Gearing concept?

[kmac530]

I am always trying to think outside of the box...maybe sometimes TOO far outside, but sometimes my stuff works out. So here goes my new gearing solution.

I can NOT find a 4.11:1 gear set for my Timken diff. I know I could just put in a 12 bolt....NOPE. Don't want too, as discussed in another thread.

So to help with my VERY low 5.571:1 diff ratio I was thinking of an alternative to changing the diff.
The 2R10 has a short drive shaft with a center carrier bearing. I have thought I could use a 4WD transfer case out of something like a Suburban that only has a low range gear of say 2:1 and is an electric engage on the fly style....run it BACKWARDS behind my trans {of course supported propperly and using U-joints on both sides} so that in HIGH gear it is my standard 1:1, then when I am getting on a hiway {like en route to the International??} I could put it in nuetral, flip a switch, and have the transfer case switch into what it thinks is LOW, but it would be splitting it UP. I could then probably shift the trans into 2nd and get up to speed, shift to 3rd and 3rd OD and that would have me running at 2.75:1 or so....freeway flyer....

Do you guys {or ladies} think this could work. I can not see why it would not, but that is why I am asking...you folks are way smarter than me.

[kmac530]

Just to clarify, I know I could use a gear vendor unit to accomplish a similar task, but, I can buy a NP205 or 203 with a 1.96:1 low gear for $250 and a gear vendor is about 3k....I am a caso who does not have 3k to even dream of spending.

[PackardV8]

Interesting concept and it could work. You'll have to ask some 4x4 guys who know that application if it can be made to run backward.

Just asking, why not just convert to a more commonly available 4.88 rear axle and use the 3-speed overdrive for a 3.42 overall?

Remember, whatever geartrain you devise is going to be coupled to a tiny, weak flathead engine. No way a Champion will pull much more than a 3.42, even unloaded. Your mythical 2.75 overall would be a flat ground only application. Any rise in the road, even a slight headwind would require a downshift.

jack vines

[mbstude]

Interesting concept and it could work. You'll have to ask some 4x4 guys who know that application if it can be made to run backward.

Just asking, why not just convert to a more commonly available 4.88 rear axle and use the 3-speed overdrive for a 3.42 overall?

Remember, whatever geartrain you devise is going to be coupled to a tiny, weak flathead engine. No way a Champion will pull much more than a 3.42, even unloaded. Your mythical 2.75 overall would be a flat ground only application. Any rise in the road, even a slight headwind would require a downshift.

jack vines

Jack, I don't think he'd have those issues. He's running a warmed over 289.

[PackardV8]

Jack, I don't think he'd have those issues. He's running a warmed over 289.

Sorry, all I saw in his first post was 2R10.

Yes, having a strong 289" is a game-changer and definitely needs higher gears. Still, the 2R10 usually has a 30"-31" tire diameter, so a 2.47 top gear will still be a hard pul on anything besides flat ground. In my experience, the stock 289" engine is happiest between 2,000-2,500 on the freeway. That equates to somewhere between 3.07 to 3.73 overall. An engine with a longer duration camshaft will want a bit lower gear.

With whatever overdrive, use a quality synthetic rear gear lube and change it every couple of years, as those Timken gears and bearings will still be spinning really fast, even if the engine isn't.

jack vines

[comatus]

Yes definitely talk to someone who has played around with the transfer case -- unless you have a mechanical engineer on hand, and sometimes even they test things to destruction instead of the calipers-and-slide-rule approach.

There is a big difference between the input and output end, not only in shaft speed but in torque load. Bearings, bushings, washers, bosses, and the support webs for the case itself are design-specified for the loads expected. The more modern and finely-engineered the box, the closer it will be to critical load in its normal operation. There are two senses of the term "over-engineered," and only one of them is on our side here.

That's not to say it can't work, but you want to be the differential pig, not the guinea pig.

[DDD]

auxillary transmission

At the 2007 international meet in south bend there was a truck that the owner had experimented with this idea. he used an under drive auxillary transmission that was turned backwards in the truck. By backwards I mean that he used the output shaft as the input shaft and he used the input shaft as the output shaft. His tuck was a 55 or 56 one ton with a flatbed dump and removable sides on the bed.The truck was green with red wheels and some red accents added in non-traditional spots. I wish I could tell you the owners name,but by posting the description here maybe someone will recognize the description and tell you who owns the truck.

[DieselJim]

That truck belongs to Rich Meadows, Lowell In.