4wd ignorance

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NoLaFSJ
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4wd ignorance

Post by NoLaFSJ »

I bought a 1990 GW and I have no idea what I'm doing... as far as the 4wd is concerned! My dad and I are mechanically inclined but we are hot rod/muscle car guys. I have restored multiple classics from the ground up with him, but when it comes to 4wd I am lost.

My ignorace was truly revealed when I called a local 4wd guru to ask what I thought was a simple question: Is there supposed to be a spring in the hubs of the front axle? All the diagrams that I found on the web showed a spring, but when we pulled ours apart, no spring was found on either side. Everything else was there and in the correct order, but no spring. Any way, this guy was throwing so much 4x4 lingo around and asking me so many questions that my head began to spin. Ultimately my question went unanswered, but not because this guy didn't know his stuff. I couldn't answer any of his questions about my own vehicle!

What are some good resources for me to learn about the 4x4 system in my GW and how it works? I want to know more about the mechanical classifications of the parts in the system. In other words, I don't just want to know the model number of the transfer case, I want to know what type of transfer case it is and what make it different from other style tranfer cases.

Give me some good reading material that can exlplain the basics to me so I don't sound like a complete idiot the next time I try to talk shop. Thanks.
Brian

1990 Grand Wagoneer
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fulsizjeep
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Re: 4wd ignorance

Post by fulsizjeep »

The only transfer case available in 1990 GW was the New Process 229. It is considered a part time transfer case so you have 2wd HI, 4wd HI, Neutral and 4wd LO shift options. It uses a vacuum switch under dash to select 2wd/4wd then uses a flag shifter on the left side of tranny hump to shift HI, Neutral and LO. The vacuum shifter uses a lockout and tcase HAS to be in 4wd to select other than HI range. In 4wd HI range, the tcase uses a viscous coupler (limited slip) to regulate power to front and rear drive shafts. Never run this tcase in 4wd HI with one drive shaft removed or with manual hubs on front axle unlocked. In 4wd LO range, the viscous coupler is locked for equal power to both front and rear drive shafts. All FSJs equipped with the NP229 had drive slug/gear in the front hubs so the front drive line spins all the time. You should have two big coil springs, one in each front axle hub behind the drive gear.

sample of front hub:
Image

directions for shifting tcase is in this 89 owners manual:
http://oljeep.com/gw/89_GW_OwnersManual ... Manual.pdf

NP229 Manual:
http://oljeep.com/np229/NP229_manual.pdf

That should get you started.
Flint Boardman
88 GW, 401/727/208, 5" lift, D44s/4.10s/locked up, 35s
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Stuka
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Re: 4wd ignorance

Post by Stuka »

The best information on the whole system is a factory service manual.

But for general info:

Your waggy has three transfer-case modes. 2wd High, 4wd High Full Time, and 4wd Low Part Time. And well technically neutral as well.

2wd High is for normal driving around.

4wd High Full Time is engaged by the knob on the dash. This is safe to drive with on the street.

4wd Low Part Time is for offroad only, and is engaged by the lever under the seat.

Neutral is also handled by the lever under the seat, and is between high and low range modes.
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will e
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Re: 4wd ignorance

Post by will e »

To expand on what they said but in more general terms and not specific to your truck:
The front axle on all 4 wheel drives fall into one of three categories (for the most part).
1. 'Manual hubs' - These are the ones that you get out and turn the center of the hub from 'free' to 'lock'. When in the free position the wheel is not connected to the axle shaft and spins independent of it. Typically these axles came with transfer cases that did not spin the front drive shaft while in 2wd. So if you watched one of these moving and the transfer case is in 2wd and the hubs are in 'free' the front drive shaft does not spin. When they are in 'lock' they are connected to the front axle shaft and you would see the front drive shaft spin as well. Normally you lock them when you are going to also place the transfer case in 4wd.
2. Automatic hubs - Basically the same as above but the locking action is controled by either a vacuum motor or some mechanical system rather than turning the center of the hub. How and when the automatic hubs are engaged or disengaged depends on the 4wd system. Some may do it as part of putting the transfer case into 4wd, others may require a separate switch.
3. (not sure of the name) I think we generally call them slugs. In this configuration the wheel is always connected to the front axle shaft. You would typically find this on a 'full time' 4wd system. The wheel never spins independent of the axle shaft and therefore the front drive shaft. Many of the Transfer Cases associated to this type of system have some kind of clutch system that allows the front/rear drive shafts to spin at different speeds. This is necessary when going around corners.
There are a bunch of different types of transfer cases. And some terms that are sometimes interchangeable. Generally:
'Part time' transfer cases. These are transfer cases that can operate in 'rear wheel only' mode.
'Full time' transfer cases. These transfer cases typically operate in 4wd all of the time.
For both types of transfer cases there can be either 'full time mode', 'part time mode' or both. When in 'full time mode' the front/rear drive shafts can spin at different speeds (again corners on high traction situations like driving down the street). In 'part time mode' the front and rear drive shafts are locked into spinning at the same speed. This is used only off road or low traction situations. Since the drive shafts are locked at the same speed they rely on a slight loss of traction at the tires to allow some slipping while turning.
Not all transfer cases have all modes. For example, my np208 was a part time transfer case that did not have a ‘full time mode’. Under no circumstance could I drive my jeep on the pavement in 4wd. There are other ‘part time’ transfer cases that do both 2wd as well as a ‘full time 4wd mode’ (safe on the streets) AND a ‘part time 4wd mode’ which is only used in low traction situations. There are even ‘full time’ transfer cases which do not have a ‘part time mode’.

Finally. Some transfer cases are single speed and others are multiple speed. Generally this is ‘high’ and ‘low’. (Some transfer cases have 3 or 4 speeds). ‘high’ mode is a 1:1 from Transmission output to transfer case output. ‘low’ mode is a mechanical reduction of the transmission output to the transfer case output. Common is around 2.6 (the transmission turns 2.6 times for each 1 time the transfercase output shaft turns). You will see this value as ‘high’ as 2 to 1 or, for a two speed transfer case, 4 to 1 is about as low as you will see.

I hope this helps you better understand some of the terminology.
81 Waggy 'WILL E' Retired
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NoLaFSJ
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Re: 4wd ignorance

Post by NoLaFSJ »

Wow guys, thanks for all of the info! Hey fulsizjeep, any chance you know who sells those pressure springs for the axle hubs? I'm definitely missing those.
Brian

1990 Grand Wagoneer

will e
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Re: 4wd ignorance

Post by will e »

Glad we could help.

When you have the drive gear cap off of the hub but the rest of it assembled, can you move the drive gear itself foward/backwards at all? It's weird that someone would have removed the springs. Is the spring cup there? It is possible it has been modified.
81 Waggy 'WILL E' Retired
82 Cherokee WT - SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau XRS Baja & 5 point retractable harness/Hella Aux lights/tuffy console/killer32 sliders/Evil Twin bumpers, rack and roll cage/WARN 8000/TT Fabworks steering brace/dual batts/custom TC skid plate/ARB fridge

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Re: 4wd ignorance

Post by FSJ Guy »

LOL! I don't think anyone's come out and actually answered your question.

YES, there IS supposed to be a spring in there. Will it seriously damage anything? I don't think so. But I'd find a junkyard replacement just to be sure.

And as far as hubs and such are concerned, you have drive slugs. Despite some people calling them "automatic" hubs. They're really not, even though it may "seem" that way.

Don't worry about possibly sounding ignorant about your Jeep. I do that quite frequently and I've had FSJ's virtually continuously since 1993! LOL!
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XJChad
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Re: 4wd ignorance

Post by XJChad »

Can manual hub lockers be put on a fsj with the NP229 since the front driveshaft is always turning and it has the VC coupler?

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1989 Grand Wagoneer, 4" Rusty's Lift, LS 5.3L swap (in progress), 4L60e, NP241c.
1991 Grand Wagoneer, all stock, a work in progress, for sale soon.
1982 Cherokee Laredo, 360ci, aluminum intake, Edelbrock carb, HEI, w/32x11.50x15, warn 8000, Dana 44/AMC 20
2001 Cherokee Sport, Old Man Emu lift (worn out), front/rear C4x4 bumpers, Smittybuilt 10,000 winch, 31x10.50x15, Edge Tuner kit w/throttle body & AFE cold air, Gibson exhaust-my daily driver until the '89 is finished.
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Re: 4wd ignorance

Post by fulsizjeep »

NoLaFSJ wrote:Hey fulsizjeep, any chance you know who sells those pressure springs for the axle hubs? I'm definitely missing those.
Check with member jsinajeep and rstep. They have a lot of FSJ parts. If not post up a wanted ad.

XJChad wrote:Can manual hub lockers be put on a fsj with the NP229 since the front driveshaft is always turning and it has the VC coupler?
Yes they can. Caution: If the hubs are unlocked when the vacuum switch is thrown for 4WD, the viscous coupler is at high risk of damage. Also Note: the only reason the front drive shaft turns all the time is because the hubs are locked. It is not a design of the 229 as it has a true 2WD feature where the front output is not turning.
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88 GW, 401/727/208, 5" lift, D44s/4.10s/locked up, 35s
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Re: 4wd ignorance

Post by XJChad »

Okay, thanks fulsizjeep, good to know! Now I have something else to order!!! :)
1989 Grand Wagoneer, 4" Rusty's Lift, LS 5.3L swap (in progress), 4L60e, NP241c.
1991 Grand Wagoneer, all stock, a work in progress, for sale soon.
1982 Cherokee Laredo, 360ci, aluminum intake, Edelbrock carb, HEI, w/32x11.50x15, warn 8000, Dana 44/AMC 20
2001 Cherokee Sport, Old Man Emu lift (worn out), front/rear C4x4 bumpers, Smittybuilt 10,000 winch, 31x10.50x15, Edge Tuner kit w/throttle body & AFE cold air, Gibson exhaust-my daily driver until the '89 is finished.
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NoLaFSJ
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Re: 4wd ignorance

Post by NoLaFSJ »

will e wrote:Glad we could help.

When you have the drive gear cap off of the hub but the rest of it assembled, can you move the drive gear itself foward/backwards at all? It's weird that someone would have removed the springs. Is the spring cup there? It is possible it has been modified.
I'm not sure, I'll have to check it out when I go back to my dad's garage. I live/work about an hour away and only get to work on it every other weekend or so... I'll let you know when I can. Thanks again.

FSJ Guy wrote:LOL! I don't think anyone's come out and actually answered your question.

YES, there IS supposed to be a spring in there. Will it seriously damage anything? I don't think so. But I'd find a junkyard replacement just to be sure.

And as far as hubs and such are concerned, you have drive slugs. Despite some people calling them "automatic" hubs. They're really not, even though it may "seem" that way.

Don't worry about possibly sounding ignorant about your Jeep. I do that quite frequently and I've had FSJ's virtually continuously since 1993! LOL!
Thanks for the direct answer haha. I am trying to learn as much as I can but it's a slow process!

And thanks to all of you for the straight forward answers and genuine help.
Brian

1990 Grand Wagoneer

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Re: 4wd ignorance

Post by mineral co »

Assuming the hubs are "stock", you have to have the spring in there. That's what pulls the outer axle section into the proper position so that the U-joint is lined up properly in the knuckle, and can turn with the steering. Without the spring the axle shaft and U-joint can move back and forth, intefering a bit with the steering action, and it is hard on the U-joint as well.
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Re: 4wd ignorance

Post by carnuck »

XJChad wrote:Okay, thanks fulsizjeep, good to know! Now I have something else to order!!! :)

One thing to remember. Unless you have the 6 cyl, your fuel economy isn't affected by the axle staying locked.
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Re: 4wd ignorance

Post by TUDrewser »

carnuck wrote:
XJChad wrote:Okay, thanks fulsizjeep, good to know! Now I have something else to order!!! :)

One thing to remember. Unless you have the 6 cyl, your fuel economy isn't affected by the axle staying locked.

Seriously? I never would have expected that...
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Re: 4wd ignorance

Post by jsinajeep »

Thanks Flint, I got a PM from him and PM sent back.
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Re: 4wd ignorance

Post by carnuck »

TUDrewser wrote:
carnuck wrote:
XJChad wrote:Okay, thanks fulsizjeep, good to know! Now I have something else to order!!! :)

One thing to remember. Unless you have the 6 cyl, your fuel economy isn't affected by the axle staying locked.

Seriously? I never would have expected that...

Me either. It made a 5 mpg difference on the highway and 7 in town with the 6 cyl when I forgot to unlock the hubs. It hurts when you realize you forgot and no longer get 20 mpg.
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Re: 4wd ignorance

Post by rstep »

If Jerry doesn't have them I do. let me know.
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Stuka
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Re: 4wd ignorance

Post by Stuka »

TUDrewser wrote:
carnuck wrote:
XJChad wrote:Okay, thanks fulsizjeep, good to know! Now I have something else to order!!! :)

One thing to remember. Unless you have the 6 cyl, your fuel economy isn't affected by the axle staying locked.

Seriously? I never would have expected that...
Every new 4wd (Except Ford Super Duties) do not have locking hubs. I have never noticed any difference in fuel economy in my J10 with or without locked hubs. Certainly not a 5mpg (!!) difference. That is huge.

There are AWD cars (Really fwd until the fronts slip) that always have the rear axle shafts and drive shaft engaged and they still mange 30mpg. Leaving that front axle engaged is very very little drag. Unless of course the bearings inside are bad causing excessive drag.
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Re: 4wd ignorance

Post by XJChad »

Ok thanks. My main thinking with the locking hubs is if an outer axle stub breaks, I should be able to drive it out without creating too much more damage. The GW I have now, I bought with a broken outer, and it destroyed the spindle and bearings when they twisted the end of the outer off. (Atleast I think this would help should that happen again??)

Sent from my SCH-R970 using Tapatalk
1989 Grand Wagoneer, 4" Rusty's Lift, LS 5.3L swap (in progress), 4L60e, NP241c.
1991 Grand Wagoneer, all stock, a work in progress, for sale soon.
1982 Cherokee Laredo, 360ci, aluminum intake, Edelbrock carb, HEI, w/32x11.50x15, warn 8000, Dana 44/AMC 20
2001 Cherokee Sport, Old Man Emu lift (worn out), front/rear C4x4 bumpers, Smittybuilt 10,000 winch, 31x10.50x15, Edge Tuner kit w/throttle body & AFE cold air, Gibson exhaust-my daily driver until the '89 is finished.
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Re: 4wd ignorance

Post by Stuka »

XJChad wrote:Ok thanks. My main thinking with the locking hubs is if an outer axle stub breaks, I should be able to drive it out without creating too much more damage. The GW I have now, I bought with a broken outer, and it destroyed the spindle and bearings when they twisted the end of the outer off. (Atleast I think this would help should that happen again??)

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Yeah it would help. You just have to make sure its in low range, or 2wd before you try driving after unlocking it. If you unlock it and it feels like the transmission is slipping, it means you are in 4 high, and you are doing damage to the viscous coupler.
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