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problems engaging 4x4 neutral and low

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delco1946

problems engaging 4x4 neutral and low

I just bought a 1981 F250, trailer special. Its a beefy truck with 4x4. I'm just staring to play with it, but it wont go past 4HI (in the transfer case). It seems that the issue is likely the truck wont "let" me shift into N or 4Lo because it thinks the needed requirements have not been met. The requirements to shift into N and 4Lo are that the automatic transmission needs to be in neutral, and the truck needs to be stopped (foot on brake so i assume there must be some sort of brake activated switch).

I think this must be some sort of electrical or vacuum issue - I'm guessing related to some sort of switch that tells the system I'm in neutral and stopped. I have twice been able to go into (transfer case) neutral and then 4Lo with the truck off, and the key in accessory position. The 4x4 lever moved smoothly (suggesting that the mechanical linkages are lubricated or a nonissue). Normally tho, i can't shift lower than 4Hi. anyone know what/where these switches might be and if they're an electrically activated switch or vacuum activated?? I will mention that in case its vacuum operated, my booster is going bad (leaks) altho i can brake fine for now. I can't find any references in my manual, repair guide or online. Im loading a picture showing some wires sticking out of my firewall near the brake pedal, hoping someone might know what they should be connected to (fingers crossed its as simple as someone disconnecting a wire harness but the wires could also be for a trailer hookup too). Any help/ideas is appreciated! Christopher

Christopher in Portland Or. 1981 F250 Ranger XLT 4x4 trailer special 351M, and auto C6

Gary Lewis

Re: problems engaging 4x4 neutral and low

Administrator

Christopher - Good news and bad news. First the good news - the connector coming out of the firewall is almost for sure the connector to the brake controller. That is probably C1101 or C1106, as shown here: Electrical/EVTM/1985 EVTM/Trailer Option. In other words, your truck is wired for the trailer brake controller, but you apparently don't have one.

And more good news - these trucks are fairly dumb/simple, and don't have any interlocks to prevent you from shifting into 4Hi or 4Lo. Further, there's no vacuum control that is going bad. It is all a mechanical linkage and you MUST be in Neutral and setting still to go into 4Lo.

Now for the bad news - I think the "Insert (Shift Forks)" have worn out on your transfer case. You didn't give us much detail in your signature, like what engine you have, but most of the trucks had the NP208 transfer case. And I know for sure that worn inserts on the NP will cause problems like you are having as I've been there, had that done to me.

My experience was that it would go into 2WD nicely. And it would go into Neutral ok, but it wasn't really in the detent on the shifter, so when you let go of the shifter it would slip out of Neutral sometimes. And it would frequently go into 4Hi. But never into 4Lo.

I had the transfer case rebuilt and everything but those inserts was fine. They put new ones in and then it shifted perfectly.

You can see the illustration, parts lists, and rebuild instructions on the transfer cases here: Driveline/Transfer Cases.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

delco1946

Re: problems engaging 4x4 neutral and low

Hi Gary, thanks for the response. I don't know what type of transfer case i have but my engine is a 351M. Based on the chart you linked to, i think i might have the W1345?? My rear axle is 3.54

Christopher in Portland Or. 1981 F250 Ranger XLT 4x4 trailer special 351M, and auto C6

delco1946

Re: problems engaging 4x4 neutral and low

I took a look at the drawings, regardless of which transfer case i have, i'd have to pay someone to do that sort of work, taking apart my transfer case is wayyyyyy beyond my comfort level and probably tool level.

Christopher in Portland Or. 1981 F250 Ranger XLT 4x4 trailer special 351M, and auto C6

grumpin

Re: problems engaging 4x4 neutral and low

I think Gary nailed it, although I have had trouble getting these to shift if there is any "load" on the driveline.

i.e. if you're in neutral and you let off the brake and the truck will roll, it may be difficult to shift past 4Hi.

On inclines I have shifted as I let off the brake.

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

Ford F834

Re: problems engaging 4x4 neutral and low

Administrator

In reply to this post by delco1946

I would expect a BW1345 in your truck based on the year and it being a F250. That’s not the only possibility, but that’s the common thing to see. I doubt they would put a NP208 in a trailer special. I’m sorry I don’t have much insight into how to fix your problem... but I will share this:

My friend Jan bought a 1986 F250 that had the C6 and BW1345 transfer case. He experienced exactly what you describe. The transfer case would not shift. If he turned the truck completely off (and in Park) he could shift it easily, but not while running, even with the C6 in park or neutral. We swapped the transmission to a ZF5, and the problem went away. The transfer case could be shifted on the fly in neutral or with clutch depressed. I don’t know what changed, but that’s what happened.

SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2

ArdWrknTrk

Re: problems engaging 4x4 neutral and low

Administrator

In reply to this post by delco1946

You might start by going under the truck and making sure the shift linkage gate is free to move forward and back, and side to side against the rubber bumper.
Maybe there's mud or rust packed up in there and the stick won't shift sideways to get into neutral or 4lo?

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: problems engaging 4x4 neutral and low

Administrator

I agree with Jim that you should slide under and check out the linkage. And, do as Jonathan suggested and try to shift with the engine off.

And, you should consider upgrading your signature to tell us more about your truck. The fact that it is a 351M may come in really handy in the future.

Gary, AKA "Gary fellow": Profile

delco1946

Re: problems engaging 4x4 neutral and low

I have tried shifting with the engine off - in fact thats the only time it has ever shifted for me, with the key in accessory position (electrical on). Its only happened twice, but as i recall it was letting me shift in either park, neutral, or in gear. I'll try to take a look at the linkages.

Christopher in Portland Or. 1981 F250 Ranger XLT 4x4 trailer special 351M, and auto C6

ArdWrknTrk

Re: problems engaging 4x4 neutral and low

Administrator

In my truck there is a rubber block that acts as a spring to prevent the shifter from moving sideways and being able to drop into the neutral gate.

If the rubber is petrified or the pivot rusted solid you won't be able to move the shifter sideways.

Maybe it just needs some cleaning or lubricant.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: problems engaging 4x4 neutral and low

Administrator

Jim - I think the BW1345 and NP208 use linkage that is all fore/aft and comes up through the transmission cover. But your BW1356 has the different linkage which pokes up through the side of the transmission hump Right?

That's why I've decided to put the built 1356 in Big Blue instead of Dad's truck as I don't want to cut the hump in Dad's truck.

Anyway, I don't think delco's truck has a rubber block/pivot in the linkage. But I may be wrong on that.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: problems engaging 4x4 neutral and low

Administrator

I did qualify my statement by saying "my truck", but yes, I imagine a 1981 truck might have a completely different linkage.

My truck has the range selector on top of the tunnel.
I don't think it was until the OBS, or at least the aeronose trucks that Ford had the second stick coming out the side of the tunnel.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: problems engaging 4x4 neutral and low

Administrator

Jim - Yes, you did qualify it. I was actually seeking to understand. And I hate to side-track this discussion, but while we are on it...

I've looked at the illustrations, and it appears that there were four different transfer case shift mechanisms:

1980 - 86: All except SROD, and it comes through the transmission cover

1980 - 86: SROD only, and it comes through the transmission cover

1987: All, and it comes through the transmission cover

1988 & on: All, and it comes through the side of the hump

I've added the 1987 and the 1988 & on illustrations to this page: Driveline/Transfer Cases on the Linkage and then Illustration tabs. Would you check to see if you agree? I need to understand this for my plans. And, it might help with our discussion here.

Gary, AKA "Gary fellow": Profile

delco1946

Re: problems engaging 4x4 neutral and low

what does SROD mean?

Christopher in Portland Or. 1981 F250 Ranger XLT 4x4 trailer special 351M, and auto C6

85lebaront2

Re: problems engaging 4x4 neutral and low

Administrator

Single Rail Over Drive transmission.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413