Topic: FJ40 Driveline Questions

[FranB]

Folks, I'm new to this Marlin forum so not sure if this question has been addressed before.  I have a 73 FJ40 with a SOA and front spring reversal riding on 37 SSRs.  My next upgrade needs to be gearing.  I'm running the stock F engine and stock 3spd tranny and tc.  I want to achieve a 100-125 crawl ratio and am exploring options.  My first plan is to remove the stock tranny with an SM465.  What are the best options for the tc?

First, does Marlin make crawler gears to fit into the stock tc?  If so, what ratio 4.70?

A dual case/TOYBOX setup would work, but sort of $$$.

Lastly, I'm considering swapping in a mini rear axle (got one) and using a mini tc and installing the 4.70 crawler gears.  Has anyone done this?  If so, what sort of performance do you get?

[BigMike]

First, does Marlin make crawler gears to fit into the stock tc?  If so, what ratio 4.70?

We used to make a 3.64:1 drop-in gear set but discontinued it way back in 1997 I believe.

I'm considering swapping in a mini rear axle (got one) and using a mini tc and installing the 4.70 crawler gears.

This would without a doubt be the most cost effective and practicle (in terms of limited driveline room) because with our front ToyBox adapter plate, you can mount a mini tc directly behind a SM465. Then you can run the 4.70:1 gear set and the total overalll length has got to be only maybe 3"-4" more than the stock setup (?) which is very reasonable.

Here is a single mini tc mounted behind a SM420 using our front ToyBox adapter plates:
http://rcrc4x4.com/ProductReviews/SM420adapter/Review.html

Cruzila will have more indepth info than I, so you might want to ask some more questions now..

Regards,
BigMike

[cruzila]

My first thought was stock 4 speed transmission and a Toybox.
That is where I am going with mine.
Taking out the SM420

[FranB [OP]]

Someone mentioned to me today their concern regarding the strength of the mini TC.  He thought it may not stand up to torque applied with low gearing, increased LC weight and greater torque of the F engine.  I wondered about this comment though,,, a mini running dual tc setup will create much greater torque - or am I mistaken.?

Cruzila, why are you swapping out the 420?  Is 1st gear too low when latched up with the Toybox?

[BigMike]

The strength concern with the gear driven RF1A mini truck transfercase is a justified concern, the mainshaft is a major weak spot, but you have to be wheeling very wild to break one.

We have many many 3.0 V6s, 3.4 Supercharged V6s, 4.3 V6s, and a hand full of V8 owners all using the RF1A transfercase double with 4.70:1 gears and Im not getting calls from these customers complaining about the strength of the transfercase.

Marlin has a tripple case setup with two sets of 4.70:1, his truck is very heavy (I would say 4,500+) and he has never broke a transfercase. Even the original case he installed back in 1994 has never needed to be removed or serviced or replaced. Still ticking with out a sweat.

But Fran, what about the stock LC 3- and 4-spd t/cases (non-split)? I hear alot of those spliting, but Ive never heard of nor seen a minitruck t/case split from to much torque...

I guess it could be argued against, but if you drive it properly, its not going to leave you stranded.

Regards,
BigMike

[FranB [OP]]

Mike, thanks for the conversation this afternoon.  It appears I don't have tooo much cost saving by going with the mini tc, coupled to a SM465.  By the time you add in the adapter cost plus 4.70 re-gearing, I'm nearing the cost of a ToyBox.  As I keep thinking about it, I like the options that a dual-box configuration provides me vice the low-only options of the single 4.70-geared transfer case.  Only issue with the ToyBox will be the added length of the driveline = shorter driveshaft.  My thought is I can regain about 3" of that by doing a spring reversal on the rear axle.  If I'm still short or have a bad angle on the driveshaft, I could invest in a cv-jointed High-Angle driveshaft.  Again, this option may be a tad more expensive, but would be worth the options given to me with the gearing.  Thoughts anyone?

[FranB [OP]]

Follow-on question here..., have noticed my clutch is seeming a little weak.  What are the replacement options?  Stock or after-market upgrades?  Any direction or recommendations would be appreciated.

[BigMike]

Decisions decisions decisions....
Its alot of work huh?


About the clutch, if your running the F engine then it doesnt really matter, but if your turning some big HP numbers then I would not suggest a plucked clutch as a daily driver.

BigMike

[cruzila]

It's snowballing on ya I want the better streetability of the 4 speed.

SM420 with 2.28 is the same as 4 speed and 4.70

around 160:1

[SpaceGhost]

Follow-on question here..., have noticed my clutch is seeming a little weak.  What are the replacement options?  Stock or after-market upgrades?  Any direction or recommendations would be appreciated.

Stock Toyota clutches are the best. Get a kit from a vendor or the dealer. But before you do, resolve your tranny choice because you may need to use a different clutch.

Cost/dependability wise, a stock four speed is the best shifting of the bunch, So if ya plan to drive it on the street, watch Scott's plans. Swap the bellhousing and tranny, and with Marlins adapters you can add a mini reduction box (ToyBox).

Flipping your rear springs will add some length, which is always good. My rear shaft is a shorty with only 8" of tube. I went to the mini flanges and ujoints for strength and the angle of operation Plenty strong enough for extreme rock crawling.

[matthewlc]

I recently emailed AA about their Orion cases. I don't want the super low gears but would love an iron case. They told me all non-US cruisers had iron t/c's. Supposedly any of the major cruiser places can get them.

[coolcruiserfj40]

I recently emailed AA about their Orion cases. I don't want the super low gears but would love an iron case. They told me all non-US cruisers had iron t/c's. Supposedly any of the major cruiser places can get them.

the criuisers made in south america, im drawing a blank on what they are called but its basicly a cruiser but made cheeper and those had the iron cases maf sells or sold them for big bucks

[Gravel Maker]

Banderante', Brazillian

[LCOwner]

The 420 and a single box mini t-case are about as long as a 420/w an AA adapter to the stock 3sp case within an inch.  I justified using the ToyBox adapter plates with 4.70 gears by using my 7.05:1 first as a "2.28" box if I don't need to be double down.  IMO ditch the LC case it's a dinosaur.

[green73]

FranB I sent you a PM.