1981 straight six manual 4x4 project

Thank you very much Cory! 😀If/when you get a chance to go get it, let me know what I owe you!

Man what an incredible thread! Great work and thanks for documenting it all! I have a lot more reading to do to follow everything but I'm hooked.

Ferdinand wrote

Man what an incredible thread! Great work and thanks for documenting it all! I have a lot more reading to do to follow everything but I'm hooked.

Glad you enjoyed it... and I have sure gotten a lot of help, parts and advice from the members here! Unfortunately I don’t have any truck time to continue the build at the moment, but it will resume once I have the new house to a livable state. I still have so much I want to do...

Well crap 💩. Less than a year since I swapped transfer cases to fix my speedometer and it’s already done. The green drive gear inside is Apple core’d and ruined. The cable feels pretty stiff. It was brand new when installed, but was an aftermarket part. The driven gear seems okay, but that’s little consolation since that is the easy one to find, and the drive gear is unobtanium. As much as I like the 1345 this stinks. I may have to consider a 1356 and a new driveshaft if I want my speedometer to work. 😡

Bummer!  Something isn't right.  Why do you think a 1356 would be better?

Gary, the 1356 is actually a down grade in my opinion on account of the rear slip yoke. Four wheelers buy SYE’s (slip yoke eliminator kits) to remove this weakness but they are not cheap. The reason I am considering it is because you can still buy the drive gears for the 1356 for about $15 bucks.

I have a 1356 laying around, but it was rode hard and put away wet from what I can tell, and my current driveshaft is a slip shaft so I would need to have one made. You can’t find rear shafts in the junkyard because they bend them when they forklift the trucks. I’ve never seen a straight one except for ones that were removed and in the bed or something. At this point I’m not paying to build a driveshaft just to get my speedometer working. Maybe later...

Oh, and to answer your question, I think the problem or reason for failure may be an inferior quality aftermarket cable. It is not seized up but has way, way too much resistance. ☹️

Yes, I thought the 1345 to be the better t-case.  But I understand.

Just download a speed app and put your phone on the dash.

Jonathan,

http://laspeedometergear.com/IMG_20130430_064027_868.jpg

http://laspeedometergear.com/Ford%20STD%20driven%20gears.htm

????

David

Thanks David, those gears look like 1356 or other transfer case drive gears. The 1345 has a metal sleeve. Cobra transmissions used to carry them, but I contacted them a year ago and they no longer had any (in any tooth count) and did not expect to be able to get more. Unfortunately this is just “one of those things”. I may be able to find another good junkyard one, but they tend to all be Apple cores as well. Seems like it’s the weak link when the cable gets stiff or seizes up.

Stolen from Corey’s thread... hopefully you see this Steve...

Steve83 wrote

The '87-up (Aluminum) master cylinder & integral residual-pressure valve...

Steve83 wrote

If you're using the later brake lines (no proportioning valve), connect the rear one to the RPV.  If you're using the old lines & prop.vlv., open the RPV, remove all its guts (so that it just becomes an adapter), and then adapt the old rear line to fit the RPV housing (as my earlier pic shows).

What would be the symptoms of having both the early proportioning valve AND a functioning RPV in use? I believe this is what I unknowingly did when I converted to hydroboost and installed the 1995 F450 master cylinder in my ‘81. I saw that post and it makes me wonder if that might be a factor in my rear brakes locking up easily?

Good question.  And did Jan convert the same way?

Gary Lewis wrote

Good question.  And did Jan convert the same way?

No. He used the original cast iron master. But if memory serves he had the same issue before converting (which makes sense). He said he didn’t use the F450 master because he thought it had bad seals or something along those lines. I was actually hoping a different master cylinder would solve his problem.

Gary Lewis wrote

Good question.  And did Jan convert the same way?

First we need to know what RPV stands for?
RPV = Reduce Pressure Valve
RPV = Residual  Pressure Valve

From what I know of doing drum / disc swapping on AMC’s there is a master for drum / drum and disc / drum brakes.
The drum / drum master has valves in it on both ports, RPV = Residual  Pressure Valve, that keeps a little psi in the lines to over come the spring pressure in the drums.

The disc / drum master only has the valve on the drum side,  RPV = Residual  Pressure Valve, that keeps a little psi in the line to over come the spring pressure in the drums.

Could this “adaptor” on the alum. Master be this RPV = Residual  Pressure Valve to the rear drum brakes? It sounds like it if you are pulling the guts out when going disc / disc brakes but not if you are running disc / drum with the balance valve (see below).

Now this has nothing to do with the portioning valve down on the frame of our older trucks. This has 2 functions. To balance the brakes front /rear (RPV = Reduce Pressure Valve?) & to set off a light when there is low psi on either front or rear of the system.
Other than the light you can get an adjustable balance valve thru any of the on line speed stores and this may work better as you can “dial in” the balance your truck works best with.

So what is this RPV on the ALUM. Master, what does it do?
Dave ----

btw: when AMC first started installing disc brakes they put the "balance" valve at the rear on the frame rail, looks like a square coupling.
They still had the pressure valve under the master on the frame rail to set off the light if the system lost psi on 1 side.
You could use a drum / drum master on a disc /drum car by pulling the flare seat out of the port to the disc side of the system, remove the guts (spring & check ball) and put the flare back in.

Ford F834 wrote

What would be the symptoms of having both the early proportioning valve AND a functioning RPV in use?

I didn't want to find out, which is why I gutted the RPV (residual pressure valve) on mine.

Ford F834 wrote

...if that might be a factor in my rear brakes locking up easily?

I guess it's possible, but I doubt it.  It's more-likely (IMO) this:



...or this:

Thanks Steve, I hadn’t thought about the shoe material, but I guess that is a possibility since I just bought what was on the shelf at the parts house. It may be something that does not behave like OEM. I don’t think mine is at all cold or weather/moisture related, as it is always the same and happens in 120*F weather after hours of use.

I cleaned and lubed the obvious moving points, but the diagram shows more minor ones that I missed. It does not seem that it should be that sensitive but maybe it is?

Ford F834 wrote

It does not seem that it should be that sensitive but maybe it is?

I've noticed a BIG improvement when the whole system is clean, lubed, & adjusted - on ALL vehicles' drum brakes; not just these.  For me, it ranks close to battery terminals in importance.

Good advice Steve! I did lube the adjuster, pivot points, and cylinder rod ends, but I didn’t know about the backing plate contact points, adjuster cable, and notches in the shoes. This is a good list/illustration 👍

A couple years ago when you were putting in the 1345 you identified that one had an input sleeve that stuck out further than the other. I just found the same today. The one I pulled out of my truck has the sleeve that sticks out but the one I was going to put in is flush. The flush one has the GV overdrive back half which is the reason for the swap.

Any idea why the difference and does it matter or are the TC's interchangeable? I can swap the back half between the two units, but just didn't want to split open the one that came out of the truck if it isn't needed.

Great info in this thread by the way.

Thanks! The transfer cases swap just fine. I’m guessing the longer sleeve on the front end may have been a strength upgrade? As mentioned recently in Gary’s thread the one with the longer sleeve also had the shift lever pointing up instead of down, and shifts by rotating ccw instead of CW. My linkage still works but the lever is mashed pretty far forward in 2H and at some point I may shorten it. That would be the other difference to check.

If you do end up splitting the case to move the GVOD rear half, consider modifying the pump anchor while you are in there. That is one thing that can make these catastrophically fail. I didn’t do it on mine (yet) but I intend to do it on my diesel’s T-case, and I will do it on my 81’s T-case when I fix the speedometer gear issue...