t18 to zf5 ?

[Tyler]

Bullnose Brothers,

I have located a zf5 and "F250 HD T-case" (not sure what that means just yet) mated to a 302 in an '86 F150 that is being parted out locally.  No prices specified in the FB add.

I love how my truck crawls uphill in 4L but would love a 5th gear.

I understand that I'll need the donor truck driveshafts and possibly the crossmember if it belongs to the zf5's original truck.

Do I need the T case from the donor truck?  Is this a good swap? Can it be done reasonably?

Thanks for your input!

[85pig]

I'm getting ready to swap to a T18, but have been intrigued by the ZF5.  I've not seen one for sale around here (yet), and am probably less likely to see one behind a small block 4x4.  Seems like it would be a good swap.  As for the T-case, not sure; check the model and see if it's a stronger unit than you have now.  If you have all of the crossmembers, shafts, etc., I don't see why it wouldn't be a straight swap.  Only real difference from what you have now is external vs. internal slave cylinder.  There will be others by here with more knowledge soon.

[Gary Lewis]

The ZF5 tranny with an OD is a good swap, but you'll give up just a little bit on the bottom end.  Your T-18's 1st gear is a 6.32 vs the 5.72 of the ZF, but that won't make a lot of difference.  Big Blue in 1st and 4Lo will walk up anything idling.

Your t-case will bolt up, as Ford didn't change the bolt pattern on them for decades.  So pick the better of the two and go with it.  But you may find that the extra ~3/4" length of the ZF causes you to want to adjust the length of the shift linkage on the t-case.  Go to Documentation/Driveline/Transfer Cases and then the Linkage and then Adjustable Linkage tabs for how I did that.

On the crossmember, it would be wise to get the one in the donor truck.  But since a ZF didn't come in an 86 it is possible that it isn't the right one.  But you can use the current one by drilling new holes in the lower flange of the frame and then bolting the gussets in using the original upper holes.  That'll cause them to twist as you tighten, but that is working on Big Blue.  Or you can use a really short drill bit and a right-angle drill to drill the proper new holes in the upper flange, but w/o lifting the cab a few inches you can't get the bolts out or put ones in.

Last, you will need the taller transmission cover that was used with the ZF5.  And the donor truck should have that.  It'll bolt right in to your truck.