Here's what my drivetrain plans are:

400/NP435/ORD 203-205/D60s.

What I am considering, for a rairly street driven rig (like between close trails and to/from close-to-home trails only).

The highest axle gears avail (3.55 for 60 I believe), and run the low range box in 2:1 all the time. - for effective ratio of 7:1 (hey - they make 7.17 gears)

That gives 3700-4000 rpm in 4th gear at 60 mph (likely top speed)

but a low range of 6.69x2x2x3.55 = 95:1 which should be about perfect with the low end grunt of a built 400.

Maybe I could even shift out of 2:1 on the highway, but use it around town to get the 38-42" tires turning from a stop.

The advantage is the strength/size/and junkyard avail. of gears in the 3.55-4.10 range for the d60

am i nuts?

Originally posted by BillaVista
am i nuts?

yes definitely :p

I guess you're weighing the cost of high ratio gears (like 7.17:1) against the complexity and cost of putting in an extra reduction box that does absolutely nothing for you.

A 203 is cheaper, but you still need the adapters to make it work. Seems to me you're going to end up at about the same place in terms of cost.

You know what I'm going to think - that's an awful waste of a 203 reduction box. The whole thing I like about it is the flexibility it gives you on the trail. Doing things this way would make it meaningless as far as a trail piece of equipment goes.......

how bout you trade me the 203-205 for a dana 20 and some cash. That way you can buy some low diff gears and have a good transfer case.

-Steve

Not 100% sold on the 'leave it in low range ' idea........ it would put a lot of load on the 203 idler pin........ especially the thrust washers..... (203 has helical cut gears...)

In do like the concept of cheap junkyard gears that are generally stronger than the small pinion of really low aftermarket gearsets.

here is my solution........ dual transmissions and 4:10's with 38 SX's.......

http://www.sierrarockcrawlers.com/data/srcforumuploads/Dual_tranny_95OTT.JPG

I expect to drive with one tranny in third most of the time.... until I hit the Hwy.... then it's overdrive city.........

dual trannies - I like it.... Custom adapter, or ????

CRO you let cat out of bag now spill details.

I think you would twist driveshafts on the trail, because it takes more torque to turn higher gears because of the lack of leverage, if all of your low gears are before you get to the diffs you are likely to twist shafts before you get the wheels to turning. Its like using a 1/2" drive breaker bar on a 5/16" bolt, you are going to twist something. Thats my opinion anyway.

I like the two tranny concept, would like to see more info on that.... PLEASE!:skull:

Built? 400M? Isn't that an oxymoron?

2 trannies is the way to go, you can get a drivable rig with SUPER low gears for a relatively low cost. A buddy of mine is building a FJ-40 and he putting 2 SM465s in it. The only thing he needs to do is get a custom adapter made. 6.55*6.55 yikes, thats low, and that's just the trannies! :eek:

Originally posted by VeloCJ
Built? 400M? Isn't that an oxymoron?

Hey,hey,hey, that's not fair.....oh,wait...yeah, you'r right it is an oxymoron:D

actually the 400M is a good low range torque motor if you can keep the smog heads from cracking.

More info on the Duel Trannies :D


Eric

hey CRO,

where are you getting the overdrive?
are you running a model 18 t-case?
or is one of your tranny's running in reverse?

Anyone remember where that one came from..........


I have had dual Trannys in my 48 Willys for a couple of years now.......
The first incarnation was a L43 toy four speed mated up to a Warner T90/Dana 18......this was 104:1 in first/first.low with 4.11 axles
the cool thing about dual trannys is the Dual reverse.... with both trannys in reverse it would crawl forwards at 182:1....
BUT........ I broke the T90 ...
and I wanted to go with a 4.3 V6........

What I did was to mate up a SM420 to a T19/Dana20(scout)
It involved custom splining on the tranny mainshafts and on the input to the second tranny. also a custom spline coupler
I did all the machining on the adapter and spline work myself

I was worried about the weight of the tranny combination (and the torque) cracking a cast bellhousing.. thus the Lakewood steel scattershield. and the bushing mounted crossmember.. the tranny/t-case bolts directly up to this..

As far as the Driveshafts and transfercase goes......... a 32 spline output is going in the Dana 20..... and with a 14 bolt and a 60 I think that the driveshaft u-joints are going to be my 'fuse'.. as it is I will run 1350's in the rear shaft

The low range with the trannys in first will be 7.05 x 6.32 x 2 x 4.10 = 365:1
in dual reverse it will just edge over 400...
although Dual reverse sounds cool I rarely used it for much as there is a lot of load on the reverse idlers.. and these are running on plain bearings usually... I wouldnt want to crawl all day in dual reverse.

The ultimate trannys to use for the Dual reverse time machine would be NP435's........ do the math with an 8:1 reverse gear.:eek:

Originally posted by fcfred
hey CRO,

where are you getting the overdrive?
are you running a model 18 t-case?
or is one of your tranny's running in reverse?

Hey Fred. the overdrive I referred to is the effect of totally incorrect gearing vs. tire size..... I found that with my old setup. 35's on 4:10 toy axles with the dual trannys I would drive with the L43 in third most of the time..(actually I liked rowing the gears in the T-90...) I think the third gear in the L43 was something like 1.35 or so........ this would get you into a simulated 5.53 axle ratio with 4:10 gears...
themn when you hit the hwy shifting both trannys into 1:1 would be like having an overdrive.(except for the heavy tires sucking all the power out of the 22re....)
the correct terminology should be "effective overdrive"

Originally posted by CRO
Anyone remember where that one came from..........


I have had dual Trannys in my 48 Willys for a couple of years now.......
The first incarnation was a L43 toy four speed mated up to a Warner T90/Dana 18......this was 104:1 in first/first.low with 4.11 axles
the cool thing about dual trannys is the Dual reverse.... with both trannys in reverse it would crawl forwards at 182:1....
BUT........ I broke the T90 ...
and I wanted to go with a 4.3 V6........

What I did was to mate up a SM420 to a T19/Dana20(scout)
It involved custom splining on the tranny mainshafts and on the input to the second tranny. also a custom spline coupler
I did all the machining on the adapter and spline work myself

I was worried about the weight of the tranny combination (and the torque) cracking a cast bellhousing.. thus the Lakewood steel scattershield. and the bushing mounted crossmember.. the tranny/t-case bolts directly up to this..

As far as the Driveshafts and transfercase goes......... a 32 spline output is going in the Dana 20..... and with a 14 bolt and a 60 I think that the driveshaft u-joints are going to be my 'fuse'.. as it is I will run 1350's in the rear shaft

The low range with the trannys in first will be 7.05 x 6.32 x 2 x 4.10 = 365:1
in dual reverse it will just edge over 400...
although Dual reverse sounds cool I rarely used it for much as there is a lot of load on the reverse idlers.. and these are running on plain bearings usually... I wouldnt want to crawl all day in dual reverse.

The ultimate trannys to use for the Dual reverse time machine would be NP435's........ do the math with an 8:1 reverse gear.:eek:

Forgot to mention that. The only crappy part is that non helical (sp?) cut reverse gears are noisey as a bastard and when you got 2 going at the same time, look out! It sounds like the whole thing is gonna blow :D

Built? 400M? Isn't that an oxymoron?

Ouuuuch! Newbie - ya just embarassed yourself!

Unless you don't consider 380hp and 486 lb ft for under $2k a good idea.

Read all about it, newbies:flipoff2: :flipoff2:

http://home.earthlink.net/~tcrocker/400.html

smack :p

Ok I'm currently working on a sm-420/lt230/4.10 r&p setup
this works out to between 85 and 95 to 1 low low. now I have the oppurtunity to use a 203 box in between the 420 and lt 230. this would double my low to 170/180 to 1. is this overkill? I'm gonna run a sbc 350 and 38,12.5 sx's. do I need the doubler or is it too much weight?

Originally posted by 44Runner


Forgot to mention that. The only crappy part is that non helical (sp?) cut reverse gears are noisey as a bastard and when you got 2 going at the same time, look out! It sounds like the whole thing is gonna blow :D

Correct me if I am wrong but if you have 2 trannys and put them both in reverse wouldn't you be going forward:confused: at a rate of 16 to 1 with 2 435's

you are correct and I think that's probably a good thing
that way you can get out and pick potatos in the field loading up the jeep as it chugs along beside you:D :flipoff2: :flipoff2:

Crazy uncle Freddy,

I think you almost HAVE to add the doubler...otherwise we'll have to start calling you "Perfectly reasonable Uncle Freddy"

Seriously...I say add the extra gearing...gearing (and the fleaxability it brings) is way cool

Originally posted by 66CJdean


Correct me if I am wrong but if you have 2 trannys and put them both in reverse wouldn't you be going forward:confused: at a rate of 16 to 1 with 2 435's

You're wrong. :flipoff2: You're right about the going forward part, but 8^2 = 64. So, with say a 205 t-case and 4.10s, you'd be at 514:1.

I've contemplated the dual trannies at times, but have yet to find a trans that would be strong enough for a full size and have decent ratios/length to work behind an auto.

Pete