Regearing Questions? READ THIS!

[Lincoln]

I don't drive it much anymore, but it was my daily driver for a long time, including a lot of mountain driving. I remember when I went from 33 to 35's I thought that the 35's were better suited to 4.56's than the 33's were.

Paul

Was your impression of fine before or after the anorexic period? Heaviest, lightest, current?

 

[CRASH]

Back to the Top for this excellent thread since we seem to have a fresh crop of newbies with dreams of big tires on small budgets.

CRASH

 

[JeepFreak21]

Just to add to this wonderful thread, here is the list of lowest gears available for the most common axles:

Dana 30 - 5.38
Dana RC30 - 4.88
Dana 44 - 5.89
Dana RC44 - 5.38
Dana 60 - 7.17
Dana RC60 - 5.38
Dana 70 - 7.17
Dana 35 - 4.88
Ford 8.8 - 5.13
Ford 9" - 7.33
Currie HP9" - 4.88
TrueHi9 - 5.38
Toyota 8" - 5.71
Toyota HP 8" - 5.29
Chevy 14 Bolt - 5.13
Chrysler 8.25 - 4.56
Ford 10.25 - 5.13
AMC20 - 4.88

Billy

 

[ChuckD]

Better define that D30,

D30HP - 4.88

D30LP - 5.38

D30LP-TJ - 4.88

If it matters.

 

[JeepFreak21]

Better define that D30,

D30HP - 4.88

D30LP - 5.38

D30LP-TJ - 4.88

If it matters.

D30HP = Dana RC30, but I'll add the TJ one if ya want
Billy

 

[Heavy_Equipment]

It's funny how everybody has a different opinion. I run 35's w/4.56's and have never really needed a lower gear, except when I was running a stick. I now run an auto and a 4.7L stroker. Lower gears would be nice, but I was doing a bit of freeway running with it, so 4.56's were a good solution.

.456's w/35's yields a virtually stock overall drive ratio.

Thank you for that.

I have a H.O. and 5spd and was going to go 35/4.56, thinking it would be a little deeper than stock.
I'll be keeping my D30, but swapping in a D44 from my parts jeep when gearing time comes. (35's and 3.07's for a few weeks ought to be interesting...)

Hmm, now to decide on 4.88's or even 5.13's.
Time to Google an RPM calculator.

On that note, add a good calculator to the gearing sticky.

 

[Yucca-Man]

Time to Google an RPM calculator.

On that note, add a good calculator to the gearing sticky.

www.4lo.com - there are a few good calculators on there.

 

[ChuckD]

D30HP = Dana RC30, but I'll add the TJ one if ya want
Billy

Oh, I missed that. Thank you for correcting me.

 

[Heavy_Equipment]

According to 4Lo's gear calculator, 35's with 5.13 gears, .78 OD (5th gear guesstimate), and 1:1 TC ratio, I'll only be turning 2304 RPM at 60 MPH.

That is very do-able.

 

[Big Red]

Here's a good gear calc link:

http://www.drivetraindirect.com/t_gear_calculator.htm

 

[Lincoln]

According to 4Lo's gear calculator, 35's with 5.13 gears, .78 OD (5th gear guesstimate), and 1:1 TC ratio, I'll only be turning 2304 RPM at 60 MPH.

That is very do-able.

With a 30 front you made your decision. 4.88's are as low as you can go.

 

[Heavy_Equipment]

http://www.naxja.org/forum/showpost.php?p=411561&postcount=43

I saw the first line "D30 - 5.38" and assumed I was ok to go with 5.13's.

Obviously not the right D30 then.

 

[Lincoln]

http://www.naxja.org/forum/showpost.php?p=411561&postcount=43

I saw the first line "D30 - 5.38" and assumed I was ok to go with 5.13's.

Obviously not the right D30 then.

If yours is the 1994 in your profile then it would be a reverse 30 which is the RC30 in the table. 4.88's are it.

Your thinking is correct though. 5.13's are a better match.

 

[Heavy_Equipment]

Yes, it's a 94.

Well, for lack of a better choice, I can live with 4.88, and go to a lower gear set in the TC if I find I need to.
I was considering that anyway, since I have a stick.

Thanks for the education guys.

 

[CRASH]

Back to the top so as to compliment the axle thread.

CRASH

 

[XJ_ranger]

ok - anyone know the stock gears in the:
1986 comanche pickup with a 2.8L V-6 and the AX-5 and hte 231?

TIA (im looking to buy this rig) - but dont have it in front of me...

 

[Lincoln]

ok - anyone know the stock gears in the:
1986 comanche pickup with a 2.8L V-6 and the AX-5 and hte 231?

TIA (im looking to buy this rig) - but dont have it in front of me...

I think those were 3.73's but don't hold me to it.

 

[Lincoln]

Add a little more since the oil people are hurting this month.

For those of you that are concerned about the right gears hurting your mileage, I'll provide a little example.

'89
Swapped in '95 motor running non-HO electronics with the HO intake and TB.
Ported and Polished Head.
Some kind of cam that seems too hot
AW-4 with the .705 OD
5.38 gears
35's
Somewhere around 6" or 7" of lift
80 mph revs around 2800

I'm averaging 16 mpg of a mix of highway and trail. With 4.10's and 33's I got 14-15 with everything else the same (I can tell you from experience that is a very shitty setup )

 

[bustercat]

Great tech article Crash. Thanks for the gearing calc link Big Red.

 

[dandecicco]

I know Crash did the numbers for general gearing, but I needed to know specifics for my application so I came up with the following for anyone who wants to see what numbers look like for the BA 10/5

RPMs for 33" tires and 4.88 gears. My BA 10/5 is mated to the NP231 and an 87 Non HO 4.0. Following Eagle's statement that the BA has a .72 overdrive I calculated the following numbers for 33s with 4.88 or 4.46.

4.88 @ 70 MPHs = 2504 RPMS on 33s
4.56 @ 70 MPHs = 2340 RPMS on 33s

For my application as I will only drive on the freeway to the trail, I have decided to go with 4.88s.