Doubling question

[77 K20]

Not to question your means but are you planning on doing a lot of rock crawling or pulling yourself up trees?

Most people who double up do it because they require a SUPER low gear to do such activities.

I've had a doubler or an atlas on my wish list for the last few years. With an automatic trans and if I'm in 4 low and in 1st gear it isn't low enough to have my truck crawl down steep areas. My friends with the manual transmissions can just idle down hills and I'm having to ride my brakes. And once I heat up my rear drums the brakes fade even more.

The doubler requires an additional cross member. That was one reason I was leaning towards the Atlas case.

But since I had some engine issues come up a new transfer case is a long ways off now.

 

[tiredtiretodd]

I've had a doubler or an atlas on my wish list for the last few years. With an automatic trans and if I'm in 4 low and in 1st gear it isn't low enough to have my truck crawl down steep areas. My friends with the manual transmissions can just idle down hills and I'm having to ride my brakes. And once I heat up my rear drums the brakes fade even more.

The doubler requires an additional cross member. That was one reason I was leaning towards the Atlas case.

But since I had some engine issues come up a new transfer case is a long ways off now.

I'm kinda in the same position as far as, I have a long list of things I need to do before I start tearing out my t case. I appreciate the feed back.

 

[tiredtiretodd]

I am going to try to buy a np205 from a coworker soon. I'm gonna see if I can talk him down to $150 since he sold his Blazer and doesn't have a need for it. Hope he takes my offer.

 

[77 K20]

I am going to try to buy a np205 from a coworker soon. I'm gonna see if I can talk him down to $150 since he sold his Blazer and doesn't have a need for it. Hope he takes my offer.

One thing I suddenly remembered while daydreaming at work tonight was there was another option for a lower geared low range if you have a NP205:


The Lomax kit converts your NP205 from a 2:1 low range to 3:1! A complete replacement case is included with the kit as the deeper gears do not fit a factory case.

http://offroaddesign.com/catalog/transfercaseparts.htm

Kinda spendy- but keeps the stock look more or less. And for me thought it would be more simple than trying to figure out a way to shift an Atlas case or how to properly support a doubler. I couldn't find the article but had read if you don't support the transfer cases correctly then the stress after a while can crack the tail of the transmission or the transfer case housing itself.

 

[tiredtiretodd]

Supports

One thing I suddenly remembered while daydreaming at work tonight was there was another option for a lower geared low range if you have a NP205:


The Lomax kit converts your NP205 from a 2:1 low range to 3:1! A complete replacement case is included with the kit as the deeper gears do not fit a factory case.

http://offroaddesign.com/catalog/transfercaseparts.htm

Kinda spendy- but keeps the stock look more or less. And for me thought it would be more simple than trying to figure out a way to shift an Atlas case or how to properly support a doubler. I couldn't find the article but had read if you don't support the transfer cases correctly then the stress after a while can crack the tail of the transmission or the transfer case housing itself.

Sound about right. I know that I read in another thread that there are two threaded bolt holes in the side of the t case that you can put a support arm on but I don't know if you could do that on a doubler? For sure it should be able to be done on a 205 that's has the replacement case on it if it has the threaded holes.

 

[nvrenuf]

Jab Conversions is not currently producing the Lonax 205 kits so you'd have to find a used one.

As for the Atlas, iirc, they have a 500 ft lbs torque limit so that could be an issue if you have or ever plan to build a strong motor.

Edit: not all 205's are drilled with side support holes. The boss is on every casting and most are drilled but not all.

 

[tiredtiretodd]

Jab Conversions is not currently producing the Lonax 205 kits so you'd have to find a used one.

As for the Atlas, iirc, they have a 500 ft lbs torque limit so that could be an issue if you have or ever plan to build a strong motor.

Edit: not all 205's are drilled with side support holes. The boss is on every casting and most are drilled but not all.

Thanks for the info. Yeah I was reading a thread about a plow truck that a guy bought and he couldn't figure out why there was a bar attached to his t case. Turned out it was there because of the weight of the plow. I'm probably going to buy just a used 205 and the adapter parts to use at some point later down the road.

 

[nvrenuf]

I've never figured out the option formula but some early to mid 70's trucks had a side mount that went to the frame and then in the late 70's GM started using a bar that went to the lower right bellhousing bolt. The side mount would seem to be for torque control but I think the bar was added support to prevent adapters from cracking due to all the weight hanging off of them.

Also, auto correct got me - it's J.B. Conversions, not Jab Conversions. Ugh....

 

[tiredtiretodd]

I've never figured out the option formula but some early to mid 70's trucks had a side mount that went to the frame and then in the late 70's GM started using a bar that went to the lower right bellhousing bolt. The side mount would seem to be for torque control but I think the bar was added support to prevent adapters from cracking due to all the weight hanging off of them.

Also, auto correct got me - it's J.B. Conversions, not Jab Conversions. Ugh....

So if I decide to go with the 205 and it has the threaded holes in it, should I brace it beings that there will be a adapter involved? I want to say that what I was reading about with the plow truck was that the owner wanted to take the brace off for header clearance?

 

[nvrenuf]

It's kind of evolved into a personal preference thing because so many of the mounts / bars have been removed and never replaced over the years.

The added support would be a good thing, just be sure that if it goes to the frame or crossmember it uses bushings. Also use the same bushing material for the engine, trans/tcase and support (rubber vs poly).

 

[tiredtiretodd]

Use rubber instead of polyurethane? I'm still very new to this!

 

[firebane]

Use rubber instead of polyurethane? I'm still very new to this!

The rubber vs poly bushing debate goes back a very long time.

Personally I would rather use rubber than poly in a truck as its more flexible and forgiving. If you have a truck that is a road queen never sees any flexing or off road usage then go poly.

But make sure you go black poly as it has graphite which helps with squeaks and such.

 

[tiredtiretodd]

The rubber vs poly bushing debate goes back a very long time.

Personally I would rather use rubber than poly in a truck as its more flexible and forgiving. If you have a truck that is a road queen never sees any flexing or off road usage then go poly.

But make sure you go black poly as it has graphite which helps with squeaks and such.

Thanks, I will not be driving this truck daily and will be using it off road. It'll probably be driven to work every once in a while so I'll want better performance off road.

 

[nvrenuf]

To clarify, all I was saying was to use the same material on all mounts. Mixing materials will have some components with stiffer mounts while others have softer, this can contribute to breakage (cracked trans cases, etc).

 

[tiredtiretodd]

To clarify, all I was saying was to use the same material on all mounts. Mixing materials will have some components with stiffer mounts while others have softer, this can contribute to breakage (cracked trans cases, etc).

Got it, thank you clarifying.