Gearing Question For Clarification

[skidoo_j]

The question is only questioning theory not availability of products.

 

Assume:

Dana 44  front and rear, both are low pinion so they both take standard cut gears.

The carrier is the same in both axles. 

There are 4.09, 4.10, and 4.11 gears available through one vendor.  

 Assume all manufactures and gears are equal in quality.  

  

 

 

What is the best combo?

 

4.09  up front with 4.11 in rear so front pulls rear?

 

4.09 Up front with 4.10 in rear so front pulls rear but closer in ratio?

 

matched gears front and rear..

 

4.11 up front with 4.09 in rear,    rear pushes front

 

etc...    

 

I'm under the impression you want the front tires to spin faster then the rear when in 4wd so it encourages turning as the fronts will pull into the turn better.     

 

 

You can select multiple options in the poll.   

[yxmj]

The only time i would feel comfortable running a different ratio is if I have the transfer case for it   (......242.....ect..)

 

Because most of mine are 231 or equivalent

 

I go with  Front = Rear 100%

 

I am even  anal about miss-matched tires (same size but different brands...... :dunno: ...... ) and go out of my way to rotate and balance on a regular basis....even match air pressure whether on road or aired down when wheeling.

 

 

Now the argument is different if we are talking strictly off road in sand mud snow....were it would be OK to have the axles working independently ....then I think i would want the front PULLING just slightly.... . :MJ 1: .

[mvusse]

It doesn't matter. The difference is smaller than what unevenly worn tires will cause, even so little so that to the naked eye they look identical. The difference between 4.09 and 4.11 is less than one half of a percent. The difference between either of those and 4.10 is less than a quarter of a percent.

 

For all practical purposed those ratios are equal.

[Blue XJ]

What sized tires? Doesn't matter for mismatched ratios, just asking. I have 4.56's with 35's and I wish they were deeper.

[Eagle]

None of those numbers are considered to be "mismatched." It's common for 4WD vehicles to have one diff in the front and another in the rear. Just within XJs and MJs, you could have (from the factory) a dana 30 in the front and an AMC 20, Dana 35, Dana 44, or Chrysler 8.25 in the rear. Different diffs have different ring gear diameters, so they have different numbers of teeth on the ring gear and on the pinion gear to achieve the "same" ratio. But, due to the different tooth counts, the "same" ration could be 4.09, 4.10, or 4.11. In factory axles, that's why we see some refer to the factory axle used with the 4.0L automatic as 3.45 and some call it a 3.55. Both are correct -- it's just a question of front axle or rear axle.

 

I would like to see what vendor offers 4.09, 4.10 AND 4.11 gears all for the Dana 44. That doesn't make any sense whatsoever.

[skidoo_j]

 

I would like to see what vendor offers 4.09, 4.10 AND 4.11 gears all for the Dana 44. That doesn't make any sense whatsoever.

 

 

That's why I said assume   :thumbsup: .    My father used to run in truck pulls and told me they would run different brand gears to get the front spinning faster then the rear.   I was just wondering if it was common practice.   

 

 

also omix ada has a 4.09 4.10  and 4.11 for the 44.   Granted some are reverse cut.  and they also change for thick cut too.   

[Jeep Driver]

 

I would like to see what vendor offers 4.09, 4.10 AND 4.11 gears all for the Dana 44. That doesn't make any sense whatsoever.

 

 

That's why I said assume   :thumbsup: .    My father used to run in truck pulls and told me they would run different brand gears to get the front spinning faster then the rear.   I was just wondering if it was common practice.   

 

 

also omix ada has a 4.09 4.10  and 4.11 for the 44.   Granted some are reverse cut.  and they also change for thick cut too.   

 

 

 

 

FWIW to ya.......

 

 

What you are describing is crucial with 4WD tractors. Kubota recommends 0-5% front over rear. Our gearing is fixed but we can gain our percentage with tire RC. Our fronts do pull our rears, I'm at a positive 3.5% and mine runs perfect with no binding.

 

Start binding on a tractor and things break.

[Alexia]

Matching ratios to prevent excess drive train wear. No point in adding more differentiation when tires can already add some.

[mvusse]

From experience I know Dana makes or made two different 3.54/3.55 tooth ratios for the reverse cut model 30.

[yxmj]

Well if 2% is acceptable.. :dunno: ....I don't have to bother looking for a front 4.10 front diff or gear set for my 4wd swap

 

I will run the stock 4.10's with 31's in the rear and then slap in a high pinion with 3.55's........run P195/75R/15's.....fat tires in the front and little ones in the back....old school Gasser set up but with 4x4   :thumbsup:

 

[Eagle]

Well if 2% is acceptable.. :dunno: ....I don't have to bother looking for a front 4.10 front diff or gear set for my 4wd swap

I think 2% may be stretching it a bit.

 

The difference between 3.54 and 3.55 is 0.3%

 

The difference between 3.07 and 3.08 is 0.3%

 

The difference between 4.10 and 4.11 is 0.2%

 

As long as you only use the 4WD on soft ground, sand, mud, or snow and ice, you won't have any breakage problems. Dunno if it might result in some unpredictable handling.

[yxmj]

Thanks for the math lesson

 

I decided to start the day with a burn out so I took the 31's down a bit......jack the air it the front tires.......Holy cow all are = now...... :thumbsup:

[Eagle]

Not a math lesson. The difference between the mismatched tire sizes and mismatched axle rations you proposed probably would be at least 2 percent (not 0.2 percent), and very possibly 3 percent or more. Since the ratio differences I posted are all basically factory setups, they are considered functionally equal and won't offer any problems. But you're talking about an overall difference in ratios that's ten times or more greater than "functionally equal." I just don't know how that would work out. I think it would be okay in loose stuff off-road, but here in the northeast some of the little wheeling we have left runs over granite bedrock outcrops, and mismatched ratios on exposed (grippy) granite would probably not bode well for the drive train.

[yxmj]

Not a math lesson. The difference between the mismatched tire sizes and mismatched axle rations you proposed probably would be at least 2 percent (not 0.2 percent), and very possibly 3 percent or more. Since the ratio differences I posted are all basically factory setups, they are considered functionally equal and won't offer any problems. But you're talking about an overall difference in ratios that's ten times or more greater than "functionally equal." I just don't know how that would work out. I think it would be okay in loose stuff off-road, but here in the northeast some of the little wheeling we have left runs over granite bedrock outcrops, and mismatched ratios on exposed (grippy) granite would probably not bode well for the drive train.

 

Maybe you should invest in a new monitor or new spectacles.....I said 2%......never said .2%.....

 

.....while you are at it.......... Google Facetious... :brows: ....and on behalf of a lot.....condescending.....  :thumbsup:

[carnuck]

If you have 2 different ratios that are real close, you want the numerically smaller number (higher ratio) in front so it PULLS you around the corner. IH did that before there were differentiated tcases. Matching ratios tend to push you straight forward with the wheels turned (as I found out with the '68 Travelall I have)

[Eagle]

Maybe you should invest in a new monitor or new spectacles.....I said 2%......never said .2%.....

 

.....while you are at it.......... Google Facetious... :brows: ....and on behalf of a lot.....condescending.....  :thumbsup:

I understand that you wrote 2% ... which is why I pointed out that your difference is greater than the factory difference by a factor of ten. The way you thanked me for the math lesson, I interpreted that to mean your 2% was a math error and that you had dropped a decimal point.

 

And I suggest you save the attitude for some other forum. I'm here to try to help people. If you don't want help, then don't ask questions.

[yxmj]

 

Maybe you should invest in a new monitor or new spectacles.....I said 2%......never said .2%.....

 

.....while you are at it.......... Google Facetious... :brows: ....and on behalf of a lot.....condescending.....  :thumbsup:

I understand that you wrote 2% ... which is why I pointed out that your difference is greater than the factory difference by a factor of ten. The way you thanked me for the math lesson, I interpreted that to mean your 2% was a math error and that you had dropped a decimal point.

 

And I suggest you save the attitude for some other forum. I'm here to try to help people. If you don't want help, then don't ask questions.

 

 

I would suggest you save your condescension for others as well.....and FYI.....I never asked a question......but as usual you felt the need to interject with your negitive comments as you had already made the decision that everyone has the right to your opinion.

[Eagle]

I would suggest you save your condescension for others as well.....and FYI.....I never asked a question......but as usual you felt the need to interject with your negitive comments as you had already made the decision that everyone has the right to your opinion.

Really?

 

Well if 2% is acceptable.. :dunno: ....I don't have to bother looking for a front 4.10 front diff or gear set for my 4wd swap

Isn't a question? What else does the :dunno: signify?

[Incommando]

The largest factory ratio difference of which I am aware is 4.27/4.30. It works fine. If anyone tries to tell you that a few hundredths makes a difference you should laugh at them. The actual difference between 4.10 & 4.11 is so small ( probably smaller than the wear differentiation on poorly maintained tires) that it makes no noticeable effect on driving, handling, tire wear, or anything else. 

 

As only a final drive ratio that includes tire height consideration is important you can surely use tire height to make up for a 3.55 front and 4.10 rear. A 26" front & 35" rear should make that work for you and not look stupid at all... :-)

[Eagle]

The largest factory ratio difference of which I am aware is 4.27/4.30. It works fine. If anyone tries to tell you that a few hundredths makes a difference you should laugh at them. The actual difference between 4.10 & 4.11 is so small ( probably smaller than the wear differentiation on poorly maintained tires) that it makes no noticeable effect on driving, handling, tire wear, or anything else. 

 

As only a final drive ratio that includes tire height consideration is important you can surely use tire height to make up for a 3.55 front and 4.10 rear. A 26" front & 35" rear should make that work for you and not look stupid at all... :-)

Just the difference in distance traveled by the front wheels vs the back wheels amounts to more than a couple of tenths of one percent, which is why we're not supposed to run part-time 4WD on dry pavement. On snowy days, I have to use 4WD to get up my driveway and out onto the street. Once I make the turn onto the street and get straightened out, I pull over to the shoulder and shift out of 4WD. Just in the portion of the turn that's on the plowed road until I stop I can feel the 4WD lurching and jumping due to binding.

 

Tire size is deceiving. Most of the tire size calculators only give the unloaded dimensions of the tires, but what really counts is how many revolutions a particular tire turns in a mile. That's a function of both size, and sidewall stiffness. Way back when I made up my gearing charts, many of the tire companies published revolutions per mile as part of their specifications. I found, as an example, that a Cooper Discoverer in a P235/75-15 turned more revolutions per mile than the "same" tire in an LT235/75-15. The reason is that the LTs had stiffer sidewalls, so the axle stayed a bit higher off the road at the same load, resulting in a higher static radius.

 

To be accurate, we really need to be comparing based on revolutions per mile, or (if that's not available) static radius. Cooper's web site no longer gives us that information. B. F. Goodrich still does: http://www.bfgoodrichtires.com/tire-selector/category/off-road-tires/all-terrain-t-a-ko/tire-details#techspecs

[Incommando]

When drag racing we would measure the roll-out distance of each slick to get as close to a matched set as possible before purchase but I don't think your local tire dealer will do that. This is pretty important when the front tires are off of the ground for 60' or so. Tire pressure was matched within a 10th of a pound. That being said this car was only moving for business for about 9 seconds at a time. I don't think getting things that tight is very necessary for a street car or 4x4. I have had no trouble driving straight in 4wd on a hard surface. It is the turning that causes the binding but the same is true with a locked axle: in a turn the inside wheel will travel further than the outside wheel causing binding in the differential. All that the transfer case amounts to is a diff. Sidewall stiffness varies with pressure, as well, so having matched tires of a similar pressure seems even more important with a locked axle, especially a welded one. Just to clarify in both the axle and the transfer case it is the turning that causes the binding and not the possibility of a negligible gear ratio difference front to rear . 

[a4xnut]

If you have 2 different ratios that are real close, you want the numerically smaller number (higher ratio) in front so it PULLS you around the corner. IH did that before there were differentiated tcases. Matching ratios tend to push you straight forward with the wheels turned (as I found out with the '68 Travelall I have)

 

Hmmm... my 1980 Scout II with a Dana 300 t-case and Dana 44's at both ends had the same ratios...  2.72's!  Between the torque of the 345 and the 727 Auto, it still pulled 32x11.50's with ease.

 

I wasn't aware of International ever using a transfer case with a differential in the Scout/Light Truck line.

 

But FWIW, I'm with the crowd that says the listed differences don't matter.