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Car Forum / Driving, Maintenance, Tuning / 4x4 Cars / March 2007Differentials, 4.09 front, 4.10 rear
Have had some more trouble finding parts. Is it true that it is ok to run 4.09 in front with 4.10 in the rear? Thanks, Vic ----------------------------------------------------------------- 1971 Chevrolet K20 3/4 Ton Long Bed Fleetside 4WD 350 4 on the floor Transmission - Muncie 465 - 6.55:1 3.58:1 1.70:1 1.00:1 Transfer case - New Process 205 - 1.98:1 1.00:1 Warn manual hubs Front Diff - Dana 44 - Open - 4.09:1 Rear Diff - Eaton H070 - Detroit Locker - 4.10:1 (Should be a (H052 for 3/4-ton, (H072 for 1-ton. (current H070 is a 1-ton from a 1965) it is normal to have the differential gears 1 point off. this makes the front turn a tad faster than the rear, which aids in the fronts pulling power. > Have had some more trouble finding parts. Is it true that it is > ok to run 4.09 in front with 4.10 in the rear? [quoted text clipped - 20 lines] > (H072 for 1-ton. > (current H070 is a 1-ton from a 1965) >it is normal to have the differential gears 1 point off. this makes the >front turn a tad faster than the rear, which aids in the fronts pulling >power. It is not a bad idea to have it that way but sometimes it is because the series of axles that they are using only come that way. It used to be pretty common long ago but you do not see it that way today on new vehicle much at all anymore. ----------------- TheSnoMan.com Sounds like a bunch of hooey to me. > it is normal to have the differential gears 1 point off. this makes the > front turn a tad faster than the rear, which aids in the fronts pulling [quoted text clipped - 24 lines] >> (H072 for 1-ton. >> (current H070 is a 1-ton from a 1965) >Have had some more trouble finding parts. Is it true that it is >ok to run 4.09 in front with 4.10 in the rear? Okay, imagine what happens with a four-wheel drive system where the front wheels are turning at a different speed than the rear wheels when you're going straight down the road. Not a good idea. --scott  Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > >Have had some more trouble finding parts. Is it true that it is > >ok to run 4.09 in front with 4.10 in the rear? [quoted text clipped - 5 lines] > Not a good idea. > --scott From the Randy's Ring and Pinion web site; Myths about differentials "The gear ratio in the front of a four wheel drive has to be different from the front so the front wheels will pull more." --------------------------------------- "There have been many different ratio combinations used in four-wheel drive vehicles, but not so that the front will pull more. Gear manufactures use different ratios for many different reasons. Some of those reasons are: strength, gear life, noise (or lack of it), geometric constraints, or simply because of the tooling they have available. I have seen Ford use a 3.50 ratio in the rear with a 3.54 in the front, or a 4.11 in the rear with a 4.09 in the front. As long as the front and rear ratios are within 1%, the vehicle works just fine on the road, and can even be as different as 2% for off-road use with no side effects." >Okay, imagine what happens with a four-wheel drive system where the >front wheels are turning at a different speed than the rear wheels >when you're going straight down the road. Actually this happens all the time and this is why you do not use convential 4x4 on pavement. It happens because of minor differences in tire rolling radiuses due to inflation and load and when ever you turn because the front and rear axle have different rolling paths in a turn. Also, the ujoints in a solid front axle that allow you to steer the axle under power are not constant veleocity and the sharper you turn, the more the speed across the joint varies as it flexs (this is why the wheel can whip and bind in a tight turn with a solid front axle on a hard tractive surface. ----------------- TheSnoMan.com >>Have had some more trouble finding parts. Is it true that it is >>ok to run 4.09 in front with 4.10 in the rear? > > Okay, imagine what happens with a four-wheel drive system where the > front wheels are turning at a different speed than the rear wheels > when you're going straight down the road. That's what 2WD mode is for ;-) Scott Dorsey <kludge@panix.com> wrote in article <etnbu6$f4i$1@panix2.panix.com>... > >Have had some more trouble finding parts. Is it true that it is > >ok to run 4.09 in front with 4.10 in the rear? [quoted text clipped - 4 lines] > > Not a good idea. Perhaps the engineers at the "Big Three" manufacturers need to be told this, because they all intentionally engineer a point or two difference. What do YOU know that THEY don't? And. why are you working at that mundane job when you SHOULD be designing cars? >Perhaps the engineers at the "Big Three" manufacturers need to be told >this, because they all intentionally engineer a point or two difference. No they do not today because I have a 79, a 89 and a 2000 that all have the EXACT same gear ratio front and rear. BTW, Detriot knew about the bind many years ago and promotted fulltime 4x4 with a differentail between front and rear axle (I have one still) from 1973 till 1979 until fuel cruch killed them off as they were more thirsty. It was a very slick setup though speaking from first hand use of one for over 20 years now. ----------------- TheSnoMan.com > BTW, Detriot knew about > the bind many years ago and promotted fulltime 4x4 with a differentail > between front and rear axle (I have one still) > TheSnoMan.com How does that work for you off-road or on loose surfaces? I would guess that a differential between the front and rear would lead to a greater likelyhood of getting stuck because both wheels on one axle lost traction and one wheel on the other axle lost traction at the same time. I have heared of some vehicles (newer Jeeps for instance) in which you can drive in "all-wheel-drive" mode (i.e. center diff), then lock the center diff for 4x4 mode. >>Have had some more trouble finding parts. Is it true that it is >>ok to run 4.09 in front with 4.10 in the rear? [quoted text clipped - 5 lines] >Not a good idea. >--scott Not enough difference to matter. Tire pressure differences would have the same effect as would changes in load. 1/100 is not enough to make a difference you will ever sense from the driver's seat. - Regards Gordie >Not enough difference to matter. Tire pressure differences would have >the same effect as would changes in load. Yup, that's true. >1/100 is not enough to make a difference you will ever sense from the >driver's seat. Is it enough to seriously impact tire wear, though? --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > Have had some more trouble finding parts. Is it true that it is > ok to run 4.09 in front with 4.10 in the rear? [quoted text clipped - 20 lines] > (H072 for 1-ton. > (current H070 is a 1-ton from a 1965) I was always under the impression that you never use 4WD on hard pavement and that was the reason. This was told to me back in the 70's... >> Have had some more trouble finding parts. Is it true that it is >> ok to run 4.09 in front with 4.10 in the rear? [quoted text clipped - 23 lines] > I was always under the impression that you never use 4WD on hard > pavement and that was the reason. This was told to me back in the 70's... test |
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