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Discussion Starter #1 (Edited)
Who is running a taco box with the auto a340f?
I have read that the torque converter acts as a reduction source of its own. [Estimated at 1.7-2.0 reduction?, big mike actually states it being 2-2.7 depending on tranny temp and what atf fluid used]
My question is with the taco box and the auto, are you guys running 4.7 and2.57 or are you guys going 2.28 and2.57?
Now i know that with running the 2.28 youve really kinda only got your low, or double low gears, almost like having a 3 speed setup as they are so close to each other, instead of the true 4 speed with the 4.7s But at the same time i feel like 4.7 and 2.57 is way to low. If you go off what big mike has posted of the torque converter being as high as 2.7 reduction, bouble low with 4.7 would be a ratio of 483:1. Thats more than twice as low as my gear drive duals with 4.7s mated to my w56. I never see needing that low of gearing.? What are you guys running? And anyone having issues with all the extra torque of the 4.7 in the front box having to go through the rear case? Seeing more broken output shafts possibly?
 

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Your usual W56 has a 3.95:1 first gear, and if you're lucky to find an R151 you have a 4.31:1 first gear. Nobody has any issue running a 2.28/4.7 combo behind those.

An A340 has a 2.80:1 first gear. Torque Converter torque multiplication is variable as the converter slips from idle to stall speed, which is like 2200RPM for a stock converter. So it may start out at 2:1ish but quickly goes to 1:1 as the revs hit 2200rpm. So as far as the gear ratios go, I'd run a 4.7 crawl box.

Now as far as the strength of the chain-drive t-case input shaft receiving torque from the 4.7 crawl box, I'm not sure about that. As well as the strength of the output shaft receiving 4.7x2.57 multiplied torque.

I'm not sure why you want to run that setup though... up here, chain-drive cases get thrown in the scrap pile and people swap to a proper 2.28x4.7 gear drive setup. Or a single 4.7 case if you're keeping it short.
 

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Discussion Starter #5 (Edited)
Interesting. Big mike makes it sound like the torque converter was always acting like a reduction box (except in decents)
https://www.tacomaworld.com/threads/tacobox-updates.573748/page-2

I havent talked to or found anyone having problems with the chain cases on their own. Or really running the tacobox with the 4.7 in that matter.i wouldnt have to deal with doing something with the exhaust staying drivers drop.
 

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Discussion Starter #7 (Edited)
How is your double low with the 4.7 and 2.57? Is it actually usefull or is it ridiculously slow?
The torque converter is whats throwing me off. I have 4.7 and 2.28 in my 4runner and its already borderline to slow. If the torque converter really is a 2x reduction, i cant imagine ever using it haha
 

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How is your double low with the 4.7 and 2.57? Is it actually usefull or is it ridiculously slow?
The torque converter is whats throwing me off. I have 4.7 and 2.28 in my 4runner and its already borderline to slow. If the torque converter really is a 2x reduction, i cant imagine ever using it haha
Here’s a short clip of everything in low.

https://youtu.be/OuQuhkSaF-s

And soup bowl same thing. Definitely useful if you really want to crawl for control.

https://youtu.be/MkTY8_CzA_s
 

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Discussion Starter #9
That looks comparable to my dual gear cases with 4.7.Definitely not twice as low as them like they were making it seam in that thread i linked.
Thank you for that.
You been running that setup for a while? Any issues with it at all?
 

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That looks comparable to my dual gear cases with 4.7.Definitely not twice as low as them like they were making it seam in that thread i linked.
Thank you for that.
You been running that setup for a while? Any issues with it at all?
Over a year and a half now on the tcases. For the first half of that I had 35s and 4.10s and IFS. Now with 5.38s and 40s it’s a little bit lower which I like. It’s not so low that it drives through the brakes. No issue other than using crappy trail gear parts. Go Marlin for sure.
 

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Discussion Starter #11
Yea ill either use marlins tacobox, or go inchworm. Tg just lacks in quality in my experience, and sucks they own allpro as well now. I see their quality dropping as well.
 

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Yea ill either use marlins tacobox, or go inchworm. Tg just lacks in quality in my experience, and sucks they own allpro as well now. I see their quality dropping as well.
They own inchworm also:confused::mad3:
Better order marlin a year in advance if you plan on getting products worth having as the good shit is back ordered every time I call!
:mad3:
 

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IIRC the 340f is related to the AW4.

Convert the tail housing and run an NWF box, d300, atlas, 4 spd atlas, etc. Itll be the same, possibly less expensive, and better.
 

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Discussion Starter #14
They own inchworm also<a href="http://www.pirate4x4.com/forum/images/smilies/confused.gif" border="0" alt="" title="Confused" >:)</a><a href="http://www.pirate4x4.com/forum/images/smilies/pissed.gif" border="0" alt="" title="mad3" >:)</a>
Better order marlin a year in advance if you plan on getting products worth having as the good shit is back ordered every time I call!
<a href="http://www.pirate4x4.com/forum/images/smilies/pissed.gif" border="0" alt="" title="mad3" >:)</a>[/QUOTE]

I spoke with trevor at marlin on Wednesday, and he said inchworm was not part of the trailgear purchasing lowrange, and inchworm is working on getting back in business on his own. And marlin may start offering their tacobox with the inchworm adapter due to the lead times of getting their own adapters.


As far as going atlas, its an option for the a340f, but to go 4speed your looking at almost 5k vs the 2500 of the tacobox. And they are so damn big, fitting them up in the frame rails starts to become quite the job.
 

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You will only have slower wheelspeed during the time the TC is slipping, which is from idle to stall speed (2200rpm for a Toyota TC). That's just the same as slipping the clutch on a manual trans truck - in the case of the auto, you'll overheat your trans fluid instead of smoking the clutch.

And it's an accepted fact that the TC Torque Multiplication varies from the maximum at idle, about 2:1 for a Toyota TC, to none at stall speed.

Read this, it's a pretty good description: https://www.hotrod.com/articles/ccrp-0310-torque-converters/

And a little more depth:
https://www.hotrod.com/articles/0808rc-torque-converters/

Inchworm still exists as an entity, but with no website and no product available I'm not sure they would be my first option. And Marlin is capable of making a good product, but good luck with availability.

Are you set on keeping your chain-drive case? Are you staying IFS? What are the plan and goals for your truck?
 

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Yotota, you say Inchworm still exists as an entity..
Yes the corporation was sold\merged\aquired by lowrange., Then bought out ultimately by t.g.
Is that what you mean?
Or is there more to the story?
T.g. Quit supporting the "lefty\verso"
And marlins version... Well M.C.!!!!

For the few of us stuck with one (mine sux Yes others love em) do you have some little known knowledge to share?
For the op
It seems the biggest issue with doubling a taco is putting the 4.7 in front of the t case...
For those with traditional duals in the hilux platform it goes against the grain somewhat.
As we can use the reduction box as an underdrive \ direct drive without a twin stick
t case (think bumper to bumper traffic)
without stressing the input ,from what I have read no one is destroying chain cases (the reason the lefty was prototyped more or less) and the inputs seem to hold up to the 4.7 input torque.
All the hype on t.c. "Magic torque" (until lockup is achieved:rolleyes:) just adds to the benefits or goes out the window at lockup. Topic for another thread.
All in all any doubled rig is GOOD.
If I hit the lottery I am going 4 Gear atlas (after waiting way to long for delivery!:mad3:)
 

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I like this thread, I am a fan of super low range and that might because I am out wheeling a heavy pig of a SAS H3 with a bunch of first gen Toyotas with dual cases and they work well. Rapier, did you use the throttle much at all or were you under 1200 or so rpm crawling the soup bowl?

I am not trying to dereail this thread but I have always wondered if you could reap both the benefits of an auto and manual. The benefits of an auto is some slip and "give" in the drivetrain when bumping obstacles hard but when crawling I have seen the benefit of that direct drive the manual gives. If the auto can handle the stress if you locked your TC at super low RPM crawling would that give it that manual direct drive type feel? It would drive through the brakes but you could use a TCC lock up switch like a clutch, on and off.
 

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Yotota, you say Inchworm still exists as an entity..
Yes the corporation was sold\merged\aquired by lowrange., Then bought out ultimately by t.g.
Is that what you mean?
Or is there more to the story?
T.g. Quit supporting the "lefty\verso"
And marlins version... Well M.C.!!!!
I could be mistaken, but I poked around a bit and it looks like the business entity may still exist in California. Unless someone else was operating under the same name.
 

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If the auto can handle the stress if you locked your TC at super low RPM crawling would that give it that manual direct drive type feel? It would drive through the brakes but you could use a TCC lock up switch like a clutch, on and off.
Yes and no...

When the TC is slipping, there's a difference in speed between the input and output RPM. The only time you can safely lock up a TC (that has a lockup function) is when the RPMs are the same... Which is above the stall speed. So yeah, once you get the RPMs above stall speed you can lock up the TC and have complete control over the drivetrain. You'd have to be careful to not stall the engine but it would be fun to try.

I know that you could easily wire in a lockup switch on a Jeep's AW4 trans, I never looked into this for Yotas but considering an A340 is virtually the same internals I bet it can be done. A quick bit of Google search shows that something similar may work for your 4L60e. Give 'er a try and let us know!
 

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Discussion Starter #20
Ive got a better understanding of how the tc works now and i get the varying in reduction from it. It essentially becomes a 1:1 at stall speed. I wasnt understanding that part at first.
Ill be doing a 4wu 3 link. Its gonna be my crawler. I was planning on keeping the chain case to keep driver drop and not deal with the exhaust thats on the passenger side.
As for gearing my thought was go 2.28 in reduction box to keep from having the extra torque running through the chain case. Figure in double low itd be close to my manual in 4.7..
If i hate it i could always full the reduction box and add 4.7s later.
I actually spoke with jim from inchworm last wednesday, and he is working on getting some distributors to start selling again.
 
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