Transfer case options (1 Viewer)

[fireball]

Thanks for sharing your input, I was really hoping the blackbox was the magic ticket. I could overcome the $$$ if it worked well and was the ultimate solution.

Unfortunately it sounds like it isn't....

I am running 285/75/17 ko2s on the 200, and really like them, but will probably try the Kenda Klever R/T at 35x10.5x17 on the bj74:

Automotive Tires, Passenger Car Tires, Light Truck Tires, UHP Tires | Automotive | Kenda Tires | Klever R/T

automotive.kendatire.com

Not quite 36s, but should work well, and close to a true 35.

 

[fireball]

Hmmm, Interco makes a 35.5 x 10 x 16.

Super Swamper Q78-16LT Tire, TSL Bias - SAM-53

Whether you're looking to maintain, optimize, or upgrade, we offer competitive pricing on Super Swamper Q78-16LT Tire, TSL Bias - SAM-53 for your Truck or Jeep at 4 Wheel Parts. With our selection of quality brands and expert advice, we help boost your vehicle's performance and make a statement...

www.4wheelparts.com

One more question Hoser - with the 4:1 I will be shifting back into hi range much more often. My usage is more HiTR than it is Rubicon. Still vote 4:1?

 

[hoser]

The Blackbox is based off a NV273/271 transfer case which usually has a 2 qt oil capacity. The current blackbox has a 3/4 qt oil capacity. I think once the oil capacity is increased, it'll be rock solid. You can wait for the revision but they have a history (like many) of estimating but not delivering on time.

One more question Hoser - with the 4:1 I will be shifting back into hi range much more often. My usage is more HiTR than it is Rubicon. Still vote 4:1?

Hmm, tough call... with your current low range gearing, do you find it kinda fast or way too fast? If way too fast, then go with 4:1, if kinda fast, go with 3:1

 

[FJBen]

Hmmm, Interco makes a 35.5 x 10 x 16.

Super Swamper Q78-16LT Tire, TSL Bias - SAM-53

Whether you're looking to maintain, optimize, or upgrade, we offer competitive pricing on Super Swamper Q78-16LT Tire, TSL Bias - SAM-53 for your Truck or Jeep at 4 Wheel Parts. With our selection of quality brands and expert advice, we help boost your vehicle's performance and make a statement...

www.4wheelparts.com

One more question Hoser - with the 4:1 I will be shifting back into hi range much more often. My usage is more HiTR than it is Rubicon. Still vote 4:1?

I wouldn't run a Q78 or TSL BIAS tires unless I was 80% or more offroad and needed a tough tire. I certainly wouldn't want if for a truck I had to drive a long ways/expedition type stuff. I had TSL's on a 55, and while they were a beast off-road, they were loud, rough, flat-spotted til warm and wore out quickly on road.

There are times I wish I would have went with a 35" tire...and I still might, but for now these 255's work excellent.

 

[MyCruiserisaHogBeast]

What model was that? All my 7* series had 16 in rims with tyres that were close to 32, I forget the metric equivalent. Some of the MWB had 15 inch rims but the tyre still brought them close the 32" height

I *think* the stock tires on this truck were a 235/75/15, which around a 30" tire. I'm not 100% sure maybe someone can chime in.. Mine is a JDM BJ74 that had factory 15s (one is still with the spare so I know for sure).

 

[FJBen]

I *think* the stock tires on this truck were a 235/75/15, which around a 30" tire. I'm not 100% sure maybe someone can chime in.. Mine is a JDM BJ74 that had factory 15s (one is still with the spare so I know for sure).

My owners manual for my BJ74 Australian market says the following for FJ70, FJ73, BJ70, BJ73, BJ74:
7.50-16-6PRLT 31.8"
7.50R 16-6PRLT 31.8"
10R15-6PRLT 31"

General markets also got the 7.0-16 size.

 

[Greg_B]

I've got the same setup at Norm: 315/75R16s, 4.11s, and Marks T case gears with 3.05:1 low and 1.08:1 high range. I think I have about 130,000kms on that setup now (installed winter/spring 2005/6 iirc). Still whine pretty good on the highway and been running MT90 in both the H55F and T-case. I've not put any additional sound deadening in place, but should. My road trip machine is the 80 now, so it's not as critical to manage the whine. These have roller bearings instead of needle bearings. The case has not been apart since install so I can not comment on how they look.

During ACT 2006 with the many river crossings I had to switch to high range between many crossings to keep up with the folk on the trip. It was a lot of changing. So 3.05:1 or 4:1...be prepared to change from low to high as needed. I was running 35x10.5R16 SSR's on that trip. Great sized tire for my setup (Belton 50mm lift at that time iirc).

I agree with Norm about wishing to have got the 1:1 high range. A larger exhaust with a little more boost moves the BJ74 along well enough for me and 1:1 would have been fine.

hth's
gb

 

[fireball]

Hi Greg, thanks for your reply! Do you happen to recall what your comfortable TopSpeed in four Lo was with your current set up?

If I’m going to be shifting anyway might as well go with the lower low range!

Not familiar with that terrain or that trip but given your experience have you found yourself wanting for lower during or happy with the 3.0 set up?

 

[Hugh Heifer]

@LDowney
Larry has regeared his and wheels regularly. He is never afraid to share some insight.

 

[fireball]

Would love to hear from Larry! Pretty sure it was his truck that I saw at coal miner a few years ago that started the wheels spinning to my initial research into a BJ 74...

 

[Greg_B]

Hi Greg, thanks for your reply! Do you happen to recall what your comfortable TopSpeed in four Lo was with your current set up?

If I’m going to be shifting anyway might as well go with the lower low range!

Not familiar with that terrain or that trip but given your experience have you found yourself wanting for lower during or happy with the 3.0 set up?

Had to go to the shop and drive the 74 around to make sure I was not giving you bad info. No tach numbers as my sensor is funky but I do know is was a bit above 2000rpm: In 4th is around 32-33kmph (20mph) and in 5th (which I would not want to stay in a long time in low) was around 36-37kmph (23mph) ish.

I've been happy with the setup, but I have not wheeled in the rocks with it (such as Moab or Rubicon). It's done what I have asked and for tootling around the backroads here I'm not in 1st much. If I want really low in the future I have one of the 1st five (iirc) Marlin Toybox for H55F still on the shelf, from an order in Canada years back. Stock low range with an additional low range box would be the shizzle.

@bj70_guy has had his 74 in Moab so could give a better idea.

I have bumped the engine into reverse rotation from hitting a rock with the front winch saddle when going real slow through a rock garden trail here (ala the photo which says early 2005). If my memory is correct this was before the t-case gear set was installed later in 2005. This was early days and the SSR's must have been new!

hth's
gb

 

[LDowney]

@LDowney
Larry has regeared his and wheels regularly. He is never afraid to share some insight.

Would love to hear from Larry! Pretty sure it was his truck that I saw at coal miner a few years ago that started the wheels spinning to my initial research into a BJ 74...

Yes it could have been my BJ70 that you saw at CMCC. We have made the drive several years now.

Georg @ Valley Hybrids overhauled my transmission and transfercase last fall. While he had the case open, he re-geared my transfer case. I am feeling rather dumb right now because I don't recall the final gear ratios. In high range, the gearing added 8% in overdrive. In low range, it is tremendous. Georg recommended gearing that would require limited machining of the transfer case housing and the performance on the trail would be very impressive. He was absolutely right. I have had the truck out twice with the re-gearing; RoundUp in March and GSMTR in May. On the rocks at Katemcy and in the rocks/hills/mud at Windrock, the difference was definitely an excellent match for my 3B. It opened the trucks ability to crawl over very challenging obstacles at an idle. If more was needed on an obstacle, just a touch of throttle could handle it. Also, I was not prepared for how much easier it made clutch control in all situations. This should be of great aid to the life of my clutch.

FYI Lance at IronPig purchased a BJ70 earlier this year and had plans to re-gear his 70 too. He has probably done this by now. Since his truck and shop are much closer to you, he might be a good resource to check out for yourself how his re-gearing turned out and what lessons he might have to share.

 

[87BJ74]

I have the Blackbox in my BJ74 but I have not been driving it too much due to fear of cooling issues with the blackbox. NWF is working on a redesign but I don't know the status of that. I might add an oil pump, cooler and reservoir. I'm just not thrilled about adding the complexity. I'm kicking myself for not getting a Toybox when I had the chance. You can read about the cooling issues in the 2nd half of this thread.

As for gearing. I run the H55, 4.1 and 35's powered by a 12HT. Cruising at 70-75 is perfect. Double low yields a crawl ratio around 105:1. The BB shifter is cable and so it doesn't have that positive engagement like the stock T-case.

I had considered the option of going with the 4:1 t-case but it seemed kinda slow for anything but technical terrain. 4:1 in 4th gear low range is almost the same as 1st gear in 4Hi. How fast can you go in 1st gear 4HI in a diesel? Not very fast... and so yes, I would imagine I would have to shift between LO and HI range fairly often.

Greetings all,

My BJ74 build has stalled a bit, but a recent trip has afforded a bit of clarity and a mission statement of what I want to be able to do with the truck: "Confidently wheel and keep up with a built 80 on 35s".

View attachment 2084947

I think a major piece of that puzzle will be either a transfer case regearing, or perhaps a Blackbox. I have been reading up on the Blackbox and searching and can't find any info for anyone who has actually installed one. There are a few different options for keeping the stock t-case and adding gears, namely 3.3:1 or 4:1 and then keeping hi range as-is or going 10% under or 10% over.

Would love to have some input and hear some thoughts from folks on the right move. Specs on my truck are as follows: 13bt with h55 5spd, 4.11 stock gears and currently running 33" MTs. Considering swithcing to 35x11x5x17s to help accomplish goal above.

Thanks in advance for any insight!

I have the blackbox with an atlas 2 tc attached to an h55f in my bj74/75 hybrid, currently rebuilding the truck from the ground up so am designing friendly kit in order to solve the cooling issues that others have had. When i talked to nwf a couple months ago they still haven't figured out what their direction is on fixing the issue other than redesigning the case(which doesn't help anyone who already has one).
When i first got the truck it had 35s on stock gears and an h55f. It would get around on its own pace.. Granted a 13bt isn't the fastest toyota diesel out there. With the way the atlas and blackbox work in 1:1 the truck just has a regear to compensate for the 37s that are on it, with everything in low it sits at 323:1. For what your doing with your truck this is extreme. Id say a diff regear to 4.56 first would treat you better than a tc regear because of the cut on overdrive speeds and the truck would be close to stock ratios on 35s. Then if your still feel the need to be little lower offroad then go with the tc gears. These trucks are pretty offroad capable, i would imagine if you just run a few moderate trails/drive daily the diff regear would work out best.

 

[hoser]

Id say a diff regear to 4.56 first would treat you better than a tc regear because of the cut on overdrive speeds and the truck would be close to stock ratios on 35s. Then if your still feel the need to be little lower offroad then go with the tc gears.

You are recommending 4.56.... while the TC gears offer 1.10 in HI range (in addition to the LO range regear) and so....

1.10 x 4.11 = 4.52

Gear whine aside, regearing the T-case HI and LO would have the economical advantage.