'82 FJ40 Prebuild thread (1 Viewer)

[Panzer]

Since we have been long on admin posts and short on LC tech for a while I thought I would kick off the winter build season with the following....

In short I am about to pull the trigger on starting my 40 build.
SOA vs. SUA-I am aware of the pros and cons of each option.

If I go SOA-that would lift my truck about 4.5 to 5.5 inches.
Wardens style SR that should move the front forward 1.5 and then run 60 rears (or 55 rears) to get the 2-3 inch aft move on the rear axle.

If I go SUA- no SR- the lift would be about 4.0-4.5 inches.
Front- HFS 4 inch 40 front springs, flipped with the mil-wrap leaf turned around and redrilled. (I think)
Rear-HFS 4 inch 60 rear springs or flipped HFS 40 4" springs

The endstate goal is low and stable as possible on 35's so..
SUA is my choice.

What I need to figure out is the axle placement.

Since I am starting from scratch I can pretty much set the axle postion and then work the other components around the positioning.

What I want to do is move the front axle forward about 1.5-2.0 inches and move the rear axle back 2.0-3.0 inches.

This is where I need some help:
I need the overall length, the short side eye to pin and the long side eye spring measurements so I can figure out what I want to do.
I searched, Mud and Pirate and so far have found some overall measurements of stock springs but not much on the aftermarket stuff but I am still searching.

Overall / short side / Long Side

Stock 40 fronts?
42.13 / /

HFS 4" 40 fronts?

Stock 55 rears?
45.47 / /

Stock 60 rears?
45.67 / /
47.25 / 22.0 / 25.25 **according one post I found.**
50.0 / 23.0 / 27.0 according to another source

HFS 4" 40 rears?

HFS 4" 60 rears?

Assistance and opinions are welcome at this point.
Let the discussion begin.....

 

[Panzer]

Sort of like this

Here is sort of what I am thinking, I like this set up with a few differences to suit my rig/needs

IH8MUD Forums - View Single Post - Ultimate SUA Suspension??

 

[Panzer]

Gearing

IIRC the 82 diff gears are 3.73 / the OEM tires were 29 inches tall / the new tires are 35
so with a little algebra this is how to figure out what new gearing would equal the original factory 1:1 Hi gearing.

29/35 = 3.73/x

29x = 35*3.73

x = (35*3.73)/29

x = 4.50

So if I install 4.88 then I will be a little taller than factory.

This is where it gets a little tricky.

The difference between the factory equal 4.50 and the planned install of 4.88 is about 8% underdriven.
(4.50/4.88=.92)

So if I am thinking correctly the Marks4wd gear set that is .08 overrdrive HI and 3.05 LOW should put me back dead nutz stock on the HI side.

On the low side going from 1.9? stock LOW to the 3.05 with the taller 4.88 diff gears should improve the walk ratio substantially. (I say walk because it won't be stupid slow as in crawl.)

 

[JasonH]

The underdrive with the 4.88's might be a good thing since your 2F is going to be dealing with the increased weight and rolling resistance of the 35's. Plus that gives you room to go to 37's.
That said, I'm running 37's with 4.11's and it runs at a comfortable rpm on the highway and will go as fast as I dare.
I'd think about 4.56's and an Orion. Good mix of highway and crawl. Is that what you're after?

 

[Panzer]

A good mix of highway and crawl is exactly what the end goal is.

The original theoretical plan was 4:88 and Orion. The 4:88 choice was originally because that was what I had in my mini truck and it put it back exactly to factory. Speedo was dead on.

After I got to digging into the details I figured out that I have the odd duck FJ40.
1982 FJ40 has the 19 spline tranny shaft, split case with (IIRC) the 1.9? transfer case and 3.73 gears.
Can't do the Orion unless you have 10 or 16 spline tranny.

I picked up an H55F a couple of years ago (also 19 spline), the 1982 had the H55F behind the 2F in other markets so I am about 95% sure it will mount with no other issues except Driveshaft length.
In the 82 the 4speed mounts to the crossmember in the same place as the 5speed so no fab work there and the fuel tank should also clear since it was the same (I think) in the non-usa petrol trucks.

If I run FJ60 rear springs it should move the axle back about the same distance as the extra tranny length and I may get away with only having to re-tube the front DS. If not no biggie, I have a great DS shop right down the street.

Now all I need is for either the overtime fairy to smile on me or the Sami-Toy to sell and I'll have it all done by Roundup. ; - )

 

[JasonH]

16 spline 4-spds are everywhere. The H55 with 4.88's would be sweet too.

 

[G-Cat]

Purdy runs on 4.56s with an H55 and 35s...perfect for the highway, good enough for me on the trails...but not stupid low like the Orion...

 

[JasonH]

You sure you can remember back that far?

 

[Green Lantern]

Hey Panzer!

Call if you need anything, I'm close by. I've got the tranny jack and an engine hoist at my house.
Happy Trails! N
(817) 455-5060 cell

 

[G-Cat]

You sure you can remember back that far?

That's a fact. The last 40 I actually wheeled was Grogan's green beast with the Orion...stupid low crawl.

 

[Panzer]

The Orion is a sweet setup, I am bummed a little that it isn't 19 spline friendly but the Marks Gears will get me close enough and I get to learn how to rebuild my Tcase in the process.

 

[tx4guns]

Anybody still keep in touch with TP? He might have some advice on what to do. Not sure how much, but I'm pretty sure he had a hand in the SOA and wheelbase adjustments on Pancho, mainly the axle swap to FJ60 axles and he had custom drive shafts built to accomodate the length change. I have a list of WHAT was done, but just no idea who or how it was done. Maybe some of you helped him do the work.

 

[JasonH]

I'm pretty sure Tom did all that fab work. He's a pretty talented m-f'er. (Metal fabricator.)

 

[tx4guns]

He didn't do the cage or the traction bar. JK Customs in Austin did all of that work. I would bet that TP did the axle work, tho.

 

[JasonH]

Tru dat.

 

[fj40tom]

Greetings gents!

I did everything on Pancho except the floorboards, roll cage, and rear track bar. Those three items were done by JK Customs.

If I remember correctly, I ended up extending the front frame rails while doing the shackle reversal. This was done to gain the final wheel base length I was after.

I would have to see Pancho again in person to remember what I did to the real axle and springs, but the real springs could have been flipped.

As far as the metal work or fab work for the frame extension and SR, it was rather straight forward. IT was all done without having access to some of the more advanced fab tools (metal shear, press break, iron worker, and tubing bender) that I have access to now.

I hope that Pancho is still being enjoyed and running great! I have tons of great memories of that truck.

Cheers,

tp

 

[tx4guns]

I hope that Pancho is still being enjoyed and running great!

He sure is! I drive him to work every now and then. The inspection is current, too!

Here's a couple snow pics from last week here in Houston! I'm planning to be at Roundup this year, so I hope you can make it to take it out for a spin or 2.

 

[Panzer]

New revelation-The marks4wd gears are .08 underdrive not overdrive.
My planned set up would bump me to .16 underdrive on the high side with 4:88s
May be switching to 4:56 if I can't get the 1:1 high gearset.

(I got the sami sold over the weekend so I can now start shopping)

 

[Panzer]

New info on the T/C ratio for 1982
34mm Idler - Manual Trans. Setup (H41/H42/H55F)
[FONT=Arial,Helvetica][SIZE=-1](8/80' - 4/86')[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Input shaft: 19 spline[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Input Gear: 34 tooth[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Primary Idler: 45 tooth[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Secondary Idler: 25 tooth[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Hi-Speed Output Gear: 34 tooth[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Low-Speed Output Gear: 43 tooth[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]PTO Gear: 31 tooth[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Total Low Range Reduction: (45/34) * (43/25) = 1.3235 * 1.7200 = 2.2764[/SIZE][/FONT]
http://www.cruiseroutfitters.com/tech_split_case.html

Roughly $2000 for Marks4wd gears doesn't seem worth it for .73 increase on low side.

 

[Panzer]

A little time and a little Photochopping and this is close to what it should look like when I am done.