How does the 4wd engage on an F350

[IslandRidge]

How expensive is it to replace the OEM front bearings? I can find OEMs for 200-300 a piece at rock auto.. so $600 to replace vs $2000 for the Dynatrac free spin kit? Why else would you replace the OEM unit bearings?

Just curious!

 

[toy_tek]

Funny, I've had problems DISengaging 4wd on my 2005 F350 with auto/manual hubs. I read the manual, under normal operation you should be able to just turn the 4wd switch and not bother moving the hubs. I guess the manual hubs are just a backup.

Anyway, for disengaging, I've had to roll forward and back in a straight line, throw the trans into N and hope it came out of 4LO. Once, I was 300 miles from home, would have been a long trip in 4LO.

 

[akfj40]

Why else would you replace the OEM unit bearings?

cheaper if they go out. initial expense is alot but wheel bearing changes are under 100.00 as oppsed to 300 to 600

 

[masterplumber]

Why else would you replace the OEM unit bearings?

cheaper if they go out. initial expense is alot but wheel bearing changes are under 100.00 as oppsed to 300 to 600

Another reason is the colatoral damage when they go. I hear it's quite dramatic & pretty much takes the rest of the outer end with them including the spindles - given that the Dynatrac looks cheap in comparision.

Doug

 

[Robthebrit]

I know nothing about domestic trucks, why do you need any sort of hub these days? What is the advantage? Why not just have a wheel connected to the axle, it seems like there is less to break.

Rob

 

[IslandRidge]

I guess if you had extra bearing for the Dynatrac conversion it would be ok. but the OEM wheel bearing are used on all truck 250-550 so they are plentiful. Plus a lot of the hardcore rockcrawlers use the OEM bearings instead of the Dynatrack-like setup.. they say it more durable.

How ofter do the OEM units fail? does anyone have a sense of that?

 

[IslandRidge]

I know nothing about domestic trucks, why do you need any sort of hub these days? What is the advantage? Why not just have a wheel connected to the axle, it seems like there is less to break.

Rob

On a smaller truck the wheel is connected to the axle. but for full size trucks 3/4 ton and over, a Full float rear axles uses a spindle and a bearing (if the axle breaks then the wheel will not go anywhere).. The front axle is usually a unit bearing with an axle thru the center and on the end of the axle is the axle engagement rotary switch (locking hubs). Unit bearing are easier for the service tech to install and there is no adjustment for the bearing. If you adjust the Dynatrac conversion incorrectly, you can mess up the spindle and or the bearings.

 

[jdholder]

How ofter do the OEM units fail? does anyone have a sense of that?

I replaced my Unit Bearings in my Excursion at 125k miles. One was bad, and I decided to replace both at the same time. Expensive, but if they lasted that long, well worth it.

My Excursion has 40" tires and has had them since I bought it with 54k miles on it. So, if 70k miles is the life of the Unit Bearing with 40's, I think they are pretty durable.

 

[ujoint]

One of the best upgrades to a Super Duty is to get rid of those plastic junk hubs and get some Warn's. They love to lock themselves! It's a really easy swap also.

 

[deserteagle56]

Thanks for all the responses. I would just assume leave the hubs locked all winter. Are there any problems with doing that?

No problems...that's what my father did on his trucks. He lived where he was in snow/ice/mud from November to April so he just locked them in in November and didn't unlock till winter was done. The only disadvantages are a small drop in fuel mileage and wear on front-end components that's unnecessary. In essence, with the hubs locked your front end is the same as my stock Ram which doesn't come with hubs.

But I have never found stopping to lock in the hubs when I encounter adverse conditions a bother. What's the cost? A few seconds of my time? If you're worried about getting your fingers dirty, carry gloves or use a rag, etc. Heck, someone even makes a tool you can keep inside the cab and use so you don't have to touch the hubs themselves. When you compare the miles most rigs put on in 2wd versus 4wd, there's simply no comparison. I guess I'm just cheap, but I see no need to be wearing out parts needlessly. I've been driving 4x4s since the early 60s; I have one now I bought new in 1976. Never have I had to change out a front end u-joint or CV joint and I believe it's because most of the time those components are not turning. And if you go in and service your front wheel bearings you've also serviced your front hubs so there's no extra maintenance. I've had locking hubs on Fords, GMCs, and even an International and never have I had a problem with one.

As soon as I can find the time my Ram (which I bought only because of the Cummins) will be wearing the Dynatrac free-spin kit.

 

[ScottBailey]

Been wondering for awhile now...

I'd been wondering how the hubs engage for awhile now; thanks for enlightening me, guys.

So, next question: does anyone have a link for a conversion from auto-engagement (i.e. push button) to lever/manual?

Thanks,
SB

 

[ujoint]

The electric shift t-case is an NV272, manual shift is a NV271. I'm not sure if you can just remove the electric shifter to make it a manual. I haven't heard of it being done, maybe someone else has. I would say that the worst case scenario is that you have to swap the t-case and get the proper linkage parts from the dealer or a donor truck.

 

[IslandRidge]

The electric shift t-case is an NV272, manual shift is a NV271. I'm not sure if you can just remove the electric shifter to make it a manual. I haven't heard of it being done, maybe someone else has. I would say that the worst case scenario is that you have to swap the t-case and get the proper linkage parts from the dealer or a donor truck.

Humm... You can flat tow the manual transfer case and you cannot with the electronic version. This probably means there is a neutral in the manual version and none in the electronic. e.g. the electronic version is always in gear. So I would say that ujoint is correct in that a new transfer case would need to be installed to make it a manual version with a lever.. Just another one of those things that you find out after you buy your truck. I would suspect very few of the manual transfer cases are sold, so they are kind of rare.. a good reason to go with an atlas..

 

[Over The Edge]

My two cents from wheeling a 1999 F250 SD for almost 10 years.

Lots of issues discussed here and applicable wheather you are running the dana 50 or 60...

Front is vacuum actuated - issues with loss of vacuum to holes, leaks etc. Additionally, the V10 and older diesels sometimes have issues with low vacuum, so you can see random disengagement.

272 transfercase is shifted via electric motor - cannot be modified to manual shift without case modification and this would void your warranty. Additionally, though this case (in it manual form has a neutral) it is not advisable to flat tow as this will create havoc with the internal oiling system.

Changing out to an Dynatrac or EMS hub replacement solution would solve a number of issues - Unit bearing are inherently weak when lateral preassure is applied to the unit, susceptible to water, mud & gunk. Additionally, due to design constraints the front axle is small and susceptible to breakage. These kits will replace the stub axle with a larger diameter unit with 35 splines (important if you user an LS or locker). Additionally with the stock setup you are limited to a fairly small tire size. They are pricey and when they fail, thats it, they can actually sieze and break your axle. Oh yeah! The factory hubs will also grenade on you when you apply multi-directional load to them, (ie., tire stuck between two rocks and climbing out).

Why a unit bearing? The decision to migrate to a unit bearing was a concession to the manufacturing processing, they are quicker and easier to install at the factory and setup.

 

[IslandRidge]

Good points. good discussion..

How many people have done the conversion to Dynatrac ?

How many people have actually seen a unit bearing fail? I have not.

I still have that vision of custom axles on a rock crawler with 37-40 inch tires with a ford unit bearing set up.. sometimes on front and rear. I suppose the weight is significantly less, but the tires and the load may be more...