Project- Suburban HD

justcuz

Explorer
In your opinion would a NP 241 with Rubicon 4-1 low range be strong enough for something like this? Does the NWF ECO box have provisions to bolt up to a NP241. Although the 205 is bulletproof, it is also heavy and only has a 1.96-1 low range. Double 241 reduction is 5.44 and Rubicon plus regular 2.72 NP 241 is 10.88. Finally double Rubicon would be 16-1. You could get over a 120-1 crawl ratio with 4.10's, a 4L80E and dual Rubicon planetaries. Is that excessive?
 
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'05TJLWBRUBY

Adventurer
Regarding steering boxes - 1980-1996 F-series and E-series Steering boxes bolt to the inside of the frame rail and have the pitman arm pointed forward. Ford fullsize passenger cars of the same model years got a steering box tha looks exactly the same, bolts to the frame rail in exactly the same manner in the same bolt pattern with same diameter bolts, and takes the same exact steering shaft coupler, but has the pitman arm pointed towards the rear. Those boxes are IIRC made for Ford by Saginaw. So if that's done from the factory, maybe you can do it as well? Or just use a truck box as is, they are quite strong actually, used on everything from Broncos to commerical F-Superduties (old F450) with 15k GVW.

Thanks for the thoughts here- Yes, that's almost exactly what I'm thinking- the difference is forward or rearward facing pitman arms- which is standard rotation for rear facing arm, or reverse worm gear for forward facing- with the Saginaw boxes, the worm drives and sector shafts are direct swaps, you just have to get the correct one you need and do the work. Good info there and opens my options a bit. Thanks for the tip.

Best of Luck,

Mike
 

legendaryandrew

Adventurer
So not to be that guy, but uh, you need to get that t-case installed and the sticks set up so people like me can drool some more. Pretty please?
 

'05TJLWBRUBY

Adventurer
In your opinion would a NP 241 with Rubicon 4-1 low range be strong enough for something like this? Does the NWF ECO box have provisions to bolt up to a NP241. Although the 205 is bulletproof, it is also heavy and only has a 1.96-1 low range. Double 241 reduction is 5.44 and Rubicon plus regular 2.72 NP 241 is 10.88. Finally double Rubicon would be 16-1. You could get over a 120-1 crawl ratio with 4.10's, a 4L80E and dual Rubicon planetaries. Is that excessive?

I like your thinking here. My head isn't clear at the moment and I'm not sure if math is correct, but it sounds close. I'll say this- I have a Jeep Rubicon that I bought new off the lot back in '05. It had the 241 with 4:1 low range. Factory setup with 4.10s was I THINK a 72:1 crawl ratio if I recall correctly. I have essentially broken all the Rubicon parts and upgraded or replaced, and built that rig up from scratch to what it is now. When I put 33" tires on with factory 4.10s, I lost 6th gear entirely and 1st became a dedicated starter gear. I HATED it's performance. In 4:1 low range, crazy as it sounds, I hated the 4.10s and 33s. Obstacles that I could idle before in 1st gear now took throttle to get over. I was not happy in high range on the street or low range off road. I put 4.88 gears in the diffs and that brought it back down to better/lower than stock ratios. I have passing power in 6th on highway and can idle again in 1st in low range. I had the finesse and control back again that I'd missed prior. Due to chasing odd vibrations I narrowed it down to a problem with the input bearing in the factory 241 case. It's a double ball bearing roller setup with a plastic cage. Over time and wheeling, one of the sprockets or teeth in the plastic cage had failed and the balls would occasionally skip a tooth. I could feel this through driver seat and went crazy until I tore it all apart and found the problem. Once I found it, I totally rebuilt the 241 case with all new bearings and seals. I sold it and replaced it with an Atlas. I liked the 4:1 so well that I went with the 4.3:1 Atlas case. Best move I ever made on the Jeep. I LOVE that thing and the ability to have 2wd low range, and front wheel drive on it's own. Crazy how much I use it actually. This is why I wanted the same ability with split axles in the Suburban. I also loved the low range crawl ratio but- odd as it sounds, wanted another "middle" gear. There are times when high range is too high but low range is too low- like moving between trails or sections of trails that are long before next obstacle or slow technical spot. Running in 5th low range kinda sucks but 1st high range isn't low enough. Because of that, I wanted a 3 speed minimum in the Suburban. That's where the NWF Eco box came to play. With both boxes in high range I have 1:1 ratio. With 205 in low range, Eco box in High range, I have 1.96:1 mid range. With Eco box in low range and 205 in high range I have 2.72 low mid range, and with both the Eco box and 205 in low range (double low) I have 5.38:1 double low range. A 4 speed box. In the Jeep with 4.46 1st, 4.3 Atlas and 4.88s in diff I have 93.5:1 crawl. Manual trans 6 speed. In Suburban with with 4L80E and 2.48 1st gear, 5.33 double low gear and 5.38s in diffs, I'd have 71.1 double low- and with autos they "say" the slush box/torque converter basically doubles it, it would be 142.2:1 effective overall crawl. I have yet to see if this performs as I hope.

So to your question- is it excessive- that depends. With the Jeep and prior to Atlas with just the factory Rubi 4:1, in Moab on various trails around Poison Spider and the loop area there, there was times where 1st low was great for crawling UP the steep stuff, but going back down was a different story. 1st on some of the steeps there was too low and caused loss of traction because the Jeep was turning slower rpm than the slick rock could hold at such steep angles. As a result, I'd slide down out of control despite the low gearing. By switching to 2nd or 3rd, I could match rate of decent slide with rpm at wheels and maintain traction and control. Where I wheel here in WA the most, I like 1st low on the steeps as it's different terrain and 2nd or 3rd is too fast to control. When I slide it's due to loose rock in 1st but soon as I catch traction again it crawls and sticks maintaining control. In snow, it's a different story. Aired down to basically zero pressure with as big a footprint as possible, and in 1st low, sometimes I want a lower crawl than what I have at 93.5:1. Long story short- would you use 120:1 or better much? Probably not much- but the ability to get there when needed would be priceless. you'll spend majority of time in the mid range ratios but having that "extra" edge when needed can mean the difference in pulling winch line or not. As much winching as I do, I like that "edge" when I can get it.

As to the "strong enough" question. It's an aluminum case, but yes, I think it's strong enough. Having done SYE conversions on 231 cases and seeing differences in the 241s as well, the 241 is just bigger, wider, stronger, better overall. 231 is 3 pinion planetary??? where the 241 is 6 pinion planetary. The Rubicon 241 is a big 4 pinion planetary but big planet gears. More surface area. The 6 pinion planetaries in the non-Rubi 241s are extremely strong, and in stock form are found in the diesel trucks. Those same cases are found in the sled pulling trucks unmodified despite the massive horsepower and torque they put out. I don't know if NWF builds and adapter to mount two 241 cases together, but I know they could if they don't. Would it work- yes. The question would be is the input shaft large enough to handle the torque multiplication of the doubled boxes. They make a big input for their "Titan" line but not sure how that relates to compounded 241s. The 205 is heavy yes as it's all cast, but it's gear drive and you gain the split axle ability. That is not possible with a doubled 241 to my knowledge. I could be wrong there but not sure that you can do it with chain drive. Never looked. The 241 chain is big/wide though and with 6 pinion planetary is capable of handling big torque loads. I have to believe it's possible yes. Is it necessary? Doubtful. Excessive? Probably. There is another product out there for Jeeps called the "Rubicrawler". It's a 10.88:1 reduction box capable of low crawls. I know a few guys who have it, and wish they never did it as it's too low for where they wheel and they can't or don't use the 10.88:1 ratio. I personally have never done an auto trans with low gearing, only been manuals. I'm curious where my doubled box will work with the 4L80e. In my mind, it will be perfect for the Suburban HD, and I can't wait to see how it plays out in reality once built. I will say having split axles and the ability to run front or rear locked or unlocked independent of the other is priceless.

Sorry for long winded response, hope that helps or at least gives something to think about.

Best of Luck,

Mike
 

'05TJLWBRUBY

Adventurer
So not to be that guy, but uh, you need to get that t-case installed and the sticks set up so people like me can drool some more. Pretty please?


Ha! Yes, I know- I am really interested to see how that all works out. The Ecobox and 205 is physically bolted up to the 4L80e currently- but I never built the crossmember for it, and now I'm glad I didn't. With the fitment of the front 14, things are going to change quick- I gotta get that engine out of the way and that means raising it from where it is now. Consequently, I'll want to raise rest of drivetrain too. I gotta source a reverse worm gear for the steering box first as my intended goal of 7" up travel will require frame modifications among other things. Not sure yet where fitment will be and I don't want to build myself into a corner and have to re-build something twice. Unfortunately it might be a while before I get the crossmember built for the t-case setup as it may change height wise to keep things in line. The triple sticks are a problem I have yet to work out- but I want to see where it will finally rest before I start building those. Crazy how things compound trying to keep the big picture and end result in mind... Thanks for interest! I love the Suburbans and can't wait for this one to be done!

Best of Luck,

Mike
 

legendaryandrew

Adventurer
Ha! Yes, I know- I am really interested to see how that all works out. The Ecobox and 205 is physically bolted up to the 4L80e currently- but I never built the crossmember for it, and now I'm glad I didn't. With the fitment of the front 14, things are going to change quick- I gotta get that engine out of the way and that means raising it from where it is now. Consequently, I'll want to raise rest of drivetrain too. I gotta source a reverse worm gear for the steering box first as my intended goal of 7" up travel will require frame modifications among other things. Not sure yet where fitment will be and I don't want to build myself into a corner and have to re-build something twice. Unfortunately it might be a while before I get the crossmember built for the t-case setup as it may change height wise to keep things in line. The triple sticks are a problem I have yet to work out- but I want to see where it will finally rest before I start building those. Crazy how things compound trying to keep the big picture and end result in mind... Thanks for interest! I love the Suburbans and can't wait for this one to be done!

Best of Luck,

Mike

Does the Eco-Box allow the same gear abilities as doing a 203/205 doubler? I.E. 2 hi in 4wd, fwd, or rwd, as well as 4 low 4wd, fwd, or rwd? I'm really wanting to swap my NP246 for a NV273 and retaining the electric shift. Wouldn't mind lower gearing....hehe.
 

'05TJLWBRUBY

Adventurer
Does the Eco-Box allow the same gear abilities as doing a 203/205 doubler? I.E. 2 hi in 4wd, fwd, or rwd, as well as 4 low 4wd, fwd, or rwd? I'm really wanting to swap my NP246 for a NV273 and retaining the electric shift. Wouldn't mind lower gearing....hehe.

Actually in my opinion, the Eco box allows for better gearing than the 203/205. I believe the 203 and 205 share the same 1.96:1 low range so essentially with 203/205 you get a 1:1 high, 1.96:1 mid and 3.84 low. The 203 is 3 pinion planetary and crazy heavy as it's all cast and large. The 203/205 combo is enough to blow your back out trying to hoist into position. Not sure actual total weight, but you're better off loading a ton of lead in the back. With the Eco box you get the 2.72:1 of a 6 pinion planetary for better gearing and substantial increase in torque value. You'd essentially still have a 1:1 high, a 2.72:1 low (same as the 241, 273, etc.) and a 7.39 double low (2.72*2.72) with Eco box and 243/246/273, etc. Again, I don't know if NWF does an adapter to mount the Eco box to the 241/243/273 style but I'm sure they can. The nice thing about the Eco box/205 is the split axles. I keep going back to that because the ability to split front or rear independent of the others is amazing offroad. With the Eco box and 205 gearing, you also get normal 2wd high range for street driving. 2wd low range for slow going mountain forest service roads- in either 1:1, 1.96:1, 2.72:1 or 5.33:1 ratios, then you get the ability to do the same in front wheel drive with rear in neutral. This is especially useful when in tight timber- I can't tell you how often in the Jeep I am in tight trees and have to kick the back end into neutral and use the front end in low range to pull me around a tree or obstacle. Once around, pop the back end back in gear and keep going. With the 205 and properly modified shift rails, you can't mix high/low range in any gear so no worry of binding the case. Done properly of course. This is one thing I miss with the Atlas in my Jeep- I can't engage front wheel high range by itself. There have been times I've wanted it. With the Eco/205, I'll have it. I may be wrong, but I don't believe you can do this with a chain drive case like the 241 or 273. The way the chain drives both gears, I don't see an easy way to separate front and rear axles. I've never looked, just what I had noticed tearing them apart. 205 is easy for split rails with all gear drive. Electronic wise, I'm sure you could fab something to make it work. I've seen guys use air to do so with pneumatic valves and such which is pretty trick, but for me, I want ease and simplicity of standard levers. Nothing to fail that way and easy to repair should there be an issue in the field. Direct engagement by user input through mechanical lever- hard to break. Nothing to cause headache and easy to diagnose if something goes wrong. I have the rest of an extra 241 in pieces on the shelf that I build the Eco box with. Guess I could look closer at it to see. I kept the 243 out of the Suburban in tact just in case so I have extra parts laying around. A few 205's both Ford and Chev also to play with.

Best of Luck,

Mike
 

justcuz

Explorer
With an automatic your maximum torque multiplication is right around the stall speed RPMs. But as RPMs increase torque multiplication decreases, so an automatic behaves differently in the same gear at different RPMs. Make sense?
I am not sure how that will apply to using the doubler, so it will be interesting to see how it behaves.
 

legendaryandrew

Adventurer
Oh interesting, I hadn't considered the chain drive vs gear drive when doing this. I honestly don't have any qualms about getting rid of the e-shift, other than my burb has the center console, so no easy place to put a floor shift. I honestly prefer the simplicity of a floor shift, and I'm sure I could use the 4wd switch location for some lockers or light or something.
 

'05TJLWBRUBY

Adventurer
The floor shifter is a good question. We've had a number of Suburbans over the years and I've never cared for the shifter location/position in any of them. I'm kind of kicking around the idea of an aluminum console of sorts with elevated shifters that are easier to reach. Unsure how to pull it off exactly but have a couple ideas when the time comes to get to that point. I have a 3000w pure sine inverter that will go in the Burb, and will likely be installing an SPod or two or similar switch panels. The inverter requires 6' max length on input cables which would put it right about the floor tunnel where the shifter should be- may tie a couple things together there for functionality but long ways off on that. Shifters have been on my mind since I did the t-case/Eco box build. Cables would make it easy- but I don't care for the feel of cables and seem to have to make everything more difficult than it really needs to be so some for of manual shift is how it's going to be. :smiley_drive:

So plans have shifted given current situation with the height and axle location with the desired travel I'm after. Looking at this thing the way it sets now with the goal I want, I only see a few options here to pull it off and even still, not sure it will happen without lifting at least a bit. This is a 1997 Suburban with original rubber on the body mounts so I'm ordering up all new rubber to replace the body mounts, engine mount and trans mounts. I found a chunk of aluminum so soon as body mounts arrive, I'm going to turn down some body lift pucks about 1" or 1.25" with shoulder to set over the new poly mounts. This may turn off a lot of folks installing a 1" BL, but doing so will allow me to do a bunch of other mods to get the travel I want. Once that's in, plan is to go in and elevate the engine. I'll relocate it as high up as I can get it without cutting new tunnel inside the cab. I am leaving this full body and fully in tact internally as it's the family rig. At the same time, and actually sooner- while I wait for body mounts to arrive, I'll be cutting up the truss on the front 14 and giving it a shave. I think I can pull about 2" out of the height on the truss by shaving the 14 and eliminating the upper ribbing, laying truss as flat to center chunk as I can get it. Kinda sucks reworking the bridge and everything but it's gotta be done to get the up travel I want. With these two major changes, I'm thinking I can squeeze at least 6" up travel out of it if I'm lucky. That will leave very minimal lift at best. The BL will also allow me to tuck the big 42 gallon fuel tank up a bit higher also. I've hit that thing enough on normal camping trips, and although bigger tires will certainly help, tucking it up as high as relatively possible will be even better. Work load on this thing just tripled but I think it will be worth it in the end.

Best of Luck,

Mike
 

steve578

New member
It's great to see you resurface. I'm definitely following this build as I've had several Suburbans and miss having one.
 

'05TJLWBRUBY

Adventurer
It's great to see you resurface. I'm definitely following this build as I've had several Suburbans and miss having one.

Well I'll be darned- good to hear from you again! How have you been? Yeah figured it was time to come out of hiding and get building something again. Taking FAR longer than originally intended, but then again, the original simple SAS goal went out the window long ago and this turned into far more than intended. Oh well, should be pretty sweet when done. Hope you've been well!

Best of Luck,

Mike
 

'05TJLWBRUBY

Adventurer
Well kinda bummed after messing with this thing a bit today. Was hoping to gain 2" here but only got 1.75". No biggie, I can work with that, and I did get an idea to rework the truss a bit to gain even more than intended. Bummed as I was going to install and lock down the diff breather fitting and the ARB bulkhead before burning the bridge back on. Couldn't find any bulkhead fittings anywhere so that put a stop to progress today. Not sure I'll be able to get it in after it's burned in or not so better do it now and be safe. Can't really call this a shave, but a trim at least.



I'll pick up a bulkhead kit tomorrow then get back to reworking the bridge once that's in.

Best of Luck,

Mike
 

legendaryandrew

Adventurer
So n00b question, baring in mind that I'm...well, a n00b. This is a FF 14 bolt right? Isn't this axle similar to a AAM 10.5"? Because looking at my 10.5 on my 'burb, I noticed it's a low pinion, which if I remember correctly, is ideal for a rear driven axle, for ring/pinion strength, right? So a front axle, you'd want a high pinion, if my logicx are in order?
 

'05TJLWBRUBY

Adventurer
So n00b question, baring in mind that I'm...well, a n00b. This is a FF 14 bolt right? Isn't this axle similar to a AAM 10.5"? Because looking at my 10.5 on my 'burb, I noticed it's a low pinion, which if I remember correctly, is ideal for a rear driven axle, for ring/pinion strength, right? So a front axle, you'd want a high pinion, if my logicx are in order?

Not sure I can explain this well enough but yes, your logic is correct- a rear axle typically is low pinion which puts power on the drive side of the ring gear tooth, which is optimal. While lots of folks do it, it's not a very good idea to build a rear diff high pinion with front mounted engine, putting power to coast side of the ring gear in rear axle application for high pinion setup. This is a great way to shred ring gear teeth. It's a different story if you were to do a rear engine which is then spinning other direction making HP rear good with power to drive side again, but that gets pretty confusing explaining how it works. With front axles, yes, a high pinion front does put power to the drive side of the ring gear, same as a low pinion in rear application. This is great for driveline angles, but also for greatest strength on the ring gear. That said, many 4wd on the road use a low pinion front axle. My '05 Jeep Rubicon for instance with D44's front and rear are the same front and rear. Many vehicles use a low pinion front. All the Dana 60's in Chevy and Dodge applications- king pin setups are all low pinion. Ford used the High pinion front which makes it highly desirable for SAS builds to get the driveline up out of the rocks and also put power on drive side of ring gear tooth.

Yes, you are correct in that my front 14 is a FF 14. This one was the factory rear axle that originally came under my Suburban. I picked up a newer full float 14 out of a Chevy 5500 box van which is dually width at 74" WMS with massive disc brakes, and 4" main tubes that are 11/16" thick. This made for the perfect rear axle for my Suburban build and as my original factory FF14 was big drum brakes, and 3.5" tubes only 3/8" thick, it made sense to cut it up and build the front out of it. While my original front 9.25" is high pinion/reverse rotation, I have no fears that the 14 up front will have any issues. It's much larger diameter, much thicker physical gear, big pinion diameter with 3 pinion bearings like a Ford 9" has, and big bearings. With the ARB up front and planned 5.38 ring gear, I have no worries of failure on this front end. Many rock bouncers pushing major horse power with massive tires run front 14s and don't break ring gears. I'm not worried, this will be overkill for what Suburban HD will see. The GM 14 bolt has been around since early 70s with 3 different versions over the years- '88 and older, '89-'97 then '98 to current. Difference is in the pinion bearings and pinion seals used with the newer ones getting better triple lip seals. There is an odd variation in '84/'85 model year which used an odd 3rd pilot bearing size- the ID is same as all of them but the OD is smaller. If you come across one of these, do NOT throw away the 3rd pilot bearing- they quit making that bearing over 20 years ago and there is nothing on market today for replacement. I know of a few shops who learned this the hard way and wound up with hours of machine time to bore the housing out to accept the normal standard pilot bearing all the other 14s used. If you have an '84/'85 FF 14- watch for that if you tear down/rebuild.

So with regards to the AAM 10.5- I'm not sure what you're referring to exactly as the AAM 10.5- things get really confusing here as typically the AAM 10.5 is a Dodge/Chrysler axle found under the Ram trucks with gas engines. It's a 10.5" axle with 3.73, 4.10 and 4.56 options for ratios, and no aftermarket support. Factory carrier and ring gear is only option, nothing to build these axles. GM used the "GM 14 bolt" as most refer to it as, but AAM built this in later years. There are 3 versions of the 14 bolt axle from/for GM-the 9.5" 14 bolt which is a 9.5" ring gear, 33 spline C-clip semi-float axles, 14 diff cover bolts and NO removable pinion support. This is common under Suburbans and 1500 trucks. Others as well but I forget specifically which exactly. The normal "GM 14" that everyone knows as "thee 14 bolt" which is what I am building here both front and rear. These use the 10.5" ring gear, with big 30 spline axles, 6 bolt removable pinion support with 3rd pinion/pilot bearing and 14 diff cover bolts. Common under 2500 and 3500 trucks trucks, and also under the 4500 and 5500 box vans which my rear came from with dually width. Other applications as well such as cab and chassis with narrow width. Then there's the AAM 11.5 which is totally different, 11.5" ring gear, no removable support, typically has big tubes, but thin wall thickness and easy to bend the housings. These are found in 2500 and 3500 GM and Dodge trucks and are often confused with "thee 14" as it has 14 diff cover bolts.

If your Suburban has a 14 bolt check to see if it has 6 bolts on a removable pinion support. If it does, great- you have the FF 14. That is easiest way to tell. If you do not have 6 removable pinion support bolts, you have the 9.5" Semi-float 14 bolt. Not to worry- the semi-float 9.5" 14 bolt is actually a decent axle, available in 6 lug and 8 lug and has aftermarket support for lockers and gears and can be built to do well. It's semi-float yes, but can still perform well. I can't remember specific applications off top of my head but that's pretty basic overview. Clear as mud? Hope it helps... :)

Best of Luck,

Mike
 

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