My Marks Transfer Case Gears

[prado t]

Hi guys and gals, I do alot of wheeling (every weekend) and more. I being very familiar with my BJ74 know that the LOW RANGE sucks the small one.
So since most of the time I am in technical areas, I hate sluffing the clutch. Coldtaco a member of MUD had a 13B-T H55F and split-case with Marks 108-1 Hi and 305-1 low. The case with around 6000miles gears with new bearings was a steal to me for 1200bucks, since threw a reliable source I heard a half decent split case is around 800bucks. The condition of the case is exellent very clean, the gears are not even broken in yet, most of all the remanents of the gear oil is golden yellow(clean, new). I would have liked to get the whole combo, but I already have spares. Did I say that Coldtaco, had the gasket kit for me and new bearings and seals to rebuild my other case.

 

[Granite Grinder]

Bugger
Good on ya!
GG

 

[bj70_guy]

I hate you
That's a great deal, the gears alone are over $1500. But I bet you knew that already...

 

[Enigma]

Way cheaper to put in a SM465 Now you need to spring over that low slung rock crawler of yours.

 

[prado t]

Dont hate me too much, They are together and in the 74, The Crawl Ratio is perfect, what a difference. On the highway 105km/h is 2500 rpm steady,but the most important part is that I can use 4th gear now at 45km/h so my intown mileage is better because on the H55F there is a big jump. With the 108 to 1 ( underdrive ) it closes the gap. Will post pics when I get my star.

 

[Glenn-BJ74]

How slow?

At your 60:1 - how slow can you go at 800 RPM (feet per minute?)

 

[Enigma]

Some gearing calculators over at bc4x4:

BC4x4.COM four wheel drive, 4x4, offroad and fourwheeling site.

More indepth one here : 4Lo.com :: Final Gear Ratio, Crawl Ratio, Tire Size Calculators


Heres an even better one with drop down menus for transmission selection, etc : Gear Ratio Calculator


using 31" tires, 4.843:1 1st gear in the h55f, 3.05:1 marks low range and at 800 rpm, I get 1.2 mph (60.71:1 crawl ratio), which equals 1.76 feet per second (105.6 feet per minute)


For comparison;

My fj40 with 35" tires, 4:11 gears, 6.55:1 SM465, 2.31:1 stock t-case at 800 rpm, I'm at 1.3 mph (62.19:1) or 1.9 fps (114.4 fpm)
300 hp @ 4800 rpm / 380 ft./lbs @ 3200 rpm

 

[Glenn-BJ74]

where is prado t --out there going slow I suppose

 

[prado t]

I am back from another trip (just around the Harrison area) very nice . At idle (700 rpm) I can walk beside the 74 while steering it at half pace (not bad) I am finally used to the whine. Its not too loud but it is there (harmonic). Whenever you have time for a trip Glenn.

Sorry I havnt figured out how many feet per minute. All in all it is a great improvement , At Hale Creek ( the harder section ) I stepped on the clutch once (1) that was to let my spotter out ( Carolyn)

 

[Granite Grinder]

I am finally used to the whine. Its not too loud but it is there (harmonic).

Ohh... that sound's totally unacceptable. Perhaps I should relieve you of the constant whine of that gearbox, which will, in the end, drive you crazy.
GG

 

[prado t]

Hey Phil if that noise was any louder we would be wearing hockey helmuts and painting the 74 light blue. LOL (the blue bus is coming to get us)

 

[BC40]

After rebuilding my transfer case with a new input gear there was a lot of gear whine (even by 3sp t.case standards). What I found helped a lot was a tube of molyslip added in at a higher than recommended dose to the gear oil. Turned the synthetic gear oil black but made a big difference in noise level.

 

[prado t]

I am running SWEPCO, isnt bad at all, it is real tacky (sticky) The whine is still there but quiet, cosidering the other case didnt make a peep. Thanks for the advise.