Don't Use a Wagoneer Front Axle

[Grantshire]

Okay, now that I have you attention/interest, here we go...

Part I

I made a lot of measurements on all kinds of axles before I did the axle swap on my Scrambler (everyone jokes about the notebooks I keep on my Jeeps). One of these days I need to post this information. Bottom line, I believe the WT FSJ Dana 44 is the best front axle for a Scrambler if you are going to stay spring under and want to run tires larger than 31". And, here comes the controversial part, I also believe it is a mistake to use a narrowed Wagoneer axle. These conclusions/opinions are based on my many measurements, my knowledge of Jeeps (limited as it may be), observations on my completed axle swap and noting what other Jeepers have done. I am not asking to debate this issue, but I do offer the following information for those who are curious about how I came to these conclusions.

All CJ's, NT FSJ's (Wagoneer and NT Cherokee) and WT FSJ's (WT Cherokee Chief and J trucks) had/have wider front axles than rear axles. So do many other vehicles, particularly four wheel drive vehicles. Why? I believe the answer is turning radius and tire size. Here are the Jeep "tread widths" Front/Rear from the 1983 Jeep Product Information and Data Book. Also included in parentheses is information from the 1981 book covering the NT Scrambler. These measurements are in inches:

CJ5 52.4/50.5
CJ7 55.8/55.1
CJ8 55.8/55.1 (81 NT's were 51.5/50)
Wagoneer 59.4/57.8
WT Cherokee 65.3/62.3
J10 65.4/64.9 (wide wheel option)
J20 64.6/65.9 (wide wheel option)

The AMC FSJ Wagoneer, NT Cherokee and WT Cherokee have the same frame and body. There are only minor modifications behind the front door to make 2-door or 4-door version. The WT Cherokee (only a 2-door) also had a flare built into the fenders like the J trucks to cover the wider axles. As you can see from the above data WT Cherokee axles were 5”-6” wider than Wagoneer front axles. AMC used the same axle on a WT Cherokee as the J10. Other than axle shaft and tube width all other axle components are interchangeable between the NT and WT. I believe this is also true among the NT and WT CJ’s.

Why did AMC put a wider axle on the Chiefs and J trucks? Answer, because the Chief was a more "sporty" 2-door with larger/taller tires and wider rims (the trucks also had taller tires than the NT’s). This enabled the vehicles to maintain maneuverability (turning radius). Standard wheels on a Wagoneer were 15 x 7” with 235/75/15 tires (28”-29” tall). Standard wheels and tires on a WT Cherokee were 15 x 8” with 31x10.50x15 tires. In order to run a 2”-3” taller tire without further adjusting the steering stops the wheel mounting surface needed to move further away from the springs and frame.

Among my Jeeps I have both NT FSJ (74 Wagoneer Custom) and WT FSJ (79 Cherokee Chief). With stock wheels/tires the Wagoneer had a 37.7’ turning radius and WT Cherokee 39.4. However, when I tried to run larger tires on the Wagoneer (33x12.50x15 on 8” rims) I had to either adjust the turning stops (reducing my turning radius) to keep the tires out of my springs (vehicle has the appropriate lift) or buy rims with less backspacing than stock (FSJ backspacing is 3.75&#8221. A 10” rim on a Wagoneer (NT FSJ) can really be challenging.

On the other hand, the Cherokee runs 35x12.50 tires on 10” rims with no issues. Why don’t I have the same problem with the Cherokee as the Wagoneer? Answer: the wheel mounting surface on the WT axle is further away from the springs. I can actually go to 4” backspacing without worrying about the springs or frame. This is more important on the front axle because the front axle wheels move toward the springs when you turn. As a result, the difference in turning radius between my “adjusted” Wagoneer and Cherokee running large tires is significant.

 

[Grantshire]

Part II

What does all of this have to do with Scramblers? Many people swap out stock CJ axles in favor of heavier duty axles that can support lower gearing, larger tires and more abuse. The Dana 44 axle is the most popular axle swap for tires up to 35” and gearing down to 4.56 (you need Dana 60’s or equivalent if you go any bigger or lower). Most people also stay spring under (all CJ’s were spring under), choosing to obtain the necessary lift by higher arched lift springs, lift shackles and body lifts (or a combination thereof). The most common rear axle is the Scout II centered Dana 44. It has a 5 on 5.5” lug pattern like a CJ and is 58” wide. For the front axle the NT Wagoneer axle is the most common (the Scout II axle can be used but there are caster issues that have to be dealt with). All FSJ axles have a 6 on 5.5” lug pattern. Ford parts are used to convert to the CJ 5 on 5.5” pattern.

FSJ NT and WT Dana 44 axles are spring under and have the spring perch cast into the axle housing on the short side. In order to use these axles on a spring under CJ the axle must be shortened on the long side to the CJ frame width (my measurements say this is 27.5” not 28” as often listed). A FSJ frame is about 4”+ wider than a CJ frame so the long side knuckle is removed; axle tube cut; axle shaft shortened and re-splined; and the knuckle re-attached (this must be done whether a NT or WT FSJ axle is used). When finished the cut Wagoneer will have the same spring perch to wheel mounting surface (WMS) distance as it always had but the perch to perch measurement will be that of a CJ not FSJ. In other words, it will have all the same tire/wheel fitment issues that a Wagoneer has. If you try to run really tall tires +33” and/or wide rims and tires you are highly likely to have to adjust your steering stops (increased turning radius).

On most CJ’s with Scout II rears and cut Wagoneer front axles I have measured the front axle is 1” narrower than the rear axle. Go back and look at the data above. The front axle should be wider, not narrower than the rear. How many guys do you know with this setup that have had to adjust their steering stops, get wheel spacers, buy new rims with less backspacing, limit their rim/tire size, or a combination of one or more of these?

For my 81 NT Scrambler axle upgrade I chose to use a NT FSJ centered Dana 44 rear axle (only ¾”-1” wider than a Scout II rear axle) and a narrowed WT Cherokee axle in front. Because I have other FSJ’s I stayed with the 6 on 5.5” FSJ lug pattern. My front axle is from a 79 WT Cherokee Chief and has been narrowed as outline above to fit the CJ frame width. The spring perch to WMS on this WT FSJ axle is 1 ¾” greater than a NT Wagoneer axle. With this setup my front axle is 1 5/8” wider than my rear axle. Therefore, running larger/taller tires and 10” rims are not issues and they do not come close to my springs, even at full lock. I have two sets of tires I use on the Scrambler. One set are 35x12.50x15 on M/T Classic II rims. The front rims are 8” (3 1/4” BS) and rear 10” (3 5/8” BS). When these are on the Scrambler my front and rear tread/track are exactly the same. My other set is 33x13.50x16 on 10” rockcrawler rims (3.75” BS). When they are on the Scrambler my front axle is 1 5/8” wider than the rear.

I currently have the Xenon Scrambler flare kit on my CJ-8. On these kits the rear flares are 6 ½” wide and the front are 5” (developed for the “narrowed” Wagoneer front axle setup). Therefore my tires stick out about 1 5/8” from under the flairs in front. If this bothers you other manufacturers make flares up to 7” that are the same width front and back.

CJ’s were designed to have great maneuverability. Don’t compromise your rigs steering radius by converting to an axle that has to have its steering stops adjusted. There is a better way.

The above information speaks only to spring under setups that use the Dana 44 cast-in spring perch. Spring over axle (SOA) setups are a completely different animal. However, the issues associated with spring perch to WMS remain the same.

Under Part III I will post pictures. Got to get back to work for now.

 

[Grantshire]

I knew this would be an interesting thread. For all of you that are reading this please don't get things confused. This thread is directed at spring under Dana 44 front axles, not spring over (SOA). Also, axle width and steering/turning issues are not really related. You can have a wide axle that still has to have the steering stops adjusted to handle larger/taller tires. Case in point is a Wrangler. My 90 YJ has stock (for now) 60" axles, much wider than the NT or WT CJ axles. However, when I swapped the 31x10:50 MT's that came on my Scrambler (not really a "large" tire) onto the stock rims they rub the springs if I turn too tight. I had to put on a wheel spacer to make them work (other options were different rims with less backspacing or adjust my turning stops).

Carl - Some people claim that using the Ford parts to convert from FSJ 6 lug to CJ 5 lug adds 1" per side. My measurements do not support this. It's more like zero to maybe 1/2" total. The Rodeo rear axles I have measured are pretty close to a NT FSJ, right at 59.5" (1"-1 1/2" wider than a Scout II).

Those of you going with a narrowed Waggy axles because you don't like wide flares should consider the Dana 44 rear axle from a Scout 800A. They had a centered Dana 44 that is about 1 1/2" narrower than the Scout II axle. That's the axle the Scout II guys swap in so they can run larger/wider tires on their Scouts. The 800A width is right between a WT CJ and Scout II.

This whole steering, wide/tall tire, spring/frame issue is simple geometry. The front wheels/tires are mounted on a pivot point some distance from the frame/springs and the wheel/tire moves in an arc. When the vehicle's steering wheel is turned the front of one front tire pivots toward the frame/springs in front of the tire. At the same time the back of the other front tire pivots toward the rear of the frame/springs on the other side. The degree of sweep or arc lock-to-lock does not change with tire size. However, the taller the tire the more distance covered.

All vehicle steering systems are designed based on a particular tire size/height. When you significantly increase the height and width of tires on a vehicle as we do with our Jeeps adjustments must be made. A lift (springs, coils, shackles, body, etc.) or sawsall will take care of the clearance issues associated with the body making contact with the tires.

Steering is another matter. There are only two ways to address tires hitting the springs or frame when the wheel is turned to full lock: (1) adjust the steering stops so the tire does not hit (costs you turning radius), or (2) increase the distance between the tire and the springs/frame. (2) is accomplished by using a rim with less backspacing (moves the tire out, away from the vehicle); adding wheel spacers to move the wheels out further; or swapping in an axle with a greater WMS to spring perch/frame width.

Well, now that that's clear...

 

[Grantshire]

Part III The Photos

Okay, first photo shows the cast-in spring under spring perch on the short side of a FSJ axle. This one is a NT Wagoneer axle. Note the length of axle tube between the U bolts and back of the axle flange. On a NT Wagoneer this measures 3 1/4" - 3 1/2".

Here is a picture of the same area on my WT FSJ axle. Note the longer axle tube length, 5" vs. the 3 1/4" - 3 1/2" above.

Here is a shot of the stock front axle with stock rim and tire on my 90 YJ (flares removed). Note how much of the tire sticks out from under the body.

Here is a similar shot of my Scrambler with the WT FSJ front axle.

More pictures to come...

 

[Grantshire]

More Part III Pictures

The following two pictures show the difference wheel width makes. In the first picture the tire is a 35x12.50 mounted on an 8" rim (I run 8" in front for airing down) with 3.25" BS:

Same Jeep and axle but with a 33x13.50 on a 10" rim with 3.75" BS:

Here are the rear axle shots. First picture is 25x12.50 on 10" rim with 3 5/8" BS:

Same rear but with the 33x13.50 on a 10" rim with 3.75" BS:

 

[GoScottoGo]

Hi Grantshire. When you cut down your WT Cherokee axle tube, were you able to use a common axle shaft? I am looking to purchase this same axle for my 84 CJ7.

 

[sdsupilot]

Hi Grantshire. When you cut down your WT Cherokee axle tube, were you able to use a common axle shaft? I am looking to purchase this same axle for my 84 CJ7.

No, you can either send the stock axle in to be shortened and re-splined or order a custom aftermarket shaft.

 

['83_401V8_CJ8]

I'm running full width Dana 60's front & rear, I just went with wider fenders.
the full width gives better articulation & stability.
Obviously covers the stock replacement part issue is covered too. ;-)

 

[Scott_P]

No, you can either send the stock axle in to be shortened and re-splined or order a custom aftermarket shaft.

Hi Grantshire. When you cut down your WT Cherokee axle tube, were you able to use a common axle shaft? I am looking to purchase this same axle for my 84 CJ7.

I sent my axle shaft into Moser Engineering - they shortened and re-splined. Easy button, no problems, cost was reasonable and service was quick (this was 10 years ago...) I actually sent in a spare at the same time so I have one on hand.

 

[John N]

I sent my axle shaft into Moser Engineering - they shortened and re-splined. Easy button, no problems, cost was reasonable and service was quick (this was 10 years ago...) I actually sent in a spare at the same time so I have one on hand.

If you send 2 at the same time, the price is better.

 

[GoScottoGo]

Thank you both for the answer! Now to start collecting parts and find rear axle.

 

[Boomer]

I had my axle shaft shortened and resplined at Dutchman axles in Portland, OR. They are pretty renown for their axle work.

The timing of me happening to need to drive to Portland for a conference at the time worked out pretty well, too.

 

[Irradiated Fuel]

So, copying and pasting from above:

Rear Axle options:

1) WT CJ Dana 44 - Hard to find but there are a few out there. 5 on 5.5"

2) Scout 800B axle (late 60's to early 70's ?) - Only slightly wider than WT CJ axle. 5 on 5.5"

3) ??? - Don't know of anything else that isn't wider.

Is this still true?

 

[sdsupilot]

WT CJ rear 44 will be too narrow for a narrowed J10 44 front. It will be good for a narrowed Wagoneer 44 though.

Scout 44s are ok but have small/weak tubes. The brake parts are hard to find and very expensive.

The ford explorer 8.8 is a good option with great availability and drum or disc brake options. It is however a C clip axle and comes with a 5 on 4.5 lug pattern. They can be drilled but the flange isn't large and you are getting towards the edge for a 5 on 5.5 pattern.

An isuzu rodeo/honda passport 44 are also a good choices. There are different width options based on year. It has a 6 on 5.5 lug pattern but can be redrilled or have custom axle shafts made.

Current pricing of new and assembled axles make it harder to go the junkyard route IMO. East Coast Gear Supply has the Dana 489 and Dana 60 rears for a pretty fair price. Make sure to do an apples to apples comparison.

I used a J10 44 front and a 99 E350 full float 60 rear. I converted the front to 8 on 6.5 with Chevy 2500 hubs. I am 62.5" WMS. Hindsight being 20/20 I now wish I wouldn't have narrowed it and left it 67" WMS.

 

[Boomer]

An isuzu rodeo/honda passport 44 are also a good choices. There are different width options based on year. It has a 6 on 5.5 lug pattern but can be redrilled or have custom axle shafts made.

What do you for brakes on the redrilled/custom axle shafts?

 

[sdsupilot]

The rotors/drums are normally pretty thin. You can get a jig online and drill them yourself.

 

[Boomer]

The rotors/drums are normally pretty thin. You can get a jig online and drill them yourself.

Can drums or rotors with 6x5.5 pattern be redrilled to a 5x5.5 pattern? Looking at it, it doesn’t appear to be that there is enough space and that some of the holes will overlap.

The reason I ask is that I’m already a good ways into a project like this. I have a FSJ WT axle already narrowed. Pairing it with an AMC 20 from a mid 1980s Grand Wagoneer.

I already had the AMC 20 axle flanges welded and redrilled for 5 x 5.5. But I am trying to figure out what to do for drums or a disc brake conversion.

 

[John N]

Can drums or rotors with 6x5.5 pattern be redrilled to a 5x5.5 pattern? Looking at it, it doesn’t appear to be that there is enough space and that some of the holes will overlap.

The reason I ask is that I’m already a good ways into a project like this. I have a FSJ WT axle already narrowed. Pairing it with an AMC 20 from a mid 1980s Grand Wagoneer.

I already had the AMC 20 axle flanges welded and redrilled for 5 x 5.5. But I am trying to figure out what to do for drums or a disc brake conversion.

The 11” drums on the FSJ rear will give you plenty of stopping power as long as you plan on using a duel diaphragm booster or go hydro on the brakes Up to at least 36” tires.

 

[Boomer]

The 11” drums on the FSJ rear will give you plenty of stopping power as long as you plan on using a duel diaphragm booster or go hydro on the brakes Up to at least 36” tires.

Yeah, I have no problem running the Grand Wagoneer OEM 11“ x 2“ drum brakes on the FSJ AMC 20. That would also still be an upgrade over the 10” brakes in the Scrambler.

The conundrum comes from trying to swap everything over to the 5 x 5.5“ wheel bolt pattern. For the front axle I’m just going to use the knuckles out from an 80s Dodge half ton.

But using the FSJ M20 in the rear gets a little trickier. The biggest problem is the diameter of the hub hole/register. On the FSJ M20, it is 3.062”. On the CJ and just about every other Jeep that ever used 11” drum brakes, it is 4.155”. I am assuming that you want the the drum to fit tightly on the hub. So finding a drum with both the 3.062 register and a 5x5.5” bolt pattern or one that can redrilled or have the register machined out a little has been difficult.

 

[sdsupilot]

If you have the small bearing spindles you can also convert to 5 on 5.5 with ford hubs/rotors for the front. Personally I would just redrill the FSJ drums. I know one of the holes is very close when drilling. The drums do not support any weight so I wouldn't worry about strength.