Vacuum diaphram replacement

[IDoc]

Hi all, first post and new '71 fj40 owner. I have done a lot of reading the past few days and found great info on this forum that led me to diagnose my problem. I believe the vacuum diaphram is ruptured. I have taken the four bolts that hold the vacuum assembly to the tfer case out. How do I get the front drive fork loose so I can get the whole assembly out? Any info would be greatly appreciated.

 

[Poser]

Welcome.




If the bolts are out you should be able to move the whole assembly for and aft just a bit to get the fork lined up with the opening in the nose cone...

 

[IDoc]

Thanks, I got it out, guess I wasn't holding my mouth right. Took the cover off and the diaphram looks brand spankin new? If you blow in on one of the vacuum lines, air seeps out of the other.....correct me if I am wrong, but that shouldn't happen should it? Any ideas?
Thanks

 

[Poser]

Thanks, I got it out, guess I wasn't holding my mouth right. Took the cover off and the diaphram looks brand spankin new? If you blow in on one of the vacuum lines, air seeps out of the other.....correct me if I am wrong, but that shouldn't happen should it? Any ideas?
Thanks

Something is preventing it from being sealed properly. If the diaphragm does not have a hole in it, then there must be something else creating this vacuum leak....

 

[Coolerman]

Rebuilding the 3 sp T-case: Reassembly Page 2

That link may help.

Was this working in the past then just quit? If so, I would suspect a pinhole around the edge of the diaphragm where it flexes. Possibly the J bolts somehow worked their way loose, and/or one of them is missing?

https://forum.ih8mud.com/40-55-series-tech/248970-transfer-case.html

That link will take you to a thread that discusses exactly how the vacuum shifter works.

Are you hearing a constant hiss of air from the other port when you put air in the other or just a puff? If just a puff it is working correctly. Do NOT apply a lot of pressure to either port! You might rupture the diaphragm.

A better test is to suck on one port. (No wise cracks please! )
You should see the shifter move. Then suck on the other and the shifter should move the other way.

 

[IDoc]

Thanks for all the help, the rebuild thread was very helpful. When you put air in one port, a constant hiss of air comes out of the other port. I will look at the diaphram better when I get home.

 

[IDoc]

Ok, here is an update...Found a hole in the diaphram. I ordered a new one and replaced it tonight. Could move the fork both directions by applying air to either port. Jacked the cruiser up, locked the hubs, put it in 4 and no movement of the front tires no matter what position the front drive pull was in. How do I diagnose if the vacuum valve should be rebuilt/replaced?

 

[Coolerman]

Are you sure you got the shift fork placed in the shift collar correctly? It goes around the center groove of the collar.

Those links I posted earlier have pics of the shift collar and fork placement.

 

[spdwaver]

Are you sure you got the shift fork placed in the shift collar correctly? It goes around the center groove of the collar.

Those links I posted earlier have pics of the shift collar and fork placement.

I am thinking the same thing here: the previous owner of my 40 had installed the shift fork outside of the collar. This resulted in extreme wear to the fork.

The end results:

The collar survived.

 

[IDoc]

OK, shift fork is in the groove and the collar is in correct postion....I have four wheel drive! Amazing what happens when the fork is in the groove. I need to rebuild my vacuum valve since the only way to get it out of 4 is to switch the tubes leaving the valve (only one side sucks no matter what you do with the pull knob). I think this should be easy to do. Thanks for all the help.

 

[cruiserbrett]

the OEM toyota rebuild kit for the vacuum solenoid is still available, and cheap. last time I ordered one it about $10. comes with new seals, etc. save all the old parts as I needed two springs in my solenoid and the kit only came with one. Tape and a touch of weatherstripping adhesive helps keep the thin cork gaskets in place...

-Brett