ok so i got an idea. if somebody could make a 1spd automatic transmission (1:1 ratio), i could mount it in front of something like an SM420 and get the torque converter effect of not having to use the clutch, but with the lower gears. only problem i can see though is shifting it, would you still need a clutch? i havent figured that part out yet. hmmmm... :D

top... i want peoples opinions on this :smokin:

i'm not really all that familier w/ auto's, but what if u put it in neutral, would that relieve the pressure from the standard tranny and allow u to shift?, also just use something like a th400 or th350 and mate something like a 465 or 420 to it, but u would need at least 110 wb

I remember reading years ago about a baja race truck that used a five speed manual with a clutch and torque converter (no second tranny), the article was in fourwheel, probably close to 10 years ago. Anyway, they didn't give any details, but said it gave the truck the ability to come to a stop in any gear, and the extra reduction of the torque coverter gave it a low end power, with the ability to lock up the coverter at higher speeds.

Actually this seems like a really interesting idea, I don't know anything about auto's, but would you even need a second tranny, wouldn't a clutch, torque converter and manual tranny work, or do torque converters require the auto tranny to work right? Could be an intersting way to increase crawl ratio for those of us with manual transmissions.

chad

tou'd need a converter and pump (the converter requires ATF to work), then you could couple it to a clutch and manual, this setup is fairly common in forklifts, and yes you need a clutch to shift still, at least on all of the forklifts with this setup I have driven...

okay, so a torque converter in front of an SM420... wheres a machine shop when ya need one! :D

Sounds like a great application for a 2spd auto (1.92:1 and 1:1) and can be built to handle big power and gobs of torque...its the Powerglide tranny intro'd well, along time ago and a old time favorite of the rear drag racers.....crank it to 7k then pull.....fairly short too...

coyote- thats a freakin awesome idea, i was only thinking of 3spd autos. forgot all about the powerglide!

ok so now we have a theory and which parts to use, so whos gonna make the prototype??? :D

Now I'm getting really intreged, but this seems pretty hypothetical still. What would be the best order, manual or auto first? Since the manual's clutch requires a flywheel (i think), and the powerglide could probably handle more torque, so put the manual first, then contrive some adapter to allow a torque converter, and a powerglide to be installed behind it? What's the length of a power glide, anyone have an idea?

With a good compound low 4-speed, and a plan jane t-case you'd be looking at a crawl ratio over a 100:1 not counting the torque converter, put in an atlas, and the numbers get really good :)

THEY MAKE THOSE

some unimogs (the case model for towing heavy loads such as airplanes) have them. They have the regular stick plus a torque converter that works so you don't have to slip the clutch ever. Apparently they are a lot slower that the regular unimogs (406) on the street (which is really damn slow). If you are really interested you goto unimog.net and call that guy i think he knows all about them (I THINK)

i would put the auto behind the manual simply because the auto would have a cable-type shift linkage, so you could mount it anywhere.

and the thing is, you probably wouldnt even need a very large torque convertor to do the job.

just did a few quick calculations:

crawl ratio with SM420, PowerGlide, 2:1 low, and 5.13 axles":

1st gear in 420, 2nd in PG= 72.3:1

1st gear in the 420, 1st in PG=141.7:1

these dont take into account the torque convertor effect- if you do that, then it would be...

1st in 420, 2nd in PG= 144:1 (same as if you had SM420 and Doubler, but you dont have the no-stall ability of the TC)

1st in 420, 1st in PG=283:1 :eek:

then like you said, add a 4:1 kit and it gets LOOOOOW

or how about a doubler with a 2:1 205 and the 3.6: kit for the 203 :eek: :eek: :eek:

7.05x(1.96x2)x2x3.6x5.13= 1020:1 :D

i like this idea A LOT, anybody know how long a PG is?

too long to use and too hard to find. i beleive they are a little shorter than a th350

Originally posted by TRD
too long to use and too hard to find. i beleive they are a little shorter than a th350

too long to use? maybe in a 83" WB jeep, but maybe not in a 105" crawler...

too hard to find? youre kidding, you can buy a completely brand NEW one for like $650, race prepped :D

you could probably lose a lot of the length too by losing the tailshaft housing and the bellhousing.

...Ya, I spent a bunch of time like last year trying to figure this out. It's a great idea...

...Obviously a locking torque converter, right... And you'd want it in front of the tranny, to save wear on the tranny, in my opinion... Plus that just means building a bellhousing extension, not some weird-ass thing on the back end of the tranny...

...Also, if you do have to shift, you could just use a hydraulic clutch... As in FULL hydro. You know how auto shifters have those buttons or handles to pull to shift out of park or whatever? Have that as a switch that would activate a pump to the clutch... Because the TC is there, you don't need to worry about the clutch grabbing fast or anything, because it's buffered by the TC... Just use a bleeder on the hydro line so when you release the clutch it takes maybe 1/2 to 1 second to engage...

*OR*... You could even use a neutral switch as the activator for the clutch. You don't need a clutch to get out of gear (or I don't use one half the time, anyways :rolleyes: ), and once it hit neutral, the clutch would disengage... And once it left neutral again, it would re-engage in 1/2 to 1 second, or whatever...

...And if you use a lock on the TC (keep in mind I don't know how they work :D), you could have it RPM-activated... So that it locks at anything over 2500 rpm, and doesn't unlock again until 400 rpm (or something under idle; some RPM it won't see unless it's because the lack of wheelspeed is loading it below idle)... Of
course you could switch it off for crawlin', but that'd be for street.

...Hell, you could even use solenoids or rams to build an auto-shift... But I'm weird like that. :D

...This would really give you the best of both worlds, and I really don't see it being that difficult to make; there's only 2 parts that need to be dealt with, which is the TC bellhousing and the shaft between that and the clutch.

my neighbor has a drag car with a turbo400 and a clutch. Uses the clutch to lanch and then the rest are auto...I can ask him about it if it would help. (it's kinda backwards to your question, though);)

Obviously the parts wouldn't work, but how were the old auto-stick VW super beetles setup? Did they have a clutch pedal for changing gears?

Pete

ColdNorth, thanks for the input. but here is what i am talking about-

engine to SM420 just like you would normally (clutch plate, etc).

then, the SM420 will go to the PowerGlide via a small torque converter.

the powerglide will mate to an NP205 via a custom made adapter.

i wish i would know how long this whole setup would be overall, cause it would really be bitchin.

anybody out there have the skills to do this and want to make one to test out?

I'm far from an expert on the auto trannys, but just a point to ponder.

If you put your manual tranny behind your engine, then go to the auto, will the torque converter/pump setup have enough pressure to run? You're cutting your engine RPMs severely - the 6500 RPM you'll never hit is what it will take to let the auto tranny see 1000 rpm (rough numbers).

My gut feel is that you'd need to put the auto in front of the stick.

What about sticking a small T-10 style tranny behind the auto or manual that's normally attached? I thought about putting one of those between my TH400 and NP205... Nice selectable low-ranges, would be nice and stout, too. And it's not a toploader so it' would be easier to make a linkage for...

Squash

Originally posted by Realsquash
What about sticking a small T-10 style tranny behind the auto or manual that's normally attached? I thought about putting one of those between my TH400 and NP205... Nice selectable low-ranges, would be nice and stout, too. And it's not a toploader so it' would be easier to make a linkage for...

Squash

only problem would be if the little T10 would be up to the task of handling the multiple reduction torque multiplying effect of the auto.

good point about the pressure thing though- never thought of that. so how about the PowerGlide in front of an SM420? this way you would also only need one custom adapter instead of two (just the one in between the two transmissions, not one for powerglide to NP205 also)

hmmmm this is sounding better...

i will ask again...


CAN ANYBODY MAKE A SM420 TO POWERGLIDE ADAPTER FOR ME???

I can't make the adapter, but I can make a drawing, and I know of several machine shops. Does anyone know more about power glides (my knowledge is strictly limited to manual trannys), dimensions, bolt patterns, weight, input/output shaft diameter and spline count. Surely with a little effort put into design someone could machine the necessary adapters, might be more costly, but the coolness factor would be way up there. Post here or e-mail me, I'll try and work out at least a preliminary design.

Also, with the power glide in front, would you still use a clutch. There was talk above about maybe not needing it, but I can't see it (I just don't have a strong knowledge of automatic tranny's) I think if you do need a clutch, you'd want it between the auto and the manual otherwise you'd stop the auto everytime you stepped on the clutch, I don't know if that would be a problem or not.

chad

Originally posted by 9-Volt


only problem would be if the little T10 would be up to the task of handling the multiple reduction torque multiplying effect of the auto.

good point about the pressure thing though- never thought of that. so how about the PowerGlide in front of an SM420? this way you would also only need one custom adapter instead of two (just the one in between the two transmissions, not one for powerglide to NP205 also)

hmmmm this is sounding better...

i will ask again...


CAN ANYBODY MAKE A SM420 TO POWERGLIDE ADAPTER FOR ME???

How much money you got? :D

Might be easier/cheaper to put a yoke on the front of the 420 and run a 2" driveshaft.

Originally posted by 9-Volt
i would put the auto behind the manual simply because the auto would have a cable-type shift linkage, so you could mount it anywhere.

and the thing is, you probably wouldnt even need a very large torque convertor to do the job.

just did a few quick calculations:

crawl ratio with SM420, PowerGlide, 2:1 low, and 5.13 axles":




dont forget the tourqu converter is almost acts like a 3 to 1 but not at high speeds

Originally posted by Mo
I'm far from an expert on the auto trannys, but just a point to ponder.

If you put your manual tranny behind your engine, then go to the auto, will the torque converter/pump setup have enough pressure to run? You're cutting your engine RPMs severely - the 6500 RPM you'll never hit is what it will take to let the auto tranny see 1000 rpm (rough numbers).

My gut feel is that you'd need to put the auto in front of the stick.

Mo you're absolutely right on that. You have to put the auto tranny first. The pump on an auto tranny runs whenever the engine is running. If you put the auto tranny second with the torque convertor inbetween, no matter what you do, the pump will only run when the manual trans is in gear and the clutch engaged. And if the manual trans is in anything but high, the pump is going to run slower than designed and probably won't go into gear.

Originally posted by Cutter
my neighbor has a drag car with a turbo400 and a clutch. Uses the clutch to lanch and then the rest are auto...I can ask him about it if it would help. (it's kinda backwards to your question, though)

Your neighbors "clutch" is most likely connected to a valve that bypasses the pump. With the pump bypassed the clutches inside are bypassed and the tranny is effectively in neutral. When the "clutch" is released the pump begins to apply pressure to the internal clutches and the trans goes into gear and will shift to the next one automatically. This is done on race cars to allow them to run without a torque convertor. I would think a setup like this retaining the torque convertor would allow you to shift the manual tranny, though it might shift tougher than it would normally.

BTW, Why powerglide? I think I would do a TH350 and take advantage of the three speeds. I would assume normally you would run the manual tranny in high and auto tranny in drive. Plus, a 4WD TH350 would probably be a lot easier to adapt to the manual tranny.

hey Grandpa-

you make some excellent points. i chose powerglide because i am assuming that because it is only a 2-speed, that it is smaller (shorter). you might be right about the TH350 though, its definetly something to look into.

anybody up to researching this more? i dont have a good rig to test it in and i dont have the skills to design/build this setup.

This is an interesting idea.I had the post of dual 465 trannnies.But this could work.I would use a 2wd tranny with a spud shaft that would fit the input of the MT.And no clutch.Just use the auto for the street.Then offroad put the auto in nuetral and shift.Put a short shifter on the manual so you don't try to shift on the street.I think this would work.Blazin:rasta:

alright i definetly think that this could work now. here is my idea- 2WD TH350 with as short of a tailhousing as you could get. a little tiny 1-2" long driveshaft mated to a custom modified SM420. here are the mods that i think you would have to do to the 420-

remove input shaft. take input shaft to machine shop and tell them you want the same thing except on the engine side of the input shaft you want a yoke instead of splines.

pay some $$$, take home, bolt in the new input shaft. using midgy driveshaft, bolt the 2WD TH350 to the "divorced" SM420, which would bolt via factory adaptor to NP205.

damn this would work!!! :eek: :eek: :eek:

oh yeah and because the two transmissions would now be mated via a driveshaft, you could run two manual trannies, or ANY 2wd transmission in front of this setup. hello wide market appeal!

This would work.So basicly you have a short driveshaft with a u-joint.What about having an input shaft made that was female on the outside of the 420 and would slip into the 350.This would help keep it shorter.Add a plate with a couplt of feet to the front of the 420 for mounts and you set.You would have 3 mounts holding everything up.Now how long is a th350 2wd?Could I fit this in a Blazer with 106.5" wheelbase.This would make for a long front driveshaft.So how about a carrier bearing in the front shaft.This would keep it off of the crossmembers.Run a shaft from the T-case to a carrier bearing mounted on the first crossmember.( the one holding the th350)then a second shaft to the dif.Would need a CV shaft in the rear.Blazin:rasta:

I guess it depends on which trans you want to shift which auto to choose.

I think I would go with a th400 and just use the manual trans as a reduction box. You wouldn't have to worry about a clutch then and would just shift into N with the auto to change gears in the manual (just like shifting into Lo w/ the t-case).

If you wanted to shift the manual trans I would go with a powerglide beacuse they are a bunch shorter (with the tail housing off...with it on they are the same length as a th350

yeah thats the idea now Triaged...

auto as your tranny, manual as your redux box.

i was (hopefully am!) going to use a TH350 though because i dont plan on running a big enough motor to need a 400.

with this setup (TH350 as your primary box) and a 420 as a redux box, you would have a choice of TWELVE different gears to be in... TWENTY FOUR when you factor in hi/lo range... :D

keep the 420 in 4th all the time until you need some extra grunt, then downshift her, boy! :p

some more quick calcs shows that with a TH350, SM420, NP205 and 5.13 gears you would have a 359:1 crawl...

if you go all out with all of the bells n whistles on this puppy, meaning doubler kit, 3.6:1 gears for the 203, 3:1 gears for the 205, and 7.17:1 gears for the axles, you can get as low as 3794:1 if you ran two SM420s in line :eek: :eek: :eek:

HOLY TOO LOW BATMAN!!! :D

but the best part about this kit is the options that you get... instead of just the 2:1 or 4:1 you get with the doubler, you have 14:1, 7:1, 3.4:1, and 2:1 low ranges.

i can definetly see some market interest in this thing.

You guys are making this harder than it should be. I have it all figured out and I will build one after I get my transfercases going. I plan to put a torque converter on the front of a 465. I suggest that you go look at a CAT backhoe model 416 to 436. They have what you want.

Originally posted by Donovan
You guys are making this harder than it should be. I have it all figured out and I will build one after I get my transfercases going. I plan to put a torque converter on the front of a 465. I suggest that you go look at a CAT backhoe model 416 to 436. They have what you want.

nope, you are making what my original idea was. now the whole thing is a helluva lot different, cause instead of just having the torque converter effect, you have the whole auto to use as your main transmission, and then the SM420/465 as a reduction box

Okay, bare with me, I am a jeep guy, but the numbers would probably be roughly the same with other combo's

Jeep 3-spd TF999 auto 16" (pulled from another post)
HD 4-speed rougly 10-12" (rough guess of the top of my head)
Dana 300 8" (another rough guess)
10-12" of bellhousing

roughly 3 1/2 feet without adapters (correct me if my numbers are off), that is a tight fit (at least in my wrangler) That would leave, what, maybe 1' (horizontal) for my drive shaft? Hey Jesse can you make a shaft for this? Well OK we don't all drive wranglers, and going to a V8 or V6 could possible gain another foot or so, plus the rear axle could be moved back another 6"... OK maybe this ain't soo bad, very interesting ideas. Imagine, you'd have 3 or 4 gears deeper than 70:1 (or more with a 4:1 kit in the Xcase), but lot's more weight, complexity, and other compromises...man I love this board :)

chad

compelxity isnt that bad. you have a custom input shaft on the 465 and a little DS. run a 2wd auto or manual mated directly to the engine. very simple, actually... and SUPER LOW GEARS

I seem to recall the big old GM C60 grain trucks around here with gas motors having 2 manual trannies stuck together.. Old being early 70's.

Squash

Originally posted by Realsquash
I seem to recall the big old GM C60 grain trucks around here with gas motors having 2 manual trannies stuck together.. Old being early 70's.

Squash

you should check into that... early 70s could mean two SM465s mated :D

There is a company called Bruno's Automotive Products (630-458-0043) that puts a torque converter on the front of a Lenco and Jerico trannies. Also there is another company that does the same thing and it is something like Pat Donovan Transmissions.( Not related and I have nothing to do with them) I will look for the phone number tomorrow.

I think if I were to do this, I'd rather have a setup that used a trans w/out a granny gear instead, something with gears more like a close ratio 4 spd out of a muscle car. There really is no need for a 14:1 low range (420 and 205), plus if you romped on it with the auto in low and the 420 in low you'd stand a good chance of breaking the output on the 420 anyway. With a close ratio 4 spd you'd have much more useable gears, 1 example would be to drive around on the street with the manual in 4th w/shorter street tires, then switch to 3rd for street driving with bigger trail tires.

The dual trannys in the older medium duty trucks are often refered to as Brownies, Brown and Lipe was one manufacturer of them. There's been a few discussions of them on the TDR at times. From this thread (http://www.turbodieselregister.com/forums/showthread.php?threadid=31873) , typical ratios are 2:1, 1:1, and .75:1. This would work out well for some. Someone in the thread said they are typically divorced units, and used ones go for $400-$800. I just posted asking how long they are.

Pete

I like I like

insted of using the auto what about a SM420 and a brouny box
does anyone have the gear reatios for that box

Here is a link for Pat Donovan's torque converter to manual tranny. www.patdonovanracing.com

Originally posted by pcorssmit
I think if I were to do this, I'd rather have a setup that used a trans w/out a granny gear instead, something with gears more like a close ratio 4 spd out of a muscle car. There really is no need for a 14:1 low range (420 and 205), plus if you romped on it with the auto in low and the 420 in low you'd stand a good chance of breaking the output on the 420 anyway. With a close ratio 4 spd you'd have much more useable gears, 1 example would be to drive around on the street with the manual in 4th w/shorter street tires, then switch to 3rd for street driving with bigger trail tires.
Pete

I think I would go with an SM465 rather than a 420 just because it has a factory adapter to the NP205. SM420s were all 2WD or 4WD with divorced transfer cases. I don't think you can get a much stronger tranny than one of the granny tranny four speeds. If you're really concerned about strength, don't use first or reverse. You probably wouldn't need it anyway. Even if you did use first, I would still guess you'd break something else further down the line before the tranny would go out.

yeah grandpa, for my rig at least i am not going to be using an SM465 because of the factory adaptor and the fact that they are much more available/cheaper. and since it will be used as a redux box, 6.6 vs. 7.05:1 doesnt make THAT big of a difference :smokin:

I think the problem with the factory adapter from a 465 to 205 is that it is just too long. I don't know for sure but, I think it was probably to help with the front drive shaft length and keep it comparable to those available for the autos. When you start stacking these things, you quickly run into length problems even in a Blazer or similar short full size rigs. That's why I don't consider the 465 to 205 adapter a plus. There is also the late model (80s) 32 spline output 465 which was mated to a 208, but that one has an output shaft/adapter even longer than the 16(?) spline 205 version. To me, the only reasonable approach is a custom adapter and short output shaft.