3spd to 4spd Swap with F Engine? (1 Viewer)

[Ron Rico]

Hi all,

So the '73, F.5 motor that's in my 71 has a burnt exhaust valve and prolly some other head damage from overheating prior to ownership. I'm picking up a rebuilt 1970 F motor tomorrow for cheap tomorrow (score!). Interestingly enough despite being a 1970 it has the F.5 / F2 oiling set up with remote oil filter by the manifold. anyone know what that's about???

I thought obviously this is a good chance to swap to a four speed. the 3speed grinds going into Reverse and First if I don't touch 2nd or 3rd first. I suspect this is a bad pilot bearing as I pulled the lid and things look pretty good inside the case and I put new GL4 but still grinds. I also have a new clutch master and slave. Any adjustment advice at the peddle or plunger advise welcomed...

Anyway to the point: what's involved in going from 3 speed to 4speed and retaining the F motor?

Do I need a different bell housing and clutch set up? (assuming yes) Flywheel? bell? pressure plate? disc? throw out arm?

Any issues with the slave location and 4spd throw out arm compatibility?

Will the 4spd mate up with the transfer case that I currently have with the 3spd?

Assuming this will require 4 speed OEM drive shafts - OEM, or do I need to modified originals or order custom?
BTW who makes decent custom shafts (opinions pls - and no I'm not trailing or crawling).

Finally I found a 3spd with over drive and correct rear drive shaft which seems rare.? It's a 3spd mated with transfer case and over drive ready to go but kinda pricey.

Anyone know how these 3spd with OD perform or does it just make more sense to get the 4spd in there?

So here's what its all about:
3spd overdrive bundle listed at $1500 (pricey) vs parts to make 4spd ($450 - trans alone) + parts and then ultimately what performs better? I suspect the 4spd shifts more smoothly than the 3 / at least what Ive heard from those who have had both.

Finally I'm missing the trans hump so just gonna get a fiberglass 3spd cover that has no holes - I assume should be a non-issue there with the 4spd under a 3spd hump?

Final finally rebuilt F motor going in comes with new clutch set up and pilot bearing so that would solve my 3spd grinding problems if I decide to just drop in motor n go.

Thanks so much guys, and anything my current foresight is missing?

 

[firemanj92]

The factory remote oil filter attached to manifold is where the 1F oil filter sits. Redline Cruisers sells a new hose kit for it as does FJparts.com and Sor.

Also check the FAQ page for your conversion needs. I think it's in there somewhere and a little grinding in a 3sp is pretty normal as it does not have syncros.

BTW, welcome to the ih8mud world!!!


1F Oil Line - https://redlinelandcruisers.com/shop/40-series/engine/1f-oil-line-kit/

https://www.fjparts.com/advanced_search_result.php?keywords=oil+line

 

[Ron Rico]

The factory remote oil filter attached to manifold is where the 1F oil filter sits. Redline Cruisers sells a new hose kit for it as does FJparts.com and Sor.

Also check the FAQ page for your conversion needs. I think it's in there somewhere and grinding in a 3sp is pretty normal as it does not have syncros.


1F Oil Line - https://redlinelandcruisers.com/shop/40-series/engine/1f-oil-line-kit/

https://www.fjparts.com/advanced_search_result.php?keywords=oil+line

correct but a 1970 motor had the spin on filter attach to the block and not the two hose remote filter option. Are you saying you can modify the F to have the 2F of F.5 oiling system? I didn't think the block had the provision for that / the two hose hook ups???

 

[BOBWhite74]

3 speed with overdrive? Is it a four speed with fourth as overdrive or is the overdrive in its own separate unit? The stock 4 speeds had no overdrive and I don't think there is much involved from swapping from a 3 to a 4 speed if everything's stock.

The old 3 speeds seemed to be geared lower than the 4 speeds (if I remember correctly) and they both have the same 1:1 top gear.

 

[pb4ugo]

1st and reverse are not synchronized in a 3 speed, so they grind. You'll need a 4 speed bellhousing. It think you can use either all 3 speed clutch parts or all 4 speed clutch parts. I don't think the bit and pieces interchange. Most folks will swap the trans and T/case together. Drive shaft lengths will be different. If you go to a 4 speed try and get the bellhousing to the t/case along with the shafts. The early model 3 speed FJ40's have a crossmember that makes the 4 speed a tight fit but it will work. As mentioned go to FAQ's at the top of the page and scroll down. Also look in tech links at the top of FAQs.

 

[charliemeyer007]

If you spend much time in low range then getting the adapter to use your 3sp's transfer case with the 4sp tranny will get you a lower first gear. 4sp is syncro on all gears - but its still 1-1 in 4th the same a 3rd in the 3 speed.

 

[ryanwk628]

This has been covered in a lot of build threads but the 4 speed has a different bell housing, clutch and flywheel. Get everything together. Get the bell housing with provisions for the motor mounts, the trans just hangs off the back. 4 speed is a physically bigger trans. My 3 speed was column shift and vac transfer case. Im switching it all to manual so that will mean new holes.

4 speed is syncronized and has a lower first. Same 1 to 1 final drive. 3 speed had a better 2.3 rather than 2.0 trans case ratio to compensate. You could put a 3 speed transfer case behind a 4 speed transmission for the best of both worlds. Cruiser Outfitters has a good writeup on this.

 

[Green Bean]

I did the swap on our 1970 not too long ago. The 4-speed transmission is slightly longer than the 3-speed. Therefore, the parking brake drum on the rear of the transfer case fits pretty snug with the existing torque tube cross member. You may want to consider mating up the transmission/T-case combo to the engine and dropping it in as a complete package. You will need to modify your transmission hump too. We kept the clutch slave on the driver side.

 

[Ron Rico]

3 speed with overdrive? Is it a four speed with fourth as overdrive or is the overdrive in its own separate unit? The stock 4 speeds had no overdrive and I don't think there is much involved from swapping from a 3 to a 4 speed if everything's stock.

The old 3 speeds seemed to be geared lower than the 4 speeds (if I remember correctly) and they both have the same 1:1 top gear.

Its a " Hone O Drive" over drive. Separate unit. Im not pursuing it. would rather the synchros and the 3 speed while having same 1:1 final 1st and second are very tractor like/ low. Im just going around town.

 

[Living in the Past]

Its a " Hone O Drive" over drive. Separate unit. Im not pursuing it. would rather the synchros and the 3 speed while having same 1:1 final 1st and second are very tractor like/ low. Im just going around town.

H42 four speed has lower gearing in first gear. The four speed is around 3.5:1 compared 2.57 as I remember. The H41 is very close to 5.0:1. 2nd gears are also lower in the two four speed. The three speed is an simpler transmission to work on which is why Toyota kept in the FJ40 until 10/82 in some markets which making repairs in the field was required. Other than being the original transmission to the cruiser I see no advantage of the J30 three speed. I really noticed the difference between the J30 and H42 traveling slowly on forest service roads is to match the H42 I need to put the J30 transfer case in low range and a higher gear to match the H42. It is also a friendlier transmission on the pavement.

Here is the first gear on the three transmissions

J30 2.757:1 which is lower than my guess.
H42 3.555:1
H41 4.925:1 this transmission was never used on US imports.
The earlier four speed used on the H45 and 9/72-9/73 FJ40 is. 5.299:1

 

[Ron Rico]

I did the swap on our 1970 not too long ago. The 4-speed transmission is slightly longer than the 3-speed. Therefore, the parking brake drum on the rear of the transfer case fits pretty snug with the existing torque tube cross member. You may want to consider mating up the transmission/T-case combo to the engine and dropping it in as a complete package. You will need to modify your transmission hump too. We kept the clutch slave on the driver side.

Thanks for the notes.
Did you marry the 4 speed with the 3speed trans?

 

[Ron Rico]

This has been covered in a lot of build threads but the 4 speed has a different bell housing, clutch and flywheel. Get everything together. Get the bell housing with provisions for the motor mounts, the trans just hangs off the back. 4 speed is a physically bigger trans. My 3 speed was column shift and vac transfer case. Im switching it all to manual so that will mean new holes.

4 speed is syncronized and has a lower first. Same 1 to 1 final drive. 3 speed had a better 2.3 rather than 2.0 trans case ratio to compensate. You could put a 3 speed transfer case behind a 4 speed transmission for the best of both worlds. Cruiser Outfitters has a good writeup on this.

I’ll check that article - I like the idea of retaining the 3 speed transfer case. Is it a chore to divorce them and remarry 4 trans to 3 transfer? Any adapter business involved?

 

[Ron Rico]

Thanks for the notes.
Did you marry the 4 speed with the 3speed trans?

Sorry - did you marry the 4spd to the 3spd transfer case?

 

[Ron Rico]

1st and reverse are not synchronized in a 3 speed, so they grind. You'll need a 4 speed bellhousing. It think you can use either all 3 speed clutch parts or all 4 speed clutch parts. I don't think the bit and pieces interchange. Most folks will swap the trans and T/case together. Drive shaft lengths will be different. If you go to a 4 speed try and get the bellhousing to the t/case along with the shafts. The early model 3 speed FJ40's have a crossmember that makes the 4 speed a tight fit but it will work. As mentioned go to FAQ's at the top of the page and scroll down. Also look in tech links at the top of FAQs.

I picked up my motor today. Can you positively ID this as a 3spd bell. It’s what the motor came with… it’s an F motor so I suspect it’s the regular 3speed. But who knows maybe someone had plans for a 4 speed and I got lucky??? Has a new clutch in there and fresh bearings from what I can see.
Will open it up tomorrow for closer inspection.

 

[charliemeyer007]

I think its a 3sp - no dowels

 

[pb4ugo]

It's not for a 4 speed. I think the 4 speed b/h has a figure 8 outline.

 

[Ron Rico]

I think its a 3sp - no dowels

ok - thanks

 

[Ron Rico]

It's not for a 4 speed. I think the 4 speed b/h has a figure 8 outline.

thanks

 

[cruiseroutfit]

....4 speed is syncronized and has a lower first. Same 1 to 1 final drive. 3 speed had a better 2.3 rather than 2.0 trans case ratio to compensate. You could put a 3 speed transfer case behind a 4 speed transmission for the best of both worlds. Cruiser Outfitters has a good writeup on this.

This one:

Cruiser Outfitters

 

[Living in the Past]

The early H42 four speed used up to 4/75 had what was thought to be a three speed transfer case. It's actually a transition case. The input gear still has twenty nine teeth. What is different is in the low range part of the idler gear and low range gear in the output shaft are not the 2.313:1 gears but the 1.999:1 gears. These are also wider gears. 4/75 all the gears were wider in the transfer case. The input gear went from twenty nine teeth to thirty one teeth. It's that four case input gear up to 4/75 that is needed to use a three transfer case on a sixteen spline transmission output shaft. Everything else that fits on the transmission output shaft has to be for the four speed.

I have never seen mid 63 and later three speed transfer case that had a spacer and not PTO gear. I know the early three speed transfer switched to a spacer at some point if a PTO was not installed. Never seen a later one with a spacer. Kurt @cruiseroutfit how common were the three speed PTO spacers?