Tim D. - 1973 Bronco Build

[Tim D.]

1973 Early Bronco

Plan of attack/proposed specs:
1973 Early Bronco
302 (until I build the 351W)
NP435
NP203/NP205 Short Shaft Doubler
HD D70 Rear
HP D60 Front
4.56:1 Gears--120:1 Crawl Ratio
Cage 5.5" Coils
Cage 5.5" Leafs
Cage Long Arms w/SAS Brackets
Cage Shock Hoops
Cage 14" Travel Shocks
38.5" Swamper SX's on HUMM-VEE Beadlocks

NP203 Rebuild:

Here’s what I picked up for the rebuild:

1978 Light & Heavy Truck Factory Shop Service Manual:

Transmission Exchange Company NP203 Rebuild Kit:

This is what I started with: NP203 Range Box and Front Output

Cleaned the case up a bit before digging into it:

1. Sprayed PB Plaster on the Poppet retainer and remove it, and the poppet spring:

2. With the poppet retainer and spring (as seen in the pic) were removed, I was able to remove the shift fork and sprag:

This is what it looks like with the above parts removed:

3. Next I pulled the shift levers and range selector shaft as well as the poppet plate:

 

[Tim D.]

4. I then pulled the lock-out selector haft out:

5. After that was out, I removed the input bearing and bearing retainer and pulled the input out:

6. Then I knocked out the counter shaft and pulled the counter-gear assembly out making sure not to loose the 72 roller bearing, spacer, and thrust washers:

Empty Case:

7. Cleaned-Up all the parts with Castrol Super Clean in my "parts washer":

 

[Tim D.]

Clean Case:

Time to put it all back together

8. I put everything back-in in reverse order from that of taking it apart. First came the cluster gear. I coated 72 new roller bearings, the thrust washers and spacer with Vaseline and placed them inside the cluster gear:

It seemed that after I pulled this can out, my friends decided it was time to leave, how come??:

9. Thrust washer in place and coated with Vaseline to keep it in place:

10. Cluster gear/thrust washers in place, counter shaft installed:

11. Slid the input gear back in place:

 

[Tim D.]

12. Installed a new input-gear bearing and snap ring:

13. Installed the bearing retainer with a new gasket:

14. Put the shifter shafts back in with a bit of gear lube and new o-rings:

15. Put the shift-fork, sprag, poppet, poppet pin, poppet spring and retainer back in:

Front Output Rebuild:
Here is the front output with low range gear, output bearing, spacers and thrust washers:

1. Took it apart – removed 2 snap rings and everything came apart. To the parts washer (oil pan full of Castrol Super Clean):

For the doubler kit, I have to modify the front output bearing retainer by removing a key:
Before:

After:

 

[Tim D.]

2. I installed a new bearing in the retainer then I put it all back together – excluding 2 thrust washers, 1 dowel pin, 1 spacer and the original output shaft – necessary for the doubler kit:

Factory shaft on the left, Doubler shaft on the right:

3. I then installed 15 roller bearing in the input shaft coating them with Vaseline and installed the output assembly in the case:

Here’s what I’m starting with:

NP435 Rebuild Kit: From Novak Conversion INC.

 

[Tim D.]

1. Starting the NP435 rebuild:

2. Pulled the throw-out bearing, clutch fork and bellhousing:

3. Removed the shifter by pressing down on the cap and rotating:

4. Removed the top-cover:

5. Internals: First speed/reverse gear on the left, second speed syncro, second speed gear, third speed gear, third/fourth gear syncro, fourth speed gear. Reverse counter gear upper left.

6. Removed the input shaft bearing retainer:

7. Pulled the input out, then slid the mainshaft back and tapped the bearing off. Then tilted the shaft upwards and pulled it out:

8. Counter-shaft and reverse counter-shaft:

 

[Tim D.]

9. Tore the mainshaft down by removing the snap rings and sliding the assemblies apart:

10. Cleaned everything up:

11. The new short-shaft for my short shaft doubler kit above, the old shaft below:

Assembly:

12. Clean Case:

13. Tapped in a new Torrington bearing, put a new thrust washer and slid the countershaft back in:

14. Pulled the roller bearing race out of the retainer with a 3-jaw puller and a bung placed in the bottom:

15. Installed a new roller bearing race, cage and rollers in the retainer. Intsalled a new thrust bearing race and thrust bearing. Installed bearing retainer:

16. Installed a new syncro brake on the second speed gear, slid it on the new mainshaft and installed the retaining ring:

17. Slid the third speed gear on the shaft:

 

[Tim D.]

18. Installed the whole pack of syncro shims and slide a syncro outer ring on, along with the syncro clutch drive gear:

19. Slid the third/fourth speed syncro on along with the front outer ring:

20. Put the mainshaft assembly back in the case and pressed the rear mainshaft bearing on:

21. I now had to remove the input shaft tapered roller bearing races. I didn’t have a puller long enough to remove the bearing from the shaft so I tried heating it, hoping it would relax enough to slide off with a few blows from a hammer. Didn’t happen. So then I figured if I took a cut-off wheel on the dremel and cut a slit as deep as I dared I’d be able to crack the race with a blow from a cold chisel. That didn’t work either. So I moved on to the retainer. The bottom of the retainer is blind, where by no means can you get a punch or puller behind the bearing, as it is pressed up against this surface. Here again, I tried cutting the bearing and hitting it with a chisel, hoping it would crack. No worky, I did however end up getting part of the race to shatter and imbed in the knuckle of my finger. The solution was to plunge a solid carbide 4 flute endmill close to the wall of the retainer and down through the race. This allowed the race to relax enough to be removed. For the shaft, that race was removed by turning it down on the lathe.

Bearing Race after plunging a solid carbide 4 flute endmill, this relief allowed the race to relax enough to be easily removed:

What remained of the race on the input after turning it down. Just had to split the rest with a hardened pick:

 

[Tim D.]

I put the input shaft in my mom’s freezer along with the retainer race. I set the oven to 200deg and put the input bearing and the retainer in. After the parts had become cold/warm, I was able to slide the corresponding components together:

Installed the roller bearings in the end of the input with Vaseline. Installed the thrust washer and retaining ring then loaded the assembly into the case.

This is where my brother called and I stopped taking pictures. First off, I set the endplay on the input/mainshaft. This is established by the thickness of gasket used behind the retainer. I put everything together sans any gaskets and measured the gap between the case and the retainer with some feeler gauges. To this I added the amount of desired endplay and selected the proper gasket combination. I then reinstalled the retainer, this time including the gaskets and set-up a dial-indicator. I zeroed the dial with the shaft pushed all the way back and then pulled the shaft forward. I adjusted gaskets till this reading was acceptable. NOVAK says the endplay should be .001 - .005, Ford says the endplay should be .007 - .017. I ended up with .010 and can’t get any lower with out getting some different gaskets. After this was established, I set the syncro back-off by adding subtracting shims. This is supposed to be set to .050 - .070. I ended up with .058. To do this, measure the gap with a 2 sets of feeler gauges, remove/add shims as necessary, re-measure, and re-adjust until correct. After setting the back-off, I rechecked the input end play.

Measure back-off between the syncro drive plate and the input gear:

Case all buttoned up and ready for paint:

Everything is being painted with the color scheme of choice:

NP205 Rebuild:

Rebuild kit from Transmission Exchange Company:

What I started with. Just like the rest of the driveline, caked with an inch of dried gear oil mixed with dirt and dust. Someone wasn’t concerned with leaks too much.

1. Sprayed down with engine-brite. I worked the biggest part of crud off with a wire brush and then hauled it off to the local coin-op for a shower:

 

[Tim D.]

2. Semi clean case ready for disassembly:

3. Unbolted the adapter and removed it along with the shifter and linkages:

I didn’t accomplish as much as planned over the weekend. The town summer festival was in full swing so I went out and spent some time with the friends. Also ran out of supplies so that slowed things down to. I did manage to tear the case down, clean all the parts and assemble the rest of the drive-train that I had painted.

4. First I pulled the yokes off. Them things were stinkin tight, had to resort to the persuader. I’m quite satisfied with it, all the power I’ll ever need out of a ½” drive:

5. Taped the front output shaft rearward to knock the bearing retainer loose, then I slid the front output assembly out the back:

6. Removed the rear output and front out bearing retainers. Pulled the input/rear output shaft assemblies out:

7. Knocked the freeze plugs into the case in order to gain access to the roll pins in the shift rails. Knocked the roll pins out with a roll pin punch and removed the shift forks and shift rails:

 

[Tim D.]

8. Removed the locking nut for the counter shaft and removed the backing plate. Knocked the shaft out of the case and carefully removed the counter gear, bearings, thrust washer and shims:

Doubler Assembly:

Painted all the components and started putting things together.

The gear teeth that engage the sliding clutch to select low/high were eaten up bad, to the point that on the low gear only half the tooth width is remaining. Appears someone tried to change range while moving at a fair speed. Gonna try and track down some new parts and at least see how much they cost.

NP205 Assembly:

9. Cleaned all the parts with Castrol Super Clean. Warning, aluminum parts left in Castrol Super Clean over night will have a thick crystalline, salt-like form of oxidation. This mess is very concentrated at the fluid line and though not as thick, but still occurs below the fluid level.

10. First step was to knock out the old bearing races in the idler gear and replace with new tapered roller bearing races.

11. Next I assembled the idler gear and shaft with its bearings, shims and spacer in order to set the preload. I then laid a tapered bearing on the bench, set the idler gear on top of it and continued the assembly: bearing spacer, shim pack, and bearing. I then slid the idler shaft through the assembly. I made a spacer to slide over the end of the shaft, slid on a thick washer the nut and torqued the assembly to 150ft/lb. Then, clamped in a vise, I set up a dial-test indicator and measured the play. When the nut is tightened, the two bearings sandwich the spacer and shim pack. The more shims you add, the more endplay you have, and vice versa. It is very important that the spacer/shim pack be compressed. If those units are loose after tightening the nut, you do not have enough shims; the bearings will fail in a short time frame. The book calls for .000 to .002 of endplay. I set mine up with all the shims I had and had right around .0005 of endplay. It felt a bit tight by hand, but the shims and spacer were properly compressed and the number is within the limits as specified by Ford.

12. Then I lathered up the new thrust washers with Vaseline and put them in there place in the case. I then very carefully (trying to keep everything together) slid the idler assembly in its place. Once satisfied, the idler shaft was slid through the assembly and pressed in place and the lock nut torqued to 120ft/lbs. Then came a new input bearing and the input shaft.

13. Then the sliding clutch was lubed and installed along with the shift fork.

14. I don’t have any in-process pics, but the rear output assembly was rebuilt with new roller bearings in the bore, new rollers for the low range gear and a new thrust washer pin. Here it is installed in the case.

 

[Tim D.]

15. I then moved on to modifying the shift rail for independent range operations of the front and rear outputs.

This is the rear output rail, (rail closest to the input), it is the rail that must be modified.

I completed this mod by extending the rear detent by 0.4375 (7/16). This material was removed to the original depth of the detent. I then modified the front detent by also extending it 0.4375. However the detent was extended while maintaining original taper. Thus material from the flat in the bottom must be removed. I was careful to only remove as little material as I had to so that engaging one output in high while the other is in low is not possible.
Before:

After:

While waiting for parts I painted the t-case and finished assembling the rear output. Pressed a new caged roller bearing in the tail-housing, installed it, a new output bearing, and the bearing retainer.

The gear and yokes I ordered came in so I was able to finish the rebuild.

1410 U-Bolt yoke compared to the stocker:

The new front output high range gear compared to the old:

16. Rebuilt the front output shaft with new roller bearings and a new high range gear:

17. Installed the shift rails:

 

[Tim D.]

18. Installed the front output shaft assembly and slid the shift fork onto the shift rail:

Finished product, minus the yokes:

picked these up: '78-'79 Ford HP D60, Ford MotorHome D70

Chassis Build:

Started with a 1973 stock rolling chassis: Out with the Old,

Sand blasted and primed the frame
The factory weld quality of this thing is really poor:

 

[Tim D.]

Went around and rewelded stuff that is not going to move during the build:

Frame up on stands and leveled:

302 back in (until the 351 is ready)
NP435 in
NP203/NP205 Doubler in
9” back (for setup only)

 

[Juntura]

Nice work! Thanks for all of the photos and info. Amazing how poor some of the factory welds are. The welds on the '66 Bronco I just picked up are way worse than anything I saw on my '66 F100.

 

[bax]

Great post. lots of good pictures and info. love that doubler, it sure is purdy.

 

[73stallion]

looks like a killer tech article!!!

 

[crawln68]

Hey Tim,

Really nice work so far. I found some pics of mine during my build for you. Here is waht mine looks like. I think you will need to lower your t-cases a bit. If you leave them where they are, you will have body fitment issues. Where I left mine, I had to notch into my floor panels to clear the 205. I have a 2 inch body lift on mine. If I was running a 3 inch body lift, I MIGHT have cleared the floor with out cutting into it.

 

[carterb]

Awsome Post!!!!
Great Info

Keepem Coming

 

[Mtn Gote]

OMG! Your avatar is so true! Your a mad scientist! Great tech write up!
Cory,