Alright. As some of you may already know, I'm fairly new here and have been trying to straighten some issues with my engine.

Next on the to-do list is my transmission and right now I'm in the 'research' part of it.

I have the 4-speed tranny but it seems likes there's two options possibly (?).

My current dilemma is that my trans won't go into gear using the clutch. I have to float it in so I'm guessing the synchro is out, correct me if I'm wrong.
I've been trying to find a good write up on a rebuild from removal of trans back to install. In searching for a good writeup I found that some have done some trans swap. I was thinking of going that route too. I'm trying to get whatever better gas mileage that I can. I know I'm not driving a Prius nor an ol' 12 valve cummins but just trying to get a lil more mpg. My first thought was to rebuild the current trans and add bigger tires. Or do a trans swap AND bigger tires. What do y'all think or recommend? All input, good or bad, is welcomed. Thanks

 

Oh btw, it's a 75 hb

 

You are correct in that your synchro's are probably gone.


However, a quest for mileage with bigger tires is unlikely to work. Bigger tires are also heaver, making any effective gearing gain a wash. A trans swap, to like a ZF, is unlikely to ever pay for itself.


Your biggest mileage gains will come from having everything tip top, no vacuum leaks, timing set correctly, etc. Then, go on to headers, exhaust.

 

Thanks. The tip top part is what I'm working on now. But I guess I also want to be able to cruise down the road without feeling like I'm at WOT. I looked at gear vendors over/under but that seems unrealistic to me right now. As far as the tires, I'm running 33"s at the moment (came with the pickup). I just wanting to upsize to 35"s possibly 37"s

 

I just drive slower lol. But yes, 4.10's and no OD... you're not keeping up with traffic.


Try Randy's Ring and pinion calculator to show what kind of rpm drop you get with bigger tires.

 

Is rebuilding the transmission a difficult task? Or is it pretty straight forward? Thanks

 

If you're mechanically inclined, and have a copy of the factory service manual, it's pretty straightforward (great instructions in there). Some manual transmissions require a press to assemble/disassemble; not sure if these do or not.

 

Ok sweet. I don't have a press if needed but I'm sure I could take it to shop. Any recommended places to get the manual?

 

You can generally find both original printed copies and CDs on eBay.

 

Sweet thanks. Hopefully it isn't too time consuming.

Without the synchro(it being destroyed inside), is it possible that it could damage my transmission? It feels like it's getting worse. There's some clatter every now and then, but I can't really pin point it to either associate it with the trans or engine. I really need to pull the pan and check the bottom end to put my mind at ease.

 

Hi,

When you say that you are having trouble getting the tranny into gear, do you mean any gear? What I'm getting at is if you are setting still and trying to get into gear and it grinds that could be a clutch issue.

If you are getting a grinding sound while shifting the other gears then "yes" that could be worn synchros.

First, you need to identify which tranny you have as I think Ford used 2 different 4-speeds. Crawl under and look for a data tag on the tranny, also see what type metal the top cover is made of: Aluminnum will be a NP-435, steel will be a T-18 (if memory is correct ;-) ).

My truck has the NP-435 and I rebuilt it many years ago. I bought the rebuild kit from:
Parts for the New Process 435 Transmission

Rebuild was straight forward, only special tools required are a Dial Indicator to check the Run-out of the input shaft.

I did also have to take one of the shafts to a Machine shop to have an old bearing removed and a new one pressed on.

Take care and if you have more questions... fire away.

 

It just third gear that doesn't go in with clutch, I have to float it in.

So the easiest way to check what trans I have would be to use a magnet right? If it sticks it's steel, if not then aluminum right?

 

A magnet would work.

Or just take a rag under there and wipe the top cover off. If it's not rusted steel and looks like "white" metal it's aluminum.