Posted by Jesse Ybarra
on 7/11/2009, 3:58:34, in reply to "Re: Dana 44 Axles"
64.12.117.15
I hope you two have really thought all of this out, and are not disappointed later.
The changes you are doing are drastic changes on the gearing, hopefully you are planning on full engine and trans repower.
The stock F-134 engine is able to move the FC-150 up a steep driveway, without going to low range, down hill the engine will hold the truck, coming down steep hills. The best torque range is at the lower rpm, compared to a V8 that needs to be wound up to get torque, the reason you have low gears is because the little FC-150 F-134 works best to move a truck that is almost as heavy as the FC-170.
To give you an idea, how it works, 5.38/4.09 = .76 Try this exercise, start out from standinig still start, or go up a steep driveway in 2nd gear, high range on the transfer case, now imagine going down a big hill in second gear instead of having the low first. Then imagine, you can slowly get it to go a little faster on flat ground, in high gear, you are in the slow lane at say 50 mph, the traffic slows down, if you give it gas there is no torque or power, are you going to put it in second gear on the highway?
The yoke matches the new pinion gear, typically the ring gear diameter matches the carrier diameter, the new smaller diameter ring gear needs to have a carrier that it will match to be bolted on.
Now the bad stuff, if you are repowering HP V6 or V8 and using an adapter, even the best rebuilt T-90/D-18, will wear the sincros quicker because the trans gears are now turning faster, these T-90s have weak syncros anyway, this is when it pops out of gear. Changing engines with an adapter, nothing has improved or changed on the trans, to the T-90 it is still like taking off in second, when starting from a standing still start, except that you have more power, at this point the FC will move quicker by slipping the clutch, to get the power / torque curve. Worse is that poping the clutch will break gears.
I know the magazines and a lot of flat fender CJ people will disagree, because it is not unusual to read about a rock crawler, CJ2a with a 500hp SBC adapted to a T-90/D-20, but remember, the math, the torque / torsion on a rock crawler, has divided all the power on all 4 wheels, in the dirt it is usually not on pavement, usually offroad, if it breaks it goes home on the trailer that brought it. Thousands of adapters have been sold with no problems, that is correct the adapters never break.
Primary use of an FC-150 is in 2 Wheel drive, on roads that are paved, the way the math works is that on a conventional older CJ2a the load is on all 4 wheels that means that on pavement half the wieght is on the rear wheels, on an FC-150 almost all the wieght is on the front wheels, on dirty or dusty pavement with a little incline, a stock FC will spin the rear wheels, with taller gears it will get worse, backing up a driveway or with a trailer will be next to impossible, with or without repower.
The repowered FC-150 and FC-170 with good steering and suspension, with taller gears are great with all components matching the new repower, best is with an automatic, and no adapter.
An argument is that later model Jeep vehicles had V8s, these usually had heavy duty automatics or 4 speed truck trans, not a T-90, or the older hard to get FC 4 speeds, these are almost impossible to adapt to and they are not a 4th gear overdrive, only a 3 speed with a lower granny gear. most later model V8s are full time 4x4 because in addition to the axle differentials, most later model full time transfer cases have an additional differential in the transfer case to divide up the torque.
OK the good news is, I can recommend an easier simple way, that I have used myself. anyone that was at my Roundup this year, that went to Red lobster couldn't help seeing Craig driving on the Highway at 65 with 12 people aboard his new tour Jeep, there we were accelerating getting on the freeway, Troy Fry in his new high performance Vortec 454 M-677 Freeway hauler and I was in my 383 SBC #1 M-677, ahead of us was Craig on the freeway with a flat head 6, yes he can do that and with stock rear end gears, the addition of a new aftermarket Advance adapter Saturn Overdrive, not adapted, but added on the back of the stock transfer case, no change is required to the original driveshafts.
How does it work? The low rpm torque is divided by 6 gears or X 2 with the transfer case. By split shifting in the best torque RPM range you can go 1st gear direct drive, shift the OD to High range, shift next to 2nd direct drive, I know it sounds complicated, but it does give you a tru close range 6 speed or double the amount if you count the transfer case. better power better mileage, it pays for itself in gas saving. Having a shop rebuild 2 axles plus parts, then spend more on gas and then have to replace clutch discs sooner, have you seen the poor quality of the new made in india clutch kits and plan on breaking gears as they do break, going a little faster is costly, the guys on the counter will say they have never had problems, well here is what is told to the buyer, just be careful,
I have never met anybody that has ever had a Jeep that was not putting the foot down on the gas pedal, or slowly letting the clutch slip out.
I'm trying to save you of all that fun of going signal to signal, in bumper to bumper traffic, being so careful to let the clutch out slowly or it will bog, it is even more fun on an incline waiting for the light to change, because 1st gear needs a lot more gas and you really need to let the clutch out real slowly.
With all that said be thinking, remember the FC-150 has a very short wheelbase.
I hope all this has helped somebody.
--Previous Message--
: Looks like I maybe wrong on the requirement
: for the reverse gear set requirement on the
: front axle.
: I just checked Genuine Gear and they list
: the kits as the same. That?s why someone
: smarter than me changed the gears. You can
: look on WWW.drivetrainwarehouse.com it gives
: you a lot of information and different
: manufactures. The box I have listed the part
: number as G/GD44-409 so it?s actually a 4:09
: ratio also the yokes were changed and I?m
: not sure why, I?m assuming there must have
: been some issue with the spline count. But
: now you know why someone smarter than me did
: it.
:
: Good Luck
:
:
:
:
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