66 FJ40 with Chevy Conversion Drivetrain Question (1 Viewer)

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First, if you couldn't see by my avatar, this is my first post to this forum. I apologize if I break any rules, and I am SURE this question has been asked before, but I couldn't find it. If you have links I would be grateful.

Next, for introductions, I bought a 1966 FJ40 last year. My first FJ, as I have been a Jeep guy until now. It had been a bit modded (poorly) with the V8 conversion done (poorly), a rear gas tank installed (poorly), new suspension installed (poorly... noticing a pattern?) etc. Basically the whole thing screams bubblegum, duct tape, and bailing wire, but it ran and it was rust free, and was inexpensive as FJs go. I plan to clean it up as I go. Drivetrain and wiring first. So there is the start of my story.

My question starts here : the drivetrain mostly comes from an 80s Chevy Blazer, as far as I can tell from part numbers. A V8 350 (I don't think this came from the Blazer) with a th350 automatic transmission (Blazer), and a Chevy transfer case (Blazer). I have 2 major issues moving forward:

1. The rear drive line in the rear is at a significant angle lining up the Chevy transfer case with the Toyota rear axel. It runs fine on the road, but that is not the goal for this truck (not a rock crawler, but not a trailer queen either). I am told this is a risk, that with any torque this can break in unexpected ways, so I should swap out the Chevy transfer case with a Toyota one and get parts from Advanced Adapters to make it work. However, talking with AA, apparently there is extensive tranny mods necessary to make this work. Makes sense. Sounds expensive.

2. The front drive line does not reach the front axel. Yes, I bought a 2WD FJ40. It's my first one and like I said, the price was right to get my foot in the door. Go ahead and laugh. Did I mention it is bright yellow (with tons of overspray of course)?

My question for the collective mind here is, what are my drivetrain options for transmission and transfer case? I called Advanced Adapters and they want my to buy a new/used 1986+ Toyota tranny and transfer case and hook that up to the V8. I am open to this but I have to imagine there are ways to make the Chevy parts work. I am not really excited about having an AT but I am on a bit of a budget, and just want to get this thing up on some light trails by next summer, maybe getting over a log or 3. Any suggestions for getting this thing back on the road, and 4WD on the cheaper/easier side?
 
Not many 'cheap' options to make things right. Aside from the options AA offered up there are others Here are my thoughts.

Issue #1 - Install a centered rear diff, like a Dana 60, 14 bolt, etc. This comes with it's own set of issues, such as width, which means a matching front axle or narrowing. I'm assuming you have the stock FJ40 front axle.

Issue#2 - Get a drive shaft built to the correct length.

I wouldn't invest in converting the TH350 to a Toyota t-case, there are better A/T options like the 4L60 that AA can mate to a Toyota t-case.

If you go back to a manual transmission, there are plenty of options the manual transmission guys can chime in about. Regardless, this route will require accumulating the requisite parts your 40 is now lacking, such as clutch pedal, slave and lines, bell housing, fly wheel, etc.

Personally, I would upgrade to the 700R4/4L60 and Toyota t-case.
 
Not many 'cheap' options to make things right. Aside from the options AA offered up there are others Here are my thoughts.

Issue #1 - Install a centered rear diff, like a Dana 60, 14 bolt, etc. This comes with it's own set of issues, such as width, which means a matching front axle or narrowing. I'm assuming you have the stock FJ40 front axle.

Issue#2 - Get a drive shaft built to the correct length.

I wouldn't invest in converting the TH350 to a Toyota t-case, there are better A/T options like the 4L60 that AA can mate to a Toyota t-case.

If you go back to a manual transmission, there are plenty of options the manual transmission guys can chime in about. Regardless, this route will require accumulating the requisite parts your 40 is now lacking, such as clutch pedal, slave and lines, bell housing, fly wheel, etc.

Personally, I would upgrade to the 700R4/4L60 and Toyota t-case.

Thanks! Any yes, the front axel is stock, as is the rear.
 
Another question: how bad is it to have that driveline angle really? I mean, it lowers the clearance a bit, and I am sure I wouldn't want to do any heavy mudding or crawling, but for some light trails and ditches am I really that at risk of a breakdown?
 
If it makes you feel any better, early FJ40's had a centered rear diff, creating the similar angles. However, it was "flatter" since it was being driven from the lower Toyota OEM rear output position. The GM location creates steeper angles. IMHO, you should explore options that drive the rear diff straight off the t-case.
 
A cheap way to cure your problem is to center your 40 rear end by using the axle tubes and axles from a 1985 or earlier rear end out of a mini truck and adapting them to your 40 rear end. Mini truck rears can be found for cheap. There's a little fab work but it's not bad.


FJ40/minitruck hybrid rear axle- Land Cruiser Tech from IH8MUD.com

IMG00062-20110501-1150.jpg
 
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Find a fj40/60 4 speed transmission/transfer, (better yet an older 3 speed transfer) Check or rebuild if needed at least replace all seals, gaskets, locate front and rear stock driveshafts, This stuff pops up fairly frequently here on classifieds or on Craigslists, get the right adaptors from Jim Downey here on Mud (I think he still provides them or can tell you where to obtain, or from Advance Adapters. Salvage yard Chev bellhousing. Parts lists are available from AA. This has been done with the SBC thousands of times and is probably the easiest way to go. Even cheaper if you find a stock 3 speed trans and transfer but then you have a non synch 1st gear. Many of us are still using that with great success. Just depends on what you figure your 40 is worth.
 
You mentioned that the front axle/diff is original. That front end will not hold up well to a V8 for very long. It has an old fork and ball type steering joint and large spline axles. Be prepared for twisted splines and broken knuckle internals.(personal experience)

As for the driveline angles and issues, get LC trans/xfer and be happy in the long run.
 
From your description, you don't have a parking brake. If you run a late model ('86) Toyota xfer case, you still won't have a parking brake. Something to consider in all your mod plans.

I laud your efforts and sense of humor in trying to right the wrongs of this truck. Many people would get massively frustrated and throw in the towel. If you could find an all-stock drivetrain from a junker mid-70s FJ40, you might consider swapping all that in. You would lose the V8, but gain a lot of normalcy.
 
Since no one else has said it I'll throw in my $.02 I'd ditch the GM auto trans and GM transfer case altogether. That drivetrain is too damn long in a stock wheelbase FJ40 and the driveshaft angles will always be horrible. Unless you like fab work, I'd leave the rear axle alone and swap out the front axle to an "upgraded" version (76'+) that has better birfields and disc brakes.

Keep an eye on CL for a used GM 465 4 speed transmission and a used FJ40 3 speed transfer case. In fact, I'm just north of you and I have about 7 or so..... The GM 465 transmission will bolt directly to the engine you currently have using a stock GM bellhousing. I'd spend the money on an adapter kit (probably AA) to mount the FJ40 transfer case to the 465 trans. Yes, you'll have to relocate/weld the rear transfer case mount within your frame but it's very straightforward. Easier than making a hybrid axle and keeping everything straight.

You can use standard FJ40 clutch components with this setup and you'll end up with a very nice 1st gear ratio for low range 4WD. It'll cruise on the highway fine too. I've been wrenching on 40's for over 16 years now and I'm just north of you so let me know if I can assist somehow...
 
I will study your problems and get back to you when I get back home, but for right now the very best deal on the planet for you is to contact "Redgrrr here on mud and buy his 1" thick TH350 adapter to Toyota Landcruiser 3 speed transfer-case, then look for a good deal on the transfer-case. In my next message I'll give you all the reasons for doing this- - -stay tuned.

Also, give us more info on your rear tank poo-poo install?????
 
Ok, I have some time right now. The reason your previous owner did not bolt up the front drive shaft is because the front upper u-joint would have been 1" inside the TH350 tranny. If you use a TH350 with a Toyota 3 speed transfer-case you will need the smaller front upper u-joint to be used with a TH350 adapter (like one I have for sale or the one Redgrrr has for sale). If you used Redgrrr's smaller front flange (ideal situation) you would also additionally need Spicer part numbers 2-2-899, 5-433X, 2-40-2211, and 2-3-8861X, all available on ebay. Then you can use front and rear drive shafts, both on the correct angle for your differentials- - -easy deal!!!!!

I'm curious about your rear tank, what is it, is it still usable. I'm only asking because I sell a whole new rear fuel cell if what you have is totally poo-poo?????
 
You mentioned that the front axle/diff is original. That front end will not hold up well to a V8 for very long. It has an old fork and ball type steering joint and large spline axles. Be prepared for twisted splines and broken knuckle internals.(personal experience)

As for the driveline angles and issues, get LC trans/xfer and be happy in the long run.
Thank you for the warning! I will watch out for that. What's the fix? Replace it with a front axel out of a larger Chevy? Or will a later model 40 front axel work?
 
From your description, you don't have a parking brake. If you run a late model ('86) Toyota xfer case, you still won't have a parking brake. Something to consider in all your mod plans.

I laud your efforts and sense of humor in trying to right the wrongs of this truck. Many people would get massively frustrated and throw in the towel. If you could find an all-stock drivetrain from a junker mid-70s FJ40, you might consider swapping all that in. You would lose the V8, but gain a lot of normalcy.
Ya, there is a parking break handle and cable, but it is not hooked up. I had not investigated the reason too much at this point, but it looks like the parking break goes to the rear axel. What about the late model t-case would not allow that to be hooked up?

The stock drivetrain has crossed my mind. I really love the V8 though so this is a last resort for me.

BTW, speaking of frustration, I did not even get into how I almost blew up the first time I filled it with fuel. I may do a separate post about that someday, but essentially don't run you fuel tank breather line to be under the tank itself while the goose neck is a foot or so higher... siphon.
 
Ok, I have some time right now. The reason your previous owner did not bolt up the front drive shaft is because the front upper u-joint would have been 1" inside the TH350 tranny. If you use a TH350 with a Toyota 3 speed transfer-case you will need the smaller front upper u-joint to be used with a TH350 adapter (like one I have for sale or the one Redgrrr has for sale). If you used Redgrrr's smaller front flange (ideal situation) you would also additionally need Spicer part numbers 2-2-899, 5-433X, 2-40-2211, and 2-3-8861X, all available on ebay. Then you can use front and rear drive shafts, both on the correct angle for your differentials- - -easy deal!!!!!

I'm curious about your rear tank, what is it, is it still usable. I'm only asking because I sell a whole new rear fuel cell if what you have is totally poo-poo?????
Thanks for the info! The transmission and t-case are currently sitting behind the read tires in my garage so I cannot verify your point about the drive line being 1" inside the transmission, but before it was removed I had looked at it and at the time I am pretty sure the driveline was just too short, but there was room for it if it were extended. I could be wrong on that one. This does sound like the "easiest" solution so far. Besides a handful of other parts essentially I would just need to source a new t-case.

Oh the gas tank that almost killed me... I briefly mentioned this in a previous reply, and I may do a whole post about it at some point with pics and things, but here is the skinny: The passenger side tank has been removed and the door welded shut. Previous owner actually did a good job welding, filling, and painting on this one. He must have had someone else do it because all other indications point to "I wouldn't let this guy wash my car, let alone fix it". It even looks smooth form the inside. Anyway, I do not know the model of the rear tank, but it is about 18 gallon or so. The filler goose neck is run through the floor in the back, then a 90 degree bend and another hole out of the rear tail gate (yes, you heard that right). When filling with fuel that 90 degree bend actually runs a bit downhill in the wrong direction, meaning gas leaks out of the openingas you fill it. Sorry environment! Next the breather line for the gas tank was run down the frame with the output being below the bottom of the tank itself. So, for a visual, there is a tank with the filler neck running ~18" above, and a breather hose going from the top of the tack to abut 6" below. Good start? Not really.

I filled it with gas for the first time and, of course, the top fill line is actually a bit within the goose neck, and certainly above the breather. I get about a half a mile from the station when I notice smoke. I pull over and the smell of gasoline is STRONG. The breather line was acting as a siphon pouring gasoline down the frame, which ran it onto the mufflers (really hot), transmission (also pretty hot), ground (not hot, but suboptimal you must admit), my face (pretty effing fuming at this point. perhaps hot enough to cause combustion), etc. My fix at this point has simply been to pull that tube up higher, and clamp it to the filler hose. I really have not driven the truck much since that day.

Not sure a fuel cell is in the cards for me at the moment. I am going to rerun the filler hose so I don't have to wear elbow-length gloves every time I fill it up, and I can work to fill the 2x 2-inch holes in the floor and the tail gate. I'll run that breather line up the hose neck so that most of the fuel stays in the truck. I really have no idea if this guy ever filled the tank up. If he did he would have had the same issues, which to me means he is a bit of an unethical seller (I had and have other descriptive words to describe this person, but this is a family show). I think this should suffice to get it on the road, but I am open to suggestions.
 
After the front in my '66 broke, on an up hill turn, I swapped in a '74 front end. Bigger parts and more spares available. Direct bolt in. Later on I upgraded the '74 to discs using parts from a'82 mini. Did this way back before it became somewhat common. Took a bit of noodle scratching but turned out excellent.
 
Thank you everyone for the info! It sounds like I have a few options, which I summarize here:
- Put in a new GM automatic transmission with a new Toyota t-case. This would also require installing a new rear axel with a centered rear diff.
- Put in a new GM manual transmission with a new Toyota t-case. I think this would still require a new rear axel and fab work to make it line up properly.
- Keep the th350 trans and t-case and install a new rear axel out of a chevy. Benefits: cheap, not a lot of new parts to source.
- Keep the th350 and source a new 3-speed toyota transfer case and a handful of adapter parts.
- Something no one has mentioned (unless I missed it, sorry!) is to source a new manual Toyota transmission and Toyota transfer case. Any downside to this option? Besides being a bit on the expensive side and having to source clutch, fly well, clutch pedal, yadda yadda?
 
It also sounds like something to add to my list is sourcing a later model rear and front axel. They are beefier, lots of parts, and will hold up better than the stock ones, especially with the added weight of a V8. They don't call it a "project" for nothing!
 
You're wrong about the GM 4 speed/Toyota transfer swap. I laid that option out for you because you will use the stock FJ40 rear axle, hence no fab work or messing around back there. I have done this conversion before, it's straightforward. On whatever you do, you'll have to have custom driveshafts made anyway.

I'd personally stay away from Toyota transmissions, especially the 3 speed. It will not handle the V8 power over time and the gearing is HORRIBLE. You need a drivetrain that will hold up behind the HP that will also maximize the offroad potential of the truck with a minimum of screwing around.

It's a 40, you should be rowing gears, not throwing it in "D"......
 
Keep the V8, it's paid for, better H.P. & M.P.G. than a stock 6 cylinder, and weighs less than a stock 6 cylinder.
Keep the TH350, it's paid for, you just need Redgrrr's adapter and a 3 speed transfer-case.
Yes, get later model front and rear differentials as soon as you can afford them.

NOTE: Also keep in mind you'll have better torque with the automatic, torque converters multiply torque going into the tranny. Additionally, automatics are much better hill climbers, slip in the fluid drive allows the tires to slow down and get fresh grip/bite when hill climbing, stick trannies keep the tires spinning so they frequently break loose and merely spin on a hill side.
 
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