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Need advice on tranny swap auto to stick

5K views 26 replies 9 participants last post by  BigCountry62 
#1 ·
So I'm trading a guy my 85 f150 for a 79 f150 with 390 4 speed, comes with a 351m, c6 tranny and tcase, 2 Dana 44 complete hub to hub, another 4 speed, radiator with electric fan and more lol, I have a 79 f150 already with a c6 and want to convert to a 4 speed, how hard would it be? And is a 4 speed better than a auto on and offroad? Or just funner lol any and all advice is appreciated


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#2 ·
in your case it's a matter of finding a tranny with the correct bell housing bolt pattern and then adjusting driveshaft and tranny crossmembers. manuals aren't necessarily better or worse. it's your opinion. i think they are more fun and they can limp home if you poke a hole in the housing and lose the fluid. autos, especially the C6, can take a lot of power and are more convenient. the downside is they are heavier and if you poke a hole in the housing, can't drive anymore. i've blown a stock nissan truck trans and was stuck with 2nd gear only. i tend to prefer manuals however, i've seen people run autos with no problems behind high power rigs. in the end, it's your call. one thing i gotta give credit to autos....they are much harder to stall.
 
#5 ·
You may be able to just find the driveshaft in a junk yard.

Other things you need to consider is the linkage for the clutch. The pedal swap is pretty straight forward, but you'll also need the components that connect the clutch to the bellhousing.

You'll also need a hole in the floor for the shifter. You can either get a center hump from a manual truck and put it into yours, or cut into your current one.


None of it is exactly hard, but it's more than just sticking the trans onto the engine.


Personally, I prefer a manual to an auto. The granny gear in the manual is also a big plus. They don't rob the engine of power like an auto does either.
 
#12 ·
auto or standard



You will also need the slutch equalizer bar. When you connect it to a 352-360-390-428--the equalizer bar has a bad lean to it. To correct this. Take the equalizer connector on the frame--and the socket on it will need to be set up so it will be as level as you can it. The everything else will be in line.
 
#17 ·
The 4 spd on the 390 will not work for you. Wrong bell housing and shift fork. What you need to convert a 79 to manual is: transmission tunnel for the floor or cut a big hole in yours, the pedal assembly the and the floor plate that allows the rod through, the frame and engine mounts for the clutch lever assembly (frame side should be standard, don't know if a 390 mount will bolt to 400-460 bolt pattern) and that lever, 400 flywheel and clutch, and drive lines. Seems like the trans mount is the same or needs to be flipped around. It sounds like a lot, but it is fairly straight forward.
 
#19 ·
Having done more than a fair share of off roading in both auto and stick trucks. And being a person who can't stand driving auto's at ALL on the street (my Bronco's a stick), auto's RULE for off road. Torque converter gives them more off idle grunt, and when (NOT IF) you need to rock it out of a hole, its ridiculous even trying in a stick. Takes so long to get from 1st to Rev. and work the clutch, that the truck has lost the little bit of momentum you gained = worthless. Plus off roading a stick = TORTURING the clutch.

Obviously this is subject to opinion (go ahead silly nerds.. RANT), and because all the other benefits of owning a stick, I'd NEVER buy an auto..

One more thing I'd say is DON'T believe most of the bashing the M5R2 gets on here. There are plenty of guys racing highly modified Super Coupes with them, even others using them behind small diesels in trucks! They are a half ton truck trans., and a good one. NOT a one ton truck trans.. If it'll stand up to the uses above... What is it you have in mind that would be worse?!? If it IS worse, then ZF all the way. :)
 
#20 ·
From what I usually hear, the M5R2 gets a bad rap because of the design flaw where they leak from the plugs, so most of them are burnt up, or close to it.

I'd say auto vs. manual depends on the type of off-roading you do. For me, I do a lot of camping, and trail crawling, so I'm not commonly stuck. A granny gear and low range is amazing for winding my way up steep old mining roads and picking my way around rocks and ruts. I'd hate to be doing that in an auto. For the few times I have been stuck, rocking myself out with a manual wasn't anything that ever made just wish it was an automatic at the moment.

Now for mudding, rock crawling, etc. etc. I can see an auto being really beneficial.
 
#21 ·
Thanks for all the info guys REALY appriciate it!, I just didn't get my last ? Awnsered lol, what bell housing will work the 400?? Will a 351m bell housing work? Or just 460,429?, I do alt of hunting and trail/mud so that's why I'm was/am leaning towards the 4 speed (plus it's kick ass on road if ya don't have to many hills haha)


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#22 ·
351M will work with a 400m. They all use the same bellhousing as the 429-460 Though the 429-460 are the "Big Blocks". The 351M and 400M have the big block bellhouse pattern but are not really "Big Blocks".


If you ever want an overdrive, find a 460 ZF5 if you are using a 351m/400m or 429/460 engine. This will take a little more work to put in though but overdrive is well worth it. ZF5 even has a low gear but not as low as the NP435.
 
#25 ·
Yup. You have to brace the firewall where the clutch master cylinder will go. Have to make or modify the current linkages for possibly and check yer trans crossmember and driveshafts.



But the answer lies with you with my questjon...is it a 460 zf5?


Zf5s came in small block (300,302,351W), big block (460), and diesel (7.3L).


If you are using a 351m/400m you will have to fix clutch issues to where the zf5 will engage it correctly.
 
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