Noob attempts D.D. Doubler install. Help wanted!

BronKitis · Dec 7, 2011

Ok, so I've got a BII, soon to have a 4" lift and 33" swampers. Went wheeling lasr weekend, ended up high centered on a rock and sliced my Driveline in half. So, bigger tires time!

I know my little 2.9 and 3.45 gears aren't going to churn those 33's very well so I started to think about dual cases and found Duffy. His prices are reasonable and said he'd even toss in another case for a little extra cake! I'm pretty excited to finally work on my BII but need to have the know-how first. I've never had a t-case apart, let alone know ANYTHING about connecting two of them together... If and when I do this with your help, I plan to document the entire thing with pics to boot.

My questions are mainly how difficult is this project? What other moss will I need to consider? I just want to spend my money wisely and not end up over my head and a dead BII in my garage. All help is greatly appreciated.

P.S. I have been reading all I can get my hands on about it, but collecting the info from one forum and piecing it together with another has been difficult so I figured I'd just ask out-right. Thanks again.

country0001 · Dec 7, 2011

Have you been to the TRS tech library?

http://www.therangerstation.com/Magazine/spring07/BW1350_1354_doubler.htm

And I see you found the 4wd systems section

BronKitis · Dec 7, 2011

Country,

I just read that entire column and it is aimed more towards designing your own doubler system with the pre-tense of the reader already has knowledge of assembling two cases together. I know nothing unfortunately.... Thanks.

country0001 · Dec 7, 2011

The link I sent you to the library is already designed. Just find you a machinist. I'm thinkin bout building it. I just need another 1350. Ive got the 1354.

unoleisu · Dec 7, 2011

Country, do you need a 1350 M or E? I have a 1350 M sitting in the back of my old 85 BII, and a 1350E I'm planning on pulling out, as soon as I get around to doing my 1354 swap. Might work a deal.

country0001 · Dec 7, 2011

I need a 1350 m. PM me. My number is listed in the social group. You could call me too

4x4junkie · Dec 11, 2011

BronKitis said:
Ok, so I've got a BII, soon to have a 4" lift and 33" swampers. Went wheeling lasr weekend, ended up high centered on a rock and sliced my Driveline in half. So, bigger tires time!

I know my little 2.9 and 3.45 gears aren't going to churn those 33's very well so I started to think about dual cases and found Duffy. His prices are reasonable and said he'd even toss in another case for a little extra cake! I'm pretty excited to finally work on my BII but need to have the know-how first. I've never had a t-case apart, let alone know ANYTHING about connecting two of them together... If and when I do this with your help, I plan to document the entire thing with pics to boot.

My questions are mainly how difficult is this project? What other moss will I need to consider? I just want to spend my money wisely and not end up over my head and a dead BII in my garage. All help is greatly appreciated.

P.S. I have been reading all I can get my hands on about it, but collecting the info from one forum and piecing it together with another has been difficult so I figured I'd just ask out-right. Thanks again.

I would call it a semi-moderately easy project, though unless things have changed since I bought my D.D. Machine kit over 4 years ago, no instructions are included with it. Fortunately there are not a lot of parts so it shouldn't be too hard to figure out how everything goes together.

You'll want to fab up another mount to support the t-case, all that weight hanging off the tranny so far back isn't good for it (be sure the mount allows sufficient movement so it doesn't bind everything up when the engine flexes on it's own mounts).

Plan on some floorpan work if you don't have a body lift.
If you run a manual-shift rear case, you'll need to make a custom shifter linkage/lever for it as well.

Couple issues I ran into with mine:
The fill hole on the rear plate was impossible to get at with the cases assembled (it was positioned too low for proper lubrication anyway), so I tapped out the hole where the stock breather hose barb was and made that my fill hole (the breather I relocated to the top-rear of the doubler case).

The tapered allen-hex bolts for the rear case adapter plate I couldn't get tight enough for them to stay tight, so I modified the case to take longer ones (50mm IIRC) that stuck through enough to put nuts on the ends (4 places), and Loctited them.

Outside of those two issues I've been completely happy with it. The machine work on the parts was all very high quality.

Hope that helps. Lemme know if you need anything else on it. :icon_thumby:

P.S., you're gonna hate driving that thing w/33s and 3.45 gears around town as well (not to mention your mileage will go deep into the crapper), I'd plan on some 4.88 axle gears for spinning those meats too.

BronKitis · Dec 30, 2011

Ugh, thanks for the response Junkie. Sounds like I've got some work ahead of me! As much as Is really like to do this doubler kit right now, I may be leaning toward 1 ton axles as I can get a set for the same cost as the d.d. kit. Plus, I've got some like new 36's off an old truck of mine. My rig is strictly trail so mileage isn't really an issue. After playing with the gear calculator here at TRS, a set of axles with a 4.10 ratio should allow that 2.9 to churn those 36's with about the same umph she turns the 31's now. Everything may be on hold right now- wedding bells are in the near future along with the purchase of a house so we'll see. gonna be a busy year! Again, thanks for the response and I'll let you know what I come up with.

Bennybooster · Dec 30, 2011

your 2.9 will NOT be able to spin 36's with 4.10s like stock. You need 5.13's or HIGHER

BronKitis · Dec 30, 2011

Dropping from a 3.45 to a 4.10 and upping the tire size by 4" and you still don't think she'll turn them?

BronKitis · Dec 30, 2011

I'm only talking about turning them in 4 low BTW. It is licensed as an ORV and gets trailered everywhere.

elpoffroad · Dec 30, 2011

my 2.9 spins 37's with 3.73 lol and getting 23mpg on the street

Now is it slower than any car out their hell yes but once on the trail with 4low on it does great ...............but dont get me wrong i still want 5.13 gears lol :icon_confused:

elpoffroad · Dec 30, 2011

I have also been thinking of doing a doubler but still on back burner.

BronKitis · Dec 30, 2011

What are you running for axles elpo?

4x4junkie · Dec 30, 2011

With 1-tons and strictly offroad, I'd go all the way to 5.38s for those tires. A 2.9L needs all the RPM it can get if you want any good power from it.

Noob attempts D.D. Doubler install. Help wanted!

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