Series transfer case Torque capability

[mongoswede]

At what torque level shoud a different transfer case be considered for a series truck? For instance...lets hypothetically say one were to put a Mercedes Sprinter diesel in which generates about 150 hp at 3800 rpm but 243 ft/lbs at 1600 rpm. Clearly one would be using a different gearbox...but would a series transfer box withstand this kind of abuse...especially if combined with a strong axle and maybe 33" tires?...or maybe the appropriate question is how long would a series transfer case withstand said abuse?

[leafsprung]

Impossible to answer. It depends on too many factors. The weak point is the material used on the output shafts, some are much better than others. Should be pretty sound with those numbers though.

[mongoswede]

Another question is where would you find a stronger transfercase without moving up to a bigger commercial truck type and where would you find an adapter? The Series transfer case is one of the strongest in its class and the strongest factory case with the front and rear propshafts in alignment.

Advance Adapters has a series of adapters to adapt the Series transfercase to American four and five speed truck gearboxes (http://www.expeditionlandrover.info/advance_Adapter.htm) commonly used in gearbox swaps behind V8s. They offer the adapters to early Land Cruiser and Jeep owners for a transfercase upgrade to a stronger box.

Anything will break given enough abuse but the Series transfercase stands up well behind high power American V8s, the GM V8 diesels and the Cummins AT6 & BT6 diesels.

The engine in my Land Rover puts out an estimated 300 lbft of torque, and my Series transfercase has been trouble free behind it for going on 12 years (including a recent rebuild with new bearings & bushings)

this is a good answer....gives me a good reference. I wasn't sure how the transfer cases compared to others on the market. So if it works behind your 8 then I suspect it would be fine.

:thumb-up:

[leafsprung]

I definitely would not use it behind a 6BT cummins . . . Ive broken an output shaft with the 6AT At 240 ft/lbs. I think you could break them at will with a real healthy V8 and some moderate abuse. . . Generally though they last pretty well and are pretty robust. Overall I wouldnt say its much stronger than a land cruiser split case or D300 (though it has much wider gears than the 300).

[leafsprung]

A) I've broken an output shaft in moderately powered 88 on a moderate obstacle. It is not the first one Ive seen break. They break, they are of moderate size and strength and are definitely the weak link in the T case.
B) Your pictures are NOT of a land cruiser split case they are of an FJ40 case; very different cases.
C) Just because someone put a series case in a truck with a big motor, doesn't make it a good idea. FWIW Timm has also broken an output shaft in a series case.

[Eric W S]

I never did specify which Land Cruiser box the pictures were from so please don't argue which one I had pictures of. :nono:

I think I found my new sig line. That has to be the most retarded rebuttle I have ever heard. Semantics to save face. :rolleyes:

[daveb]

Eric
The correct spelling is "rebuttal." :)


I think I found my new sig line. That has to be the most retarded rebuttle I have ever heard. Semantics to save face. :rolleyes:

[109 Pretender]

Timm Cooper and I had this very conversation about 1 month ago. The series SIIA transfer case is good - better than most factory cases. A built 6Bt will destroy any transfer case if you put your mind to it. A 4 Bt would be a better choice and would actually fit - 6Bt will never fit unless you build whole chassis around it.

Atlas case is also quite good. Timm thinks gears are about equal between series and Atlas cases. The problem comparing them is the 40 years wear and tear on the LR case internals and the eventual fatigue that results (see Ike's comments).

NP205 is pretty stout but case dimensions won't allow anything beyond 1:1. There used to be a custom NP205 setup that had custom case and gear sets that would allow deep gears for crawling - they don't make them anymore. Name was Low??? something...

All planetary transfer cases - (all chain drive and Orion) - can't be built up much at all because of the restrictions related to the planet gears.

Old LC FJ40 type cases are about same as LR - pretty good for most needs.

This brings me to why I posted this while mentioning Timm Cooper. Timm has just finished designing and building his own transfer case. It has an indexed split case and from what he is saying it might handle a well built 6Bt w/twin sequential turbos - something around say 1000ft/lbs torque.

By the way, for those interested, Timm gave me the OK to say that he's back and will soon have a new website up and running. For those of you who don't know who I am speaking about - ck around. Timm is very highly respected in the 4WD Land Rover world. I expect his transfer case to be extremely H.D! No info on when or how much at this time. As always, Timm is a very busy man.:thumb-up:

[109 Pretender]

Mongo,

My 109 has the series transfer w/3.9 Rover V-8 running dual SU's. I did have the stock 6 cyl tranny - it's not good enough (even w/~$3k in new internals - every single part was replaced w/new).

After my 109 got wrecked I decided to go ahead and change the tranny (Timm Cooper is building me an adapter for the NP435 w/the Chevy 35 spline output). I will be using the stock transfer case.
Salisbury d-60 F&R 4.7:1 w/Ashcroft hi gear set for the transfer. I didn't like 1st gear (too high) w/Ashcroft gears so much. NP435 will be much lower geared in 1st and should work fine.

I don't crawl with this rig - it's for camping - mostly secondary and fire roads.

I wouldn't use the factory transfer case for H.D. rock crawling (ie The Hammers) or high torque engines (>350-400ft/lbs). All this series LR stuff is just too old to abuse much w/o serious breakages. Now if you could get some new gears, shafts, etc made out of more modern materials - who knows...

TeriAnn made an important point here too - there's not much to choose from if you want to retain the rt. side alignment of the axles/driveshafts. Unless you go for a divorced mount.
Flat fender Dodge power wagons used a divorced D200 (predecessor to NP205). It had same drivetrain layout as our Rovers. Used closed knuckle front axles too!

I think you will be OK w/series transfer as long as you respect its age and limitations.

[leafsprung]

Cruiser split case with park brake or Orion (which is gear driven) is probably the best, most cost effective option on the market with dual RH outputs. Good parts availability with lower gearing options.

[Momo]

Not to hijack the thread mongo, but if you are looking to go with a sprinter motor you are in for some torture. The electronics on that thing basically make it inseparable from the transmission from what I gather. I was looking into this as a conversion option last year and there's about enough wiring and brains in those things to fill a bathtub. If you can make it work you are the MAN!

[leafsprung]

You would have to use a mechanical pump or know someone that could reprogram the computer.

[Momo]

Exactly... the EFI talks to the gearbox... so unless you could adapt a mechanical injection pump you would have to get an expert involved. And I doubt if you could ever get the motor to run properly without the electronics. Modern diesels are heavily dependent on it.