I have a 1986 Ford Bronco straight six 300 4 speed manual NP 435

She grinded a bit when shifting from a stand still but nothing terrible for an old rig but leaked oil bad from the rear main seal so I took out the tranny/t case to put in new clutch, throw out bearing, pilot bearing, and rear main seal. When I put it all back together shifting into 1st would grind like CRAZY. So would reverse but not near as bad. So I took it all back apart inspected everything even torqued the clutch to specification. Put it back together and same result. So I replaced the slave/master cylinder thinking the clutch wasn't pushing enough bench bled it and still no luck. Open to any suggestions

 

You might want to toss this question into the transmission section of the forums to get a wider audience, since the NP435 was in a lot more than Broncos (and more Broncos came with autos than manuals).

Clutch, Transmission, Differential, Axle & Transfer Case - Ford Truck Enthusiasts Forums

With 1st, you're talking about the actual granny low 6.69:1 1st, correct? (Just checking as lot of people see that as "low" and 2nd gear as their "1st".)

However, reverse and 1st are non-synchro'd, non-helical cut so it still is more than likely something to do with your clutch.

How are the other gears once you start driving?

Can you shift into 1st and reverse when the engine is off?

 

That is correct the granny gear 1st, took it for a test drive and 2nd gear grinded too, I did notice that if i hit the gas to up the rpms then shift sometimes it'd shift smooth but most the time it was REALLY stiff trying to shift and grinded. 3rd and 4th were good no problems there. Yes it does shift into 1st and reverse when powered off.

 

Hey abandoned Bronco I noticed your carb setup. How do you like the 450cfm? Any recommendations on what builds are good for the 300 I6 that's next on my list

 

How was the input shaft retainer when you put the stuff back together?

I know this isn't the same transmission, but I have a very similar issue with my T5 in the Camaro. It ended up being that my input shaft retainer (what the throwout bearing slides across) wasn't smooth enough and caused it so the clutch wouldn't fully disengage when pressing the clutch pedal. When I took down the transmission again, I lightly sanded and polished that shaft, then greased it up with wheel bearing grease so the throwout bearing slid very nicely across the retainer. I haven't had a problem with it since.

Another thing I'd take a close look at is the pivot ball the clutch fork rides against. If that is heavily worn, it will cause issues like you are describing as well. I don't know how the NP 435 transmission is setup, but I'd assume it has a replaceable pivot ball.

 

In '84 they went to hydraulic, which doesn't have the pivot ball anymore. Otherwise, I'd definitely be looking at the linkage. On that note, though, look at the arm that's on the end of the pedal shaft. Up under the dash, there's a long rod that the brake and clutch pedals ride on (about 1" diameter) and on the end of it, there's an arm that presses and depresses the clutch master cylinder on the firewall. Make sure it's still moving full swing when you press the clutch in. While you're at it, replace the bushing between the arm and the clutch rod. If that wears out, that arm is near irreplacable and has been discontinued (so take good care of it!)

It definitely sounds like a clutch issue, especially since it's doing it with the 1st and reverse.


I love the 450cfm carb. It's just about the perfect size for the 300. The QuickFuel carb is also insanely tuneable, which is great.

 

It ended up being the push rod on the master I though I had it set but my buddy went and extended it and now she rides like beaut still some slight grinding but the more what you expect with a 250,000 tranny.

Kewl, the carb is the next thing I'm looking to upgrade I know I'll need to do an intake and possibly headers but that's an area I'm not familiar with so I gotta do some research

 

That'd do it! Basically like trying to shift with only pushing the clutch pedal partway down.
Still... replace that bushing.

TONS of info on the carb and exhaust upgrade over on the 300 dedicated forum. www.fordsix.com as well.

 

I'll make sure to check that out, is there an official name for that bushing or is it pretty easy to find one if I remove it and take it into a store?

 

I tried numerous parts stores and they usually pointed me toward their universal kit, which has around 5 - 10 different bushings of different diameters in it. None of which fit.

I think it comes down to the fact that they only used the setup for 3 years. They switched to the hydraulic clutch in '84 and then redesigned the whole thing in '87 with the new body style.

However, I found that this one worked.

Dorman 74014

https://www.amazon.com/Dorman-74014-.../dp/B009XA8IP2

It just needs to be modified slightly with a pair of snippers or a razor blade. It'll "work" as is, but you won't be able to put your cotter pin back in, so the arm will occasionally fall off and your pedal will go to the floor. Not good when you're going through an intersection, as I found out.



If you cut that end part off, you can put your cotter pin in, and off you go. My clutch is so much smoother now, and it's worked great for a year or more.