part time vs full time

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I have about 75K with PT on my current 80 I also run it on my LX470 but with more caster and love the way they both drive. Most people that have driven my 80 dont even notice. One of the biggest reason IMO is I run a solid 4° of caster and it provides tracking comfort at speed with good wheel feel. I have run/tried PT in other 80 and did not like it with the suspension set up as the 80 had to much lift when leaving from a dead stop. The front end was not stable and had a lot of up, down, and diving. The other part that I really like is zero vibs at any speed.:flipoff2:

Pull your drive plates and drop your front drive line and it will not take you long to figure out if PT its for you or not.
How do you like running the extra caster? Any drawbacks to a little extra caster?

I’m still getting some mild vibration at highway speeds after PTing the case, so I’m not sure what that’s from. Maybe needs more caster? Maybe rear panhard? Maybe rear driveshaft?
 
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LandCruiserPhil

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How do you like running the extra caster? Any drawbacks to a little extra caster?

I’m still getting some mild vibration at highway speeds after PTing the case, so I’m not sure what that’s from. Maybe needs more caster? Maybe rear panhard? Maybe rear driveshaft?
I like lots of caster ran 7° on my 40 and you could run at 100mph with comfort. My long term plan is to go up to 5° on the 80 series.

Rear panhard will not change any vibs but a needed part with many benefits on a lifted 80. I would not think more caster would make a difference either unless you are extreme negative now.
Have you balanced your rear drive line? I have the driveline balanced with the slip yoke is the ride height position for best results.
 

LandCruiserPhil

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Its going to have to be for me.... as im doing Om606/h55f/ split case in the 80. So part time for sure.

the engine tranny tcase is 200lbs . less than the 1fz/auto that just came out. and it will be positioned slightly rearward to where the 1fz sat in relation to the front axle. rear end will be losing 300lbs of seats. so im hoping a 4200lb-4300lb 80 will be a tad more nimble handling wise.
a touch more castor correction and raising the panhards and UCA mounts and im hoping it wont handle too bad. Its currently got some 315/ 12.5. but im not at all opposed to trying 255/80 skinnies if the wider 35s track poorly or are sluggish on turn in. I guess i will just be doing lots of fiddling with castor/ toe/ mounts and overall suspension tuning with the Frankies springs which im hoping are a tad softer than the ones i have on Baconbits right now.
Very cool to see the results of a ~4300lbs 80 you will be in uncharted area. Im guessing a split case for even lower gears?
 
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I like lots of caster ran 7° on my 40 and you could run at 100mph with comfort. My long term plan is to go up to 5° on the 80 series.

Rear panhard will not change any vibs but a needed part with many benefits on a lifted 80. I would not think more caster would make a difference either unless you are extreme negative now.
Have you balanced your rear drive line? I have the driveline balanced with the slip yoke is the ride height position for best results.
Great intel. Thank you.

I was vascilating between the DVS 2 inch radius arms and the 4 inch (I have a 2.5” OME lift). It sounds like there is no downside to running the extra 4” radius arms.

I have not balanced my rear driveline, but I didn’t know that was necessary.

You need to balance the driveline after a lift? How do you balance with the slip yoke “in the ride height position”? Mark it on the truck before you take the driveshaft to be balanced?
 
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Great intel. Thank you.

I was vascilating between the DVS 2 inch radius arms and the 4 inch (I have a 2.5” OME lift). It sounds like there is no downside to running the extra 4” radius arms.

I have not balanced my rear driveline, but I didn’t know that was necessary.

You need to balance the driveline after a lift? How do you balance with the slip yoke “in the ride height position”? Mark it on the truck before you take the driveshaft to be balanced?
Be aware the Delta radius arms are designed to be at the top of the caster spec for the given lift heght. I.e., if you have a 2" lift and run the 2" radius arms, you will be close to +4* caster. This is a good thing, but there is a potential to overdo it, so definitely talk to them before ordering.
 

LandCruiserPhil

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Great intel. Thank you.

I was vascilating between the DVS 2 inch radius arms and the 4 inch (I have a 2.5” OME lift). It sounds like there is no downside to running the extra 4” radius arms.

I have not balanced my rear driveline, but I didn’t know that was necessary.

You need to balance the driveline after a lift? How do you balance with the slip yoke “in the ride height position”? Mark it on the truck before you take the driveshaft to be balanced?
Talk to @Delta VS they can recommend the correct arms to get 4° caster. The difference in driving an 80 between 2° - 4° caster is huge.

Ride height of a 2.5" OME lift changes with weight so saying I have a 2.5" is a variable. I run OME 850Jw/spacer & 863J rear and measure ~2.5 of lift due to gross weight.

You do not 'need' balance your rear drive line after a lift but you are trying to eliminate a vib and a drive line could be it.:meh: When the position of the slip yoke changes on a used drive line its not uncommon for the balance to change.
 

bugsnbikes

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Very cool to see the results of a ~4300lbs 80 you will be in uncharted area. Im guessing a split case for even lower gears?
My Fzj55 (80) is 4300lbs on completely stock height suspension with 35's full time......handling is much more planted and maintains 265/stock tire handlings nimble feel. alot less body roll than stock mainly due to weight and im running no sway bars front or rear and its alot more planted than a stock cruiser. this 80 is going to be on 3in. Frankies lift- so it should be slightly more tippy/ higher cog.......i may need to toss on a rear sway bar, but we will see how the Progressive Frankies do with 4300lbs 3" higher up. My old 80 that ran the same springs 37s at 5300lbs was fine with just the rear swaybar only.

The split case will be stock gearing for starters--as the h55f first gear is a notch lower than the 1fz/auto. I will see how the stock split case gears work before jumping to the weaker and noisier 3:1marks gears. the om606 will be putting out a bunch more torque than the 1fz.......and the 25% drivetrain loss of the auto trans is going bye-bye which should move a 4300lb unloaded 80 nicely.
the goal is to be loaded for trips at stockish 80 weight- 4800-4900stock w/ 35s p/4.11's with 25% more torque and hp than a stock 1fz auto. The om606 guys are running 40psi+/500ish + hp and torque fairly safely...... Im only going to be running a 1.5bar actuator -22psi roughly-with a 150cc pump (hopefully spending most time in the 110-130cc fueling-1/4-1/2throttle) which should put me in the 250-260hp at the wheels. And maybe 330tq. WIll see what the dyno says.
 
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a slightly off-topic question, those of us with factory part time and H4 button, at what speed can we still engage H4, is it on the fly, or has to be stopped and in "N"?
no hi-jack is intended
 

rghouse

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In summary, please correct/add/subtract where neccessary (isnt that what forums are for? lol). Assuming the rig has not been heavily modified and is at or close to stock specs the following is true for the part time 4wd mod (with manual locking hubs):

positives:
less wear and tear on front end
reduced vibration and road noise
possible fuel consumption gains
more versatiliy in regards to auto-locking front diffs
more versatility on the trail in certain situations
more responsive throttle and or more torque to rear (not 100% split, 100% rear)
all wheel drive (previous, stock condition) can still be achieved with hubs free and CDL off

negatives:
will not corner as well
steering is different
have to get out and manually adjust hubs when engaging 4x
more complexity/components means more can go out (CDL, hubs)
further mods are neccessary to correct/minimize handling issues and/or castor needs adjustment if lifting or heavily modified
responsiveness and agility/handling is worse *safety*


I seem to remember reading a thread on this topic where someone stated that South American 80s came stock with Aisin hubs/part-time for a while and they were sought after and preferred by drivers in that region (which had me sold). I have to say that IMO for a stock or near stock rig the positives out weigh the negatives and probably more so for a 3fe. But...hard to put a value on the last negative bullet point: handling. That one just about cancels out all of the positives because of safety.

In my case, the 92' is quite loud and viby as well as very sluggish. I dont corner fast anyway, and I dont plan on heavily modding it any time soon. As far as MPGs go the incentive is strong to go for PT even though this varies on a case by case basis. It would seem that this particular mod is well-suited for some, but not others. Strong consideration should be weighed based on road conditoins, cargo, mods, $$ (does wear and tear and mpg matter to you), driving style, miles driven, on and on

Still on the fence, saving for gears...
 
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I have a factory part-time 80. I've never driven a factory full-time 80 to compare against mine. The fact that under normal circumstances there is no 'drive' to the front wheels could well make for quite different handling on-road compared to full-time 4wd 80's.

One good thing with part-time is that the front diff gets nearly zero wear. The rear one is bigger and beefier for a reason. ;)

There is much less to break with part-time 4wd in the factory config. I can't comment on the Marks and similar full-time to part-time conversion kits.

HF1a transfer case has no CDL like on factory full-time 4wd. It also has a lot less parts, is lighter weight, and using real Aisin hubs (not junk AVM ones) makes for a very reliable rugged package.

I do not see how having full-time 4wd makes something 'safer'. The same argument probably gets used to justify having an auto gearbox instead of a manual one... lol
 
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cody c

 
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I have a factory part-time 80. I've never driven a factory full-time 80 to compare against mine.

I do not see how having full-time 4wd makes something 'safer'.
So, I assume your from a warmer climate, maybe Australia, but for colder climates, or specifically winter snowy and icy roads AWD is better than 4WD for highway driving, with the centre diff AWD can be left on and is much nicer here where you are doing tight turns in a dry parking lot and then cruising winding icy backcountry roads not long after.

You can put a vehicle in 4WD for the windy icy roads, but 4WD will break traction easier than AWD and a few club members have mentioned they noticed a significant difference, if your not familiar with the logic, your front axle will travel in a smaller circle than the rear axle, this will cause the rear wheels to drag the slightest bit with the CDL engaged ((4WD) whereas an AWD vehicle has a centre diff to alleviate the difference.

Also, engaging and disengaging 2WD/4WD as you are continually transitioning from dry pavement to snow and ice is not user friendly, and driving a 4WD on pavement is much harder on components than AWD is, as there are more binding forces without a centre diff
 
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80t0ylc

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Question for PT kits....when you put center diff or transfer case lever in neutral, are the drive shafts locked together or are they independant?
 

baldilocks

Battle Ground, WA
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Question for PT kits....when you put center diff or transfer case lever in neutral, are the drive shafts locked together or are they independant?
Will still be independent until low range is selected or the center diff switch is pushed into the “on” detent.
 
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