hey all

i got some questions regarding a transmission swap. i have a 1986 f150 4x4 with a 4.9 300 and a standard 3 speed with od and i am wondering how much of a challenge it would be to put a small block zf5 onto it. any info would help me out alot! thanks!

 

It should be an easy swap. I'm going from an NP435/NP208 combo to the ZF5/NP208 behind a 351M in my '81 and it is a bit of a challenge because Ford never put that tranny behind that engine. But, they did put it behind a 351W, if not the 302, so yours should be almost a bolt-in. You should already have a hydraulic clutch setup, so that works perfectly with the small-block ZF as it has an integral slave cylinder so you pretty much have to go hydraulic. And, you should already have the bolt-on transmission tunnel and boots, so that will be easy.

There are only two issues that may be a minor problem. One is the drive shaft length - I don't know if the ZF is longer than your tranny. But, the drive shafts are available so that should be easy although a bit more expensive. The other issue is the flange on the bottom of the firewall - I understand that needs to be either trimmed or bent out of the way in one area as it will hit the ZF otherwise. But, several have done it so that shouldn't be a problem either.

Please start a thread on your swap, or maybe just continue with this one and update it.

 

I swapped out a C6 for the ZF5 and didnt have to trim the firewall. Once i got my driveshafts shortened/lengthened it was a bolt in deal.

 

okay cool so so far i only have to worry about my driveshaft length. and i dont have to worry about different flywheels or anything?

 

Look up on autozone's or some other site, the flywheel for your truck and write the number down. Then pick a 87-up truck that came standard with the 300 and the zf(you may have to pick a f250) and see if the flywheel number is the same as yours. If it's different, I bet yours won't fit.

It might be because the zf was a heavier duty tranny and always came with a larger clutch. But that still won't help you if you can't get a smaller clutch disc to fit the zf splines. So while you are looking this stuff up, write down notes on it also. I know autozone's site will list sometimes in the specs the spline counts of clutch kits, and the clutch's diameter.

 

the flywheels for a 4.9 on a 86 f150 and the part number on a 93 4.9 f250 are the same so would that mean it will work?

 

i looked on autozone and the clutch kit part numbers are different but im readin 10 spline count for both the 86 and 93 4.9

 

If you had both trucks, and wanted a new flywheel for both, they would give you the same flywheel, so yes I would say they are the same. You can verify this on another site like rockauto or somewhere else just to make sure.

About the clutch kits being different; The depth may be different on the zf bellhousing, and it may have a different throwout bearing, so I would use your flywheel, and get the proper zf clutch kit for it. You can research the individual clutch parts using the same method if you like. The disc's may be the same, but the other parts may be different.