I am restoring a "74" FJ40. I now have a 3spd transmission. I dont plan on any serious off roading. It would more than likely just be a sunshine and pavement ride. That being said, would a 4spd transmission get me any more speed on the road? I read somewhere that the 3rd gear in a 3 speed is the same ratio as the 4th gear in a 4spd. Is this true? Is there a 5spd I could get to work? Thanks guys, David
FJ40 3spd vs 4spd, to swap or not to swap.
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Yes the 4 speed and 3 speed tranys have the same high gear (1:1). 4 speed shifts a lot nicer and holds up a little better, if you want a cheep solution if it is truly only going to be on the street you could swap to 3.73 diffs and there is always bigger tires 
5 speed tranys are none U.S. and are a common swap, I think the 5 speeds are (h41 and h42)? I can't remember.
The older GM nv4500s are the shiznit with granny and a overdrive
5 speed tranys are none U.S. and are a common swap, I think the 5 speeds are (h41 and h42)? I can't remember.
The older GM nv4500s are the shiznit with granny and a overdrive
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The 4spd is much nicer on road in terms of shifting, but 4th gear and a 3spd 3rd gear are both the same 1:1 ratio, so there will be no speed difference. Best way to get speed IMO is to get some larger diameter tires like 33" and install the 4spd. The lower 1st gear helps with bigger tires, but in high gear, the tires will help with speed.
Off road the lower first gear is nicer with the 4spd when using 4hi, though the final ratio in 4Lo is hardly different.
The 4spd is also a stronger unit.
Its possible to put in a 5spd unit, but it requires more extensive modifications and way more cost.
Matt
Off road the lower first gear is nicer with the 4spd when using 4hi, though the final ratio in 4Lo is hardly different.
The 4spd is also a stronger unit.
Its possible to put in a 5spd unit, but it requires more extensive modifications and way more cost.
Matt
'74 should have a 4spd from the factory. Go with the 4spd. Far superior. Get the "transition gear" and keep your 3spd t-case.
My '70 FJ40 still has the three speed (in the tree I might add) 
. I use it as my DD and 70mph is not a problem. BTW it sits on 31" tires for now. The thing I don't like is First is not synchronized. Other than that it doesn't bother me. If i was going to spend money on a tranny with more gears I'd skip the 4 and look at a 5 speed.
. I use it as my DD and 70mph is not a problem. BTW it sits on 31" tires for now. The thing I don't like is First is not synchronized. Other than that it doesn't bother me. If i was going to spend money on a tranny with more gears I'd skip the 4 and look at a 5 speed.
cheapest overdrive out there is a set of 33x9.5 BFG AT's. Great looks, no suspension changes required.
IMO, the 4-speed will be mucho nicer on the street, better shifting, better in town gear selections.
IMO, the 4-speed will be mucho nicer on the street, better shifting, better in town gear selections.
Don't forget, changing to a 4 speed means more than just switching gearboxes. It means a different bellhousing, clutch, clutch slave, etc. But definitely doable.
IDave said:
different bellhousing, yes, and related inspection cover, but 3 speed clutch can be retained, along with 3 speed flywheel, and infact early 4 speeds actually had the 3 finger clutch.
The 4 speed is SO much better to drive. I would keep the stock axle gears and go with a set of 33" narrow BFG's too. If thats not enough, then go to 3.73, theyre easy to find from FJ60s, etc.
5 speed is going to cost you about $2k min unless you are able to swing a great deal.
3 speed is the J30(use thru 74)
us 4 speed is the H42(74-87)
non US 4 speed with lower 1st is the H41
non US 5 speed is the H55F(same low 1st as the H41 and an overdrive)
I would swap to the US H42 and run 33x9.5's or if you don't mind the non syncro'd 1st of the 3 speed then keep that and do 33x9.5
us 4 speed is the H42(74-87)
non US 4 speed with lower 1st is the H41
non US 5 speed is the H55F(same low 1st as the H41 and an overdrive)
I would swap to the US H42 and run 33x9.5's or if you don't mind the non syncro'd 1st of the 3 speed then keep that and do 33x9.5
I just swapped in the H41 4speed that was imported from Australia. I also swapped in the Orion tcase. I have a few things still to do like installing a custom front drive shaft. But I REALLY notice the difference in the almost 5:1 first over the stock H42...
But to the first question: get the 4speed and look into keeping the older 3speed case. You will need the transition gear. You will have a nicer, better spaced gear set and a lower crawl due the lower 1st in the 4speed and a lower ratio in the older 3speed case. This is an easy common swap. BUT TAKE THAT RIG OFF ROAD!!! That is what it is designed to do. With that gearing and caution your truck will do just fine and yoiu will gain a lot more affection and respect for your cruiser...
Max
But to the first question: get the 4speed and look into keeping the older 3speed case. You will need the transition gear. You will have a nicer, better spaced gear set and a lower crawl due the lower 1st in the 4speed and a lower ratio in the older 3speed case. This is an easy common swap. BUT TAKE THAT RIG OFF ROAD!!! That is what it is designed to do. With that gearing and caution your truck will do just fine and yoiu will gain a lot more affection and respect for your cruiser...
Max
CruiserMax said:
H55F is nice, however, the crawl options are rather poor.
H55F - split case - 4.88s nets an overall crawl ratio of 57:1.
This setup will cost probably about $5000 when it's all said and done.
You can get a set of 3.0?:1 gears for the split case, however, these are also really expensive.
No Marlin Toybox is available for the H55 yet.
No AA Rockbox is available.
No Orion is available.
My SM420 is at 57:1 with a STOCK 4 speed t-case, and STOCK gearing, and cost me $500 when it was all said and done. No skidplate mods. No driveshaft mods. No tranny hump mods.
That said, if I could get an orion or a toybox for an H55, I would throw my SM420 away and do that instead.
NV4500 isn't really a great option behind an f/2f.
The gear spread is too high IMHO.
With V8s NV4500's are a non-issue (as they were desgined for this).
CruiserMax said:
I wouldn't bother with the 3spd transfer when swapping transmissions. This net difference in lo-range is minimal and probably not even noticable. If you want gear reduction, just get the H41, SM420, ToyBox, Orion, etc. or change diff gears.
Just my 2 cents...
Restoring to me means there isn't really an option, your trucks a three speed so thats how it should stay. That said, if your not truely restoring the H42 four speed is a good option. I swapped in a 4 speed/3spd t-case into my truck and it was a noticable improvement over the original 3 speed gearing wise. It still has plenty of gear whine and really isn't quite low enough geared tho, so eventually it'll get swapped out again. Prolly put in an H41 and live with the noisy transfer case.
I guess I must be the only one but I prefered the 3 speed for city driving. I had floor shift so I'd shift 2nd then 1st each time to keep from grinding gears. The gear spacing was just right for the 31" tires. The four speed first gear is a bit lower than needed to get rolling, but its a bit rough on the clutch to start in 2nd unless on flat or downhill.
A five speed is a very nice setup but major work and $$$.
Since you are leaning toward road use I wouldn't consider a GM four speed, since you drive them like a three speed on road.
I guess I must be the only one but I prefered the 3 speed for city driving. I had floor shift so I'd shift 2nd then 1st each time to keep from grinding gears. The gear spacing was just right for the 31" tires. The four speed first gear is a bit lower than needed to get rolling, but its a bit rough on the clutch to start in 2nd unless on flat or downhill.
A five speed is a very nice setup but major work and $$$.
Since you are leaning toward road use I wouldn't consider a GM four speed, since you drive them like a three speed on road.
Cryptic said:
It's really not that bad, I was agains using a GM tranny for the longest time, now I am sort of disappointed that I did not do it sooner.
Around town, I don't notice the difference, but where I see the big difference is going up a hill going over US-6 to Price. 3rd to 4th is a little too wide for my 2F.. I will run at 3500 rpm with the 2F SCREAMING, then shift to 4th and my engine rpms drop to 1800, abnd I get slower and slower and slower.....
but for the money, the SM420 is really hard to beat for doubling your crawl ratio.
my two cents on the matter is that the swap is worth it. I did it a while ago, the trannies (two of them) were $100 for both, plus an extra $350 for the adapter gear to the 3spd xfer, drive shafts, bolts, shifter, gaskets, back up switch, etc, etc. However, this was with two incomplete trannies that a regular user of this board promised to send me the rest of the parts for. Thanks alot jeff, still waiting for that nose cone, shifter, and fork! I only did this swap because my 3spd was shot and barely worked anymore. I only used the 3spd xfer because I did not have a 4spd case and the transition gear + bearing was only $70. Kept the vacuum and dash shift controls. The driveline shop lengthened my shift linkage for $10, 3.5".
The 4spd is more like an older car transmission, not a truck tranny, so you would be pleased with it on road. It shifts well, but when you retain your 3spd cased you will be mating an old, worn out gear with a newer, relatively unused gear. This will cause a little more noise, and for on road purposes, probably not worth the effort to retain. If I was to do it again, I would plunk down the $600 for the H41 for romantic value, or tour the junk yards for a NV4500. H55s are way too ovepriced in my opinion. but hell, it's only money, right?
The 4spd is more like an older car transmission, not a truck tranny, so you would be pleased with it on road. It shifts well, but when you retain your 3spd cased you will be mating an old, worn out gear with a newer, relatively unused gear. This will cause a little more noise, and for on road purposes, probably not worth the effort to retain. If I was to do it again, I would plunk down the $600 for the H41 for romantic value, or tour the junk yards for a NV4500. H55s are way too ovepriced in my opinion. but hell, it's only money, right?
david if all you want is a little more speed get yourself a set of 3:70 gears, you can find them on FJ60's used. or you can buy a new r&p set and go that route. the 4 speed tranny and case would be a great addition just fer the 4 speed. nice gear spread on them. if you decided you like that idea you can probly find folks to trade you straight up for almost everything you need and it would literally be a bolt-in affair.