for sure if they had 300's or not. I know the 5's did, but they were all sticks.

[paddyp]

Right now the tires are just 30X9.5 BFG ATs, but soon I will be going up to 33s. Strength really isn't the concern, crawling ability up and down hills is.

[joe]

Originally posted by goldhammer:
Cecil- was thinking about a CJ7 with auto from around 80 or so, but don't know for sure if they had 300's or not. I know the 5's did, but they were all sticks.The TF999/D300 combo was avail In 80+ CJ7's and 81+ CJ8's. I think they were available all the way till the end in 86. Not sure about the 87 and later YJ's though.

edit: Just my two cents but you won't gain anything by going to the above combo. I'd regear the axles if ya want more grunt. I too think 3.73's are a good all around ratio but your mpg's will suffer.

[ November 09, 2004, 05:54 AM: Message edited by: -joe ]

[scotty]

does the QT have a low range? if not,swapping in a low range unit should be first on the list smile.gif the QT low range is good at 2.61:1. you wont really gain anything with the t18 in the way of crawl ratio. the torque convertor effectively doubles the 1st gear in the tranny,making it "feel" like a truck with a 5:1 first instead of a 2.5:1 first. the t18 has a better 1st gear,but a higher low range in the d20.

crawl ratio with 3.07s,assuming a th400 has a 2.5:1 first:2.5x2x2.61x3.07=40.06

crawl with a t18 in granny: 6.39x2.03x3.07=39.82

as you can see,they are almost identacle.going to 3.73 is a good idea,and should be easy enuff with the common high carrier and used gearsets if ya dont want to spend a bunch of $$ on new. new crawl will look liek this: 2.5x2x2.61x3.73=48.67 which is not alot,but enuff you will prolly be able to feel it. also it will help you keep from twisting driveshafts and/or pinions in half,wich is a common prollem with too high an axle gear. even a common 3.54 would be an improvement over a 3.07.

i personally dont like automatics. for anything,not just for wheelin. there are alot of very good reasons to swap in a t18,but a better crawl ratio is not really one of em. id be the last person to talk you out of swappig in a t18(i love mine),but if you are otherwise happy with the auto get a low range in the transfer case,then swap out the gears. an auto is alittle easier on parts,and youll have a dependable,very capable rig.

my $.02 smile.gif

[ November 09, 2004, 06:28 AM: Message edited by: scotty ]

[paddyp]

I've got the reduction unit already, guess I'll regear the axles first, then go from there. I have a line on a T18/D20 combo, may pick it up anyways and save the money for the TeraLow 3.15 gearset for the 20 :D Thanks for all the inputs.

[Serious Johnson]

Patrick:

If you swap in a T-18 and go to 33" tires I'd bet that you'll REALLY dislike those 3.07 gears.

My 360 wag runs a T18-a, 208, 3.73s, & 33" tires. It all works very well for my purposes off-road. On road, granny is fine, but 1st is a bit tall for starting on a hill. 2nd goes past 80 MPH, and who needs that? Fuel mileage with this setup is around 15-19 MPG, and seems limited mostly by downshifting to second on hills, so I'd guess that an even steeper gear than 3.73 wouldn't be a major handicap.

SJ