[FJ40] H55 + SOA Is it possible? (1 Viewer)

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pcoppala

pcoppala

Joined
Feb 1, 2013
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Location
Austin, TX
I'm at a crossroads in the rebuild of my 1982 FJ40. I intended to have my H42 rebuilt, however the transmission shop has informed me that the 2nd gear syncro is toast. The only way to replace this part is to order the whole assembly. Of course the part has long been discontinued by Toyota, so all that remains are used assemblies. I'm a bit hesitant to spend all this money rebuilding a transmission to install a used wear item. Since I have a late-model 40 with the cross brace and rear parking brake, the H55 is an excellent candidate for a transmission swap with minimal modification.

My original intentions had been to convert my 40 to SOA using the stock 40 springs. But I'm afraid SOA + H55 will create a nasty drive shaft angle. Does anyone know if this combination is possible? Would I need to flip the springs and move the axle back a few inches to lessen the angle?
 
Moving the axle back is going to make it better, in any case. You're probably going to have to move the tubular cross brace. If you're going to do it, do it right and rotate the pinion up and use a CV drive shaft. You will probably also want to move the fill plug up a little. It will work out fine.
 
Thanks Fast Eddy. This is the information I was looking for. I could find plenty of information on SOA write-ups as well as H55 into FJ40s, but there was a real lack of information combining the two.
 
White Stripe said:
H55 is the 5 speed tranny right? I have found that with 35s and 4:10s I have a pretty good cruising rpm in 4th gear in my sm465. I used to think 5 speeds were the bees knees till I went to 35s, I really see no need for a 5th gear. I get 15mpg or so as is with the 2f in 4th at 70mph.
Click to expand...

I agree I have ok RPMS. I may see 14mpg at 65mph. I have to pull in the secondaries to maintain 70 though, so, um, less.

I averaged about 11.6 on my 500 mile Rubithon trip, including 12 miles of tough crawling and another 50 miles of rocky dirt roads.
 
My main point of moving to the H55 is that I already have the correct transmission cross brace. The modifications needed to allow a H55 to work over the sm465 with my current setup is minimal. When I rebuild the diffs, I was planning on moving back down to 4.11s anyways. They should complement the 35s nicely.

Thanks everyone for you input
 
I've been researching putting a H55F in my 79 FJ40. I have parts off a 82 FJ40 including Transmission, transfer case, crossmember and L brackets. One thing I found out a 82 transfer case is missing a few things to mate to a five speed. Believe a oil cup for the fifth gear and a bolt hole. Cruiser Outfitters site has a good chart on the differences in split case as what is needed to work with the five speed. No help with the driveline angles since I don't plan on going SOA.
 
At this point, I think I'm going to order the H55, and then figure out if I can run SOA after I have the engine/transmission mounted in the frame. Flipping the rear springs should give me another 3-4" Which is about the how much the transmission output would be extended by adding H55.
 
I flipped springs and went from 3 speed to 4 speed. The spring flip gave me just a little bit more then the added length of the 4 speed. I don't know the difference in length from 4 to 5 speed, but my guess is the new driveshaft length with flipped springs will be close to the original length. And since lots of people go spring over with 4 speed, the combo should work. Whether or not you'll need or want a cv drive shaft and to rotate the axle is a different story. Seems like doing it in steps like you're planning is a good approach.

Btw, Fast Eddy's metal fender flares are a clean way of repositioning the wheel well opening (not sure if he's doing buys for those anymore).
FJ40_fenders.jpg
 
Nice cruiser Philly. Thanks for the picture.

I managed to score a FJ62 FF rear end a few months ago. Since I already have to move the spring perches, I'm just going to rotate the pinion up. That should help alleviate some of the driveshaft angle woes.

Does anyone know of a SOA 40 with toybox or rockbox? They would run in to the same type of problems.
 
pcoppala said:
Does anyone know of a SOA 40 with toybox or rockbox? They would run in to the same type of problems.
Click to expand...

SOA FJ40s w/SBC & 700R4 have the same issue. Moving the rear axle back is an easy fix.
 
Do some research on driveshaft angles. If I recall, standard driveshaft should have the pinion flange parallel with the output flange from the T-case. CV type driveshaft should have the pinion pointing directly at the center of the output flange. So you probably need to decide on which type of driveshaft you're going to use before doing the rotation.

I don't think Eddy's flares would work with the 62 axle due to the extra width, which will make the tires protrude a bit (3" wider I think). What's your plan for the wheel wells?
 
Philly, you're correct about the flange and the drive-shaft type. From my readings, the CV shafts and tipping the pinion up seem to be the most popular solution for the SOA guys.

The FJ62 axle is 1.5" wider on each side. I wanted more options for wheels without rubbing the inside of the tub. Moving the wheels out a bit may help with stability as I raise my CoG. I haven't really shopped for flares yet. I really like IPOR's metal flares that they have on their 40. I may try to build something similar.
iporfj40rearb_B_LRG-500x500.jpg

Image Credit: Iron Pig Offroad
 
IMHO, the easiest thing to do with an SOA conversion is go with the double Cardan rear drive shaft. Even if a standard drive shaft will "work" for on-highway use, without the expense of high angle U-joints performance will likely be marginal during extreme articulation. :(:(:(

Of course, if money is no object, a high pinion diff will alleviate some of the problems. :)
 
I have a 75 FJ40 and had an H55 put in, along with an SOA. My SOA conversion is not a cut-and-turn so the pinion and output angles are parallel. The front and rear leafs are stock but both are flipped which yields a 6" longer wheel base overall. The drive shaft angles are kind of extreme and material had to be relieved from the U-joints to accomodate this. I run 35" tires. I've never seen a need to cruise down the highway in 4WD so can't comment for sure on that. In 2WD, all is smooth at 65-70 mph on the pavement.

Having said that, I am not really comfortable long-term with this set up and have thought about high-angle u-joints and also having a cut-and-turn done. I just got a 72 out of Reno, NV because my tub is too far eaten away by rust. The 72 is rust free and already frame-off prepared with a new SBC and 700R4 set-up and in place. I plan on swapping all of the goodies from my 75 into the 72.

Now the dilema begins: I could swap in my existing SOA set up or start over cut-and-turn, etc. So, at the very least I think I will cut-and-turn the front and go with double cardan rear shaft. I intend to look into a high pinion diff for the rear but I need to know more about the total cost first. I have just begun to talk with Rough Stuff Specialties about this, they are very knowledgable people and make increadible housings. Seems like we are on the same decision making path here.

Good Luck
 
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