using an h42 as a rox bock

[lowtideride]

This is most def going in Velveeta...Uranus the 62/80 is a DD.

Top gearing is still 1:1
I dont plan to shift both trannies while driving on the road. I was just saying that when I go from 37s to 40s and Above I wont have to re-gear my diffs agian. Since I have re-geared them once already. I will just leave the second box in 3rd to reduce my gearing for tooling around town.

dual h42s well the purpose I was going for was the low gearing, Because I need somthing that is at least at a 100:1, Hopefully the cost will be less than an rock box when its all said and done, never been done before that I know (with h42s)....and the coolest part of all its all cruiser...

 

[lowtideride]

The Second Tranny could act in place of lower Gears.. instead of putting in 5.29's
you keep the Stronger 3.7 Gears in the axles and put the second tranny in 3rd gear. Keep it in 3rd gear around town.. Second Gear in 4th for driving on the highway. Get to the trail, Drop the t-case in low, then when you get to an obstical that requires lower gearing than 1:1 you can use 3rd, 2nd, and even 1st to steep down the crawl ratio..
It gives you a bunch of options!

Pirate mini truck section has a some threads going on this, Most people are of the opinion that the second trans will blow up, and in a couple of cases people have broken the second tranny while in 1st/1st with the Pickup 5 speeds.. maybe the h42 will survive better than the pickup trannys.. Time will tell..

Yulp...beat me to the punch while I was typing. Im pretty sure the tranny will hold up, the only weak point I see if the output shaft....if anything goes it will be that.


Time will tell for sure if it holds up to a beating...Ill try my best to beat on it.

 

[lowtideride]

The question is.. the second tranny are ready to handle constant load in 3rd gear from the factory tranny .. ?

Im sure it will...thats not really that much load from 1:1....4.8:1 in reverse will be the test..

 

[agent orange]

I wonder if youll have to double clutch to work the second tranny. I know you have to do that in a road tractor if you dont have an air operated splitter.

 

[lowtideride]

More than likely, I heard its hard on the synchros, I dont plan on shifting it while moving...Just as a normal crawler box.

 

[GLTHFJ60]

Here's another stupid question. If you put both in reverse, won't you go foreward and have a significantly lower final drive ratio???

 

[FLYINGLOW]

Yulp, I have thought of that...And Im not really sure if there is anything I can do about it. My best guess is that somthing further down the line will go first since it will be seeing upwards of 220:1 Like the axle shafts,birfs, r&r...all of them easier to change on the trail than a kaput output shaft...I guess ill test out the waters..

Pirate mini truck section has a some threads going on this, Most people are of the opinion that the second trans will blow up, and in a couple of cases people have broken the second tranny while in 1st/1st with the Pickup 5 speeds.. maybe the h42 will survive better than the pickup trannys.. Time will tell..

Trannys are build to stand up to a couple hundred ft lbs of torque, t-cases are made to hold up to a 1000 ft lbs or more. Use a diesel input, fine spline and it think it might be a little bigger too.

I love the concept and hope you can make it work, but this is one draw back. BTW, this thread has gone too long without pics!

 

[FLYINGLOW]

Here's another stupid question. If you put both in reverse, won't you go foreward and have a significantly lower final drive ratio???

Yes.

 

[lowtideride]

Trannys are build to stand up to a couple hundred ft lbs of torque, t-cases are made to hold up to a 1000 ft lbs or more. Use a diesel input, fine spline and it think it might be a little bigger too.

I love the concept and hope you can make it work, but this is one draw back. BTW, this thread has gone too long without pics!

Will grab some shots of what I got and what I am talking about so far...Ill post some tonight.

 

[Sputnik40]

Neat project!

Have those fenders for you - pick em up next time you're down south, or I'll be up there in April for a wedding.

Surf was chest this morning - caught it before winds went sideshore. It's a good day already .

 

[Tapage]

Hey dude .. go for it and show us the big lesson !

 

[Sputnik40]

Al - Something Jim, Alan H. and I were discussing that has turned out to be worthy of consideration. I've got a set of 40" MTR's waiting on rims to show up and had planned on installing fine spline 4.11's. However, while the gear surfaces on the 4.11's are stronger than 4.88 or 5.29's, the added torque to the pinion is increased with the bigger tires. Irregardless of my SM420 and transition case, or in the case of your doubler. I asked the question last week and it was confirmed that going to 4.88's was like an 18% increase in pinion strength, 5.29's were even stronger, but then you hit the weakness at the gear mesh.

If you use a lever at the point of tire rotation as an example this makes perfect sense. The real question is does it really matter - say if I ran a cryo 4.11 pinion versus running straight 4.88's - I mean it's only 40's right . What gears are folks running with 44's - or I guess it's irrelevant - they've probably converted to D60's or Mogs, etc.

Let me know your thoughts.

 

[lowtideride]

Al - Something Jim, Alan H. and I were discussing that has turned out to be worthy of consideration. I've got a set of 40" MTR's waiting on rims to show up and had planned on installing fine spline 4.11's. However, while the gear surfaces on the 4.11's are stronger than 4.88 or 5.29's, the added torque to the pinion is increased with the bigger tires. Irregardless of my SM420 and transition case, or in the case of your doubler. I asked the question last week and it was confirmed that going to 4.88's was like an 18% increase in pinion strength, 5.29's were even stronger, but then you hit the weakness at the gear mesh.

If you use a lever at the point of tire rotation as an example this makes perfect sense. The real question is does it really matter - say if I ran a cryo 4.11 pinion versus running straight 4.88's - I mean it's only 40's right . What gears are folks running with 44's - or I guess it's irrelevant - they've probably converted to D60's or Mogs, etc.

Let me know your thoughts.

I dont know about the gears man, Even just putting the 4.56 next to the 3.7s The whole pinion looked a great deal smaller. I understand what you are saying but it seems that a good deal of people running large tires seem to do the gearing before it even reaches the R&P...but hell thats just what Ive noticed

If this turns out to work I might switch out the re-geared diffs I have for some fine spline fj62 3rds...

-Al

 

[lowtideride]

Alright here are some shots...

top cover is a one from an earlier tranny which moves the shifter forward. And the other shows how far the roller bearings go into the input not allowing it to be broached. The other is a coupling from an sm465 just for reference of what I have to have made.

 

[bustanutley]

What gears are folks running with 44's - or I guess it's irrelevant - they've probably converted to D60's or Mogs, etc.

To answer this question, 4.11s
My group all run 40's and up, yota running gear throughout. The lower gear sets would fail often, everyone now runs stock 4.1 gears, no more issues.

 

[Sputnik40]

To answer this question, 4.11s
My group all run 40's and up, yota running gear throughout. The lower gear sets would fail often, everyone now runs stock 4.1 gears, no more issues.

Dude! I like this answer seeing as how a already have an FJ80 R/P ready for a build up. It's a lot cheaper finding these than buying new 4.88's...

 

[bustanutley]

Just make sure that you have a fine spline third in the back and you should be good to go.

18% reduction to the pinion is marginal compared to the amount of material that is lost to the pinion teeth.

 

[Jetboy]

I was under the impression that in order to have the trannies live in this situation you would want to use the rear as your usual shifted tranny and the front as the crawler box. Sounds backwards, but it would put the least torque on the input to the rear tranny. I don't know from experience though, but it makes sense as far as leaving front tranny in 4th would just put normal torque on rear for daily driving and front in 3rd would be similar to increasing engine torque by 30% or something like that.

Good luck

 

[lowtideride]

Jet,
I understand what you are saying. although I think It would be too much of a pain in the butt that way. I Dont see having extra torque on it for normal driving to be that much to worry about. I think where its going to see the most stress is on the trail. But thats my 2 cents and how Im seeing it in my noodle.

 

[bustanutley]

There is too much inertia in the system for syncros to line up and shift gears while in motion to use the second tranny.