Gear Reducer or....

[Broncobowsher]

OK, I want to toss out a few thoughts out there. With that much power, and more coming, I have a few worries. While the engine makes the torque, the transmission(s) multiply it. But the torque that is grown in the gearboxes is anchored with the motormounts. But to get there it goes through the bellhousing. I can remember a friend with a high HP car (that doesn't have nearly as much torque growth in the transmission) tearing up a bellhousing.

Now I know the ZF is a stout transmission. But you are looking at putting double, triple(?) the torque INTO the transmission. Now with extra reduction in the transfer case the output torque will be several times what the ZF originally handled. Remember the Newton's lay about equal and opposite reactions? The driveshaft will have, lets call it 2000 Ft-lbs of torque. Lets say 10:1 gear reduction in the transmission (easy math) and the engine at light throttle making only 200 ft-lb of output. As a package the engine/trans/transfer case are taking the opposite of the driveshaft torque, 2000 ft-lb trying to lift the drivers side motor mount. But the engine is only making 200 ft-lb. If you separated the engine and the transmission, think of a divorced transfer case, the engine will be making 200 ft-lb. The reaction is the engine is only trying to lift the drivers motor mount by 200 ft-lb of torque. Wait, wasn't that 2000 with the transmission attached? Yes! The transmission is trying to twist at 1800 ft-lb of reactionary torque. Normally that goes through the bellhousing.

Now think of how much power you are making. I would strongly look at trying to contain that torque at the transfer case. To try and keep the transmission from twisting up. And twist they can. I worked with a guy who had a hot rod tri five chevy with a 4-speed. He managed to twist (but not break) the transmission case. Threw the gears out of alignment. Lets just say the transmission never worked right and it took a long time to figure out why. I know he didn't have nearly the power you have.

 

[sykanr0ng]

The early ZF5s (S5-42) are rated for 420 ft/lbs of torque and the later ZF5s (S5-47) are rated for 470 ft/lbs of torque.
I have seen it said on another forum that ZF underrated them by 15%, but that only means they will really take 483 ft/lbs or 540 ft/lbs, if true.

You may get them to stand up to more, but for how long?

 

[Broncobowsher]

Given the European source, those ratings are probably Newton-Meters and not Foot-Pounds.

Automatics are rated very similar, but with a catch. That is the input shaft torque, not engine output. The torque convertor is the multiplier that makes it hard to compare.

Also consider that the same basic transmission is also used behind big blocks, and diesels. Including powerstrokes that have had the wick turned up. So they should be good. And there really isn't any other option that is any better.

I was pointing out that you are probably stressing the transmission pretty good just in the power you have. Adding extra gearing in the transfer case is pretty much doubling, again, what the case is having to take. But putting a nice wide set of mounts on the transfer case ring will take so much stress off the transmission case, Leaving more room for pure engine stress.

 

[nvrstuk]

I've run ZF/203/D20 12yrs

4r70 KluneV/Atlas 4.3:1 7yrs

4r70W/KluneV/205 1yr. 2 Moab trips, 1 Sand Hollow so its being tested

There is WAY too much to type about all the differences and pros and cons ...on my cell...not by my keyboard

--205 only weighs appr 15# more than ATLAS...i have carefully weighed them both

--doubler with 205 is NOT longer than a 4 spd Atlas

--you arent losing less than 14% parasitic loss from your drivetrain...600 HP crank does not equal 522HP rear wheel HP. Closer to 30-35% loss in. Bronco. 12% in a well desgned rice burner...sorry... but the only 2 Broncos that I know that dyno'd both were over 30% ...both of them
BUT you will need to upgrade the China made yokes front and back on an Atlas as new stock ones now are really cheap so upgrade to forged...at least

--205 behind my Klune is shorter than the Atlas was behind the same Klune...by exactly 1"

--you will need to build 205 mounts to the frame with big tires/torque/good traction and a heavy right foot or just good traction and idling-thats how grenaded both

I prefer a doubler with a 205 ratio because you get 2:1 reduction for sand dunes and snow so you can have wheel speed of 50mph or so at appr 6Krpm and if you double them up you have 4.7:1 which if you keep the ZF (gear splits were waaay too wide for me but i ran it 12 years) you will be too low geared unless you just want to walk next to it up a sand dune or something while it idles up it just for fun...

--new Titan is even shorter...I've run a TrueHi9 since about '11 and my DS was about 22 1/2" until 1 1/2 yrs ago...

That ZF is a lot stronger than most give it credit for but what axles in the frt/rear and what knuckles on hopefully a D60 up front...other things will go boom...I have a tendency to find the "fuse link" as they say...if you add turbos you will have a lot of trouble going straight so tires biting in on a slide then a roll might be your next breakage. nobody wants that...

My buddy did it with his 454 Ford stroker...soooo easy to do sideways in a narrow, short wheelbased, high COG Bronco.

Good luck, have fun, go wheeling

 

[Montoya]

^^^ This!

I plan to do a couple things and I'm calling it phase II: two mounts on the TC, a motor plate to tie into the cage, and I'm looking for a place to cryo the gears in the ZF47 I have (if anyone knows a place please let me know). Also there is a tripple plate clutch to take up the shock.

I'm hoping the lower weight of the Bronco compared to the F-250 it came from will also help offset the larger tires and torque but we'll see. If it breaks I'm looking for options but they all get real $.

I'll also probably tune the ECU to keep low boost in lower gears and increase with speed/gears.

 

[Boss Hugg]

Bowsher's got me rethinking if I want a doubler behind my explorer 5.0/4R70W!

The engine plate will help, but at that point you certainly need to have everything mounted solid. No bushings. Distribute the stresses to the chassis that way as much as possible. I'm thinking you might even slide a plate between the doubler and t-case?

 

[Montoya]

I'm thinking you might even slide a plate between the doubler and t-case?

I haven't thought of that but that's a great idea. I'm probably going to break stuff but that's part of the fun!

I'm wondering if it's possible to have your cake and eat it too. I wonder if I could plate mount the motor but sandwich the plates in a rigid plastic for vibration purposes. I want the strength but believe it or not I plan to drive this everywhere so I don't want to rattle myself like a ball in a whistle. I don't think my daily driver Volkswagen e-golf will pull it very far.

 

[Boss Hugg]

I haven't thought of that but that's a great idea. I'm probably going to break stuff but that's part of the fun!



I'm wondering if it's possible to have your cake and eat it too. I wonder if I could plate mount the motor but sandwich the plates in a rigid plastic for vibration purposes. I want the strength but believe it or not I plan to drive this everywhere so I don't want to rattle myself like a ball in a whistle. I don't think my daily driver Volkswagen e-golf will pull it very far.

You probably could get away with bushings at the ends of the plates. But it needs to be thicker bushings to absorb vibration. They would have more leverage further from centerline.


Sent from my iPhone using Tapatalk

 

[Montoya]

You probably could get away with bushings at the ends of the plates. But it needs to be thicker bushings to absorb vibration. They would have more leverage further from centerline.


Sent from my iPhone using Tapatalk

Hmmm....I wonder if anyone has ever welded a tube to the plates where it mates up with the frame and press bushings into the tubes? I've never seen it but I can't think of a reason why it wouldn't work?

 

[nvrstuk]

I used 2 mtr mounts behind the trans. One on the t-case and one doubler.

I used very high duromoter rated poly bushings at the frame ends, 2" dia x 1 1/2" thick. I also used a plate on the end of the Atlas that is sold on Pirate.

Dana 20 cases arent very tough as i cracked 4 of them over 12 years and lots of internals.

Atlas and 205 are holding up fine but things break and twist with your power... here's a 35 spline ARB case that I sheared in half a while back...

First pic i will try to delete..accidentally posted it. 2nd pic is the ARB case twisted in half.

You're running more power than me now and with hundreds more in the future you will probably be chasing a lot of parts...it just happens! lol

 

[Yeller]

And I can attest 1350 ujoints are stronger than the 28 spline pinion.

 

[Boss Hugg]

Hmmm....I wonder if anyone has ever welded a tube to the plates where it mates up with the frame and press bushings into the tubes? I've never seen it but I can't think of a reason why it wouldn't work?

That’s what I was imagining.


Sent from my iPhone using Tapatalk

 

[Montoya]

I used 2 mtr mounts behind the trans. One on the t-case and one doubler.

I used very high duromoter rated poly bushings at the frame ends, 2" dia x 1 1/2" thick. I also used a plate on the end of the Atlas that is sold on Pirate.

Dana 20 cases arent very tough as i cracked 4 of them over 12 years and lots of internals.

Atlas and 205 are holding up fine but things break and twist with your power... here's a 35 spline ARB case that I sheared in half a while back...

First pic i will try to delete..accidentally posted it. 2nd pic is the ARB case twisted in half.

You're running more power than me now and with hundreds more in the future you will probably be chasing a lot of parts...it just happens! lol

That case twisted in half is amazing! That must have been one hell of a noise when that went. I've destroyed my last Dana 20 and refuse to run them again unless it's a completely stock Bronco. My NP205 has been a tank and I just rebuilt it and found nothing even slightly out of spec.

When you run these kinds of power levels it's inevitable that stuff is going to break. I try to design in failure points on purpose such as weaker U-joints that are easy to fix on a trail instead of a driveshaft or weak wheel hubs so they break before an axle.

This obviously has it's limits but if you secure the snot out of the drivetrain and stiffen your chassis sufficiently, hopefully you mitigate the damage. Chassis flex (doesn't even have to from huge power) is one of the biggest killers of transmissions and t-cases.

When I was building NHRA drag cars, this was the most critical aspect of the chassis design for both consistent pulls and keeping equipment alive.

I know the ZF is my weak link now with the aluminum housing so I might try to reinforce it somehow. I may end up welding a flange on the output side and create a mini "motor" plate for the tail. If I do this, I can almost create a torque tube that encompasses the trans leaving the TC as the weak link.

This all brings me back to two things, 1) is an NP205 with a doubler stronger than a new Atlas? and 2) Anyone know of a good ZF trans shop that can heat treat gears?

Thanks for all the input guys, it' been a great discussion.

 

[nvrstuk]

A good cyro place will have a lot of experience doing gears...we were doing this with sleds back in the day...but that's another story...

Custom longer doubler input shaft to allow for a plate is a good idea...guys are basically running the same ZF with chipped diesels and they are standing up to it...

 

[nvrstuk]

Research i was doing on torque loads 2 yrs ago had the 205 handling more torque than an Atlas. I know the input load of my Klune can handle 5500ft lbs, with the new 4340 mainshaft I upgraded to I'm good. The new Titan is supposed to be stronger than that and it is 3/4" shorter.

I think you're strength is in a Titan/205 combination as the numbers I found showed the 205 good for up to 10,000ftlbs.

I have no idea what the Atlas gear reduction unit can handle.

 

[nvrstuk]

What ECU are you using and how are you controlling all the parameters you need to change for those numbers? I run a Moates Qtrhorse and have Garry do the tweaking...

 

[Montoya]

Research i was doing on torque loads 2 yrs ago had the 205 handling more torque than an Atlas. I know the input load of my Klune can handle 5500ft lbs, with the new 4340 mainshaft I upgraded to I'm good. The new Titan is supposed to be stronger than that and it is 3/4" shorter.

I think you're strength is in a Titan/205 combination as the numbers I found showed the 205 good for up to 10,000ftlbs.

I have no idea what the Atlas gear reduction unit can handle.

This is what I was able to find also but I can't find any torque ratings on the Atlas and in doing my digging, I found a bunch of stories of broken Atlas cases and very few on 205's and even then they were minor or old units.

 

[Montoya]

What ECU are you using and how are you controlling all the parameters you need to change for those numbers? I run a Moates Qtrhorse and have Garry do the tweaking...

I'm using the AEM Infinity unit:AEM Infinity ecu

I also run their methanol injection kit but I made a larger tank that goes where the stock side tank would mount (but smaller and all stainless)

I plan on adding the dash display but having it pop up from behind my dash bar so it looks old school until I want to use it.

 

[KyleQ]

Do NOT run the yokes that AA provides with the Atlas, they went away from providing a quality forged unit to a cast yoke, that WILL break and destroy the drive shaft and whatever else it hits when it goes flying. I went through three of them before going to ancient Spicer stuff and finally to 1410. Funny, things stopped breaking when I made that change...

If you are sticking with 1310 or 1330 stuff grab the yokes off a NP205 or get anything else you need from NorthernDrivetrain.com. Gabe can even custom make you stuff if needed - he is able to broach splines IN HOUSE.

 

[Montoya]

Wow! Good to know. I wonder why they would downgrade like that? I know it saves them money but it's not like their stuff is cheap to begin with and I can't imagine the few extra bucks for a forged unit would cause customers to complain. That's a bad business decision.