david@tekig.UUCP (David Hayes) (02/28/85)
> > > > As a matter of fact on some four wheel drive vehicles the front and rear > > ratios are slightly different. 4.10 to 1 as opposed to 4.11 to 1 for > > > > Christopher Latham > > U.C.San Diego > > Because the front drive shaft is offset, the difference in differential ratios > is probably to compensate for some gearing in the transfer case. The wheels > would then turn at the same speed, front and rear. This makes the only sense. > Since most people know so little about 4W drive train components, I am willing > to go to Off-Road Mail column to get the correct answer. I am curious myself. > By the way the orginal posting was about rotating tires. Every tire dealer I > have talked to says you must rotate tires on a 4-wheel drive. Dick Cepek, > (Largest retail off-road tire dealer) recommends rotation every 5K mi., 2.5K if > you have posi. I typically get 40-45K from my mud tires. This is excellent > considering the wild tread pattern. > > > DAC I thought the reason for the different drive ratios was the physical size difference of the ring gear in some front versus back applications. Like a Dana 44 being 4.11 while the closest Dana 30 ratio is 4.10 due to the smaller diameter, different tooth size etc. My CJ5 has a T-18 transfer case which offsets both front and rear drive lines, they actually are connected to the same shaft, so they have to be turning the same speed. Does anyone have any experience with the Dana 20 transfer case? This is regarded as a "straight thru" type that is supposed to be stronger than the T-18. Does the rear driveline come straight off the back, in line with the transmission main shaft? Also, does this setup put more of an angle on the rear driveline in lifted applications? Will the Warn overdrive work here? After slogging around in the muck, I usually pop back into 2wd, even on the hard pack dirt roads back to camp, just to make sure I don't risk windup. Has anyone converted front drum to disc? There is a kit available for around 300 bucks, but can I buy a hub/ rotor, caliper, and make my own bracket for less?? Any info or just conversation of your 4 wheeler is appreciated. Tektronix!tekig!david
jeepcj2a@fluke.UUCP (Dale Chaudiere) (03/05/85)
My system could not find the sender for a reply, so I'm posting a followup. > > I thought the reason for the different drive ratios was the physical > size difference of the ring gear in some front versus back applications. > Like a Dana 44 being 4.11 while the closest Dana 30 ratio is 4.10 > due to the smaller diameter, different tooth size etc. > > My CJ5 has a T-18 transfer case which offsets both front and rear > drive lines, they actually are connected to the same shaft, so they > have to be turning the same speed. Does anyone have any experience > with the Dana 20 transfer case? This is regarded as a "straight thru" > type that is supposed to be stronger than the T-18. Does the rear > driveline come straight off the back, in line with the transmission > main shaft? Also, does this setup put more of an angle on the rear > driveline in lifted applications? Will the Warn overdrive work here? > > After slogging around in the muck, I usually pop back into 2wd, even > on the hard pack dirt roads back to camp, just to make sure I don't > risk windup. > > Has anyone converted front drum to disc? There is a kit available > for around 300 bucks, but can I buy a hub/ rotor, caliper, and > make my own bracket for less?? > > Any info or just conversation of your 4 wheeler is appreciated. > > > Tektronix!tekig!david The differential gear ratio is the number of teeth on the ring gear divided by the number of teeth on the pinion. This may or may not be affected by the size of the ring gear, but larger ring gears use larger pinion gears. I have a model25 front end and a model 44 rear end. The 44 is larger then the 25, but both are 5.38:1 gear ratios. The driveshaft on the straight thru transfer case comes right out the back. Yes they put more angle on the rear driveshaft when the vehicle is lifted, that is why many lift kits include wedges to tilt the rear differential. A Warn overdrive cannot be used with a straight thru transfer case. Look into a Ranger unit. By the way, yes take the jeep out of 4wd when you get out of the mud, but leave those hubs locked in for a while. You need to get the front axle warmed up at road speed to evaporate any water condensation. Many people fail to run their front axle until good and warm at least once a month and the gears and bearings fail due to pitting not wear. DAC