2wd low setup

[puglyfe]

I'm looking to add a 2wd low setup to my 2002 HO 6speed. From what I found so far there are 3 kits available, BD, Pacbrake, and Posi-Lok. Is there a preference of one over the others? is there anything else I missed? Two are vacuum based and the other is a mechanical setup.

 

I want it for trailer maneuvering, taking some stress off the clutch.

[dripley]

Does your 02 have the CAD axle? Some late 02's do not. My early 02 does. 

[puglyfe]

I think it has the CAD. Option on the truck are the shift on the fly 241 transfer case and Dana M60/248MM front axle.

[dripley]

The CAD will be on the passanger side of the axle. Rectangular in shape with vacuum lines attached. I do not know what is on the non CAD axle.

 

@Mopar1973Man has a non CAD and could add something.

Edited January 14, 2019 by dripley

[trreed]

non CAD axle is just a straight tube.

[Tractorman]

6 hours ago, puglyfe said:

I think it has the CAD. Option on the truck are the shift on the fly 241 transfer case and Dana M60/248MM front axle.

 

The option "shift on the fly" is advertised with or without CAD (center axle disconnect).  You will need to look at the axle to see if there is a CAD unit attached.  If you do not have the CAD - end of conversation.  If you do have the CAD, my preference for control would be the vacuum switch. 

 

The one disadvantage of the mechanical cable setup shows itself when you attempt to engage or disengage the CAD and the axle splines are not lined up when engaging, or if there is torque being applied to the axle when disengaging.  One hand will always be dedicated to having to push or pull the cable control until engagement or disengagement occurs.  Sometimes that can be annoying.

 

With a vacuum switch control, you just flip the switch and the vacuum motor does the rest when the axle splines are lined up or when axle torque is removed.

 

I didn't buy a kit - I just used a $2.00 vacuum controlled HVAC switch from a GM vehicle in a salvage yard.  It has worked fine for over 300,000 miles.

 

Which ever way you go, you will like it.

 

- John

Edited January 14, 2019 by Tractorman

[KATOOM]

2 lo is one of the best things I've done to my truck.  But...as others have stated, you must have the CAD front axle otherwise the 2 lo kits wont work.  The CAD was discontinued in 2002 but some of those early build trucks were still equipped with them.

And just to clarify, the CAD unit is on the longer passenger side of the front axle housing.  You cant miss it either...

 

[BBHD]

I agree with @Tractormanand @KATOOM! I made my own setup with a vacuum switch.

[Ed ke6bnl]

I have some of those air switches in 1/4 in. one in and either port out. did you have a diagram of the install by any chance that would be an easy mod.

[BBHD]

2 minutes ago, Ed ke6bnl said:

I have some of those air switches in 1/4 in. one in and either port out. did you have a diagram of the install by any chance that would be an easy mod.

Here you go. This was from @Haggar 

[KATOOM]

Companies like PacBrake makes a 2 lo kit for those people who want something pre-built.

[Ed ke6bnl]

Do you by pass the transfer case vacuum switch and do it all manually? and to go into 4x4 lock do you engage the transfer case then activate the vacuum switch in that order?

 

[BBHD]

6 minutes ago, Ed ke6bnl said:

Do you by pass the transfer case vacuum switch and do it all manually? and to go into 4x4 lock do you engage the transfer case then activate the vacuum switch in that order?

 

Yes I bypassed the vacuum switch on top of the t-case. 1/4" air line fits nicely in the vacuum supply end. I typically do just as you said and engage 4x4 then flip the switch. When I need to be in and out of 4x4 a lot I just leave the switch on/engaged.  

[Tractorman]

13 minutes ago, Ed ke6bnl said:

Do you by pass the transfer case vacuum switch and do it all manually? and to go into 4x4 lock do you engage the transfer case then activate the vacuum switch in that order?

.

I bypassed the transfer case vacuum switch and plugged off the ports.  I installed the new vacuum switch in the cab. 

 

If my truck is stopped I can engage either the transfer case or the CAD first for 4 Lo or 4 Hi.  If I want to shift to 4 Hi on the fly, I slow the truck to around 20 mph and shift the transfer case first because it has a synchronizer that absorbs the energy to bring the front driveshaft up to speed.  Once the front drive shaft is up to speed, I then lock the CAD.  I also leave the CAD locked and just use the transfer case to go in and out of four wheel drive as needed.

 

- John

Edited January 14, 2019 by Tractorman

[Ed ke6bnl]

Thanks for the prompt replies, so helpful, this site is unbelievable.

[Mopar1973Man]

On 1/14/2019 at 9:29 AM, Ed ke6bnl said:

Thanks for the prompt replies, so helpful, this site is unbelievable.

Thank you for the kind comments...

[puglyfe]

11 hours ago, Mopar1973Man said:

Thank you for the kind comments...

Agreed, the site is quite helpful to us Cummins owners.

 

I do have the CAD axle. Seems the vacuum setup is the preferred. Any difference between BD and PacBrake? Pictures of the 2 kits look roughly the same.

[Mopar1973Man]

I would consider PacBrake more so over BD. Look at the one with the double valve.

[puglyfe]

Thanks to all for the input.

[vineyardmh]

OR - recognize that the front wheel hubs sometimes have problems - and if you put in a "Free Spin" kit....you just leave the hubs unlocked when you want 2L.

 

I did the free spin installation many years ago - and the hubs have bigger bearings, and can be removed and re-lubricated - vs. replacing the entire assembly.  And - as a bonus - the u-joints in the front drive and the front differential are not being turned all the time...so less wear and tear on the parts.