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351m / 400 transmission & TC options

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#1 · (Edited)
351m / 400 transmission & TC options (chose ZF-5 + Dana20)

I have done quite a bit of reading over at FTE but wanted to post up here as well as this forum is a bit busier (more active) so might get more eyes on.

I have about had it with the NP435, love the granny gear but hate just about everything else. Shifts like a bag of hammers, clutch takes the hulk to engage (centerforce clutch?), gearing is spaced out like half of Colorado and while I could probably live without the overdrive I do quite a bit of highway miles, enough that it would make a difference to have it.

I know my options are pretty limited considering I will need a transmission that has the big block bolt pattern while trying to keep the rear driveshaft as long as possible.. this is on an early bronco by the way. I love the granny gear, would like to retain that either through the transmission or transfer case. Overdrive.. half the reason i would like to do this swap.

Keeping a manual transmission what are my options, what about transfer cases?

EDIT: Decided to go with a ZF-5 out of a 460 truck and use the adapter to retain the Dana 20. I will keep this thread updated as my build thread too :)

I'm currently leaning toward a big block zf-5 (some machine work and fab envolved) with either the $$$ adapter mated to a D20 or an $$$$ atlas... I know the np205 mates directly to the zf-5.. but the length!
 
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#89 ·
You will appreciate the larger u joints, they will handle the torque from that monster you have as an engine- much better. It looks as though you about have this thing licked..... I am surprised that you have run into so many issues. I thought that this would be an easier job.
Are you going to "farm out" the cross member, or are you going to fab it yourself? As far as your pedal assy goes, could you post more detail of how you plan on modifying the linkage and will it clear mastercylinder /booster.
Again, thank you for taking the time to post this swap!!! Please post a bit of info afterwards to let us know if your swap proves to be as awesome as I think it will be.
 
#90 ·
Thanks, well nothing about this swap has been easy going, as far as I know its never been done in an early bronco with a 400 in it.. so new ground and all that.

I'm going to fab up a cross member. My trans pivot point should be here today so hoping to have it made this weekend.

I have hydroboost and the bracket stands out from the firewall so should clear just fine as a few of the early bronco guys have hydro clutches and hydroboost...
 
#91 ·
Hydraulic Clutch Reservoir installed and linkage lined up perfectly and clears the hydroboost, still have to run the hard line down the remote slave but getting there..





I have the rest of the pieces from Ruff Stuff to complete my cross member so I will start on that tomorrow :)
 
#92 ·
Thanks for the detail on the clutch master cylinder- modification. I didn't think that the actuator rod was adjustable, but I see that it will be. I am guessing that there will be a turnbuckle installed on the threaded area to adjust for pedal placement. Locknuts are already there. Is that a Mini-Heim that you placed at the pedal arm or is there something that I am missing?
 
#93 ·
I cut and used a die to thread both sides of the original clutch rod, I drilled out the end of the rod just enough to go over the brake pedal stud (thats what I am using as a clutch pedal) - its not perfectly tight so it wouldn't be a surprise if i replace it with a mini heim or something later.

Yes I'm going to use a double threaded turnbuckle type of connection, got it at ace should work out for now.
 
#94 ·
Only welded a handful of times so my welds are not the prettiest - still working on my technique :)

Welded the pivot point, ironiclyhy the inner welds are better than the outside ones but seeing as this will be under the Bronco don't think anyone will see it.



Pivot point mocked up on the ZF



Anyway finally got around to fabbing up the crossmember however goofed up the driver side bend to clear the front driveshaft so I will be re-bending to try again as I have several feet of DOM left over so might as well do it right!



I goofed and shorted the distance on the loop... probably could have thrown something together but might as well do it right.



1350 rear driveshaft - waiting to install the rear pinon, need a inch pound torque wrench should be here tomorrow...



A few more little things done as well - hydro clutch is installed and bled, I rotated the transfer case up a bit and had to redo the twin stick linkage and bent the sticks to clear my legs :)

hopefully will have the cross member installed and painted by the weekend.
 
#99 ·
Well I like your welds- they look strong.....to me!!! I see what you mean regarding your mount. It still looks good though :toothless .
making tabs is a PITA, but you are way, way, more patient than I am. That is one FANCY cross member. You are going to have to lay a mirror in the grass when you park at bronco gatherings to show it off. However- pop those tabs off and if you are lucky- you can recycle them to there new location.

Now once you get this done you should have a bullet proof mount. I think you said that you are going Poly on the mount? If that is the case I would suggest that you do the same with your motor mounts. I am afraid that you made that mount so well the engine mounts will no longer do there job of absorbing ' torque shock'. They make the same type of mounts (pre-fab) for your engine as well, and would 'unify' your mounts. Another option is to deviate from the poly and use rubber instead at the trans/transfercase mount. which would also let your mounts work together. Just my .02, for what its worth.
 
#95 ·
Actually i messed up.. one of the Colorado Bronco guys just pointed out that I didn't isolate the transmission.. i essentially made a solid mount.. ha.. opps..

so I will go with my original idea and weld a small section of 1/4" plate to the bottom of the poly pivot DOM to the crossmember to isolate the trans or pull the end tabs off and cut reliefs in them to mount to the center poly DOM housing... opps - what was I thinking!
 
#100 ·
Allot was accomplished today -

Thanks to another Bronco member we were able to bend up the crossmember so that it was one piece. It was a close but got it to fit pretty well. After my last mistake of a solid mount I decided to mount the pivot joint right to the crossmember and added a couple of gussets to strengthen the pivot weld area.



I went a little crazy on the welding as this was my first fabrication and wanted to make sure the crossmember stayed together but all in all I am pretty happy with how it turned out.



all painted up..



Mounted up...





Hangs down about as far as the radius arms, when I go long arm they should be even...



Also swapped out the rear Yoke for a 1350.



I was going to try something with teh engine shielf but it didn't work out so I used it as an excersize to practice my welding. I cut the metal shielding and fitted it under the oil pan so that If I need to I can remove it and see whats going on with the throwout bearing and starter. Installed the starter as well, went with a 351w Auto mini starter.. hoping it works a quick peak showed i MIGHT have half engagement with the flywheel.. we will find out soon enough...



I will be drilling and bolting up the crossmember tomorrow, then installing the steering cloumn and see if this thing starts!
 
#101 ·
I was wondering if you were going with a mini starter. IIRC there should be a 460/Zf5 mini-starter, as I think I replaced one on an F-250 or 350 several years ago? My memory's not so great these days. But if there is one, that's the one you should be going with; half-engagement increases the chance of broken teeth.
 
#104 · (Edited)
Yes that spacer mounts between the flywheel and the crank, the bolts go through the flywheel and the spacer into the crank.

I have a 351W auto starter that should work - it has one of the longest throws I know of however right now its not engaging. Could be a few things but I will pull the shield off and take a look and see whats going on - i will probably have to leave the shield off underneath the starter and fab a shield anyway to gain as much engagement as I can.

Ran out time today to troubleshoot but everything is together so I expect I can figure this one out.
 
#107 ·
Pulled the starter and the shield off and everything looks good. I can see where the starter teeth have touched the flywheel it should be plenty to turn it. I sat underneath the bronco and had my wife turn the key a few times, the starter doesn't even touch the flywheel and needs to be moved in a bit. I dont really see any adjustment on the starter or the bellhousing, but honestly its cooooold out there and i called it a night after watching the starter miss the flywheel.

Is there something I am missing or am I going to have to slot the starter and or the bell housing?
 
#109 ·
Starter



You mean the starter gear is not close enough to the ring gear on the horizontal plane right? Like if you had the both sitting on a flat surface they would not touch? I think it's your starter since you said you are using a 351W starter.

I have both a small block and a 460 PMGR starter sitting here so I went and measured them. In relation to the bolt holes the 460 starter appears to be closer to the flywheel by about 3/32. I only have two hands so I couldn't hold the ruler in these pics as well as the camera LOL. The cleaner one with the blue spot is the 460 one.
 

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#113 ·
Landshark, I know what you mean about the oversize starters, been scrapping my spare old style ones LOL. They are a lot heavier too trying to get them up there and get the bolts in.

If you can compare the factory PMGR automatic trans starter (Motorcraft # F2TZ11002BRM ) to the standard trans starter (Motorscraft # F2TZ11002CRM) maybe you can answer why they have different part numbers. The one I have is an automatic one, I will try to take some meausrements of the throw.
 
#114 ·
The mini HT 400 starter (460 as well - same starter) worked.

A few nights ago I threw the seat in and reinstalled the steering column and took it for a spin. Man it shifts nice no more hulk shifting.

Still a little bit concerned about the throw out bearing, but as mentioned it seems to be the norm for it to touch a bit and I heard once the system is used for a while it will be ok.
Next up are new 3 point seat belts and figure out a couple of tunnel covers.

One thing I noticed was how poorly the seats are mounted. Won't get to it before Moab (end of April) but definitely will be figuring out a way to tie them into the cage before summer.

Guess I will post up some finish photos and a video or two to close out the thread. Will be next week before I can get to that.
 
#116 ·
got the floor patch in with the shift boots, works pretty good but will be taking the floor piece into line x to match the floor and help the heat and noise.







On the lookout for a bigger shift boot, will have to keep my eye out at the boneyard

so far so good, no issues and hope I dont have any in Moab in a few weeks :)
 
#117 · (Edited)
well after about 4000 or so miles the throw out bearing finally gave up the ghost and barfed its bearings out at the bottom of the inspection plate. I will have to pull the transmission off to see what caused it but i suspect its engaged just a bit too far and finally gave up.

I guess my two options are to cut and weld the fork so it angles back just a bit... or put a spring on the other end of the fork to pull it back off the clutch pressure plate. I am favoring the cut and weld option right now.

Any other ideas? The dodge bearing which i used (i think), seems like its the better option of the two to try as its thinner. I will check it against the other throw out bearing I bought...

Other than the throw out bearing its been a great swap so far. Consistently getting 14+ MPG, easier shifting and much easier on me and the Bronco when driving long distances.

I was about to pull it into the garage to fix the rear ARB as its leaking and suspect that its the seal housing or seals... have a feeling the line was installed short and not allowing the seal housing to move - which i guess its supposed to so will kill two birds with one stone ;)
 
#119 ·
I pulled the transmission and swapped in the dodge throwout bearing. The old throw-out bearing basically disintegrated into its basic pieces. It looks like there was quite a bit of heat generated which could mean it didn't like riding the pressure plate all the time but as pointed out I think the clutch fingers also had a role to play. I would need CSI to really find out what went wrong as there wasn't too much left as you can see from the pics.

The new dodge bearing is a bit thicker and it does ride the pressure plate quite a bit. I drilled a couple of holes in the fork while I had it out and plan on putting a spring to back off the bearing slightly. It only needs 1/8" or less to stop it from riding the pressure plate all the time.. should help.

Crossing my fingers as its not easy to stuff that zf back in an early bronco with a 400, takes some creative engine strapping to tilt things..





 
#120 ·
I'm surprised it lasted as long as it did. I had a 4 speed 70 SS Camaro back in the day (wish I had it now so I could sell it) and I adjusted it so it had no play (didn't know squat back then). Wasn't but a week and that thing was trashed. :popc1:
 
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