How close do gear ratios have to be?

[TJDale]

I have an 8.8 in the rear and want to put a d44 in the front of my Jeep. I'm running 4.88s fr/rr now but when I swap the front I'd like to go down as low as I can. From what I'v seen the available ratios are as follows...

8.8 - 5.13, 5.71, 6.14
d44 - 5.13, 5.38, 5.89
d44hp - 5.13, 5.38

I wanted the d44hp but I want to go lower than the 5.13 with my 4cyl. Will the 5.71 in the rear work with a 5.89 in the front? Is the 5.89 not available in the hp d44?

[The Rockslut]

The 5.38's are the best you you can do.

[kury]

Will the 5.71 in the rear work with a 5.89 in the front?

no.. you will tear stuff up running in 4wd

If your trying to get more umpff out of that 4 banger though you could always look at changing the gearing in the transfercase or to add a doubler in there.. (just something to look into)

[TJDale]

The 5.38's are the best you you can do.

You mean for the HP44. Randy's ring and pinion's web site says a difference of 1% is ok for the road and 2% is ok for off-road. 5.71 and 5.89 is 3.1% off, so that may be too much. The lowest I can go with an 8.8 and d44 combo looks like 5.13, I'm not sure its worth the money to swap 4.88s for 5.13s. Is that enough differenc to notice? That would be like swaping 3.55s for 3.73, it hardly seems worth it.

[TJDale]

Anyone running a difference of 3%?

[Robert]

No, you will break things.
Running something close like a 4.09 and a 4.11 is ok, but the 5.71 and 5.89 will cause too much binding in the drivetrain.

[kury]

That 1% difference is the difference between 3.07 & 3.08 gears
or 4.11 & 4.10 not 5.71 and 5.89, you will tear stuff up running that combo.
If your dead set on getting the lowest gears you can talk to the different vendors about what available for your axle. Alot of companies have made gear ratio's for axles that never used to have say a 4.11 gearing option..

check it out..

[TJDale]

3.08 and 3.07 is a difference of 0.3%. A 1% would be 3.08 and 3.11. A 2% would be 3.08 and 3.14. A 3% would be 3.08 and 3.17. I know what will happen if you ratios don't match but Randy's ring & pinion says 2% is ok off-road. I'm not saying Randy's is the all knowing but I would tend to trust most of whats on there web site. I just want to know if anyone has ran a 3% difference.

[kury]

I have seen 1% & 2% as the standard cut off's but the same people that say 1% & 2% also say 1% is 0.01 difference between gears..

So that would be 3.08 & 3.07.

Other than that... I don't know what to tell ya. Try talking to Randy see what he thinks.

[DOUG38S]

I know people that have run 4.56's and 4.11's staggered, all offroad with no problems.

[Inferno]

I've seen 4.56 and 4.88 before... but it was on a mud racer, needed more speed in the front wheels to keep it tracking straight, with the back wheels providing the power..

I guess it would depend on how loose the trails are you run.

[squirriljeep]

Dale- I got your solution-


Driveshaft Clutch

http://home.cshore.com/astroman/farmallm/html_files/images10/bh08.jpg

Mount one of these on your rear output and it will take out all the binding before it gets to the tcase. :flipoff2:



On a serious note, your only option is the 5.13s. If you really have to keep the 8.8 and go lower, get 4:1 tcase gears or doubler. Or you can get both the front HPD44 and the 9" rear from a Ford.



btw- the clutch thing was a joke. :D

[kury]

I've seen 4.56 and 4.88 before... but it was on a mud racer, needed more speed in the front wheels to keep it tracking straight, with the back wheels providing the power..

I guess it would depend on how loose the trails are you run.

other than loose ground/mud/water/sand the only way I can see that this wouldn't break is to have different size tires on the front & back to compensate for the difference..

[AfterThisNap]

the only way I can see that this wouldn't break is to have different size tires on the front & back to compensate for the difference..
That is exactly how the mud racers do it.


I am positive I have seen a XJ running 5.71 and 5.89 on 38" tires in the rocks, using a 9" and 44. It's gonna take a little digging for me to find documentation of it though.

[The Mac]

We sell a lot of 5.38 gears to guys swapping Dana 44s in to the front of Toyotas with 5.29’s in the rear and that seams to work just fine. I road in a Toyota that was setup that way, and on the pavement it definitely sounded like it was going to explode, but in the dirt seamed to work fine. Any more separation than that and I’d bet you have some issues even off road. I say run the 5.13s and be happy.

Mac

[kury]

We sell a lot of 5.38 gears to guys swapping Dana 44s in to the front of Toyotas with 5.29’s in the rear and that seams to work just fine. I road in a Toyota that was setup that way, and on the pavement it definitely sounded like it was going to explode, but in the dirt seamed to work fine. Any more separation than that and I’d bet you have some issues even off road. I say run the 5.13s and be happy.

Mac


and running a gear difference like this on the pavement will eat the @#$)( out of the tires.

[jptrvlr]

kinda what i was thinking. and just generally not good on the drive train. oh well. there's a guy i knew that was running 3.55s (30) and 4.10s (44) in an xj and didn't believe anyone. blew the 44 last i heard and was having DS issues. to each their own but i wouldn't fuk my junk up by doing it.

jp

[TJDale]

Well I have 4.88 now and just dont see it being worth the money to just go to 5.13. So I may just stay were I am.

[FlexCJ5]

you break that 30 this weekend??

Id go to 5.13s and a doubler 231/300 (DesertCJ on here)

[The Rockslut]

Well I have 4.88 now and just dont see it being worth the money to just go to 5.13. So I may just stay were I am.

Yeah, I typed 5.38 instead of 5.13

I personally wouldnt see the value in swapping from 4.88 to 5.13's in your case. A doubler does sound like a good idea though.