The Transmission in my Bronco has a 152,000 Miles on it. I started hearing a tapping noise when the Bronco was under load in fourth gear. I assumed it was the valve train or a transmission problem.

Since I have already removed the Trans form the Bronco in the process of repairing the Rear Crank seal. While removing it I popped the Rear output shaft form the case. I decided it was time for a rebuild just to be safe.

My Transmission is a 4 speed Manual produced by New Process Gear. The NP435 used by Ford form 1964 to 1987 in there truck. This Trans was used in the One tons too so it will handle the big block power. They have also been called a granny Tranny

The NP435 can be identified by the following characteristics:
• Top loaded, tower shift
• cast iron case and rectangular aluminum top (that is retained by eight bolts)
• This transmission is 10.8" long eight bolts.
• The Ford NP435 has a 1-1/16" diameter, ten spline input shaft that has a stick-out of 6-1/2" from the front face of the transmission.
• The front bolt pattern is the symmetrical Ford "butterfly" pattern; roughly 8-1/2" wide by 6-5/16" tall.

This Trans is also on the low tech side with its non-synchronized in 1st gear. Second gear through 4th synchros are aluminum ring/pin assemblies and the 3rd/4th synchro has outer "pie plates". There are no brass synchro rings.

The shifting pattern for all of the 435's is in the standard "H" pattern with reverse gear being to the right side, and down.
Gear Ratio
NP435E (Ford)1st 6.68, 2nd 3.34, 3rd 1.74, 4th 1.00, R8.26

The Ideal Lube for this Trans is An 80W-90, API-GL5 or MT-1 rated Gear Oil

Here is were the work begins. With Trans out of the Bronco you can see it has almost 30 years of funk on it.




I started to clean the case up to get it ready for paint and the rebuild.





I then removed the eight bolts form the top cover of the transmission. I tagged and bagged the Bolts Like CSI. So I get back together correct.



Here are some pictures of the inside of the transmissions, and the shift forks.






More to come.

 

All of the Gear in the top portion of the transmission are in good shape. The Part that has started to go bad is the 3/4 gear sycro. It is the portion that looks like metal pin sandwiched between two pie Pans. I will not know the Condtion of the lower gears till I get it a part. That should be this Wed cause I am taking a mental health day form work.

 

Those are big globs of Grease that fell into the case. The gears is in good Shape.

 

Well I took a mental health day form work. So I did some work on the transmission.

Here are some pics of the tear down.





Here is the case completely empty


Here is the case completely cleaned and degreased.


I masked off all of the Area on the Case were the seals go.


Here is the Case painted with POR-15


Here is as for as I got today. A coat of Ford Corporate Blue engine enamel.


More to Come.

 

What is it that you are changing out in this rebuild?

 

All of the gears are good. I will be replacing all of the Sycoros, bearings and seals. I will also be repalacing all of the Shift tower parts.

 

I am glad I bought the factory servise manual.