Dana 30 SFA/IFS gear compatibility

[Forest Fab]

Hey guys,

First of all let me give you some background.
I'm in South Africa, and I own a 2002 KJ (Cherokee, as it's called here) 2.5CRD manual.
I've bought a 2005 2.8CRD manual that rolled, and will be doing an engine swap very soon.

After this operation, I'll be looking at the possibility of a SFA swap.
IMPORTANT Note:
Here we are not as fortunate as you guys in the US when it comes to axles availability. Very few F100s, no F150s, a few F250s but the D60 are hellishly expensive, and the few D44s out of a Rubicon are sold for as much as their weight in gold in the blink of an eye. So yeah, options are rather LIMITED!

Second note:
The intended use for me would NOT be ******** 4x4 or rock crawling or stuff like that. The main purpose is to increase the ground clearance that is very limited with the IFS. Run 32" tires, maybe 33" further down the line, but I'm set on 235/85 R16 as a starting point. And then take it for mellow to a bit more involved wheeling, but nothing extreme. This is my daily drive (although I don't drive daily :emotions34: ) and I don't intend on damaging it.


That leaves us (me) with the following options, considering availability, compatibility and costs as well:
- XJ Cherokee D30 with open diff
- WJ Grand Cherokee D30 with Vari-Lok diff (Quadra-Drive transmission)
I would prefer the WJ D30 for the Vari-Lok. Also remember that buying a locker will cost an arm and a leg to import here.
The problem I now have is gearing. The local WJs came in either 3.73 (petrol) or 3.55 (diesel). 3.55 is too low, 3.73 is pretty much spot on for 32" tires. BUT my KJ came with 4.1s, and the second one I bought has 3.55s.
The first option I had considered was swapping both axles from a WJ, the rear being a D44a (aluminium casing) but after doing some reading, it seems that the stock AMC 8.25 is at least as good, if not better.
This led me to look at a front axle swap only, but now I have to get around the gearing issue.

After this long introduction, my question is: are the ring/pinions interchangeable between the IFS D30 and the SFA D30 found in the WJ?
If I trust the Crown Automotive part numbers, not so:
52419.0040 for a 3.73 for a WJ D30 SFA (ratios available: 3.55, 3.73, 3.91)
52419.0042 for a 3.73 for a KJ D30 IFS (ratios available: 3.55, 3.73, 4.1)

Do you guys have any idea on this?

Should I rather look at the XJ front axle, as you can find 4.1 gears for it?
(edit) The PCD on the XJ is the same as the KJ, whilst the WJ's is different. So it's going towards the XJ then...(/edit)

Any opinion welcome.
Thanks guys!
Fab.

 

[tommudd]

You're not really going to gain any ground clearance by going SFA
32 inch tall tire which the 235-85-16s are will give same ground clearance with IFS really , maybe a bit more since there isn't a diff hanging down in the middle.
All depends on where you measure
Good 4 inch lift, 32 inch tires and 4.10 gearing would do wonders
Wouldn"t go with the WJ diffs on either end, IMO
The XJ front diff while you can get gearing the same as the 8.25 is narrow, will work but would need to use coilovers since space is limited for lower mounts

 

[tjkj2002]

No the KJ and WJ/XJ/TJ/JK/XK/KK/WK or any other D30 gear set are not interchangeable.

The KJ's D30A gear set is unique and only works in the D30A diff.

 

[HoosierJeeper]

To be honest, it doesn't sound like you're a candidate for an SFA. If you only want to run a 32-33" tires, you can do some stuff to the IFS to make that work great at a fraction of the cost. An SFA minimum you'll be at 7+" of lift I believe which is a lot of work to just run a 32 inch tire. Get a JBA steel front diff and sleep soundly at night with a lot more money under your mattress!

 

[Forest Fab]

You're not really going to gain any ground clearance by going SFA
32 inch tall tire which the 235-85-16s are will give same ground clearance with IFS really , maybe a bit more since there isn't a diff hanging down in the middle.
All depends on where you measure
Good 4 inch lift, 32 inch tires and 4.10 gearing would do wonders
Wouldn"t go with the WJ diffs on either end, IMO
The XJ front diff while you can get gearing the same as the 8.25 is narrow, will work but would need to use coilovers since space is limited for lower mounts

I believe I will gain ground clearance especially when going downhill. At the moment with the weight transfer to the front wheels, the sump guard turns into a plough... With a SFA, the ground clearance will remain the same whether I'm going up or downhill.
And a lift is in the cards at the same time as the swap, depending on what's necessary for clearance purposes.
The XJ front track is about 2" less than the standard KJ, which is in turn slightly wider than the rear track. Spacer could be made up if tires were rubbing.

Please elaborate on your comment about the WJ's axles?

No the KJ and WJ/XJ/TJ/JK/XK/KK/WK or any other D30 gear set are not interchangeable.

The KJ's D30A gear set is unique and only works in the D30A diff.

Thanks, that's the crystal clear answer I was looking for. although I thought it's what it was since P/Ns were different.

To be honest, it doesn't sound like you're a candidate for an SFA. If you only want to run a 32-33" tires, you can do some stuff to the IFS to make that work great at a fraction of the cost. An SFA minimum you'll be at 7+" of lift I believe which is a lot of work to just run a 32 inch tire. Get a JBA steel front diff and sleep soundly at night with a lot more money under your mattress!

Although you have very valid points (yes, I'm going half way in with 32" tires), the cost would be less doing an SFA swap than importing stuff, keeping in mind that I can do all drawings of necessary brackets, have them cut and bent, and do the welding.
Just to give you an idea, I can find a complete XJ or WJ or ZJ for the price of a 2" lift kit here (EFS). Then I'm left with a lot of odds and ends to sell or crush to get some bucks back. That's around ZAR15.000 ($1.000 give or take).
And JBA's steel diff would cost me roughly ZAR30.000 landed, excluding duties, excluding bearings and install of my current diff in the new housing.
So, sadly, way more expensive! (edit) Add to that new gears worth $400 or $500, plus shipping, taxes and duties (/edit)
The alternative would be to do the 2" EFS lift only along with the 32" tires, and look out for worn CVs and cracked diff housing. It is a viable option after all.

In regards to your comment about the lift, are you saying that I'd need around 7" lift for the SFA to clear underneath the chassis?





Thanks to all for your input, it's much appreciated :favorites13:

 

[HoosierJeeper]

That's where everyone that has wanted to keep it low ends up...seems to be a common theme in all the builds.

 

[Forest Fab]

OK, thank you very much, this is precious information.
It does indeed change the scope of the swap altogether... :emotions34:

 

[HoosierJeeper]

LOST JEEPS • View topic - And so it begins.. err.. continues...JJ's SFA KJ

This is a good build.

Hopefully tjkj will chime in but here's his thread
http://www.jeepkj.com/forum/f264/sits-level-40063/

I think he tried to keep it as low as possible too.

 

[Forest Fab]

Thanks, I'll be doing some reading

 

[tommudd]

I've inspected one KJ with an XJ front 30 installed .
I know the ones who run them, but I would never. The coilover had to be angles in at the bottom to clear everything and have a good mounting position, was not impressed at all

Now as far as going down a hill with IFS it would be lower than with a SFA????Please explain how you came up with that

 

[HoosierJeeper]

I think his rationale is that going down hill, the front end of the KJ squats down too much and with an SFA, the clearance under the axle is constant.


Which technically is true, but 1. sounds like the springs on the KJ are too soft and 2. the clearance under the axle on an SFA isn't the whole story, it could still sag just as much and expose other stuff.

 

[tommudd]

I think his rationale is that going down hill, the front end of the KJ squats down too much and with an SFA, the clearance under the axle is constant.


Which technically is true, but 1. sounds like the springs on the KJ are too soft and 2. the clearance under the axle on an SFA isn't the whole story, it could still sag just as much and expose other stuff.

True in a way BUT if springs are that soft even on a SFA the front would dip down, of course would still be same amount under the diff, BUT the front end/ body would still come down lower and may drag on rocks etc.

Not seeing the rational in the thinking behind this if only a DD every now and again. Lots of money and time for what?

My buddy has 32s on his XJ, he has to choose his lines better than I do at times over rocks etc
I've went through places where I had to get out and spot for him , which gets his blood boiling:happy175:

 

[Forest Fab]

Thanks Hoosier Jeeper, this is my thinking exactly.
Actually, this is my experience: went up, then down the same trail, and was busy dragging rocks on the way down that I did not touch on the way up. Maybe my springs are a bit tired, maybe not, in all honesty I don't really think so but I could be wrong. Remember I've got a diesel, so it's probably heavier than you guys V6s (again, I could be wrong...).

My line of thinking was also that I never got hung up on the rear axle, so surely I should be able to clear the same size rock/obstacle/whatever with the front than with the rear if I had a SFA?
And although the bottom of the pumpkin itself might be lower than the sump guard in some occasions (conjecture), it's easier to pick a line where the pumpkin will clear, instead of having to grade half the road for the sump guard to not drag...

Regarding your comments about the body coming close to the ground even with a SFA, you're absolutely right, but I don't think I'll put myself in this kind of situation. Refer to my first post describing the intended use.
Also note that if I had experienced body/chassis clearance issue, I would rather look at bigger tires and a decent lift. In actual fact, I'd be looking at something else than a KJ.

And why spend the time and money doing the mod? Well, all the time I've spent so far was thinking about it, and gleaning information about what the actual mod entails.
And even if I did it to solve my dumb issues, or just to prove that I can do it, it's my time and my money isn't it? And to carry on with the rant, when I see the amount of money and time spent on some builds here, I have no intention to come anywhere close to this. I'm thinking on a budget, and again if I ever had that much cash to spend on a rig, it will very likely not be on a KJ. There are much better bases for mods out there, Jeep or others.

Anyways, it's bed time here, I still appreciate you guys taking the time to answer my questions, it definitely helps towards making the right decision. Even the judgmental comments are welcome, because in the end it still allows me to explain/describe the why and how I see the mod in my particular case. So no offense to anyone, OK?

Good night folks :happy107: :cheers:

 

[HoosierJeeper]

What are you running now for suspension? If you're still stock, then a proper lift is entirely different, way better! I've never noticed the weight transfer to the front being an issue on steep hills, even with the winch.

 

[Forest Fab]

Yes, I am stock.

A lift sounds more and more like the better option.
2" lift + 32" tires and I've got a smile for a while

I must admit that the technical challenge of the SFA swap still tickles me. I'll keep it in the back of my mind and will take some measurements when the occasion arises. For example I'd be curious to see the difference in the frame rails between a XJ/ZJ and the KJ, to see how they achieve the chassis/axle clearance on the first two versus needing a 7" lift on the KJ. Just to satisfy my curiosity.

Such a mod is always so much easier and painless when you simply think about it. I must thank you guys again for giving me some first (or even second ) hand experience, and some reading that I still need to do. :cheers:

 

[dude1116]

Yes, I am stock.

A lift sounds more and more like the better option.
2" lift + 32" tires and I've got a smile for a while

I must admit that the technical challenge of the SFA swap still tickles me. I'll keep it in the back of my mind and will take some measurements when the occasion arises. For example I'd be curious to see the difference in the frame rails between a XJ/ZJ and the KJ, to see how they achieve the chassis/axle clearance on the first two versus needing a 7" lift on the KJ. Just to satisfy my curiosity.

Such a mod is always so much easier and painless when you simply think about it. I must thank you guys again for giving me some first (or even second ) hand experience, and some reading that I still need to do. :cheers:

For your requirements, a lift and a little bit of lower bumper portion cutting will solve all of your problems for a fraction of the effort and cost. Hell...get 790 (OME) springs and get a bumper if you can get it with minimal duties and you'll have some good clearance.

 

[HoosierJeeper]

Yes, I am stock.

A lift sounds more and more like the better option.
2" lift + 32" tires and I've got a smile for a while

I must admit that the technical challenge of the SFA swap still tickles me. I'll keep it in the back of my mind and will take some measurements when the occasion arises. For example I'd be curious to see the difference in the frame rails between a XJ/ZJ and the KJ, to see how they achieve the chassis/axle clearance on the first two versus needing a 7" lift on the KJ. Just to satisfy my curiosity.

Such a mod is always so much easier and painless when you simply think about it. I must thank you guys again for giving me some first (or even second ) hand experience, and some reading that I still need to do. :cheers:

I think the need for a big amount of lift was oil pan clearance...not sure, it's in a build thread somewhere.

 

[tommudd]

Yes, I am stock.

A lift sounds more and more like the better option.
2" lift + 32" tires and I've got a smile for a while

I must admit that the technical challenge of the SFA swap still tickles me. I'll keep it in the back of my mind and will take some measurements when the occasion arises. For example I'd be curious to see the difference in the frame rails between a XJ/ZJ and the KJ, to see how they achieve the chassis/axle clearance on the first two versus needing a 7" lift on the KJ. Just to satisfy my curiosity.

Such a mod is always so much easier and painless when you simply think about it. I must thank you guys again for giving me some first (or even second ) hand experience, and some reading that I still need to do. :cheers:

2 inch lift will never get you enough room to run 32 inch tall tires, no way at all with 32 inch tires
You need that much to clear the oil pan etc , there is not much room in there at all. Since the front diff does not move they could put the engine down close, but SFA you need room for the suspension to work.
I think you'd be surprised when you actually tore it down

 

[JeepinJarhead03]

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that's 790s with a top plate and clevis lift and 235-85R16s i pulled from a dualie while waiting for the tires i actually wanted to put on to be released to the market

put a good engine skid on it and there's nothin to worry about

 

[Forest Fab]

Thanks again all.
I had a look under a XJ and a WJ over the weekend to see what's actually different, and besides the frame rails that come up higher (the top of the coil springs rest underneath them), the main difference as mentioned here is the oil pan that leaves space for the SFA. I'd be curious to see if the oil pan from the 2.5TD XJ would fit on the 2.5 or 2.8 CRD KJ.

Anyways, thanks again for the comments, it's of great help