Np205 in a k5. Thinking about adding a viscous coopler so it can be driven in 4wd on pavement snow and ice. Has anyone done this?
CK5
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thinking about adding a viscous coupler
- Thread starter wazzabie
- Start date
I would be interested to hear if anyone has done it. I remember when they first came out.
I liked the idea, but just could not bring myself to do it. I used to go places I would have problems walking out of, so my equipment was built to work.
My winch could break a 3/8 steel cable with a full spool, manual shifted transfer case with manual hubs.
I did not want any safetys, or any automatic anything that I could not help.
The hub just sounded like something to go wrong at the worst possible time.
Since I don't get much ice and snow in Fl, I did not need it to run on the highway, but I often went from wet, hard packed sand or dry clay, to mud and back again.
Unlike most folks here, who build things so strong that they just run locked on dry pavement and let the tires slip, I always kicked it out of 4WD when the ground dried up.
Figured the clutch would make life easier. But if it broke, I might be a long time getting home, so I never tried one.
I have not seen an ad for one for a while, figured they must not have worked out.
I liked the idea, but just could not bring myself to do it. I used to go places I would have problems walking out of, so my equipment was built to work.
My winch could break a 3/8 steel cable with a full spool, manual shifted transfer case with manual hubs.
I did not want any safetys, or any automatic anything that I could not help.
The hub just sounded like something to go wrong at the worst possible time.
Since I don't get much ice and snow in Fl, I did not need it to run on the highway, but I often went from wet, hard packed sand or dry clay, to mud and back again.
Unlike most folks here, who build things so strong that they just run locked on dry pavement and let the tires slip, I always kicked it out of 4WD when the ground dried up.
Figured the clutch would make life easier. But if it broke, I might be a long time getting home, so I never tried one.
I have not seen an ad for one for a while, figured they must not have worked out.
I think they are in subarus. Could be a possible source.
R
RIPPEDK5
Guest
Check AWD F*rds like Expl*rers, or Expeditions, or Sport-tracs
but why not just keep hubs locked and put it in 2wd?
but why not just keep hubs locked and put it in 2wd?
Not uncommon around here to have them locked in 4wd on the streets in the winter months. On and off of snow pack, ice and dry pavement. Sometimes at low, low highways speeds as well. Helps keep the front end out front.
I just drove in 2wd with hubs locked as said above. My 208 had no problems shifting into 4hi while driving down the road. (dont know if this can be done with a 205). I didnt do it alot because im sure its not the best for them, but a few times it was necessary. 4x4 in the k5 and i felt i could drive on the nastiest of roads wuth ease. I was very impressed with my 27 year old rig 
COCHEV
1/2 ton status
Or just get a np203 and use it how it was designed. My old 78 was great on snowy/icy roads without ever locking it into 4 hi
would it be safe to say, this sort of thing isn't all bad with open diffs?
I don't have snow here unless I hunt for it, still though I'm locked f/r.
I don't have snow here unless I hunt for it, still though I'm locked f/r.
I can get my 205 into 4hi at least to 25MPH, but I've got a clutch. Not sure an automatic in gear will allow that.
Like i said aid no idea on the 205. Never had one. But ive popped tbe 208 in at 45 or so. Freeway was horrid one day and i couldn't stop or barely slow down, just pure ice. Popped it in 4 (glad i had the hubs locked) and damn if she didnt do everything my right foot told her too
In the early 80's there was a syncro'd 205 (identified by an oiling vein on the lower rear cover) that would do what you want but I agree with COCHEV about using a good 203, this is what it was made for. By going to a 203 the parts would be easy to find and probably dirt cheap.
The viscous coupler idea hit the market back in the 90's as a piece to be added between the front shaft and t-case. Lot's of advertisements and a couple of "new parts" spotlights in magazines but it never caught one.
The viscous coupler idea hit the market back in the 90's as a piece to be added between the front shaft and t-case. Lot's of advertisements and a couple of "new parts" spotlights in magazines but it never caught one.
I have had a 203 in the winter that still functioned as full time.
Great case man great case. Worked flawlessly through 2 winters.
I have shifted a 205 in and out of 4 hi at 50 mph, no problems. It was an 86 truck I did it in.
In Horton I have shifted the front axle in and out at probably 30 mph.
So in bad situations you don't really have to stop to shift the 205 into 4wd just your hubs have to be locked
Great case man great case. Worked flawlessly through 2 winters.
I have shifted a 205 in and out of 4 hi at 50 mph, no problems. It was an 86 truck I did it in.
In Horton I have shifted the front axle in and out at probably 30 mph.
So in bad situations you don't really have to stop to shift the 205 into 4wd just your hubs have to be locked
COCHEV
1/2 ton status
I remember the 203 used to get such a bad wrap. The only thing I didn't like about it was taking one out! Not to mention putting one back in. 175lbs I think.
The synchro 205 was created for auto hubs on Dana 60 front axles (a fairly rare option), as you try to shift the 205 into 4WD the synchros speed up the front driveshaft causing the front auto hubs to engage. Once they engage, everything is spinning the same speed and the t-case will shift into 4HI.
NP208's etc have synchros for this same reason.
205's (and really most any part time case) can be shifted from 2HI to 4HI at virtually any speed as long as the front axle is engaged (i.e. hubs locked etc). I wouldn't try it at 80 mph in a corner though
When I had my '77 GMC k2500,I used to keep the hubs locked all winter,and used 2hi most of the time,if the road conditions became snow covered I'd just shift it into 4hi ,it never ground gears or gave any indication it didn't like it...here the roads go from deep snow on side streets to bare tar on the salted to death highways in a matter of a few hundred feet after a storm,and if you dont have the hubs locked and the plow on the truck,good luck getting it to move after stopping on the snowy sections of road!...and if you didn't put it back in 2hi as soon as you hit the bare tar,the truck would bind up and scrub the front tires on turns..........................................................................................................................................................................................................I've seen those viscous couplers used on VW "Syncro" Busses for a few years when they came out with a all wheel drive version..it was a dismal failure,if I remember correctly...not sure if they make a viscous coupling that'll hold up under V8 power when a 3 ton truck is in 4lo and under a decent load,I'd bet they aren't that strong...
Are the syncro np205 desirable? What is the best year for np205s?
The synchro 205's are generally undesirable because you can't upgrade to a 32 spline front output shaft without buying another complete 205 for parts. The shift rails, one of the forks, a couple of the gears, etc. are all unique to the synchro 205.
So just an aside to all this.
To someone who is doubting you can shift a 205 into 4x4 hi while driving with your hubs locked remember your driveshaft is in fact spinning because of your hubs being locked so everything is already spinning. It goes in just fine as in almost all transfer cases with front locking hubs or drive flanges
To someone who is doubting you can shift a 205 into 4x4 hi while driving with your hubs locked remember your driveshaft is in fact spinning because of your hubs being locked so everything is already spinning. It goes in just fine as in almost all transfer cases with front locking hubs or drive flanges
Being one of the few people that have put a 205 through more bullsh!t than it should go through, you can shift a 205 from 2wd high range into 4wd high range without issue provided the hubs are locked. Like said above I wouldn't do it in the middle of a corner at 80 but it will take it.
You can do the same in low range as well.
If your really good you can shift from 2wd high range into 2wd low range while moving at a pretty good clip. I think it might be loud but if you're wearing a helmet you can't hear it
and if you move the lever fast enough it only makes ugly noises for a short period of time.
The 205 is a VERY durable case and you almost can't hurt them in a normal 4wd truck situation.
You can do the same in low range as well.
If your really good you can shift from 2wd high range into 2wd low range while moving at a pretty good clip. I think it might be loud but if you're wearing a helmet you can't hear it
and if you move the lever fast enough it only makes ugly noises for a short period of time.The 205 is a VERY durable case and you almost can't hurt them in a normal 4wd truck situation.
xenomarine
1/2 ton status
I've shifted my 208 on the fly, at speeds up to 45. Also shifted into low range at 20 or so. It doesn't sound nice but I never broke a case doing that
