FJ55 rear third member compatibility (1 Viewer)

Joined
Apr 21, 2005
Messages
19,892
Ahhh ok

I I got a 73. Just missed it

the triple drilled flanged off trail gear will work?

Can't answer that the switch in the 40/55 series was right about the change to a four speed. Not sure why the 60 series changed 8/84 that was three months prior to the start of the 70 series. Not that we got any here but show the late 4X series changed 8/84 as well.
 
Joined
Aug 29, 2020
Messages
12
Location
new jersey
Hmm Interesting. But wait, why can’t I take the flange off my ‘55 third member and put it on the 60 series third member??
 
Joined
Apr 21, 2005
Messages
19,892
Hmm Interesting. But wait, why can’t I take the flange off my ‘55 third member and put it on the 60 series third member??

Has to do with fine spline pinion on the 78+ pinion and the earlier coarse spline. Then their is the issue of 4.11:1 ring and pinion and the 1/79-7/87 3.70:1 ring and pinion. Could use a 1/74-8/84 flange off of a driveshaft shaft U joint to handle the flange issue. Still leaves the difference in ring and pinion gearing.
 
Joined
Aug 29, 2020
Messages
12
Location
new jersey
Has to do with fine spline pinion on the 78+ pinion and the earlier coarse spline. Then their is the issue of 4.11:1 ring and pinion and the 1/79-7/87 3.70:1 ring and pinion. Could use a 1/74-8/84 flange off of a driveshaft shaft U joint to handle the flange issue. Still leaves the difference in ring and pinion gearing.

No that’s ok. That’s actually the whole reason I’m putting the ‘84 gears in because I want the 3.70 ratio. I’m using a TH350 3 speed trans in my fj55 and want good highway gearing. (I’m not wheeling this)

I’m reading that I can drill my own holes or buy a multi hole flange. So that answers my question. Thank you!

Another question/s for ya if you don’t mind!!

I noticed the pinion seals were leaking bad, so I took one of the nuts, then washer off but didn’t do a good job of counting the threads, the flange came right off with no effort, and there’s lots play in the shaft...like moving up and down (FYI not educated on this at all)

I keep hearing mix reviews but I fear I might have screwed up preload.

Do I really have to get some to take apart the entire diff now?

what’s the trick to doing the next one so I don’t have to go through that? just being more careful and counting the threads?

If you don’t mind I have another question out of pure curiosity...thanks for listening so far.

I can tell the gears I picked up have a lot of miles on them. I was thinking...what if I take ‘84 third member that was originally in the FRONT diff and put in the REAR of my fj55.

Im thinking the front has a lot less wear and would be a good idea to put in the rear for reliability. Especially since I don’t wheel.
is my thinking over-the-top?
 
Joined
Feb 6, 2002
Messages
15,248
Location
OC, CA
You should be able to tighten the pinion nut to remove all the play. The nut should have a deformed lip that was “staked” into the slot cut across the pinion threads. If you are using the same nut, tighten it until the staked part is just past where it was originally staked and stake it again. It is best to check the preload (turning force) before and after tightening the nut. It should be no more than 20 inch pounds higher than before tightening it.
 

cruiseroutfit

Supporting Vendor
Moderator
Joined
Jan 9, 2003
Messages
10,394
Location
Utah
possible to get more info on this?
Im about to put fj60 third members in my fj55

So I can’t take my 55 flange and put it on the 60 third member??

where can I buy a flange that fits?

Depends on the year of your FJ55, nearly all have a course spline pinion flange and all FJ60’s have a fine spline. Easy fix:
 
Joined
Aug 29, 2020
Messages
12
Location
new jersey
Thank you all.

i recently ordered a 373HP Chevy 350 crate from blueprintengines.com with a holley sniper.
I figured with the sniper kit, I’m @ at least 400HP

more than I want or need.
Will my stock fj55 drive train be ok?
I’m on 33” Tires.
 

Users who are viewing this thread

Top Bottom