Gear ratio question (SAS)

I'm in the VERY begining stages of a SAS information gathering. Given the multitude of parts available for the Dana 30 axle it seems a prospect for a swap. ZJ's & XJ's regularly run 33" tires with no problems with the D30. It's also high pinion, on the correct side, and upgradable to 29 splines and various lockers and manual hubs.You can get the D30 geared down to 4:56 or 4:88. Question is...is 4:56 too far away from the Xterras 4:636? I know it sounds goofy but i've heard of some 4x4's that have slightly differant ratios front & rear. I'd definatley like to keep the X rear diff.

I don't know about the gear ratios, but have you thought about going w/ a bit beefier axle? Just a thought, and I very well may be missing something, but it seems with like all the work that a SAS requires it would be worth going with a D44 or something.

Edit - just re-read your post and see I missed a few things, so disregard my post if it's stupid!

Why wouldn’t you go with a Dana 44? You can get one from a Wagoneer with a drivers side drop. It’s quite a bit stronger and has just as many, if not more, gearing and locker options.
For more info on selecting a R&P ratio, check this link out.

Randy\'s Ring and Pinion

Doug

I agree ,the D44 is stronger but front D44's are hard to find, unless you want to spend mass $$ for a dynatrac one.The D44 also only has 4:56 & 4:88(closest ratio to the X)
Wouldn't the Wagoneer D44 need to be shortened?
Are the ratios too far off?

The Wagoneer axle is a good close fit. It's only a couple inches longer than the rear. I think it even has the same bolt pattern for the wheels. Someone will be along shortly to correct me if I'm wrong.

Take a look at my other post for R&P calcs. I have a 4.9 R&P in my 02. If I went with a 4.88 in the front, that would be far less than 1% between the two.
Steve is right. The length is very close and the bolt pattern is the same (6 bolt). The axle from a 80-85 Wagoneer is easy to find once you start looking.
I started looking at Dynatrac. With an ARB they wanted over 4k for one. Having one built up from a junk yard donor, you should come in at less than 2k.

Doug

Hmmm. Food for thought. Sounds like a Wagoneer front might be the way. I assume it has manual hubs.I'm confused..was the Wagoneer the full size tunaboat looking truck? I don't think the Wagoneer D44 is high pinion. Its not a must but it is nice to have more clearance and less driveline angle.
On the other hand, another reason I was leaning towards the D30 from an XJ/ZJ was the coil & link arm mounts are there.(I'm shooting for coils)So much stuff.....ugh!

From what I've read, I'd skip the D30.

Not nearly as strong as a D44. Sure you could get a D30 in good shape for damn near free (seriously, a lot of people give them away), but why do all that work and have a less than stellar finished product.

You can find a 44, you just have to look a little. Check pirate4x4.com often. There's a sh*tload of axles for sale there.

edit: I think I'd go 4.88s and no bigger than 35's. Much bigger than that and other drivetrain stuff will start breaking.

I had planned on running 33's.

Gearing wise you want to keep your gears within about 2-3% of one another.

To figure this take your numerically smaller ratio and divide it by the larger ratio.

Multiply your answer by 100

Subtract this number from 100

the answer is your percent difference.

4.56/4.636=.9836
x100=98.36
100-98.36=1.64%
=NO PROBLEM

4.88s would be 5% difference which is no good.

Justin

There are usually 2 or 3 available every week at Pull-N-Save here in Denver. Have you scrounged around the junkyards in GJ ?

Smart choice.

I've also read in many places that it's not smart to run different gear ratio's front/rear. I can't verify why, just thought I would post what I've read.

Also, I just read in this months issue of 4 Wheel drive & sport utility magazine



about a guy doing a IFS to SAS swap on his pathfinder. While this isn't an Xterra, they do give references to a Nissan Vendor and gearing options. The guy in the article (I think) went to a D44 in the front (4.88 gears) while the rear had the stock 4.875 gears (or the gearing ratios are the other way around, I can remember).

Hope this helps

IceChickenX

AC has a selection on gears for the rear end web page One of these might do better with what you can get for the d44..

Looks like it will be close enough with D44/D30 4:56 and Nissan 4:636. Like Justin said it a differance of 1.64%. Ac does have a 4:75 R&P available. That would be almost identical to the 4:88.
I'm still curious about what to do with the ABS system though.

Everything I've seen says if you're going to go with different ratios, they should be within 1% if you expect to use 4WD on the street, 2% tops for trail use.
I've seen what happens when they're off, different size tires have the same effect. Friend of mine had two different pairs of 31x10.50 tires front and rear on his Pathfinder, one listed at 30.4" diameter new, the other at 30.8" diameter new. That doesn't sound like much, but it's a 1.3% difference. A couple of months ago he was driving in 4Hi in some mixed snow/clear conditions. Any time he was on pavement he was getting an awful vibration and power loss, and when he was on snow it was squirrelly and twitchy. Couldn't make heads or tails of it. I test-drove it that night, same thing, also noted it would not disengage 4WD (light would not go out) unless you backed up or made a very tight turn. Not even I could come up with an explanation, but I felt it was t-case related. Someone else eventually asked about the tire sizes and it clicked. He swapped to his set of 4 32" MT/Rs and the problem went away. I looked up the specs on the tires and did the math, that confirmed it.

4.56 vs. 4.636 is a bigger difference than the above scenario and is not close enough to work unless you plan to be 4WD only on the trail. 4.88 is close enough to 4.90 to work all around though.

Brent

A front axle (D-30/D-44) from an Early Ford Bronco is within 1" WMS/WMS measurement as the stock IFS in the Xterra, and is the correct side drop.

As well, the D-44 can use Chevrolet knuckles, allowing disc brakes and the 6-bolt pattern that matches the OEM Nissan pattern.

Another issue is if you wanted to use a Jeep front axle (specifically out of a wrangler or newer cherokee) they are factory equipped with a Center Axle Disconnect, and would have to be converted to manual locking hubs if you want to run a front locker...an extra $750.00.

As well with the Coil/Radius arm setup, installation would be relatively easy. All you would need for axle location are upper spring perches, revised crossmember for radius arm mounting (at current area of Torsion Bars mounting), and a Panard bar.

This setup would allow re-use of the stock front bumper and/or ARB with no other modifications.

For Reference stock springs on a EB set the axle at 7" fom the bottom of the frame. More than enough room for 33's.

This is just a difference in philosophy, so i run the 2% rule. Why would anyone use four wheel drive on pavement not slick enough to allow individual tire spin? You put it in 4x, take off, as soon as you're moving it goes back into 2x. If you need 4x to drive normally then conditions are bad enough to qualify it as "trail".

Justin

4.9 to 4.88 is a closer match

You did note that even on the snow-covered parts of the road the difference in rotation front/rear made for twitchy handling as the discrepancy was continually working its way out of the system randomly among the 4 tires as traction varied moment to moment, right?
He wasn't using 4WD on grippy pavement, he was flipping back and forth as conditions dictated, not to mention it was needed to change lanes safely across the ridge of snow/slush in between even when the lanes themselves were relatively clear.
The biggest problem was with shifting back and forth between 2Hi and 4Hi as conditions warranted. He has manual hubs, so that's one less thing to worry about, but even so, engaging 4Hi was much harsher than normal because the front and rear gearsets were spinning out of sync. Not to mention shifting back to 2Hi didn't exactly work. As I noted, the gears in the t-case, meshing under load as a result of the discrepancy, simply would not disengage despite throwing the lever back to 2Hi. We've all seen this at times, you often have to back off the gas and coast a moment to get the indicator light on the dash to go out which is the true indicator of the t-case engagement status. This was a much more extreme case that wasn't cured by coasting, he would have to stop and back up to release things or continue down the road with significant driveline binding going on. Not something I would want to put anyone through.

Brent

Found some interesting info on a D44 vs D30 (high pinion HP) Suprising to say the least.

www.naxja.org/forum/showthread.php?t=20626

I also found the pics of the Pathfinder SAS. I'd like to go this route instead of a leaf spring setup. I am a tad skeptical of the long term durability of the heim joints.

www.ok4wd.com/album.asp?mode=profile&id=firstone&page=1

Just wondering where this came from?

And 4.9 to 4.88 would be ideal, but the original choices were 4.88 and 4.56.

Justin

Well I went and spoke with a local shop here
www.aor4x4.com They have a lot of experience in SAS conversions on Toyota's.(Lots of those badass Toyotas running aroun GJ and Moab) They said that they could fab a front leaf set up for a ballpark of around $2500. They weren't opposed to doing coils either.