Builds The LF40 Wheeler Build - Twin Turbo & 8 Speed Auto FJ40 (17 Viewers)

[Godfather90]

The sides are pretty open, and there is pretty good room around the cases for air to flow. I do have a second Dakoda Digital temp sensor and BIM I could install. Do you think it would be worth using the Toybox drain as a temp plug? I think I may have a fitting that would work.

I'm not sure what your plate looks like inside, but on mine there is too much thread on the plug bore to allow for the sender to get into the fluid far enough.

My ToyBox runs really cold now. The only time it starts to warm up is in the sand when I'm going at it for long periods. Even then it's pretty cold. It's a th average between the transfer and the transmission temp normally. I would worry a bit more about the transfer temp. They are always making heat when you do down the road.

I added the temp sender to the ToyBox to warn me if something was going bad. That hasn't happened yet since adding it fortunately.

My orion makes a lot of heat however. Yours should be better with the original gears and aluminum case however.

Hope that makes sense,

Mike

 

[Godfather90]

Also, @Godfather90 , are you back to your rig yet? I would love to know how long your rear driveshaft is to compare. I haven't seen any other 40's with the 5 speed+toybox.

I'll go measure it right now. Sorry I forgot before haha

 

[DangerNoodle]

I'll go measure it right now. Sorry I forgot before haha

No problem, I'm just curious.

 

[DangerNoodle]

I'm not sure what your plate looks like inside, but on mine there is too much thread on the plug bore to allow for the sender to get into the fluid far enough.

My ToyBox runs really cold now. The only time it starts to warm up is in the sand when I'm going at it for long periods. Even then it's pretty cold. It's a th average between the transfer and the transmission temp normally. I would worry a bit more about the transfer temp. They are always making heat when you do down the road.

I added the temp sender to the ToyBox to warn me if something was going bad. That hasn't happened yet since adding it fortunately.

My orion makes a lot of heat however. Yours should be better with the original gears and aluminum case however.

Hope that makes sense,

Mike

It is a split case, and I'm not really sure how hot those run. Do you know if the helically cut gears generate more or less heat than the straight cuts?

 

[Godfather90]

Its a hair over 24" from flange to flange. I imagine its about 25" from center to center.

Helical gears always generate more heat than straight gears. You do not want straight gears on something you're going to drive very often however


Mike

 

[DangerNoodle]

View attachment 2580617

Its a hair over 24" from flange to flange. I imagine its about 25" from center to center.

Helical gears always generate more heat than straight gears. You do not want straight gears on something you're going to drive very often however


Mike

Do you know what your rough wheel base is? I'm guessing your engine is pretty far forward to have that long of a driveshaft.

 

[pb4ugo]

When you are working on your driveshaft be sure to take in consideration the suspension at full droop in the rear to make sure the yokes dont' bind. My nephew has been running this shaft for several yrs with no problems. Obviously its not in a 40.

 

[Godfather90]

My wheelbase in 100"

My engine was right off the firewall originally but I moved it forward 2-3" and the transfer case up 2" at the rear to get the driveline angles where I wanted them.

The tunnel and floor got re-shaped and the transfer is probably 1" higher than where the floor used to be. There is ~1/2-1" between the floor and the highest part of my transfer now. The highest part is the transfer case saver thing that's on the top cover.

The frame is about 20" off the ground and the transfer lowest part around 18.5:

This is with 39" tires.


I'm not sure about the dimensional height of your transfer but I do know the Orion hangs lower than a typical single piece aluminum case because of the shape of the casting.

Mike

 

[DangerNoodle]

My wheelbase in 100"

My engine was right off the firewall originally but I moved it forward 2-3" and the transfer case up 2" at the rear to get the driveline angles where I wanted them.

The tunnel and floor got re-shaped and the transfer is probably 1" higher than where the floor used to be. There is ~1/2-1" between the floor and the highest part of my transfer now. The highest part is the transfer case saver thing that's on the top cover.

The frame is about 20" off the ground and the transfer lowest part around 18.5:

View attachment 2580679View attachment 2580680

This is with 39" tires.


I'm not sure about the dimensional height of your transfer but I do know the Orion hangs lower than a typical single piece aluminum case because of the shape of the casting.

Mike

The split case hangs down really low. I'm not sure why. I'm right at 23" for frame, and I'm thinking it will probably settle out about another 1" once everything is in. How flat are your springs right now? Mine still have some arch, and I'm thinking that I'm going to change out to 6" shackles to gain some more droop on the rear.

 

[DangerNoodle]

When you are working on your driveshaft be sure to take in consideration the suspension at full droop in the rear to make sure the yokes dont' bind. My nephew has been running this shaft for several yrs with no problems. Obviously its not in a 40. View attachment 2580665

That's good to know. Having the driveshaft that short does scare me, but I've heard of a lot of people running them with no problems.

 

[GLTHFJ60]

The fact that it's short is itself not an issue. The problem is that usually our tcase outputs are very high in relation to the rear pinion, meaning the driveshaft u-joints (DC or not) can't handle the angle.

My rear driveshaft is just shy of 32" long and I'm right at the limit of a 1350 DC joint angle capability. Granted, I have a centered rear output tcase, so my output is higher, but it's something you need to really figure out before you burn mounts in.

 

[DangerNoodle]

The fact that it's short is itself not an issue. The problem is that usually our tcase outputs are very high in relation to the rear pinion, meaning the driveshaft u-joints (DC or not) can't handle the angle.

My rear driveshaft is just shy of 32" long and I'm right at the limit of a 1350 DC joint angle capability. Granted, I have a centered rear output tcase, so my output is higher, but it's something you need to really figure out before you burn mounts in.

My rear axle is barely tacked, so I can rotate it if needed. However, I think the outputs are pretty close and are not super steep.

 

[GLTHFJ60]

My rear axle is barely tacked, so I can rotate it if needed. However, I think the outputs are pretty close and are not super steep.

No, I mean your driveline mounts.

What's vertical separation between your tcase output and pinion as it sits now? what about at full rear suspension droop/compression? That's what you should figure out.

DC joints can't work reliably at anything more than say 25*, and bind hard at 30*. 30* isn't "super steep" imo.

Driveline Geometry 101

Driveshaft Angle Explained This video will demonstrate the proper angles for a drive shaft in a stock Jeep or Truck and how the rules change when you add a suspension lift. The video below demonstrates what is happening to the shaft at different angles, how improper angles can cause speed...

4xshaft.com

 

[DangerNoodle]

No, I mean your driveline mounts.

What's vertical separation between your tcase output and pinion as it sits now? what about at full rear suspension droop/compression? That's what you should figure out.

DC joints can't work reliably at anything more than say 25*, and bind hard at 30*. 30* isn't "super steep" imo.

Driveline Geometry 101

Driveshaft Angle Explained This video will demonstrate the proper angles for a drive shaft in a stock Jeep or Truck and how the rules change when you add a suspension lift. The video below demonstrates what is happening to the shaft at different angles, how improper angles can cause speed...

4xshaft.com

I've read a lot of stuff on the driveline angles to make sure I made everything work. Here are my measurements. The driveshaft is right about 17" center to center.

Tcase Output:

Pinion:

Rough angle (14.5°) :

 

[DangerNoodle]

My pinion is a bit off to get my 0° at cruise, but I have it pretty close I think.

 

[DangerNoodle]

I haven't been able to really flex this thing out much, so I cant really give numbers at full droop/compression.

 

[Godfather90]

The split case hangs down really low. I'm not sure why. I'm right at 23" for frame, and I'm thinking it will probably settle out about another 1" once everything is in. How flat are your springs right now? Mine still have some arch, and I'm thinking that I'm going to change out to 6" shackles to gain some more droop on the rear.

So I built my suspension with in mind that I will have main and second leaves made by Deaver springs down the road from me with a reversed eye configuration.

I have been putting it off for years mainly due to time and having the top off for a long time (they need the vehicle at full weight before I head in)

With that said I have probably 2" of arch into eh springs before they go flat. My springs do go negative before hitting the bump stops.

Forgive me for my bad photos, its hard to capture.

My rear drive flange is ~22 3/4" off the ground.

There are some driveline angle things in my thread here on post 276:

Builds - Mike's 1978 FJ40 Turbo Diesel Refit Project and Cross Country Road Trip!

I ended up skipping the Bakersfield swap meet in exchange for a car show and a little 4wheeling up in the mountains. It was really beautiful and green after all this rain. Only issue I ran into is that the Ford Taurus fan died on me (for the 4th time) so good thing I carry a trail spare now. I'm...

forum.ih8mud.com

and more here on 303:

Builds - Mike's 1978 FJ40 Turbo Diesel Refit Project and Cross Country Road Trip!

I ended up skipping the Bakersfield swap meet in exchange for a car show and a little 4wheeling up in the mountains. It was really beautiful and green after all this rain. Only issue I ran into is that the Ford Taurus fan died on me (for the 4th time) so good thing I carry a trail spare now. I'm...

forum.ih8mud.com

 

[Godfather90]

That's pretty crazy that your rear drive flange is about the same height as mine and your frame is 3" higher.

I worked really hard to get my truck this low. Its gotten to the point with the 39" tires where I really could make it a bit taller.

The reversed eye springs are going to be great with a little more arch. I built the traction bar adjustable just for that reason.

The flatter springs however are really easy on the spring u-bolts and cycle really easy due to less sliding motion between the leaves however.

It's a balancing act of course!

Mike

 

[DangerNoodle]

That's pretty crazy that your rear drive flange is about the same height as mine and your frame is 3" higher.

I worked really hard to get my truck this low. Its gotten to the point with the 39" tires where I really could make it a bit taller.

The reversed eye springs are going to be great with a little more arch. I built the traction bar adjustable just for that reason.

The flatter springs however are really easy on the spring u-bolts and cycle really easy due to less sliding motion between the leaves however.

It's a balancing act of course!

Mike

I'm shooting for ~ 22" at ride height. I think I'm close there, but time will tell. Your leaves look to be a lot flatter than mine. I probably have 3+ till they go flat. I'm hoping I can get some 6" shackles on there without too many consequences. I barely have any doop with the 4" on there now.

 

[Godfather90]

I'm shooting for ~ 22" at ride height. I think I'm close there, but time will tell. Your leaves look to be a lot flatter than mine. I probably have 3+ till they go flat. I'm hoping I can get some 6" shackles on there without too many consequences. I barely have any doop with the 4" on there now.

What size tires?

Here's my rear prop shaft setup:

Rear end:

Rear shaft:

Rear drive flange:

I set this up with the top off. There is usually 1-2* in less the rear.

Here's the angle of the truck:

SO about 2* butt side up.

Hope that helps,

Mike