1978 FJ40 Transmission Swap

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jaltoon183

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Jul 27, 2009
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Hi all, this will be my first post. My apologies for lagging behind a good deal as far as experience/knowledge goes. Car-less for a year I decided to finally go for my dream car and buy a 1978 FJ40 on a student's budget.

First thing I have to tend to is replacing the transmission with a 5-speed so I can keep up with traffic here. I've done some searching on the forums and google and it seems like on some years changes are required as well for the breaks, shift/transfer levers, etc. Not sure if this is the case for the '78.

I was wondering if someone could help point me in the right direction as far as which transmission is best, what price I'm looking at for the entire overhaul, etc. I've seen estimates of about $4000 for parts/labor, but figured you guys would have the most accurate estimate.

Thanks so much and I look forward to learning more.
 
jaltoon183 said:
Hi all, this will be my first post. My apologies for lagging behind a good deal as far as experience/knowledge goes. Car-less for a year I decided to finally go for my dream car and buy a 1978 FJ40 on a student's budget.

First thing I have to tend to is replacing the transmission with a 5-speed so I can keep up with traffic here. I've done some searching on the forums and google and it seems like on some years changes are required as well for the breaks, shift/transfer levers, etc. Not sure if this is the case for the '78.

I was wondering if someone could help point me in the right direction as far as which transmission is best, what price I'm looking at for the entire overhaul, etc. I've seen estimates of about $4000 for parts/labor, but figured you guys would have the most accurate estimate.

Thanks so much and I look forward to learning more.
Click to expand...

Here is some advice: Don't bother.

Stick with the 4 speed if it works, you won't go much faster with a 5 speed. Plus, a 5 speed, plus transfercase, plus install, plus tcase rebuild, plus driveline changes, plus new cross member, will add up to more than you paid for your truck. I'm guessing it would cost about $5000 all told. Spend a year or two getting to know the beast before dropping that kind of coin. You'll be much better informed about what it needs, and you be more able to do some of the work yourself.

They are not fast trucks. Stay below 3000 rpm and you'll be happy. SPend your $$ on getting it really well sorted out so it's reliable transportation. Remember, it isn't really that safe to go fast in a short wheel base narrow truck. It's a tractor, not a sports car. Learn to enjoy life in the right lane.
 
Welcome

Jaltoon,
Welcome to MUD!
This is a huge under taking for as first thing to do to your cruiser. Putting a 5 spd tranny and split transfercase from a newer 40 would be the easiest but they are hard to find. The problem is that the park brake on your 40 is on the back of the t-case and most of the splitcases are found on FJ60's which had parking brakes on the rear axle. You could upgrade to rear disc brakes and mock up a disc park brake system from a Cadilac. What I am getting at is that it is not just simply finding a 5 spd and bolting it in there are way more other systems tied into this. There have been a lot of posts regarding this on hear already. If you use the search feature (look for H55) you will find several really good ones. There is even info in the FAQ section: IH8MUD Forums - FAQ
Good Luck
Gavin
 
a 5-speed wont help you keep up with the traffic , what you want is a v8 .:flipoff2:

rubber overdrive or get some 3.73 gears for your truck .

for a 5 speed the nv4500 is a good but expensive choice . Advance Adapters NV4500 Retrofit Adapter Packages | Engine & Transmission Conversion Adapters - Advance Adapters

what about a ranger overdrive ? 1500$ plus some driveshaft changes . Ranger Torque Splitter Overdrives & Underdrives | Engine & Transmission Conversion Adapters - Advance Adapters

the rangers are tough , i saw a v8 cruiser get 3 gears of rubber with one , the output shaft on the toy 4 speed had some serious spline damage but the ranger was in great shape .

i drive around with 36's a v8 and a sm420 4 speed , it goes as fast as i'm willing to take it on swampers , usually to the point were the softop tries to peal off .

i really thing a ranger is the cheapest option . and then you will have a 8 speed .
 
I have a '78 with stock gears, tranny and TC. I'm running 33x10.50-15 BFG KO. I can cruise at 70/75 and can pull moderate grades with little loss in speed. Personally, I would keep the 4-speed as the 5-speed will require your rear drive shaft to be shortened and rebalanced. I would put the coin into a carb rebuild and maybe have the head rebuilt. What are the compression values for each cylinder?
 
We see this all the time. College kid buys 40 as primary driver and has big plans. These big plans take either a fat wallet or facilities, tools, know-how, time, error, blood, sweat and tears and another vehicle to drive while it's tore down. Usually they have none of the aforementioned things. Nothing sucks worse than laying on your back in the gravel while it's raining in the dark with a flashlight and having the pressure of needing to drive this thing to work/school/wherever the next day having not the knowhow, right tools or parts to get it going.

My advice to you would be take the $4K and buy a good used Civic. Economical, safe and will run almost forever. Use your 40 as a toy/hobby and make improvements as you can afford. Every man needs a toy. Reliable starting, good braking and steering are $$ well spent. Make it safe & reliable as you practically can without investing $20K and enjoy it as that. If at some point your interests change, sell it.

I and many others here have been exactly where you are at some point. Don't be discouraged, but these can be very impractical & expensive toys that can be very needy. I am not trying to pee on your campfire...this is the same advice I will give my own kids someday.
 
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Another thing to consider that is considerably less expensive would be to install third members from an FJ60 with the 3.73 ratio and as big of tires as you can realistically fit. These two mods will make it less of a punishment to drive on the road and are less $$$ than tranny swaps.

With increased speeds, high-maint manually adjusted brakes, high center of gravity, the aerodynamics of a barn door and a stock steering system that has 354 places for wear causing sloppy steering are factors that become even more of an issue.

Did I mention one gets all this at the cost of ~10 MPG if you are lucky?

That air conditioned Civic with powersteering, modern brakes, airbags and 30MPG is looking pretty attractive about now isn't it?
 
Thanks for all the replies. It's a bit to parse through, but certainly helpful/appreciated.

I don't plan on driving this car at around 70mph consistently, and don't mind riding the right lane 90% of the time. There is a trip I have to make every now and again, however, on a one-lane highway where pulling over and back on isn't really feasible.

What about many of the FJ's being sold with V8 crate engines dropped in? Should I be avoiding these and stick only to original engine?

Thanks again.
 
now we are going to the 2F/F V8 debate?



no engine substitution is just "dropped in" & your questions are just too vauge

if you can be more specific, I and many others will be glad to help. You have 2 posts. I am not belittling you...my advice to you is to search, read, read, read some more & then come back with more specific questions. Then make your own informed decision based upon needs, wants, desires, abilities and budget.
 
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I'm searching the forums/Google quite a bit and while I know my questions are vague, I'm gaining a lot more knowledge as I go (in no small part because of the helpful responses I've been getting here as well). I've actually changed my plan to be some what like you suggested; use a different car for any trips and work on the FJ in my spare time.

Right now one of the FJ's I'm looking at has had its engine replaced with GM 350 crate engine. I've searched the forums and found plenty of people who put a Chevy V8 and was wondering if this was a common engine replacement, or something I should avoid.
 
Yeah--Go slow here. You have years to worry about what type of motor swap you want to do or is practical. I will reiterate that there is no substitute for sorting out all of the little problems and neglect your truck has now. That will take 6 months to a year. At the end of that time you will be in a much better place to make decisions about what you want to do.

Drive awhile with the 2F. It isn't a bad motor, just slow and thirsty. It's generally dead nuts reliable. You don't have to swap anything and there are no hidden issues. The 2F, stock 4 speed and transfer will take you a long way and many places with minimal hassle. If you live in an area with no smog inspection, you could consider a desmog (done right) to simplify the motor.

Have you baselined all the fluids, rebuilt the brakes and front axle yet? If not, do not even consider swaps and mods. You have a lot of work to do first. Hook up with some local cruiser guys and spend a feww weekends helping other guys with their trucks. It will be like free instruction for you.

Post pics of what you have.


Edit: I gather you don't actually have an FJ40 yet?

Personally, I would avoid one with a V8 swap unless it was done professionally. Otherwise you'll have no way of knowing what issues you'll run into, and lots of V8 swaps are hack jobs. Some are great, though, you just have no way to judge. In general, and original motor and drivetrain is preferable for your first Cruiser.
 
I've owned my FJ40 for just over 23 years and have put in excess of 130,000 miles on it. In that period of time it only broken down once and that was my fault. It has made a 70mph blast from Tucson AZ to Monterey CA and back and many trips rock crawling or 4 wheeling here in the Arizona desert. For years it was my only vehicle, making the round trip daily drive. It has been one of the most reliable vehicles I've owned. It has been far more reliable than my Tahoe, my Mercedes or my 3 Volvos.
 
bsevans said:
I have a '78 with stock gears, tranny and TC. I'm running 33x10.50-15 BFG KO. I can cruise at 70/75 and can pull moderate grades with little loss in speed. Personally, I would keep the 4-speed as the 5-speed will require your rear drive shaft to be shortened and rebalanced. I would put the coin into a carb rebuild and maybe have the head rebuilt. What are the compression values for each cylinder?
Click to expand...
At what rpm are you turning to get 70-75?
 
bsevans said:
I've owned my FJ40 for just over 23 years and have put in excess of 130,000 miles on it. In that period of time it only broken down once and that was my fault. It has made a 70mph blast from Tucson AZ to Monterey CA and back and many trips rock crawling or 4 wheeling here in the Arizona desert. For years it was my only vehicle, making the round trip daily drive. It has been one of the most reliable vehicles I've owned. It has been far more reliable than my Tahoe, my Mercedes or my 3 Volvos.
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I agree. My 81 was my do everything vehicle. I even took it to Kuwait while attached to the Embassy as my wife's and children's "Escape to Saudi" vehicle. As dependable as a brick.
 
BullHab said:
At what rpm are you turning to get 70-75?
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This thread you replied to is from 2009 and the person you quoted hasn't logged on since 2014......
 
You can find rpm calculators on the internet. If you want accurate info, be sure to physically measure your tires. They are usually shorter than advertised.
 
When I ordered my H55F and TC Georg called me to talk about my build and I wanted to OD the HR and go to 4:1 in the LR and when I informed him I was using the R2.8 and 35" tires he said I had enough rubber over drive and with the R2.8 I would not need 4:1 LR.

He advised that I go to the Cummins web page with the RPM calculator and check out what the projected rpms would be.

The highest highway speed limit in Wyoming is 80 mph and with the ratios in the axles which are 4:11 and the over drive ration it showed 2650 rpm. With the F and 2F motors and the 4 speed it was turning almost 4000 rpm at 55 which was the national speed limit when it was build and I bought it. For my build the H55F makes since.
 
POPO AGIE said:
When I ordered my H55F and TC Georg called me to talk about my build and I wanted to OD the HR and go to 4:1 in the LR and when I informed him I was using the R2.8 and 35" tires he said I had enough rubber over drive and with the R2.8 I would not need 4:1 LR.

He advised that I go to the Cummins web page with the RPM calculator and check out what the projected rpms would be.

The highest highway speed limit in Wyoming is 80 mph and with the ratios in the axles which are 4:11 and the over drive ration it showed 2650 rpm. With the F and 2F motors and the 4 speed it was turning almost 4000 rpm at 55 which was the national speed limit when it was build and I bought it. For my build the H55F makes since.
Click to expand...

Something's wrong with the tach reading. I haven't checked an rpm calculator, but i would guess 35s at 55mph would be around 2600 rpm maybe less. I ran 36's with 4.88's at about 60 mph and the rpm was about 2800 . I think the h55 is a 20% overdrive.
 
Rpm calculator, 4000 rpm, 4.11 and 35's you would have been going 101 mph.
 
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