Ramblings about doubler options (1 Viewer)

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Is the rockbox a 4.7 case? Is it available?

Its an old AA product. 3.44 low. Not in production anymore which makes parts hard to find. I'm kind of apprehensive about it, but it's a good price, and most likely rebuildable.
 
Its an old AA product. 3.44 low. Not in production anymore which makes parts hard to find. I'm kind of apprehensive about it, but it's a good price, and most likely rebuildable.
So is there one available? I'm typically apprehensive about a driveline component that's no longer in production.
 
So is there one available? I'm typically apprehensive about a driveline component that's no longer in production.

I have a guy that is looking to sell. I haven't really seen any gripes about them, but they look pretty strong and this one is supposedly pretty low miles. I do worry about breaking it, but I can always pull it out and lengthen the driveshafts.
 
My experience on the Rubicon in an FJ40 with ~60:1(SM465, lc case and 4.11 gears) with 35s showed me it wasn't quite deep enough. My ride-along with exact same rig but the doubler showed it to work well.(Both V8s)

FWIW, 4:1 in my dana 300 wasn't enough for me. Low range was too slow for bopping around trails, and too fast in the rocks. I wasn't a fan. I'm much happier with a doubler setup than I ever was with a single case.

Late edit here: I think this is heavily dependent on tire size. I've been on 42s for a few years, and 39.5s for a bit before that. Before that, 37s and 35s. 4:1 may well have been plenty with 37s or lower, but with the bigger tires, I didn't think it was enough. Just putting my experience in context.
 
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I would avoid ANY NP203 based doubler like the plague. They add a TON of slop to the drivetrain. The shifter in my experience has problems staying in gear(two different rigs) I swapped out an NP203 to a plain split case behind an NV4500.

and now it's in my rig, thanks :flipoff2:
Now that I have a quiet Nv4500 I can hear the doubler on decel. :p
 
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I was interested in putin in a rock box years ago when they were the thing to do and then the Toy box was there .i went with the Toy box it works good enough for me . Alec had his before me and he's good with it, his 4 speed is a SM420 and mine is a 4 speed out of a 87' FJ60.
 
I was interested in putin in a rock box years ago when they were the thing to do and then the Toy box was there .i went with the Toy box it works good enough for me . Alec had his before me and he's good with it, his 4 speed is a SM420 and mine is a 4 speed out of a 87' FJ60.

I'd really like to find a toybox, as I believe that parts are more available, but Marlin isn't making them any more which really sucks. Havent seen any for sale either.

I guess I'll take whatever I can get my mitts on, though.
 
Really wish @Marlin Crawler would produce the toy box again or at least do group orders of them. 100% would have gone that way instead of the 4:1 gears in my splitcase. I’ll still only be at 68:1 even with 4:1 gears where as a toy box would have yielded 152:1...

I feel the same way. For basically the same price, you get a lot more options with better reductions.
 
Not likely. I’m into my 4:1 gears for $1300 with a fully rebuilt tcase and a few other odds and ends. I bet a toy box would be $2500.

Think so? I was under the impression that they would be around $1700
 
I mean, the taco box kit is $999.00.
 
Not to mention driveshaft mods, cross member mods/additions, spacial constraints, etc. A crawlbox, toybox or not, is way way way more expensive than low range gears.
 
Not to mention driveshaft mods, cross member mods/additions, spacial constraints, etc. A crawlbox, toybox or not, is way way way more expensive than low range gears.

True. I was just looking at my assumed cost of the box. Didn't really think about eveything else.
 
Ok.... I've reached a point where I don't believe that the seller of this Rockbox is willing to really sell, so I'm back to looking at options.

A toybox seems like it would be pretty simple to do. It would need custom adapters, but I think that could be figured out. My problem is that I cannot find an NV4500 to 21/23 spline tcase adapters. It looks like AA used to make one, but not anymore. Do you guys think that this is worth the time to look at seriously doing?
 
Can you adapt your NV4500 to a NP203, then use this in front of your current 16 spline case?


I don't quite have the length, plus I have heard that the NP doublers are really loud.
 
Ok.... I've reached a point where I don't believe that the seller of this Rockbox is willing to really sell, so I'm back to looking at options.

A toybox seems like it would be pretty simple to do. It would need custom adapters, but I think that could be figured out. My problem is that I cannot find an NV4500 to 21/23 spline tcase adapters. It looks like AA used to make one, but not anymore. Do you guys think that this is worth the time to look at seriously doing?

Doesn't make sense when a black box exists.
 

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