H41 Upgrade in '71 FJ40 - Options (1 Viewer)

[4Cruisers]

I'm looking into the multitude of options for installing an '84 H41 4-speed, from an HJ47 with ~47,000 miles, and a rebuilt '82 split transfer case into my '71 FJ40. The FJ40 has a '76 2F mated to a '78 FJ55 H42/transfer case combination (drum parking brake), with driveshafts from an early 4-speed FJ40.

1. I believe the easiest and least expensive option would be to swap out the rear axle with an axle from a late FJ40, using the 4.11 differential currently in the '71, driveshafts from a late FJ40, transmission crossmember from a late FJ40, and parking brake lever/cable from a late FJ40.

2. I've been researching the option of a split case with drum parking brake, which would still require the transmission crossmember, plus I'd have to have my driveshafts re-done. That option is pretty expensive, and I'd have to dis-assemble my transfer case to add the drum parking brake. The first option wouldn't require any work on the transmission/transfer case - it would bolt right in behind the 2F bellhousing.

3. I could try to source another early H41 like the one I have in my '76 FJ40, and use either a one-piece 3-speed transfer case or the '78 FJ55 case that's currently in the '71.

4. I could install a disc brake parking brake on the back of the split case.

5. I'll also look into using FJ60 rear drum brake hardware, with parking brake, on the '71 FJ40 axle. Starting my Internet search now. If the parts are compatible that might be even easier than option 1., considering I have all of the parts from my '86 FJ60 (it's getting axles and parking brake hardware from my '89 FJ62 donor vehicle.

Any input would be greatly appreciated.

 

[pjohnson]

6. You could put a line lock on your rear brake circuit. I would go manual instead of electric. The rear line off the master is routed to a ball valve on the dash before going back out to the rear brakes. Even better, put one on both front and rear circuits.

7. You could put mini-truck ends on your rear axle housing and mount mini truck rear drums with parking brake. Obviously, you need to work out the cable part of the system. Woody did a write up on this many, many years ago.

 

[4Cruisers]

Thanks. How would the mini-truck ends be different than FJ60 ends? I already have the FJ60 parts.
I'll try to dig up Woody's write-up.

 

[Cruiserdrew]

I'm a big fan of split cases, so would lean that direction.

One option you didn't mention is to rebuild your existing H42 with the H41 gearset. This works, and I've been using that tranny for years. Then you can keep everything else the same. If you do this, swap the reverse idler too, or it will run noisy in reverse. BTDT. I rebuilt my '84 H42 with an H41 gearset I got from Marksoffroad. That was 7-8 years ago and still running strong in my FJ60.

Or, you can source the split case parking brake stuff-if Georg still has any. This would be my #1 choice. And disassembling a split transfer case is not difficult at all. Much more user friendly than a 1 piece case. You could get around some of the drive shaft issues with the multi pattern pinion flanges sold by Cruiseroutfitters. If you have to get driveshaft lengths changed, that is no big deal. $100-$125 per shaft, a small expense in the overall scheme of your project.

Or, if low gearing is your goal, scrap the weaker 1 piece case and get an Orion, keeping everything else the same. This is a very good option but not cheap. It would let you use your existing drum brake, driveshafts and axles, so that would offset some of the Orion costs.

FJ60 brakes will not go on the early FJ40 axle, the backing plate mounting is not compatible. But you could use a complete FJ60 axle in the rear of your 40 (this is a very easy/beneficial swap) and then of course you would have FJ60 brakes including it's excellent e-brake mechanism.

What's your goal with this project? Lower gearing, higher strength? I'm going to assume it's gearing you want. What's the budget? Gearing of all types gets expensive fast and costs snowball more than you would think.

For the ultimate low you could run the H41 and swap the 4:1 gear set into the split case. That would give a really deep low gear and would be a pretty sweet set up. $$$$

There are other options too:
SM420 with the 7:1 low gear. You'd need an early bellhousing and an adapter plate but doable

SM465 with 6:1 low gear. Same early bellhousing and SM465 adapter plate needed.



Just a comment-Don't let driveshafts hold up the right choice. Driveshafts can often be swapped, shortened, legnthened, adapted or custom made to any combo you need. Toyota slip spines were the same for a long time, and so even swapping on yokes with different patterns is usually possible. Don't sweat this. A good driveline shop is your friend here.

 

[4Cruisers]

Thanks for answering the backing plate compatibility question, that confirms what I read in an earlier post I ran across during my search here on MUD.

I've done driveshaft/yoke/pinion flange swaps, agreed that's no big deal. I've also removed/dis-assembled/installed split transfer cases, on Land Cruisers and my '90 4-Runner. Again, no big deal. When all is said and done, an Orion case might just be the best way to go. I do like the gear spacing in the H42 better than the H41 I have in my '76 FJ40, especially for around town and driving to the trailheads, but the H41 and 3-speed transfer case combination was great for Black Bear Pass and Engineer Pass this past weekend at the Solid Axle Summit.

The cost of going with the Orion option would be offset in part by selling the low-mileage one-piece transfer case from the '78 FJ55 and the very low mileage '84 HJ47 H41 with freshly re-built '82 split transfer case .

 

[4Cruisers]

Follow-on question to the Orion option. I'll have to look at the gear ratio combinations using Excel, comparing final gearing of the H41/3-speed transfer case/4.11 differentials in my '76 FJ40 and the H42/Orion/4.11 differentials with this new option. I imagine, when wheeling, I'd probably be using 3rd and 4th gears more with the Orion, compared to 2nd and 3rd gears with my '76. I'll do some calculations and post what I discover here.

 

[Cruiserdrew]

but the H41 and 3-speed transfer case combination was great for Black Bear Pass and Engineer Pass this past weekend at the Solid Axle Summit.

Ya-no kidding. Low gears rule. Better than any other mod! I keep going lower and lower. Recently had Georg put an Orion behind my SM420. Such a nice combo off road.

Regrading the low mile H41 you have, I believe that with a new main shaft with 10 spline output, you could run an Orion behind it. Then a direct swap into your FJ40, and no driveshaft/crossmember changes. That would give you gearing just north of 80:1 which would be pretty cool.

Unfortunately, It all comes down to budget and parts on hand!

 

[4Cruisers]

Now you've got me thinking - why not call @cruiseroutfit and order an Orion for my '76 to see how it performs? I imagine I can do the swap in a day and get some real-time performance data.

BTW, I think I realized a tiny bit of better trail performance with my '76 because I used the heavier 3-speed flywheel and 3-finger clutch when I installed the H41 and 3-speed transfer case, every little bit helps.

 

[Mr Cimarron]

I found the H41 real nice last week on Black Bear and the other trails as well. I don't think I touched the brakes on Engineer pass much at all. I have another H41 in the garage with a split case that I will rebuild and install when the time comes. I will be switching the parking brake to the rear axle since my full floater is set up for it already.

 

[4Cruisers]

Now you've given me another option, swap out my rear axle to FF w/parking brake and be done with it. I imagine that might be cheaper than the Orion option.

 

[4Cruisers]

Another follow-on question. Are the '71 FJ40 rear axle shafts compatible with the later ('81 and up FJ40) axle housing? If so, I could use:

'86 FJ60 parts (I have all of this) - rear brake drums/hardware/backing plates, parking brake lever/cable/hardware (modified as needed)

'71 FJ40 parts (I have all of this) - 4.11 differential, rear axle shafts

'81 and up FJ40 parts (I'd need to source these) - rear axle housing, front and rear driveshafts, transmission crossmember

'84 HJ47/'82 ??? parts (I have all of this) - H41 4-speed transmission mated to split transfer case (w/o drum parking brake)

 

[Living in the Past]

Issue is the bolt pattern for the backing plate from a 8/80 is completely different and adding later brake parts setup for hand brake to early axles is no easy task.

 

[pjohnson]

I have an H41 with a 4.7 Toybox and 3sp gears in a 4sp case. (Wow, that's a mouthful )

Most of the time I use 1st or 2nd gear and the 4.7 Toybox, leaving the t-case in high. I love it!

 

[S4Cruiser]

I have an H41 with a 4.7 Toybox and 3sp gears in a 4sp case. (Wow, that's a mouthful )

Most of the time I use 1st or 2nd gear and the 4.7 Toybox, leaving the t-case in high. I love it!

Once Marlin re-releases their toybox I plan the h42 toybox splitcase with low range gears. Georg needs to reproduce those splitcase parking brake pieces or I'll have to go with a FF rear axle.

 

[Cruiserdrew]

Once Marlin re-releases their toybox I plan the h42 toybox splitcase with low range gears. Georg needs to reproduce those splitcase parking brake pieces or I'll have to go with a FF rear axle.

Not sure I follow. Nothing magic about a FF rear axle. On 40s and 60s it has the same brake components as the semi float.

 

[Cruiserdrew]

I have an H41 with a 4.7 Toybox and 3sp gears in a 4sp case. (Wow, that's a mouthful )

Most of the time I use 1st or 2nd gear and the 4.7 Toybox, leaving the t-case in high. I love it!

Same here. Talking FJ60 H41/Toybox/Split case. 99% of the time I leave the transfer case in high range, and the Toybox in low. Then 1-2-3 gears for most trail use. Only for really slow and critical things, does the transfer case go into low range. Marlin himself told me the transfer is stronger in high range and so using the Toybox like I described is a good way to go. And when we had this conversation, he signed my truck inside the glovebox. I'm hoping that means immunity from drive train disasters.

 

[Living in the Past]

Not sure I follow. Nothing magic about a FF rear axle. On 40s and 60s it has the same brake components as the semi float.

I agree and the semi floater 60 series is the easiest to find in the US, second is the 40 series 8/80 and newer. As for being the same use to think the same until seen someone wanting drums for 60 series full floater. Looking up the part number full floater and semi have a different part number. Have a 8/80 40 series full floater missing a drum. Years ago someone gave me the from the backing plates off what I assumed are from a US 60 series. Guy had a 66 FJ40 and I figured he found they won't work so when I bought some parts he threw them in. Thought when I got around to rebuilding the axle I would dig out the 60 series brake parts to use. Now I'm not sure.

 

[S4Cruiser]

I should've clarified that I would search for a 70 series FF rear with integrated parking brake.

 

[1911]

FWIW, I run an H41/Orion/3.70 diifs/33" tires combination, and find this very agreeable for most all of the 4-wheeling I do, plus it's still great on the street and highway.

 

[4Cruisers]

FWIW, I run an H41/Orion/3.70 diifs/33" tires combination, and find this very agreeable for most all of the 4-wheeling I do, plus it's still great on the street and highway.

I'll add that combination to my Excel spreadsheet RPM table.