BOLT-ON PART TIME/AWD kit: gauging interest

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G

girraffe

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I've been working on a design on and off over the last year. It looks like I have found someone to produce the parts for me now. I just want to start gauging interest who would be in for a kit. I don't have prices set yet but am trying to keep it sub $500. Most people go with AISINS with the marks part time kit anyway so I'm not including hubs with this. Though I may try to carry new ones for those who want them. This kit would include a shifter lever, linkage, front transfer case spacer and 2 piece front shaft. Parts aren't made yet but patent/design security is coming along.

You will not have to mess with your center diff, gears, or back half of you transfer case. I basically redesigned the front output shafy and housing to accomidate what is needed to select between 4WD, AWD, 2WD, or completely open. I need to check and see but i believe you would be able to flat tow with this kit too.

This kit will be available for the 80 series as well(after testing/fitting). So i woll posting this there too.

Here are a couple pics of the shafts. First one is of the stock shaft with the pressed on gear. This is the gear inside the transfer case that the center diff is coupled to when you select 4WD.

And here is the new 2 piece shaft. The part on the left is on piece and keeps the original location of the 4WD/AWD gear. On the left is a new output shaft with a new gear to accommodate another OEM shift collar. At this point I have the total length down to 18mm longer than stock. I may be able to squeeze that down a little more to around 12-13mm, but for now it is good at 18mm, so thats 3/4"?


So who would be in?
 
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4wd we have, selectable CDL
AWD we have, standard configuration
Completely open, we have, AWD is completely open.
For the 80 series with viscous coupling, this would not be achievable?
2wd, locked CDL with no output to front shaft?
So an extra lever would have to be located in the cabin to select the front shaft?
 
With my setup you will have to have CDL locked, and the front drive shaft disconnected via the kit to achieve 2wd.

What I posted in 80 section earlier:

I have not converted to part time either. The BIGGEST reason is SAFETY. I live in co and it gets snowy here. Not as bad as the Canadians but still the occasional storm that covers the ground pretty good for some time. Basically you will have another shifter fork and ring inside the front transfer case housing. The existing shaft is replaced with a 2 piece shaft. In order to accommodate the additional shift fork and collar, the front housing will have a spacer (about an inch). All the factory bearings and seals are retained. This will allow the front DS to be disconnected inside the TC instead of outside like the trail gear setup
 
100 TD said:
4wd we have, selectable CDL
AWD we have, standard configuration
Completely open, we have, AWD is completely open.
For the 80 series with viscous coupling, this would not be achievable?
2wd, locked CDL with no output to front shaft?
So an extra lever would have to be located in the cabin to select the front shaft?
Click to expand...

Yes. But I also will be adding options over time like a pneumatic ram or electric ram actuator to select with.
 
I live in Austin and only need four wheel drive a couple times a year. If the kit would help with MPG that would be awesome and I am in but it sounds like a lot of work for maybe minimal gain?
 
bamabrock said:
With the CDL locked and hubs not engaged, I don't see how the front end spinning would hurt. I know some of the NP transfer cases will spin the front shaft and center sections, like in a jeep TJ.
Click to expand...

But what would it save? All the parts are still turning at the same rate. The saving is only by decoupling the front, both at the shaft and at the hubs. Only then are you not using fuel to spin the front drivetrain.
 
Lets not forget that the drive lines will need to be modified to work with this since the position of the I/O flanges will change.

I'm guessing between the labor cost, conversion kit, hub modification, and drive line modifications you would have to get a huge increase in MPG to make this worth while.
 
OregonLC said:
But what would it save? All the parts are still turning at the same rate. The saving is only by decoupling the front, both at the shaft and at the hubs. Only then are you not using fuel to spin the front drivetrain.
Click to expand...

The front is free spinning, but not driving the wheels. That is the saving. The part time conversion kits (I have not installed a marks 4x4 kit, but have converted a jeep quadratrac case in a CJ7 that worked the same) install a spool in place of the coupler in the transfer case. The front gear set spins on most domestic vehicles. I know the dodge and ford HD trucks have the front diffs spinning.
 
But the front tires are already spinning so if the cv and drive flange are spinning at the same rate I don't think much is saved by not completing the circuit and powering the front tires. What's the default rear bias anyway? Is it 50/50?

My limited understanding is that the energy waste is in turning all the mechanical bits up front which it is still doing. Probably saps at least a horse or two. And at cruise it's probably only putting down 40-50hp so that would be a 1-2% gain if you stopped spinning those parts. Just a guess in that amount.
 
I have done 2WD by modification in the transfer case
if you do it for economy it's not what you looking for, I believe the gains well not exceeds 2-5%
in performance side the truck well be more lighter and if you have a hard foot rear tires now have half of its previous life in AWD
in turns first few days you well not be familiar with it, but you well like it after knowing how to drive it
if you want a great turns its not AWD well help you much like the quality and diameter of tires
only when I do high speed in offroading and want to keep the high speed in some turns I really mess the AWD but that happened twice a year

my really reason was my front drive shaft had some noises when shifting gears (manual trans) when i tell my mechanic he said that even if you change it with new one you well get that sound after 3 months a maximum
and that commonly happen to all the old LC's
the best and cheapest choice was 2wd and I couldn't be happier!
I'm looking now for a free hub to get ride of the front vibration and I'm done
 
rusty_tlc said:
Lets not forget that the drive lines will need to be modified to work with this since the position of the I/O flanges will change.

I'm guessing between the labor cost, conversion kit, hub modification, and drive line modifications you would have to get a huge increase in MPG to make this worth while.
Click to expand...

I am going to finalize the drawings this week. Once that happens ill know how much further out the flange will be. I'm hoping to have the smallest spacer possible to avoid any driveline mods.
 
OregonLC said:
But the front tires are already spinning so if the cv and drive flange are spinning at the same rate I don't think much is saved by not completing the circuit and powering the front tires. What's the default rear bias anyway? Is it 50/50?

My limited understanding is that the energy waste is in turning all the mechanical bits up front which it is still doing. Probably saps at least a horse or two. And at cruise it's probably only putting down 40-50hp so that would be a 1-2% gain if you stopped spinning those parts. Just a guess in that amount.
Click to expand...

The advantage is not simply fuel mileage savings, but also driveability. fulltime 4wd is a pain in the ass at times. I really liked the option the GM transfercase in my sierra offered with 2wd, AWD, 4wdHI, & 4wdLo
 
bamabrock said:
The advantage is not simply fuel mileage savings, but also driveability. fulltime 4wd is a pain in the ass at times. I really liked the option the GM transfercase in my sierra offered with 2wd, AWD, 4wdHI, & 4wdLo
Click to expand...

I personally wouldn't do this anyway because it's our main family rig, just out of safety for my family, and wife that's driving it.

That being said, out of curiosity, when is fulltime 4wd a pita? I'm just trying to formulate arguments on this topic and I cannot really see a huge upside to do this, but perhaps there's a part of it I'm missing. Thoughts? I mean, I know the driving dynamics would change, as I've driven sequoias and 4runners and the LC does handle differently, however I'm trying to figure out how awd could ever be for the worse (other than the fuel economy difference - which is very minor)... Towing? maneuverability?

I like the Sequoia's selectable Rwd/Awd/4wd functions
 
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